Moon dust and the age of the solar system

TJ Archive > Volume 7 Issue 1 > Moon dust and the age of the solar system

	First published: TJ 7(1):2–42 April 1993 Browse this issue

by Dr Andrew A. Snelling and David E. Rush

s still not sufficient to bring the curves in Figure 6 together (that is, to overcome this disparity between the two sets of data). Furthermore, with respect to the lunar microcrater data, Hughes pointed out that two other assumptions, namely, the ratio of the diameter of the microcrater to the diameter of the impacting particle being fairly constant at two, and the density of the particle being 3g per cm³, needed to be reconsidered in the light of laboratory experiments which had shown the ratio decreases with particle density and particle density varies with mass. He suggested that both these factors make the interpretation of microcraters more difficult, but that ‘the main problem’ lies in estimating the time the rocks under consideration have remained exposed on the lunar surface. Indeed, he pointed to the assumption that solar activity has remained constant in the past, the key assumption required for calculation of an exposure age, as ‘the real stumbling block’ - the particle flux could have been lower in the past or the solar-flare flux could have been higher. He suggested that because laboratory simulation indicates that solarwind sputter erosion is the dominant factor determining microcrater lifetimes, then knowing this enables the micrometeoroid influx to be derived by only considering rock surfaces with an equilibrium distribution of microcraters. He concluded that this line of research indicated that the micrometeoroid influx had supposedly increased by a factor of four in the last 100,000 years and that this would account for the disparity between the lunar microcrater data and the satellite data as shown by the separation of the two curves in Figure 6. However, this ‘solution’, according to Hughes, ‘creates the question of why this flux has increased’ a problem which appears to remain unsolved.

In a paper reviewing the lunar microcrater data and the lunar micrometeoroid flux estimates, Hörz et al.¹⁰⁷ discuss some key issues that arise from their detailed summary of micrometeoroid fluxes derived by various investigators from lunar sample analyses. First, the directional distribution of micrometeoroids is extremely non-uniform, the meteoroid flux differing by about three orders of magnitude between the direction of the earth’s apex and anti-apex. Since the moon may only collect particles greater than 10¹²g predominantly from only the apex direction, fluxes derived from lunar microcrater statistics, they suggest, may have to be increased by as much as a factor of p for comparison with satellite data that were taken in the apex direction. On the other hand, apex-pointing satellite data generally have been corrected upward because of an assumed isotropic flux, so the actual anisotropy has led to an overestimation of the flux, thus making the satellite results seem to represent an upper limit for the flux. Second, the micrometeoroids coming in at the apex direction appear to have an average impact velocity of only 8km/sec, whereas the fluxes calculated from lunar microcraters assume a standard impact velocity of 20km/sec. If as a result corrections are made, then the projectile mass necessary to produce any given microcrater will increase, and thus the moon-based flux for masses greater than 10^-10g will effectively be enhanced by a factor of approximately 5. Third, particles of mass less than 10^-12g generally appear to have relative velocities of at least 50km/sec, whereas lunar flux curves for these masses are based again on a 20km/sec impact velocity. So again, if appropriate corrections are made the lunar cumulative micrometeoroid flux curve would shift towards smaller masses by a factor of possibly as much as 10. Nevertheless, Hörz et al. conclude that

‘as a consequence the fluxes derived from lunar crater statistics agree within the order of magnitude with direct satellite results if the above uncertainties in velocity and directional distribution are considered.’

Although these comments appeared in a review paper published in 1975, the footnote on the first page signifies that the paper was presented at a scientific meeting in 1973, the same meeting at which three of those investigators also presented another paper in which they made some further pertinent comments. Both there and in a previous paper, Gault, Hörz and Hartung^108,109 had presented what they considered was a ‘best’ estimate of the cumulative meteoritic dust flux based on their own interpretation of the most reliable satellite measurements. This ‘best’ estimate they expressed mathematically in the form

N=l.45m^-0.47                               l0^-13<m<l0^-7,
N=9.l4 x l0^-6m^-l.213                      l0^-7<m<l0³.

Figure 7. The micrometeoroid flux measurements from spacecraft experiments which were selected to define the mass-flux distribution (adapted from Gault et al.¹⁰⁹) Also shown is the incremental mass flux contained within each decade of m, which sum to approximately 10,000 tonnes per year. Their data sources used are listed in their bibliography.

They commented that the use of two such exponential expressions with the resultant discontinuity is an artificial representation for the flux and not intended to represent a real discontinuity, being used for mathematical simplicity and for convenience in computational procedures. They also plotted this cumulative flux presented by these two exponential expressions, together with the incremental mass flux in each decade of particle mass, and that plot is reproduced here as Figure 7. Note that their flux curve is based on what they regard as the most reliable satellite measurements. Note also, as they did, that the fluxes derived from lunar rocks (the microcrater data) ‘are not necessarily directly comparable with the current satellite or photographic meteor data.’ ¹¹⁰ However, using their cumulative flux curve as depicted in Figure 7, and their histogram plot of incremental mass flux, it is possible to estimate (for example, by adding up each incremental mass flux) the cumulative mass flux, which comes to approximately 2 x 10^-9gcm^-2yr^-1 or about 10,000 tons per year. This is the same estimate that they noted in their concluding remarks:-

‘We note that the mass of material contributing to any enhancement, which the earth-moon system is currently sweeping up, is of the order of 10¹⁰g per year.’¹¹¹

Having derived this ‘best’ estimate flux from their mathematical modelling of the ‘most reliable satellite measurements’ their later comments in the same paper seem rather contradictory:-

‘If we follow this line of reasoning, the basic problem then reduces to consideration of the validity of the “best” estimate flux, a question not unfamiliar to the subject of micrometeoroids and a question not with- out considerable historical controversy. We will note here only that whereas it is plausible to believe that a given set of data from a given satellite may be in error for any number of reasons, we find the degree of correlation between the various spacecraft experiments used to define the “best” flux very convincing, especially when consideration is given to the different techniques employed to detect and measure the flux. Moreover, it must be remembered that the abrasion rates, affected primarily by microgram masses, depend almost exclusively on the satellite data while the rupture times, affected only by milligram masses, depend exclusively on the photographic meteor determinations of masses. It is extremely awkward to explain how these fluxes from two totally different and independent techniques could be so similarly in error. But if, in fact, they are in error then they err by being too high, and the fluxes derived from lunar rocks are a more accurate description of the current near- earth micrometeoroid flux.’(emphasis theirs )¹¹²

One is left wondering how they can on the one hand emphasise the lunar microcrater data as being a more accurate description of the current micrometeoroid flux, when they based their ‘best’ estimate of that flux on the ‘most reliable satellite measurements’. However, their concluding remarks are rather telling. The reason, of course, why the lunar microcrater data is given such emphasis is because it is believed to represent a record of the integrated cumulative flux over the moon’s billions-of- years history, which would at face value appear to be a more statistically reliable estimate than brief point-in-space satellite-borne detector measurements. Nevertheless, they are left with this unresolved discrepancy between the microcrater data and the satellite measurements, as has already been noted. So they explain the microcrater data as presenting the ‘prehistoric’ flux, the fluxes derived from the lunar rocks being based on exposure ages derived from solar- flare track density measurements and assumptions regarding solar-flare activity in the past. As for the lunar microcrater data used by Gault et al., they state that the derived fluxes are based on exposure ages in the range 2,500 - 700,000 years, which leaves them with a rather telling enigma. If the current flux as indicated by the satellite measurements is an order of magnitude higher than the microcrater data representing a ‘prehistoric’ flux, then the flux of meteoritic dust has had to have increased or been enhanced in the recent past. But they have to admit that

‘if these ages are accepted at face value, a factor of 10 enhancement integrated into the long term average limits the onset and duration of enhancement to the past few tens of years.’

They note that of course there are uncertainties in both the exposure ages and the magnitude of an enhancement, but the real question is the source of this enhanced flux of particles, a question they leave unanswered and a problem they pose as the subject for future investigation. On the other hand, if the exposure ages were not accepted, being too long, then the microcrater data could easily be reconciled with the ‘more reliable satellite measurements’.

Other Techniques

Only two other micrometeoroid and meteor influx measuring techniques appear to have been tried. One of these was the Apollo 17 Lunar Ejecta and Micrometeorite Experiment, a device deployed by the Apollo 17 crew which was specifically designed to detect micrometeorites.¹¹³ It consisted of a box containing monitoring equipment with its outside cover being sensitive to impacting dust particles. Evidently, it was capable not only of counting dust particles, but also of measuring their masses and velocities, the objective being to establish some firm limits on the numbers of microparticles in a given size range which strike the lunar surface every year. However, the results do not seem to have added to the large database already established by microcrater investigations.

The other direct measurement technique used was the Passive Seismic Experiment in which a seismograph was deployed by the Apollo astronauts and left to register subsequent impact events.¹¹⁴ In this case, however, the particle sizes and masses were in the gram to kilogram range of meteorites that impacted the moon’s surface with sufficient force to cause the vibrations to be recorded by the seismograph. Between 70 and 150 meteorite impacts per year were recorded, with masses in the range 100g to 1,000 kg, implying a flux rate of

log N = -1.62 -1.16 log m,

where N is the number of bodies that impact the lunar surface per square kilometre per year, with masses greater than m grams.¹¹⁵ This flux works out to be about one order of magnitude less than the average integrated flux from microcrater data. However, the data collected by this experiment have been used to cover that particle mass range in the development of cumulative flux curves (for example, see Figure 2 again) and the resultant cumulative mass flux estimates.

Figure 8. Constraints on the flux of micrometeoroids and larger objects according to a variety of independent lunar studies (adapted from Hörz et al.¹⁰⁷)

Conclusion

Hörz et al. summarised some of the basic constraints derived from a variety of independent lunar studies on the lunar flux of micrometeoroids and larger objects.¹¹⁶ They also plotted the broad range of cumulative flux curves that were bounded by these constraints (see Figure 8). Included are the results of the Passive Seismic Experiment and the direct measurements of micrometeoroids encountered by spacecraft windows. They suggested that an upper limit on the flux can be derived from the mare cratering rate and from erosion rates on lunar rocks and other cratering data. Likewise, the negative findings on the Surveyor 3 camera lens and the perfect preservation of the footpad print of the Surveyor 3 1anding gear (both referred to above) also define an upper limit. On the other hand, the lower limit results from the study of solar and galactic radiation tracks in lunar soils, where it is believed the regolith has been reworked only by micrometeoroids, so because of presumed old undisturbed residence times the flux could not have been significantly lower than that indicated. The ‘geochemical’, evidence is also based on studies of the lunar soils where the abundance of trace elements are indicative of the type and amount of meteoritic contamination. Hörz et al. suggest that strictly, only the passive seismometer, the Apollo windows and the mare craters yield a cumulative mass distribution. All other parameters are either a bulk measure of a meteoroid mass or energy, the corresponding ‘flux’ being calculated via the differential mass-distribution obtained from lunar microcrater investigations (‘lunar rocks , on Figure 8). Thus the corresponding arrows on Figure 8 may be shifted anywhere along the lines defining the ‘upper’ and ‘lower’ limits. On the other hand, they point out that the Surveyor 3 camera lens and footpad analyses define points only.

Table 4. Summary of the lunar meteoritic dust influx estimates.

Table 4 summarises the different lunar meteoritic dust estimates. It is difficult to estimate a cumulative mass flux from Hörz et al.’s diagram showing the basic constraints for the flux of micrometeoroids and larger objects derived from independent lunar studies (see Figure 8), because the units on the cumulative flux axis are markedly different to the units on the same axis of the cumulative flux and cumulative mass diagram of Gault et al. from which they estimated a lunar meteoritic dust influx of about 10,000 tons per year. The Hörz et al. basic constraints diagram seems to have been partly constructed from the previous figure in their paper, which however includes some of the microcrater data used by Gault et al. in their diagram (Figure 7 here) and from which the cumulative mass flux calculation gave a flux estimate of 10,000 tons per year. Assuming then that the basic differences in the units used on the two cumulative flux diagrams (Figures 7 and 8 here) are merely a matter of the relative numbers in the two log scales, then the Gault et al. cumulative flux curve should fall within a band between the upper and lower limits, that is, within the basic constraints, of Hörz et al.’s lunar cumulative flux summary plot (Figure 8 here). Thus a flux estimate from Hörz et al.’s broad lunar cumulative flux curve would still probably centre around the 10,000 tons per year estimate of Gault et al.

In conclusion, therefore, on balance the evidence points to a lunar meteoritic dust influx figure of around 10,000 tons per year. This seems to be a reasonable, approximate estimate that can be derived from the work of Hörz et al., who place constraints on the lunar cumulative flux by carefully drawing on a wide range of data from various techniques. Even so, as we have seen, Gault et al. question some of the underlying assumptions of the major measurement techniques from which they drew their data - in particular, the lunar microcrater data and the satellite measurement data. Like the ‘geochemical’ estimates, the microcrater data depends on uniformitarian age assumptions, including the solar-flare rate, and in common with the satellite data, uniformitarian assumptions regarding the continuing level of dust in interplanetary space and as influx to the moon. Claims are made about variations in the cumulative dust influx in the past, but these also depend upon uniformitarian age assumptions and thus the argument could be deemed circular. Nevertheless, questions of sampling statistics and representativeness aside, the figure of approximately 10,000 tons per year has been stoutly defended in the literature based primarily on present-day satellite-borne detector measurements.

Finally, one is left rather perplexed by the estimate of the moon’s accumulation rate of about 500 tons per year made by Van Till et al.¹¹⁷ In their treatment of the ‘moon dust controversy’, they are rather scathing in their comments about creationists and their handling of the available data in the literature. For example, they state:

‘The failure to take into account the published data pertinent to the topic being discussed is a clear failure to live up to the codes of thoroughness and integrity that ought to characterize professional science.’¹¹⁸

And again:

‘The continuing publication of those claims by young- earth advocates constitutes an intolerable violation of the standards of professional integrity that should characterize the work of natural scientists.’¹¹⁹

Having been prepared to make such scathing comments, one would have expected that Van Till and his colleagues would have been more careful with their own handling of the scientific literature that they purport to have carefully scanned. Not so, because they failed to check their own calculation of 500 tons per year for lunar dust influx with those estimates that we have seen in the same literature which were based on some of the same satellite measurements that Van Till et al. did consult, plus the microcrater data which they didn’t. But that is not all - they failed to check the factors they used for calculating their lunar accumulation rate from the terrestrial figure they had established from the literature. If they had consulted, for example, Dohnanyi, as we have already seen, they would have realised that they only needed to use a focusing factor of two, the moon’s smaller surface area apparently being largely irrelevant. So much for lack of thoroughness! Had they surveyed the literature thoroughly, then they would have to agree with the conclusion here that the dust influx to the moon is approximately 10,000 tons per year.

Pre-Apollo Lunar Dust Thickness Estimates

The second major question to be addressed is whether NASA really expected to find a thick dust layer on the moon when their astronauts landed on July 20, 1969. Many have asserted that because of meteoritic dust influx estimates made by Pettersson and others prior to the Apollo moon landings, that NASA was cautious in case there really was a thick dust layer into which their lunar lander and astronauts might sink.

Early Speculations

Asimov is certainly one authority at the time who is often quoted. Using the 14,300,000 tons of dust per year estimate of Pettersson, Asimov made his own dust on the moon calculation and commented:

‘But what about the moon? It travels through spacewith us and although it is smaller and has a weaker gravity, it, too, should sweep up a respectable quan tity of micrometeors.
To be sure, the moon has no atmosphere to friction the micrometeors to dust, but the act of striking the moon’s surface should develop a large enough amount of heat to do the job.
Now it is already known, from a variety of evidence, that the moon (or at least the level lowlands) is covered with a layer of dust. N o one, however, knows for sure how thick this dust may be.
It strikes me that if this dust is the dust of falling micrometeors, the thickness may be great. On the moon there are no oceans to swallow the dust, or winds to disturb it, or life forms to mess it up generally one way or another. The dust that forms must just lie there, and if the moon gets anything like the earth’s supply, it could be dozens of feet thick.
In fact, the dust that strikes craters quite probably rolls down hill and collects at the bottom, forming “drifts” that could be fifty feet deep, or more. Why not?
I get a picture, therefore, of the first spaceship, picking out a nice level place for landing purposes coming slowly downward tail-first … and sinking majestically out of sight.’¹²⁰

Asimov certainly wasn’t the first to speculate about the thickness of dust on the moon. As early as 1897 Peal¹²¹ was speculating on how thick the dust might be on the moon given that ‘it is well known that on our earth there is a considerable fall of meteoric dust.’ Nevertheless, he clearly expected only ‘an exceedingly thin coating’ of dust. Several estimates of the rate at which meteorites fall to earth were published between 1930 and 1950, all based on visual observations of meteors and meteorite falls. Those estimates ranged from 26 metric tons per year to 45,000 tons per year.¹²² In 1956 Öpik¹²³ estimated 25,000 tons per year of dust falling to the earth, the same year Watson¹²⁴ estimated a total accumulation rate of between 300,000 and 3 million tons per year, and in 1959 Whipple¹²⁵ estimated 700,000 tons per year.

However, it wasn’t just the matter of meteoritic dust falling to the lunar surface that concerned astronomers in their efforts to estimate the thickness of dust on the lunar surface, since the second source of pulverised material on the moon is the erosion of exposed rocks by various processes. The lunar craters are of course one of the most striking features of the moon and initially astronomers thought that volcanic activity was responsible for them, but by about 1950 most investigators were convinced that meteorite impact was the major mechanism involved.¹²⁶ Such impacts pulverise large amounts of rock and scatter fragments over the lunar surface. Astronomers in the 1950s agreed that the moon’s surface was probably covered with a layer of pulverised material via this process, because radar studies were consistent with the conclusion that the lunar surface was made of fine particles, but there were no good ways to estimate its actual thickness.

Yet another contributing source to the dust layer on the moon was suggested by Lyttleton in 1956,¹²⁷ He suggested that since there is no atmosphere on the moon, the moon‘s surface is exposed to direct radiation, so that ultraviolet light and x-rays from the sun could slowly erode the surface of exposed lunar rocks and reduce them to dust, Once formed, he envisaged that the dust particles might be kept in motion and so slowly ‘flow’ to lower elevations on the lunar surface where they would accumulate to form a layer of dust which he suggested might be ‘several miles deep’. Lyttleton wasn’t alone, since the main proponent of the thick dust view in British scientific circles was Royal Greenwich astronomer Thomas Gold, who also suggested that this loose dust covering the lunar surface could present a serious hazard to any spacecraft landing on the moon.¹²⁸ Whipple, on the other hand, argued that the dust layer would be firm and compact so that humans and vehicles would have no trouble landing on and moving across the moon’s surface.129 Another British astronomer, Moore, took note of Gold’s theory that the lunar seas ‘were covered with layers of dust many kilometres deep’ but flatly rejected this. He commented:

‘The disagreements are certainly very marked. At one end of the scale we have Gold and his supporters, who believe in a dusty Moon covered in places to a great depth; at the other, people such as myself, who incline to the view that the dust can be no more than a few centimetres deep at most. The only way to clear the matter up once and for all is to send a rocket to find out.’¹⁵⁰

So it is true that some astronomers expected to find a thick dust layer, but this was no means universally supported in the astronomical community. The Russians too were naturally interested in this question at this time because of their involvement in the ‘space race’, but they also had not reached a consensus on this question of the lunar dust. Sharonov,¹³¹ for example, discussed Gold’s theory and arguments for and against a thick dust layer, admitting that ‘this theory has become the object of animated discussion.’ Nevertheless, he noted that the ‘majority of selenologists’ favoured the plains of the lunar ‘seas’ (mares ) being layers of solidified lavas with minimal dust cover.

Research in the Early 1960s

The lunar dust question was also on the agenda of the December 1960 Symposium number 14ofthe International Astronomical Union held at the Puikovo Observatory near Leningrad. Green summed up the arguments as follows:

‘Polarization studies by Wright verified that the surface of the lunar maria is covered with dust. However, various estimates of the depth of this dust layer have been proposed. In a model based on the radioastronomy techniques of Dicke and Beringer and others, a thin dust layer is assumed, Whipple assumes the covering to be less than a few meters’ thick.
On the other hand, Gold, Gilvarry, and Wesselink favor a very thick dust layer. … Because no polar homogenization of lunar surface details can be demonstrated, however, the concept of a thin dust layer appears more reasonable. … Thin dust layers, thickening in topographic basins near post-mare craters, are predicted for mare areas.’¹³²

In a 1961 monograph on the lunar surface, Fielder discussed the dust question in some detail, citing many of those who had been involved in the controversy. Having discussed the lunar mountains where he said ‘there may be frequent pockets of dust trapped in declivities’ he concluded that the mean dust cover over the mountains would only be a millimetre or so.¹³³ But then he went on to say,

‘No measurements made so far refer purely to marebase materials. Thus, no estimates of the composition of maria have direct experimental backing. This is unfortunate, because the interesting question “How deep is the dust in the lunar seas?” remains unanswered.’

In 1964 a collection of research papers were published in a monograph entitled The Lunar Surface Layer, and the consensus therein amongst the contributing authors was that there was not a thick dust layer on the moon’s surface. For example, in the introduction, Kopal stated that

‘this layer of loose dust must extend down to a depth of at least several centimeters, and probably a foot or so; but how much deeper it may be in certain places remains largely conjectural.’¹³⁴

In a paper on ‘Dust Bombardment on the Lunar Surface’, McCracken and Dubin undertook a comprehensive review of the subject, including the work of Öpik and Whipple, plus many others who had since been investigating the meteoritic dust influx to the earth and moon, but concluded that

‘The available data on the fluxes of interplanetary dust particles with masses less than 10⁴gm show that the material accreted by the moon during the past 4.5 billion years amounts to approximately 1 gm/cm2 if the flux has remained fairly constant.’¹³⁵

(Note that this statement is based on the uniformitarian age constraints for the moon.) Thus they went on to say that

‘The lunar surface layer thus formed would, therefore, consist of a mixture of lunar material and interplanetary material (primarily of cometary origin) from 10cm to 1m thick. The low value for the accretion rate for the small particles is not adequate to produce large-scale dust erosion or to form deep layers of dust on the moon. …’.¹³⁶

In another paper, Salisbury and Smalley state in their abstract:

‘It is concluded that the lunar surface is covered with a layer of rubble of highly variable thickness and block size. The rubble in turn is mantled with a layer of highly porous dust which is thin over topographic highs, but thick in depressions. The dust has a complex surface and significant, but not strong, coherence.’¹³⁷

In their conclusions they made a number of predictions.

‘Thus, the relief of the coarse rubble layer expected in the highlands should be largely obliterated by a mantle of fine dust, no more than a few centimeters thick over near-level areas, but meters thick in steep- walled depressions. …The lunar dust layer should provide no significant difficulty for the design of vehicles and space suits. …’¹³⁸

Expressing the opposing view was Hapke, who stated that

‘recent analyses of the thermal component of the lunar radiation indicate that large areas of the moon may be covered to depths of many meters by a substance which is ten times less dense than rock. …Such deep layers of dust would be in accord with the suggestion of Gold.’¹³⁹

He went on:

‘Thus, if the radio-thermal analyses are correct, the possibility of large areas of the lunar surface being covered with thick deposits of dust must be given serious consideration.’¹⁴⁰

However, the following year Hapke reported on research that had been sponsored by NASA, at a symposium on the nature of the lunar surface, and appeared to be more cautious on the dust question. In the proceedings he wrote:

‘I believe that the optical evidence gives very strong indications that the lunar surface is covered with a layer of fine dust of unknown thicknes.’¹⁴¹

There is no question that NASA was concerned about the presence of dust on the moon’s surface and its thickness. That is why they sponsored intensive research efforts in the 1960s on the questions of the lunar surface and the rate of meteoritic dust influx to the earth and the moon. In order to answer the latter question, NASA had begun sending up rockets and satellites to collect dust particles and to measure their flux in near-earth space. Results were reported at symposia, such as that which was held in August 1965 at Cambridge, Massachusetts, jointly sponsored by NASA and the Smithsonian Institution, the proceedings of which were published in 1967.¹⁴²

A number of creationist authors have referred to this proceedings volume in support of the standard creationist argument that NASA scientists had found a lot of dust in space which confirmed the earlier suggestions of a high dust influx rate to the moon and thus a thick lunar surface layer of dust that would be a danger to any landing spacecraft. Slusher, for example, reported that he had been involved in an intensive review of NASA data on the matter and found

‘that radar, rocket, and satellite data published in 1976 by NASA and the Smithsonian Institution show that a tremendous amount of cosmic dust is present in the space around the earth and moon.’¹⁴³

(Note that the date of publication was incorrectly reported as 1976, when it in fact is the 1967 volume just referred to above.) Similarly, Calais references this same 1967 proceedings volume and says of it,

‘NASA has published data collected by orbiting satellites which confirm a vast amount of cosmic dust reaching the vicinity of the earth-moon system.’^144,145

Both these assertions, however, are far from correct, since the reports published in that proceedings volume contain results of measurements taken by detectors on board spacecraft such as Explorer XVI, Explorer XXIII, Pegasus I and Pegasus II, as well as references to the work on radio meteors by Elford and cumulative flux curves incorporating the work of people like Hawkins, Upton and Elsässer. These same satellite results and same investigators’ contributions to cumulative flux curves appear in the 1970s papers of investigators whose cumulative flux curves have been reproduced here as Figures 3, 5 and 7, all of which support the 10,000 - 20,000 tons per year and approximately 10,000 tons per year estimates for the meteoritic dust influx to the earth and moon respectively - not the ‘tremendous’ and ‘vast’ amounts of dust incorrectly inferred from this proceedings volume by Slusher and Calais.

Pre-Apollo Moon Landings

The next stage in the NASA effort was to begin to directly investigate the lunar surface as a prelude to an actual manned landing. So seven Ranger spacecraft were sent up to transmit television pictures back to earth as they plummeted toward crash landings on selected flat regions near the lunar equator.¹⁴⁶ The last three succeeded spectacularly, in 1964 and 1965, sending back thousands of detailed lunar scenes, thus increasing a thousand-fold our ability to see detail. After the first high-resolution pictures of the lunar surface were transmitted by television from the Ranger VII spacecraft in 1964, Shoemaker¹⁴⁷ concluded that the entire lunar surface was blanketed by a layer of pulverised ejecta caused by repeated impacts and that this ejecta would range from boulder-sized rocks to finely-ground dust. After the remaining Ranger crash-landings, the Ranger investigators were agreed that a debris layer existed, although interpretations varied from virtually bare rock with only a few centimetres of debris (Kuiper, Strom and Le Poole) through to estimates of a layer from a few to tens of metres deep (Shoemaker).¹⁴⁸ However, it can’t be implied as some have done¹⁴⁹ that Shoemaker was referring to a dust layer that thick that was unstable enough to swallow up a landing spacecraft. After all, the consolidation of dust and boulders sufficient to support a load has nothing to do with a layer’s thickness. In any case, Shoemaker was describing a surface layer composed of debris from meteorite impacts, the dust produced being from lunar rocks and not from falling meteoritic dust.

But still the NASA planners wanted to dispel any lingering doubts before committing astronauts to a manned spacecraft landing on the lunar surface, so the soft-landing Surveyor series of spacecraft were designed and built However, the Russians just beat the Americans when they achieved the first lunar soft-landing with their Luna 9 spacecraft. Nevertheless, the first American Surveyor spacecraft successfully achieved a soft-landing in mid- 1966 and returned over 11,000 splendid photographs, which showed the moon’s surface in much greater detail than ever before.¹⁵⁰ Between then and January 1968 four other Surveyor spacecraft were successfully landed on the lunar surface and the pictures obtained were quite remarkable in their detail and high resolution, the last in the series (Surveyor 7) returning 21,000 photographs as well as a vast amount of scientific data. But more importantly,

‘as each spindly, spraddle-legged craft dropped gingerly to the surface, its speed largely negated by retrorockets, its three footpads sank no more than an inch or two into the soft lunar soil. The bearing strength of the surface measured as much as five to ten pounds per square inch, ample for either astronaut or landing spacecraft.’¹⁵¹

Two of the Surveyors carried a soil mechanics surface sampler which was used to test the soil and any rock fragments within reach. All these tests and observations gave a consistent picture of the lunar soil. As Pasachoff noted:

‘It was only the soft landing of the Soviet Luna and American Surveyor spacecraft on the lunar surface in 1966 and the photographs they sent back that settled the argument over the strength of the lunar surface; the Surveyor perched on the surface without sinking in more than a few centimeters.’¹⁵²152

Moore concurred, with the statement that

‘up to 1966 the theory of deep dust-drifts was still taken seriously in the United States and there was considerable relief when the soft-Ianding of Luna 9 showed it to be wrong.’¹⁵³

Referring to Gold’s deep-dust theory of 1955, Moore went on to say that although this theory had gained a considerable degree of respectability, with the successful soft-landing of Luna 9 in 1966 ‘it was finally discarded.’¹⁵⁴ So it was in May 1966 when Surveyor I landed on the moon three years before Apollo 11 that the long debate over the lunar surface dust layer was finally settled, and NASA officials then knew exactly how much dust there was on the surface and that it was capable of supporting spacecraft and men.

Since this is the case, creationists cannot say or imply, as some have,^155-160 that most astronomers and scientists expected a deep dust layer. Some of course did, but it is unfair if creationists only selectively refer to those few scientists who predicted a deep dust layer and ignore the majority of scientists who on equally scientific grounds had predicted only a thin dust layer. The fact that astronomy textbooks and monographs acknowledge that there was a theory about deep dust on the moon,^161,162 as they should if they intend to reflect the history of the development of thought in lunar science, cannot be used to bolster a lop-sided presentation of the debate amongst scientists at the time over the dust question, particularly as these same textbooks and monographs also indicate, as has already been quoted, that the dust question was settled by the Luna and Surveyor soft-landings in 1966. Nor should creationists refer to papers like that ofWhipple,¹⁶³ who wrote of a ‘dust cloud’ around the earth, as if that were representative of the views at the time of all astronomers. Whipple’s views were easily dismissed by his colleagues because of subsequent evidence. Indeed, Whipple did not continue promoting his claim in subsequent papers, a clear indication that he had either withdrawn it or been silenced by the overwhelming response of the scientific community with evidence against it, or both.

The Apollo Lunar Landing

Two further matters need to be also dealt with. First, there is the assertion that NASA built the Apollo lunar lander with large footpads because they were unsure about the dust and the safety of their spacecraft. Such a claim is, inappropriate given the success of the Surveyor soft-landings, the Apollo lunar lander having footpads which were proportionally similar to the relative sizes of the respective spacecraft. After all, it stands to reason that since the design of Surveyor spacecraft worked so well and survived landing on the lunar surface that the same basic design should be followed in the Apollo lunar lander.

As for what Armstrong and Aldrin found on the lunar surface, all are agreed that they found a thin dust layer .The transcript of Armstrong’s words as he stepped onto the moon are instructive:

‘I am at the foot of the ladder. The LM [lunar module ] footpads are only depressed in the surface about one or two inches, although the surface appears. to be very, very fine grained, as. you get close to it. It is almost like a powder. Now and then it is very fine. I am going to step off the LM now. That is one small step for man, one giant leap for mankind.’¹⁶⁴164

Moments later while taking his first steps on the lunar surface, he noted:

‘The surface is fine and powdery. I can - I can pick it up loosely with my toe. It does adhere in fine layers like powdered charcoal to the sole and sides. of my boots. I only go in a small fraction of an inch, maybe an eighth of an inch, but I can see the footprints. of my boots and the treads in the fine sandy particles.‘

And a little later, while picking up samples of rocks and fine material, he said:

‘This is very interesting. It is a very soft surface, but here and there where I plug with the contingency sample collector, I run into a very hard surface, but it appears to be very cohesive material of the same sort. I will try to get a rock in here. Here’s a couple.’¹⁶⁵

So firm was the ground, that Armstrong and Aldrin had great difficulty planting the American flag into the rocky and virtually dust-free lunar surface.

The fact that no further comments were made about the lunar dust by NASA or other scientists has been taken by some^166-168 to represent some conspiracy of silence, hoping that some supposed unexplained problem will go away. There is a perfectly good reason why there was silence - three years earlier the dust issue had been settled and Armstrong and Aldrin only confirmed what scientists already knew about the thin dust layer on the moon. So because it wasn’t a problem just before the Apollo 11 landing, there was no need for any talk about it to continue after the successful exploration of the lunar surface. Armstrong himself may have been a little concerned about the constituency and strength of the lunar surface as he was about to step onto it, as he appears to have admitted in subsequent interviews,¹⁶⁹ but then he was the one on the spot and about to do it, so why wouldn’t he be concerned about the dust, along with lots of other related issues.

Overn’s Testimony

Finally, there is the testimony of Dr William Overn.^170,171 Because he was working at the time for the Univac Division of Sperry Rand on the television sub-system for the Mariner IV spacecraft he sometimes had exchanges with the men at the Jet Propulsion Laboratory (JPL) who were working on the Apollo program. Evidently those he spoke to were assigned to the Ranger spacecraft missions which, as we have seen, were designed to find out what the lunar surface really was like; in other words, to investigate among other things whether there was a thin or thick dust layer on the lunar surface. In Bill’s own words:

‘I simply told them that they should expect to find less than 10,000 years’ worth of dust when they got there. This was based on my creationist belief that the moon is young. The situation got so tense it was suggested I bet them a large amount of money about the dust. … However, when the Surveyor spacecraft later landed on the moon and discovered there was virtually no dust, that wasn’t good enough for these people to pay off their bet. They said the first landing might have been a fluke in a low dust area! So we waited until ,.,. astronauts actually landed on the moon. …’¹⁷²

Neither the validity of this story nor Overn’s integrity is in question. However, it should be noted that the bet Overn made with the JPL scientists was entered into at a time when there was still much speculation about the lunar surface, the Ranger spacecraft just having been crash-landed on the moon and the Surveyor soft-landings yet to settle the dust issue. Furthermore, since these scientists involved with Overn were still apparently hesitant after the Surveyor missions, it suggests that they may not have been well acquainted with NASA’s other efforts, particularly via satellite measurements, to resolve the dust question, and that they were not ‘rubbing shoulders with’ those scientists who were at the forefront of these investigations which culminated in the Surveyor soft-landings settling the speculations over the dust. Had they been more informed, they would not have entered into the wager with Overn, nor for that matter would they have seemingly felt embarrassed by the small amount of dust found by Armstrong and Aldrin, and thus conceded defeat in the wager. The fact remains that the perceived problem of what astronauts might face on the lunar surface was settled by NASA in 1966 by the Surveyor soft-landings.

Moon Dust and the Moon’s Age

The final question to be resolved is, now that we know how much meteoritic dust falls to the moon’s surface each year, then what does our current knowledge of the lunar surface layer tell us about the moon’s age? For example, what period of time is represented by the actual layer of dust found on the moon? On the one hand creationists have been using the earlier large dust influx figures to support a young age of the moon, and on the other hand evolutionists are satisfied that the small amount of dust on the moon supports their billions-of-years moon age.

The Lunar Regolith

To begin with, what makes up the lunar surface and how thick is it? The surface layer of pulverised material on the moon is now, after on-site investigations by the Apollo astronauts, not called moon dust, but lunar regolith, and the fine materials in it are sometimes referred to as the lunar soil. The regolith is usually several metres thick and extends as a continuous layer of debris draped over the entire lunar bedrock surface. The average thickness of the regolith on the maria is 4-5m, while the highlands regolith is about twice as thick, averaging about 10m.¹⁷³ The seismic properties of the regolith appear to be uniform on the highlands and maria alike, but the seismic signals indicate that the regolith consists of discrete layers, rather than being simply ‘compacted dust’. The top surface is very loose due to stirring by micrometeorites, but the lower depths below about 20cm are strongly compacted, probably due to shaking during impacts.

The complex layered nature of the regolith has been studied in drill-core samples brought back by the Apollo missions. These have clearly revealed that the regolith is not a homogeneous pile of rubble. Rather, it is a layered succession of ejecta blankets.¹⁷⁴ An apparent paradox is that the regolith is both well mixed on a small scale and also displays a layered structure. The Apollo 15 deep core tube, for example, was 2.42 metres long, but contained 42 major textural units from a few millimetres to 13cm in thickness. It has been found that there is usually no correlation between layers in adjacent core tubes, but the individual layers are well mixed. This paradox has been resolved by recognising that the regolith is continuously ‘gardened’ by large and small meteorites and micrometeorites. Each impact inverts much of the microstratigraphy and produces layers of ejecta, some new and some remnants of older layers. -The new surface layers are stirred by micrometeorites, but deeper stirring is rarer. The result is that a complex layered regolith is built up, but is in a continual state of flux, particles now at the surface potentially being buried deeply by future impacts. In this way, the regolith is turned over, like a heavily bombarded battlefield. However, it appears to only be the upper 0.5 - l mm of the lunar surface that is subjected to intense churning and mixing by the meteoritic influx at the present time. Nevertheless, as a whole, the regolith is a primary mixing layer of lunar materials from all points on the moon with the incoming meteoritic influx, both meteorites proper and dust.

Figure 9. Processes of erosion on the lunar surface today appear to be extremely slow compared with the processes on the earth. Bombardment by micrometeorites is believed to be the main cause. A large meteorite strikes the surface very rarely, excavating bedrock and ejecting it over thousands of square kilometres, sometimes as long rays of material radiating from the resulting crater. Much of the meteorite itself is vaporized on impact, and larger fragments of the debris produce secondary craters. Such an event at a mare site pulverizes and churns the rubble and dust that form the regolith. Accompanying base surges of hot clouds of dust. gas and shock waves might compact the dust into breccias. Cosmic rays continually bombard the surface. During the lunar day ions from the solar wind and unshielded solar radiation impinge on the surface. (Adapted from Eglinton et al.¹⁷⁶)

Lunar Surface Processes

So apart from the influx of the meteoritic dust, what other processes are active on the moon’s surface, particularly as there is no atmosphere or water on the moon to weather and erode rocks in the same way as they do on earth? According to Ashworth and McDonnell,

‘Three major processes continuously affecting the surface of the moon are meteor impact, solar wind sputtering, and thermal erosion.’¹⁷⁵

The relative contributions of these processes towards the erosion of the lunar surface depend upon various factors, such as the dimensions and composition of impacting bodies and the rate of meteoritic impacts and dust influx, These processes of erosion on the lunar surface are of course extremely slow compared with erosion processes on the earth, Figure 9, after Eglinton et al.,¹⁷⁶ attempts to illustrate these lunar surface erosion processes.

Of these erosion processes the most important is obviously impact erosion, Since there is no atmosphere on the moon, the incoming meteoritic dust does not just gently drift down to the lunar surface, but instead strikes at an average velocity that has been estimated to be between 13 and 18 km/sec,¹⁷⁷ or more recently as 20 km/sec,¹⁷⁸ with a maximum reported velocity of 100 km/sec.¹⁷⁹ Depending not ,ony on the velocity but on the mass of the impacting dust particles, more dust is produced as debris.

A number of attempts have been made to quantify the amount of dust-caused erosion of bare lunar rock on the lunar surface. Hörz et al.¹⁸⁰ suggested a rate of 0.2-0.4mm/10⁶ year (or 20-40 x 10^-9cm/yr) after examination of micrometeorite craters on the surfaces of lunar rock samples brought back by the Apollo astronauts. McDonnell and Ashworth¹⁸¹ discussed the range of erosion rates over the range of particle diameters and the surface area exposed. They thus suggested that a rate of 1-3 x 10^-7cm/yr (or 100-300 x 10^-9cm/yr), basing this estimate on Apollo moon rocks also, plus studies of the Surveyor 3 camera. They later revised this estimate, concluding that on the scale of tens of metres impact erosion accounts for the removal of some 10^-7cm/yr (or 100x 10^-9cm/yr) of lunar material.¹⁸² However, in another paper, Gault et al.¹⁸³ tabulated calculated abrasion rates for rocks exposed on the lunar surface compared with observed erosion rates as determined from solar-flare particle tracks. Discounting the early satellite data and just averaging the values calculated from the best, more recent satellite data and from lunar rocks, gave an erosion rate esti mate of 0.28cm/10⁶yr (or 280 x 10^-9cm/yr), while the average of the observed erosion rates they found from the literature was 0.03cm/10⁶yr (or 30 x 10^-9cm/yr). However, they naturally favoured their own ‘best’ estimate from the satellite data of both the flux and the consequent abrasion rate, the latter being 0.1 cm/10⁶yr (or 100 x 10^-9cm/ yr), a figure identical with that ofMcDonnell and Ashworth. Gault et al. noted that this was higher, by a factor approaching an order of magnitude, than the ‘consensus’ of the observed values, a discrepancy which mirrors the difference between the meteoritic dust influx estimates derived from the lunar rocks compared with the satellite data.

These estimates obviously vary from one to another, but 30-100 x 10^-9cm/yr would seem to represent a ‘middle of the range’ figure. However, this impact erosion rate only applies to bare, exposed rock. As McCracken and Dubin have stated, once a surface dust layer is built up initially from the dust influx and impact erosion, this initial surface dust layer would protect the underlying bedrock surface against continued erosion by dust particle bombardment.¹⁸⁴ If continued impact erosion is going to add to the dust and rock fragments in the surface layer and regolith, then what is needed is some mechanism to continually transport dust away from the rock surfaces as it is produced, so as to keep exposing bare rock again for continued impact erosion. Without some active transporting process, exposed rock surfaces on peaks and ridges would be worn away to give a somewhat rounded moonscape (which is what the Apollo astronauts found), and the dust would thus collect in thicker accumulations at the bottoms of slopes. This is illustrated in Figure 9.

So bombardment of the lunar surface by micrometeorites is believed to be the main cause of surface erosion. At the Current rate of removal, however, it would take a million years to remove an approximately 1mm thick skin of rock from the whole lunar surface and convert it to dust. Occasionally a large meteorite strikes the surface (see Figure 9 again), excavating through the dust down into the bedrock and ejecting debris over thousands of square kilometres sometimes as long rays of material radiating from the resulting crater. Much of the meteorite itself is vaporised on impact, and larger fragments of the debris create secondary craters. Such an event at a mare site pulverises and churns the rubble and dust that forms the regolith.

The solar wind is the next major contributor to lunar surface erosion. The solar wind consists primarily of protons, electrons, and some alpha particles, that are continuously being ejected by the sun. Once again, since the moon has virtually no atmosphere or magnetic field, these particles of the solar wind strike the lunar surface unimpeded at velocities averaging 600 km/sec, knocking individual atoms from rock and dust mineral lattices. Since the major components of the solar wind are H⁺ (hydrogen) ions, and some He (helium) and other elements, the damage upon impact to the crystalline structure of the rock silicates creates defects and voids that accommodate the gases and other elements which are simultaneously implanted in the rock surface. But individual atoms are also knocked out of the rock surface, and this is called sputtering or sputter erosion. Since the particles in the solar wind strike the lunar surface with such high velocities,

‘one can safely conclude that most of the sputtered atoms have ejection velocities higher than the escape velocity of the moon.’¹⁸⁵

There would thus appear to be a net erosional mass loss from the moon to space via this sputter erosion.

As for the rate of this erosional loss, Wehner¹⁸⁶ suggested a value for the sputter rate of the order of 0.4 angstrom (Å)/yr. However, with the actual measurement of the density of the solar wind particles on the surface of the moon, and lunar rock samples available for analysis, the intensity of the solar wind used in sputter rate calculations was downgraded, and consequently the estimates of the sputter rate itself (by an order of magnitude lower). McDonnell and Ashworth¹⁸⁷ estimated an average sputter rate of lunar rocks of about 0.02Å/yr, which they later revised to 0.02-0.04Å/yr.¹⁸⁸ Further experimental work refined their estimate to 0.043Å/yr,¹⁸⁹ which was reported in Nature by Hughes.¹⁹⁰ This figure of 0.043 Å/yr continued to be used and confirmed in subsequent experimental work,¹⁹¹ although Zook¹⁹² suggested that the rate may be higher, even as high as 0.08Å/yr.¹⁹³ Even so, if this sputter erosion rate continued at this pace in the past then it equates to less than one centimetre of lunar surface lowering in one billion years. This not only applies to solid rock, but to the dust layer itself, which would in fact decrease in thickness in that time, in opposition to the increase in thickness caused by meteoritic dust influx. Thus sputter erosion doesn’t help by adding dust to the lunar surface, and in any case it is such a slow process that the overall effect is minimal. Yet another potential form of erosion process on the lunar surface is thermal erosion, that is, the breakdown of the lunar surface around impact/crater areas due to the marked temperature changes that result from the lunar diurnal cycle. Ashworth and McDonnell¹⁹⁴ carried out tests on lunar rocks, submitting them to cycles of changing temperature, but found it ‘impossible to detect any surface changes’. They therefore suggested that thermal erosion is probably ‘not a major force.’ Similarly, McDonnell and Flavill¹⁹⁵ conducted further experiments and found that their samples showed no sign of ‘degradation or enhancement’ due to the temperature cycle that they had been subjected to. They reported that

‘the conditions were thermally equivalent to the lunar day-night cycle and we must conclude that on this scale thermal cycling is a very weak erosion mechanism.‘

The only other possible erosion process that has ever been mentioned in the literature was that proposed by Lyttleton¹⁹⁶ and Gold.¹⁹⁷ They suggested that high-energy ultraviolet and x-rays from the sun would slowly pulverize lunar rock to dust, and over millions of years this would create an enormous thickness of dust on the lunar surface. This was proposed in the 1950s and debated at the time, but since the direct investigations of the moon from the mid- 1960s onwards, no further mention of this potential process has appeared in the technical literature, either for the idea or against it. One can only assume that either the idea has been ignored or forgotten, or is simply ineffective in producing any significant erosion, contrary to the suggestions of the original proposers. The latter is probably true, since just as with impact erosion the effect of this radiation erosion would be subject to the critical necessity of a mechanism to clean rock surfaces of the dust produced by the radiation erosion. In any case, even a thin dust layer will more than likely simply absorb the incoming rays, while the fact that there are still exposed rock surfaces on the moon clearly suggests that Lyttleton and Gold’s radiation erosion process has not been effective over the presumed millions of years, else all rock surfaces should long since have been pulverized to dust. Alternately, of course, the fact that there are still exposed rock surfaces on the moon could instead mean that if this radiation erosion process does occur then the moon is quite young.

‘Age’ Considerations

So how much dust is there on the lunar surface? Because of their apparent negligible or non-existent contribution, it may be safe to ignore thermal, sputter and radiation erosion. This leaves the meteoritic dust influx itself and the dust it generates when it hits bare rock on the lunar surface (impact erosion). However, our primary objective is to determine whether the amount of meteoritic dust in the lunar regolith and surface dust layer, when compared to the current meteoritic dust influx rate, is an accurate indication of the age of the moon itself, and by implication the earth and the solar system also.

Now we concluded earlier that the consensus from all the available evidence, and estimate techniques employed by different scientists, is that the meteoritic dust influx to the lunar surface is about 10,000 tons per year or 2x10^-9g cm^-2yr^-1. Estimates of the density of micrometeorites vary widely, but an average value of 19/cm³ is commonly used. Thus at this apparent rate of dust influx it would take about a billion years for a dust layer a mere 2cm thick to accumulate over the lunar surface. Now the Apollo astronauts apparently reported a surface dust layer of between less than 1/8 inch (3mm)and 3 inches (7.6cm). Thus, if this surface dust layer were composed only of meteoritic dust, then at the current rate of dust influx this surface dust layer would have accumulated over a period of between 150 million years (3mm) and 3.8 billion years (7.6cm). Obviously, this line of reasoning cannot be used as an argument for a young age for the moon and therefore the solar system.

However, as we have already seen, below the thin surface dust layer is the lunar regolith, which is up to 5 metres thick across the lunar maria and averages 10 metres thick in the lunar highlands. Evidently, the thin surface dust layer is very loose due to stirring by impacting meteoritic dust (micrometeorites), but the regolith beneath which consists of rock rubble of all sizes down to fines (that are referred to as lunar soil) is strongly compacted. Nevertheless, the regolith appears to be continuously ‘gardened’ by large and small meteorites and micrometeorites, particles now at the surface potentially being buried deeply by future impacts. This of course means then that as the regolith is turned over meteoritic dust particles in the thin surface layer will after some time end up being mixed into the lunar soil in the regolith below. Therefore, also, it cannot be assumed that the thin loose surface layer is entirely composed of meteoritic dust, since lunar soil is also brought up into this loose surface layer by impacts.

However, attempts have been made to estimate the proportion of meteoritic material mixed into the regolith. Taylor¹⁹⁸ reported that the meteoritic compositions recognised in the maria soils turn out to be surprisingly uniform at about 1.5% and that the abundance patterns are close to those for primitive unfractionated Type I carbonaceous chondrites. As described earlier, this meteoritic component was identified by analysing for trace elements in the broken-down rocks and soils in the regolith and then assuming that any trace element differences represented the meteoritic material added to the soils. Taylor also adds that the compositions of other meteorites, the ordinary chondrites, the iron meteorites and the stony-irons, do not appear to be present in the lunar regolith, which may have some significance as to the origin of this meteoritic material, most of which is attributed to the influx of micrometeorites. It is unknown what the large crater-forming meteorites contribute to the regolith, but Taylor suggests possibly as much as 10% of the total regolith. Additionally, a further source of exotic elements is the solar wind, which is estimated to contribute between 3% and 4% to the soil. This means that the total contribution to the regolith from extra-lunar sources is around 15%. Thus in a five metre thick regolith over the maria, the thickness of the meteoritic component would be close to 60cm, which at the current estimated meteoritic influx rate would have taken almost 30 billion years to accumulate, a timespan six times the claimed evolutionary age of the moon.

The lunar surface is heavily cratered, the largest crater having a diameter of 295kms. The highland areas are much more heavily cratered than the maria, which suggested to early investigators that the lunar highland areas might represent the oldest exposed rocks on the lunar surface. This has been confirmed by radiometric dating of rock samples brought back by the Apollo astronauts, so that a detailed lunar stratigraphy and evolutionary geochronological framework has been constructed. This has led to the conclusion that early in its history the moon suffered intense bombardment from scores of meteorites, so that all highland areas presumed to be older than 3.9 billion years have been found to be saturated with craters 50-100 km in diameter, and beneath the 10 metre-thick regolith is a zone of breccia and fractured bedrock estimated in places to be more than 1 km thick.¹⁹⁹

Figure 10. Cratering history of the moon (adapted from Taylor²⁰⁰). An aeon represents a billion years on the evolutionists’ time scale, while the vertical bar represents the error margin in the estimation of the cratering rate at each data point on the curve.

Following suitable calibration, a relative crater chronology has been established, which then allows for the cratering rate through lunar history to be estimated and then plotted, as it is in Figure 10.²⁰⁰ There thus appears to be a general correlation between crater densities across the lunar surface and radioactive ‘age’ dates. However, the crater densities at the various sites cannot be fitted to a straightforward exponential decay curve of meteorites or asteroid populations.²⁰¹ Instead, at least two separate groups of objects seem to be required. The first is believed to be approximated by the present-day meteoritic flux, while the second is believed to be that responsible for the intense early bombardment claimed to be about four billion years ago. This intense early bombardment recorded by the crater-saturated surface of the lunar highland areas could thus explain the presence of the thicker regolith (up to 10 metres) in those areas.

It follows that this period of intense early bombardment resulted from a very high influx of meteorites and thus meteoritic dust, which should now be recognisable in the regolith. Indeed, Taylor²⁰² lists three types of meteoritic debris in the highlands regolith- the micrometeoritic component, the debris from the large-crater-producing bodies, and the material added during the intense early bombardment. However, the latter has proven difficult to quantify. Again, the use of trace element ratios has enabled six classes of ancient meteoritic components to be identified, but these do not correspond to any of the currently known meteorite classes, both iron and chondritic. It would appear that this material represents the debris from the large projectiles responsible for the saturation cratering in the lunar highlands during the intense bombardment early in the moon’s history. It is this early intense bombardment with its associated higher influx rate of meteoritic material that would account for not only the thicker regolith in the lunar highlands, but the 12% of meteoritic component in the thinner regolith of the maria that we have calculated (above) would take up to 30 billion years to accumulate at the current meteoritic influx rate. Even though the maria are believed to be younger than the lunar highlands and haven’t suffered the same saturation cratering, the cratering rate curve of Figure 10 suggests that the meteoritic influx rate soon after formation of the maria was still almost 10 times the current influx rate, so that much of the meteoritic component in the regolith could thus have more rapidly accumulated in the early years after the maria’s formation. This then removes the apparent accumulation timespan anomaly for the evolutionists’ timescale, and suggests that the meteoritic component in the maria regolith is still consistent with its presumed 3 billion year age if uniformitarian assumptions are used. This of course is still far from satisfactory for those young earth creationists who believed that uniformitarian assumptions applied to moon dust could be used to deny the evolutionists’ vast age for the moon.

Given that as much as 10% of the maria regolith may have been contributed by the large crater-forming meteorites,²⁰³ impact erosion by these large crater-producing meteorites may well have had a significant part in the development of the regolith, including the generation of dust, particularly if the meteorites strike bare lunar rock. Furthermore, any incoming meteorite, or micrometeorite for that matter, creates a crater much bigger than itself,²⁰⁴ and since most impacts are at an oblique angle the resulting secondary cratering may in fact be more important²⁰⁵ in generating even more dust. However, to do so the impacting meteorite or micrometeorite must strike bare exposed rock on the lunar surface. Therefore, if bare rock is to continue to be available at the lunar surface, then there must be some mechanism to move the dust off the rock as quickly as it is generated, coupled with some transport mechanism to carry it and accumulate it in lower areas, such as the maria.

Various suggestions have been made apart from the obvious effect of steep gradients, which in any case would only produce local accumulation. Gold, for example, listed five possibilities,²⁰⁶ but all were highly speculative and remain unverified. More recently, McDonnell²⁰⁷ has proposed that electrostatic charging on dust particle surfaces may cause those particles to levitate across the lunar surface up to 10 or more metres. As they lose their charge they float back to the surface, where they are more likely to settle in a lower area. McDonnell gives no estimate as to how much dust might be moved by this process, and it remains somewhat tentative. In any case, if such transport mechanisms were in operation on the lunar surface, then we would expect the regolith to be thicker over the maria because of their lower elevation. However, the fact is that the regolith is thicker in the highland areas where the presumed early intense bombardment occurred, the impact-generated dust just accumulating locally and not being transported any significant distance.

Having considered the available data, it is inescapably clear that the amount of meteoritic dust on the lunar surface and in the regolith is not at all inconsistent with the present meteoritic dust influx rate to the lunar surface operating, over the multi-billion year time framework proposed by evolutionists, but including a higher influx rate in the early history of the moon when intense bombardment occurred producing many of the craters on the lunar surface. Thus, for the purpose of ‘proving’ a young moon, the meteoritic dust influx as it appears to be currently known is at least two orders of magnitude too low. On the other hand, the dust influx rate has, appropriately enough, not been used by evolutionists to somehow ‘prove’ their multi-billion year timespan for lunar history. (They have recognised some of the problems and uncertainties and so have relied more on their radiometric dating of lunar rocks, coupled with wide- ranging geochemical analyses of rock and soil samples, all within the broad picture of the lunar stratigraphic succession.) The present rate of dust influx does not, of course, disprove a young moon. 

Attempted Creationist Responses

Some creationists have tentatively recognised that the moon dust argument has lost its original apparent force. For example, Taylor(Paul)²⁰⁸ follows the usual line of argument employed by other creationists, stating that based on published estimates of the dust influx rate and the evolutionary timescale, many evolutionists expected the astronauts to find a very thick layer of loose dust on the moon, so when they only found a thin layer this implied a young moon. However, Taylor then admits that the case appears not to be as clear cut as some originally thought, particularly because evolutionists can now point to what appear to be more accurate measurements of a smaller dust influx rate compatible with their timescale. Indeed, he says that the evidence for disproving an old age using this particular process is weakened, but that furthermore, the case has been blunted by the discovery of what is said to be meteoritic dust within the regolith. However, like Calais,^209,210 Taylor points to the NASA report²¹¹ that supposedly indicated a very large amount of cosmic dust in the vicinity of the earth and moon (a claim which cannot be substantiated by a careful reading of the papers published in that report, as we have already seen). He also takes up DeYoung’s comment²¹² that because all evolutionary theories about the origin of the moon and the solar system predict a much larger amount of incoming dust in the moon’s early years, then a very thick layer of dust would be expected, so it is still missing. Such an argument cannot be sustained by creationists because, as we have seen above, the amount of meteoritic dust that appears to be in the regolith seems to be compatible with the evolutionists’ view that there was a much higher influx rate of meteoritic dust early in the moon’s history at the same time as the so-called ‘early intense bombardment’.

Indeed, from Figure 10 it could be argued that since the cratering rate very early in the moon’s history was more than 300 times today’s cratering rate, then the meteoritic dust influx early in the moon’s history was likewise more than 300 times today’s influx rate. That would then amount to more than 3 million tons of dust per year, but even at that rate it would take a billion years to accumulate more than six metres thickness of meteoritic dust across the lunar surface, no doubt mixed in with a lesser amount of dust and rock debris generated by the large-crater-producing meteorite impacts. However, in that one billion years, Figure 10 shows that the rate of meteoritic dust influx is postulated to have rapidly declined, so that in fact a considerably lesser amount of meteoritic dust and impact debris would have accumulated in that supposed billion years. In other words, the dust in the regolith and the surface layer is still compatible with the evolutionists’ view that there was a higher influx rate early in the moon’s history, so creationists cannot use that to shore up this considerably blunted argument.

Coupled with this, it is irrelevant for both Taylor and DeYoung to imply that because evolutionists say that the sun and the planets were formed from an immense cloud of dust which was thus obviously much thicker in the past, that their theory would thus predict a very thick layer of dust. On the contrary, all that is relevant is the postulated dust influx after the moon’s formation, since it is only then that there is a lunar surface available to collect the dust, which we can now investigate along with that lunar surface. So unless there was a substantially greater dust influx after the moon formed than that postulated by the evolutionists (see Figure 10 and our calculations above), then this objection also cannot be used by creationists.

De Young also adds a second objection in order to counter the evolutionists’ case. He maintains that the revised value of a much smaller dust accumulation from space is open to question, and that scientists continue to make major adjustments in estimates of meteors and space dust that fall upon the earth and moon.²¹³ If this is meant to imply that the current dust influx estimate is open to question amongst evolutionists, then it is simply not the case, because there is general agreement that the earlier estimates were gross overestimates. As we have seen, there is much support for the current figure, which is two orders of magnitude lower than many of the earlier estimates. There may be minor adjustments to the current estimate, but certainly not anything major.

While De Young hints at it, Taylor (Ian)²¹⁴ is quite open in suggesting that a drastic revision of the estimated meteoritic dust influx rate to the moon occurred straight after the Apollo moon landings, when the astronauts , observations supposedly debunked the earlier gross over-estimates, and that this was done quietly but methodically in some sort of deliberate way. This is simply not so. Taylor insinuates that the Committee for Space Research (COSPAR) was formed to work on drastically downgrading the meteoritic dust influx estimate, and that they did this only based on measurements from indirect techniques such as satellite-borne detectors, visual meteor counts and observations of zodiacal light, rather than dealing directly with the dust itself. That claim does not take into account that these different measurement techniques are all necessary to cover the full range of particle sizes involved, and that much of the data they employed in their work was collected in the 1960s before the Apollo moon landings. Furthermore, that same data had been used in the 1960s to produce dust influx estimates, which were then found to be in agreement with the minor dust layer found by the astronauts subsequently. In other words, the data had already convinced most scientists before the Apollo moon landings that very little dust would be found on the moon, so there is nothing ‘fishy’ about COSPAR’s dust influx estimates just happening to yield the exact amount of dust actually found on the moon’s surface. Furthermore, the COSPAR scientists did not ignore the dust on the moon’s surface, but used lunar rock and soil samples in their work, for example, with the study of lunar microcraters that they regarded as representing a record of the historic meteoritic dust influx. Attempts were also made using trace element geochemistry to identify the quantity of meteoritic dust in the lunar surface layer and the regolith below.

A final suggestion from De Young is that perhaps there actually is a thick lunar dust layer present, but it has been welded into rock by meteorite impacts.²¹⁵ This is similar and related to an earlier comment about efforts being made to re-evaluate dust accumulation rates and to find a mechanism for lunar dust compaction in order to explain the supposed absence of dust on the lunar surface that would be needed by the evolutionists’ timescale²¹⁶ For support, Mutch²¹⁷ is referred to, but in the cited pages Mutch only talks about the thickness of the regolith and the debris from cratering, the details of which are similar to what has previously been discussed here. As for the view that the thick lunar dust is actually present but has been welded into rock by meteorite impacts, no reference is cited, nor can one be found. Taylor describes a ‘mega-regolith’ in the highland areas²¹⁸ which is a zone of brecciation, fracturing and rubble more than a kilometre thick that is presumed to have resulted from the intense early bombardment, quite the opposite to the suggestion of meteorite impacts welding dust into rock. Indeed, Mutch,²¹⁹ Ashworth and McDonnell²²⁰ and Taylor²²¹ all refer to turning over of the soil and rubble in the lunar regolith by meteorite and micrometeorite impacts, making the regolith a primary mixing layer of lunar materials that have not been welded into rock. Strong compaction has occurred in the regolith, but this is virtually irrelevant to the issue of the quantity of meteoritic dust on the lunar surface, since that has been estimated using trace element analyses.

Parks²²² has likewise argued that the disintegration of meteorites impacting the lunar surface over the evolutionists’ timescale should have produced copious amounts of dust as they fragmented, which should, when added to calculations of the meteoritic dust influx over time, account for dust in the regolith in only a short period of time. However, it has already been pointed out that this debris component in the maria regolith only amounts to 10%, which quantity is also consistent with the evolutionists, postulated cratering rate over their timescale. He then repeats the argument that there should have been a greater rate of dust influx in the past, given the evolutionary theories for the formation of the bodies in the solar system from dust accretion, but that argument is likewise negated by the evolutionists having postulated an intense early bombardment of the lunar surface with a cratering rate, and thus a dust influx rate, over two orders of magnitude higher than the present (as already discussed above). Finally, he infers that even if the dust influx rate is far less than investigators had originally supposed, it should have contributed much more than the 1.5%’s worth of the 1-2 inch thick layer of loose dust on the lunar surface. The reference cited for this percentage of meteoritic dust in the thin loose dust layer on the lunar surface is Ganapathy et al.²²³ However, when that paper is checked carefully to see where they obtained their samples from for their analytical work, we find that the four soil samples that were enriched in a number of trace elements of meteoritic origin came from depths of 13-38 cms below the surface, from where they were extracted by a core tube. In other words, they came from the regolith below the 1-2 inch thick layer of loose dust on the surface, and so Parks’ application of this analytical work is not even relevant to his claim. In any case, if one uses the current estimated meteoritic dust influx rate to calculate how much meteoritic dust should be within the lunar surface over the evolutionists’ timescale one finds the results to be consistent, as has already been shown above.

Parks may have been influenced by Brown, whose personal correspondence he cites. Brown, in his own publication,²²⁴ has stated that

‘if the influx of meteoritic dust on the moon has been at just its present rate for the last 4.6 billion years, then the layer of dust should be over 2,000 feet thick.’

Furthermore, he indicates that he made these computations based on the data contained in Hughes²²⁵ and Taylor.²²⁶ This is rather baffling, since Taylor does not commit himself to a meteoritic dust influx rate, but merely refers to the work of others, while Hughes concentrates on lunar microcraters and only indirectly refers to the meteoritic dust influx rate. In any case, as we have already seen, at the currently estimated influx rate of approximately 10,000 tons per year a mere 2 cm thickness of meteoritic dust would accumulate on the lunar surface every billion years, so that in 4.6 billion years there would be a grand total of 9.2 cm thickness. One is left wondering where Brown’s figure of 2,000 feet (approximately 610 metres) actually came from? If he is taking into account Taylor’s reference to the intense early bombardment, then we have already seen that, even with a meteoritic dust influx rate of 300 times the present figure, we can still comfortably account for the quantity of meteoritic dust found in the lunar regolith and the loose surface layer over the evolutionists’ timescale. While defence of the creationist position is totally in order, baffling calculations are not. Creation science should always be good science; it is better served by thorough use of the technical literature and by facing up to the real data with sincerity, as our detractors have often been quick to point out.

Conclusion

So are there any loopholes in the evolutionists’ case that the current apparent meteoritic dust influx to the lunar surface and the quantity of dust found in the thin lunar surface dust layer and the regolith below do not contradict their multi-billion year timescale for the moon’s history? Based on the evidence we currently have the answer has to be that it doesn’t look like it. The uncertainties involved in the possible erosion process postulated by Lyttleton and Gold (that is, radiation erosion) still potentially leaves that process as just one possible explanation for the amount of dust in a young moon model, but the dust should no longer be used as if it were a major problem for evolutionists. Both the lunar surface and the lunar meteoritic influx rate seem to be fairly well characterised, even though it could be argued that direct geological investigations of the lunar surface have only been undertaken briefly at 13 sites (six by astronauts and seven by unmanned spacecraft) scattered across a portion of only one side of the moon.

Furthermore, there are some unresolved questions regarding the techniques and measurements of the meteoritic dust influx rate. For example, the surface exposure times for the rocks on whose surfaces microcraters were measured and counted are dependent on uniformitarian age assumptions. If the exposure times were in fact much shorter, then the dust influx estimates based on the lunar microcraters would need to be drastically revised, perhaps upwards by several orders of magnitude. As it is, we have seen that there is a recognised discrepancy between the lunar microcrater data and the satellite-borne detector data, the former being an order of magnitude lower than the latter. Hughes²²⁷ explains this in terms of the meteoritic dust influx having supposedly increased by a factor of four in the last 100,000 years, whereas Gault et al.²²⁸ admit that if the ages are accepted at face value then there had to be an increase in the meteoritic dust influx rate by a factor of 10 in the past few tens of years! How this could happen we are not told, yet according to estimates of the past cratering rate there was in fact a higher influx of meteorites, and by inference meteoritic dust, in the past. This is of course contradictory to the claims based on lunar microcrater data. This seems to leave the satellite-borne detector measurements as apparently the more reliable set of data, but it could still be argued that the dust collection areas on the satellites are tiny, and the dust collection timespans far too short, to be representative of the quantity of dust in the space around the earth-moon system.

Should creationists then continue to use the moon dust as apparent evidence for a young moon, earth and solar system? Clearly, the answer is no. The weight of the evidence as it currently exists shows no inconsistency within the evolutionists’ case, so the burden of proof is squarely on creationists if they want to argue that based on the meteoritic dust the moon is young. Thus it is inexcusable for one creationist writer to recently repeat verbatim an article of his published five years earlier,^229,230 maintaining that the meteoritic dust is proof that the moon is young in the face of the overwhelming evidence against his arguments. Perhaps any hope of resolving this issue in the creationists, favour may have to wait for further direct geological investigations and direct measurements to be made by those manning a future lunar surface laboratory, from where scientists could actually collect and measure the dust influx, and investigate the characteristics of the dust in place and its interaction with the regolith and any lunar surface processes.

Conclusions

Over the last three decades numerous attempts have been made using a variety of methods to estimate the meteoritic dust influx to both the earth and the moon. On the earth, chemical methods give results in the range of 100,000-400,000 tons per year, whereas cumulative flux calculations based on satellite and radar data give results in the range 10,000-20,000 tons per year. Most authorities on the subject now favour the satellite data, although there is an outside possibility that the influx rate may reach 100,000 tons per year. On the moon, after assessment of the various techniques employed, on balance the evidence points to a meteoritic dust influx figure of around 10,000 tons per year.

Although some scientists had speculated prior to spacecraft landing on the moon that there would be a thick dust layer there, there were many scientists who disagreed and who predicted that the dust would be thin and firm enough for a manned landing. Then in 1966 the Russians with their Luna 9 spacecraft and the Americans with their five successful Surveyor spacecraft accomplished soft-landings on the lunar surface, the footpads of the latter sinking no more than an inch or two into the soft lunar soil and the photographs sent back settling the argument over the thickness of the dust and its strength. Consequently, before the Apollo astronauts landed on the moon in 1969 the moon dust issue had been settled, and their lunar exploration only confirmed the prediction of the majority, plus the meteoritic dust influx measurements that had been made by satellite-borne detector systems which had indicated only a minor amount.

Calculations show that the amount of meteoritic dust in the surface dust layer, and that which trace element analyses have shown to be in the regolith, is consistent with the current meteoritic dust influx rate operating over the evolutionists’ timescale. While there are some unresolved problems with the evolutionists’ case, the moon dust argument, using uniformitarian assumptions to argue against an old age for the moon and the solar system, should for the present not be used by creationists.

Acknowledgements

Research on this topic was undertaken spasmodically over a period of more than seven years by Dr Andrew Snelling. A number of people helped with the literature search and obtaining copies of papers, in particular, Tony Purcell and Paul Nethercott. Their help is acknowledged. Dave Rush undertook research independentl yon this topic while studying and working at the Institute for Creation Research, before we met and combined our efforts. We, of course, take responsibility for the conclusions, which unfortunately are not as encouraging or complimentary for us young earth creationists as we would have liked.

Abstract

Using a figure published in 1960 of 14,300,000 tons per year as the meteoritic dust influx rate to the earth, creationists have argued that the thin dust layer on the moon’s surface indicates that the moon, and therefore the earth and solar system, are young. Furthermore, it is also often claimed that before the moon landings there was considerable fear that astronauts would sink into a very thick dust layer, but subsequently scientists have remained silent as to why the anticipated dust wasn’t there. An attempt is made here to thoroughly examine these arguments, and the counter arguments made by detractors, in the light of a sizable cross-section of the available literature on the subject.

Of the techniques that have been used to measure the meteoritic dust influx rate, chemical analyses (of deep sea sediments and dust in polar ice), and satellite-borne detector measurements appear to be the most reliable. However, upon close examination the dust particles range in size from fractions of a micron in diameter and fractions of a microgram in mass up to millimetres and grams, whence they become part of the size and mass range of meteorites. Thus the different measurement techniques cover different size and mass ranges of particles, so that to obtain the most reliable estimate requires an integration of results from different techniques over the full range of particle masses and sizes. When this is done, most current estimates of the meteoritic dust influx rate to the earth fall in the range of 10, 000-20, 000 tons per year, although some suggest this rate could still be as much as up to 100,000 tons per year.

Apart from the same satellite measurements, with a focusing factor of two applied so as to take into account differences in size and gravity between the earth and moon, two main techniques for estimating the lunar meteoritic dust influx have been trace element analyses of lunar soils, and the measuring and counting of microcraters produced by impacting micrometeorites on rock surfaces exposed on the lunar surface. Both these techniques rely on uniformitarian assumptions and dating techniques. Furthermore, there are serious discrepancies between the microcrater data and the satellite data that remain unexplained, and that require the meteoritic dust influx rate to be higher today than in the past. But the crater-saturated lunar highlands are evidence of a higher meteorite and meteoritic dust influx in the past. Nevertheless the estimates of the current meteoritic dust influx rate to the moon’s surface group around a figure of about 10,000 tons per year.

Prior to direct investigations, there was much debate amongst scientists about the thickness of dust on the moon. Some speculated that there would be very thick dust into which astronauts and their spacecraft might ‘disappear’, while the majority of scientists believed that there was minimal dust cover. Then NASA sent up rockets and satellites and used earth-bound radar to make measurements of the meteoritic dust influx, results suggesting there was only sufficient dust for a thin layer on the moon. In mid-1966 the Americans successively soft-landed five Surveyor spacecraft on the lunar surface, and so three years before the Apollo astronauts set foot on the moon NASA knew that they would only find a thin dust layer on the lunar surface into which neither the astronauts nor their spacecraft would ‘disappear’. This was confirmed by the Apollo astronauts, who only found up to a few inches of loose dust.

The Apollo investigations revealed a regolith at least several metres thick beneath the loose dust on the lunar surface. This regolith consists of lunar rock debris produced by impacting meteorites mixed with dust, some of which is of meteoritic origin. Apart from impacting meteorites and micrometeorites it is likely that there are no other lunar surface processes capable of both producing more dust and transporting it. It thus appears that the amount of meteoritic dust and meteorite debris in the lunar regolith and surface dust layer, even taking into account the postulated early intense meteorite and meteoritic dust bombardment, does not contradict the evolutionists’ multi-billion year timescale (while not proving it). Unfortunately, attempted counter-responses by creationists have so far failed because of spurious arguments or faulty calculations. Thus, until new evidence is forthcoming, creationists should not continue to use the dust on the moon as evidence against an old age for the moon and the solar system.

Introduction

One of the evidences for a young earth that creationists have been using now for more than two decades is the argument about the influx of meteoritic material from space and the so-called ‘dust on the moon’ problem. The argument goes as follows:

‘It is known that there is essentially a constant rate of cosmic dust particles entering the earth’s atmosphere from space and then gradually settling to the earth’s surface. The best measurements of this influx have been made by Hans Pettersson, who obtained the figure of 14 million tons per year.¹ This amounts to 14 x 10¹⁹ pounds in 5 billion years. If we assume the density of compacted dust is, say, 140 pounds per cubic foot, this corresponds to a volume of 10¹⁸ cubic feet. Since the earth has a surface area of approximately 5.5 x 10¹⁵ square feet, this seems to mean that there should have accumulated during the 5-billion- year age of the earth, a layer of meteoritic dust approximately 182 feet thick all over the world!

There is not the slightest sign of such a dust layer anywhere of course. On the moon’s surface it should be at least as thick, but the astronauts found no sign of it (before the moon landings, there was considerable fear that the men would sink into the dust when they arrived on the moon, but no comment has apparently ever been made by the authorities as to why it wasn’t there as anticipated).

Even if the earth is only 5,000,000 years old, a dust layer of over 2 inches should have accumulated.

Lest anyone say that erosional and mixing processes account for the absence of the 182-foot meteoritic dust layer, it should be noted that the composition of such material is quite distinctive, especially in its content of nickel and iron. Nickel, for example, is a very rare element in the earth’s crust and especially in the ocean. Pettersson estimated the average nickel content of meteoritic dust to be 2.5 per cent, approximately 300 times as great as in the earth’s crust. Thus, if all the meteoritic dust layer had been dispersed by uniform mixing through the earth’s crust, the thickness of crust involved (assuming no original nickel in the crust at all) would be 182 x 300 feet, or about 10 miles!

Since the earth’s crust (down to the mantle) averages only about 12 miles thick, this tells us that practically all the nickel in the crust of the earth would have been derived from meteoritic dust influx in the supposed (5 x 10⁹ year) age of the earth!’²

This is indeed a powerful argument, so powerful that it has upset the evolutionist camp. Consequently, a number of concerted efforts have been recently made to refute this evidence.^3-9 After all, in order to be a credible theory, evolution needs plenty of time (that is, billions of years) to occur because the postulated process of transforming one species into another certainly can’t be observed in the lifetime of a single observer. So no evolutionist could ever be happy with evidence that the earth and the solar system are less than 10,000 years old.

But do evolutionists have any valid criticisms of this argument? And if so, can they be answered?
Criticisms of this argument made by evolutionists fall into three categories:-

1. The question of the rate of meteoritic dust influx to the earth and moon,
2. The question as to whether NASA really expected to find a thick dust layer on the moon when their astronauts, landed, and
3. The question as to what period of time is represented by the actual layer of dust found on the moon.

Dust Influx to the Earth

Petterson’s Estimate

The man whose work is at the centre of this controversy is Hans Pettersson of the Swedish Oceanographic Institute. In 1957, Pettersson (who then held the Chair of Geophysics at the University of Hawaii) set up dust-collecting units at 11,000 feet near the summit of Mauna Loa on the island of Hawaii and at 10,000 feet on Mt Haleakala on the island of Maui. He chose these mountains because

‘occasionally winds stir up lava dust from the slopes of these extinct volcanoes, but normally the air is of an almost ideal transparency, remarkably free of contamination by terrestrial dust.’¹⁰

With his dust-collecting units, Pettersson filtered measured quantities of air and analysed the particles he found. Despite his description of the lack of contamination in the air at his chosen sampling sites, Pettersson was very aware and concerned that terrestrial (atmospheric) dust would still swamp the meteoritic (space) dust he collected, for he says: ‘It was nonetheless apparent that the dust collected in the filters would come preponderantly from terrestrial sources.’¹¹ Consequently he adopted the procedure of having his dust samples analysed for nickel and cobalt, since he reasoned that both nickel and cobalt were rare elements in terrestrial dust compared with the high nickel and cobalt contents of meteorites and therefore by implication of , meteoritic dust also.

Based on the nickel analysis of his collected dust, Pettersson finally estimated that about 14 million tons of dust land on the earth annually. To quote Petterson again:

‘Most of the samples contained small but measurable quantities of nickel along with the large amount of iron. The average for 30 filters was 14.3 micrograms of nickel from each 1,000 cubic metres of air. This would mean that each 1,000 cubic metres of air contains .6 milligram of meteoritic dust. If meteoritic dust descends at the same rate as the dust created by the explosion of the Indonesian volcano Krakatoa in 1883, then my data indicate that the amount of meteoritic dust landing on the earth every year is 14 million tons. From the observed frequency of meteors and from other data Watson (F.G. Watson of Harvard University) calculates the total weight of meteoritic matter reaching the earth to be between 365,000 and 3,650,000 tons a year. His higher estimate is thus about a fourth of my estimate, based upon theHawaiian studies. To be on the safe side, especially in view of the uncertainty as to how long it takes meteoritic dust to descend, I am inclined to find five million tons per year plausible.’¹²

Now several evolutionists have latched onto Pettersson’s conservatism with his suggestion that a figure of 5 million tons per year is more plausible and have thus promulgated the idea that Pettersson’s estimate was ‘high’,¹³ ‘very speculative’,¹⁴ and ‘tentative’.¹⁵ One of these critics has even gone so far as to suggest that ‘Pettersson’s dust- collections were so swamped with atmospheric dust that his estimates were completely wrong’¹⁶ (emphasis mine). Others have said that ‘Pettersson’s samples were apparently contaminated with far more terrestrial dust than he had accounted for.’¹⁷ So what does Pettersson say about his 5 million