https://jatan.space/the-tiniest-of-impact-craters/ Jatan's Space * About * Moon Monday * Articles * Indian Space * Browse * Email me Sign in Subscribe Articles The tiniest of impact craters [Guest post] Small meteorites constantly bombard the Moon and create micro-sized craters. Jatan Mehta Jatan Mehta Aug 20, 2019 -- 2 min read When we think about craters on the Moon, we usually think of ones that can be seen with a telescope or in images sent by spacecraft around the Moon. But there are also ones we can only see with a microscope. Here's a micro-sized crater on a Moon rock! [https-3a-2]A truly tiny crater, little more than 10 microns wide, on a Moon rock brought to Earth from Apollo 12. Credit: NASA Astronauts on the Apollo 12 mission brought 45 rocks from the Moon to Earth. The featured micro crater in an olivine mineral grain is from the rock 12075, as seen in a scanning electron microscope. It spans a little more than 10 microns, compared to the ~60 micron width of a human hair strand. The grain of dust that created this tiny impact crater was probably only about a micron wide. Here's a quick size comparison of a micro crater with a tardigrade and a human hair strand. Thanks Dad for the suggestion! [https-3a-2]Comparison of micro-sized lunar crater with a small tardigrade and a human hair strand. Image sources: 1, 2. We don't see such micro craters on Earth, as small meteorites burn up in our atmosphere before they even reach the ground. We see some of those burning things as "shooting stars", but the grain that made this impact is too small even for that. Because the Moon doesn't have an atmosphere, every little piece of cosmic dust can make an impact. Such small impact craters are called "micrometeorite impacts" or sometimes "zap pits". Some of the rocks that the Apollo program returned were covered with micro craters on the surface, but just on one side, the side that faced upwards on the Moon and was exposed to space. Like this one from Apollo 17, lunar rock 70215. [https-3a-2]Apollo 17 rock 70215, subjected to space weathering. Credit: NASA Micrometeorite impacts are part of the process of "space weathering", which slowly changes the properties of lunar rocks and soils, making them appear darker with time. That is why young craters are so bright . Impacts expose fresh material that is bright, but because of all of these tiny impacts and effects of the solar wind, those rays disappear over millions of years and the soil gets dark. Micrometeorites could be a hazard to future lunar visitors and residents. While these tiny grains seem to hit all the time on a geologic time scale, on a human scale, they are actually pretty rare. You'd have to be very unlucky to get hit by one on a short EVA, but if you are designing habitats for long-term use, they are definitely something you need to take into account. Did you know? You can view Apollo samples with a virtual microscope! Here's rock 12075 Know more - --------------------------------------------------------------------- This is a guest post by Dr. Sarah Noble. Sarah Noble is a planetary geologist and a Program Scientist in the Planetary Sciences division at NASA HQ. Her area of expertise is space weathering processes. She was the Program Scientist for NASA's LADEE spacecraft, and is currently the Program Scientist for the Psyche mission. --------------------------------------------------------------------- - Browse the Blog | About | Donate Read more Discussing India's lunar exploration heading with Carnegie India (podcast) I was a guest on Carnegie India's podcast Interpreting India. In light of the recently approved Chandrayaan 4 sample return mission, we discuss for a good 45 minutes where India's Moon exploration plans are heading, and what are the enablers and constraints on the increasingly complex road for Oct 19, 2024 Moon Monday #197: Starship Artemis, and lunar mission updates NASA's road to the Moon inches through Starship SpaceX's fifth launch of its fully integrated Starship Super Heavy rocket on October 13 was a resounding success, with both the Super Heavy booster and the Starship second stage completing their flight as well as soft return objectives. With this Oct 14, 2024 Indian Space Progress #20-21: ISRO's plan to study Venus alongside NASA and ESA Also in this special edition: ISRO's ambitions to fetch samples from the Moon, build a space station, and develop a heavy-lift rocket! Oct 11, 2024 Moon Monday #196: Confusion about lunar water and LUPEX, and papers plus mission updates You can now follow my articles on some non-questionable social networks that also federate (interoperate): Flipboard, Mastodon and Bluesky. The hunt for water on the Moon continues US researchers find that permanently shadowed regions up to 77deg latitude--which is outside the Moon's south pole--could host surface and Oct 7, 2024 Jatan's Space * Home * About * Browse * Email me * Personal Blog / Powered by Ghost Get space updates in your inbox Blog of Jatan Mehta, a globally published independent space writer, author of Moon Monday, and invited speaker. [ ] Subscribe Share via Email -