Late Heavy Bombardment put under the microscope

https://www.nature.com/articles/d41586-018-01074-6

The article goes over the case against the cataclysm scenario, and it turns out the case isn’t as rock-solid (sorry, had to put a pun in here somehow) as previously thought. It turns out that what we previously thought was evidence for the Late Heavy Bombardment was actually a sampling error, as the article attests to in the quote below:

Yet just when the idea of the LHB finally seemed unimpeachable, holes began to appear. Apollo data and ‘crater counting’, which estimates the order in which craters were laid down on the basis of how they overlap, had indicated that three of the largest crater basins on the Moon’s near side — Imbrium, Nectaris and Serenitatis — might all be about 3.95 billion years old (see ‘Sampling the Moon’). But high-resolution maps from NASA’s Lunar Reconnaissance Orbiter, which started circling the Moon in 2009, spotted rays of debris extending from Imbrium5. This suggested that the impact that formed the crater might have knocked rocks into nearby Serenitatis, contaminating the Apollo samples picked up there. In 2010, a reanalysis of rocks thought to have been ejected from Nectaris indicated that they were also chemically and geologically similar to Imbrium material6. “We started realizing that maybe we were sampling Imbrium over and over,” says Zellner.

The article goes on further, saying that “we find no evidence of a large spike in impacts occurring around the 3.9 billion year mark” (slight paraphrasing). It also mentions the existence of crystals dated to 4.1 Ga that “demonstrate the existence of relatively calm pools of liquid water,” which would’ve been supposedly evaporated from the surface of the Earth from that period of if the LHB hypothesis is correct.

The article concludes by saying that at the most the evidence indicates a “more prolonged period of bombardment, as opposed to the sudden spike in impact events as predicted by the cataclysm hypothesis.” Others are skeptical of even that, instead believing that there was one single rapid spike that occurred very shortly after the solar system formed, whereas others believe there was no spike nor period of bombardment at all.