Dating planetary surfaces Freemilfdates
The abstract states: The small crater populations (diameter smaller than 1 km) are widely used to date planetary surfaces.
The reliability of small crater counts is tested by counting small craters at several young and old lunar surfaces, including Mare Nubium and craters Alphonsus, Tycho and Giordano Bruno.
Based on high-resolution images from both the Lunar Reconnaissance Orbiter Camera and Kaguya Terrain Camera, small craters in two different diameter ranges are counted for each counting area.
Large discrepancies exist in both the cumulative (absolute model ages) and relative plots for the two different size ranges of the same counting areas.
Astronomers had hoped that secondaries could be identified, thereby alleviating the confusion.
Non-impact structures (like volcanic vents) can sometimes look like craters.Crater count dating would be straightforward if impactors of predictable size came in at a predictable rate within predictable rates of speed, were made of predictable materials and impacted a uniform surface material and left marks distinct from those of any other source.Even correcting for known complicating factors, astronomers thought they could calibrate the “old” and “young” craters with radiometric measurements from Apollo samples.In addition, the uncertainties they learned from testing the method on the moon and Mars extends to the whole solar system: “All crater counting ages on other celestial bodies,” they warned, “are based on certain assumptions about the origin and impact rate of the impactors.” The take-home message from the paper was bleak: In general, statistics of small craters are affected by numerous factors, e.g., contamination of secondaries and different target properties.Crater counting is a subjective process which causes more uncertainties to the results.