![\"LRO_apolloimpact\"](\"http:\/\/lroc.sese.asu.edu\/news\/uploads\/M109420042LE_thumb.png\")
<\/a><\/p>How do we know it’s new? Because we made it.<\/em><\/p> That’s the impact scar<\/a> of the third stage of the Saturn V rocket (technically designated S-IVB) that carried Apollo 13 to — but sadly, not on — the Moon. Earlier missions had placed seismic instruments on the lunar surface to measure if the Moon had any activity. They found it did<\/a>, and in fact several moonquakes were big enough that had you been standing there, you would have felt them quite strongly (and probably been knocked on your spacesuit’s backside).<\/p> The crater image above is from the Lunar Reconnaissance Orbiter, and shows the Apollo 13 booster impact. The crater itself is a few dozen meters across, and the material ejected forms a blanket around it for many meters more. The bright material indicates this is a fresh crater; note how gray the more distant undisturbed material around the crater is.<\/p> The impact site looks obvious in that picture, doesn’t it? But try finding it in the original full-resolution image returned from LRO<\/a> and see if you can locate it, then! I found it relatively quickly starting at the top, and was shocked at how far I could trace the rays — the linear ejected debris features around the crater — from the impact site. One of them is clearly about a kilometer long… that’s over half a mile! Those rays are from plumes of material ejected from the impact site, a common feature. They also indicate the crater’s youth: over time, cosmic rays, the solar wind, and even thermal stress from the Moon’s day\/night cycle slowly erase the rays. Any crater with such extensive rays has to be young.<\/p> Some of the other S-IVB impact sites have been identified; the LRO blog has an image of the Apollo 14 S-IVB crater<\/a>, for example. Knowing where these impact sites are helps scientists understand the Moon better, since it a more precise location means the data from the old Apollo missions can be interpreted more clearly. I wonder if future colonists may visit those sites the way we do Plymouth Rock, or Jamestown, or other early exploration and colony sites on Earth?<\/p> Credit: NASA, NASA\/GSFC\/Arizona State University<\/em><\/p> On April 14th, 1970, a new crater was carved into the surface of the Moon:How do we know it’s new? Because we made it.That’s the impact scar of the third stage of the Saturn V rocket (technically designated S-IVB) that … Continue reading <\/a>The S-IVB upper stage accelerated the astronauts to the Moon from Earth orbit. Once that was done, they had one final mission: in Apollos 13 – 17 the stages were aimed at the Moon itself, and impacted a few days later. The impacts were detected by the seismometers and could be used to determine how seismic waves travel through the lunar surface, a trick that’s been used on Earth for a long time. This information can be used to figure out what the lunar subsurface structure is like. <\/p>