Possible sighting for Apollo 15 Ascent Module impact crater

[onebigmonkey]

I sort of took up a challenge at International Skeptics (JREF as was) to look for Apollo impact craters, and having successfully found Apollo 13's crater in an Apollo 14 image (but tnot Apollo 12), I've been seeing what else I could find.

After much googling it seemed that no-one has yet managed to find the impact crater for Apollo 15's ascent module.

The official location is given as 26.36 N 0.25 E (decimal degrees), and while there is nothing obvious at that location on the LRO's quickmap site, 2.6 km to the west at 26.3727 N 0.1535 E there is this 20 m wide crater:



and zoomed in a bit more:



It seems like a good candidate because it is not evident on Metric Mapping Camera images taken by Apollo 15 relatively early in the mission, such as this detail from AS15-M-0416 taken on rev 16:



But there is a hint of it being there on Rev 60 in AS15-M-2050, taken after the LM impact:



Here they are together:



I've used the highest quality images possible from here

http://wms.lroc.asu.edu/apollo/browse

This is where someone tells me it was found years ago...

[ka9q]

Have you compared it with the known impact craters from the other LMs?

Have you looked at the (pre-Apollo) Lunar Orbiter Image Recovery Project images of the same area?

[ka9q]

This reminds me -- it would be really neat to discover the ascent stage impact sites for Apollo 11 (Eagle) and 16 (Orion). Both were abandoned in lunar orbit, Eagle by design and Orion when it proved impossible to perform the de-orbit burn. Lunar orbits are inherently unstable due to perturbations by the earth and sun, so they almost certainly hit the surface well within a year.

We know from the other LM impacts what their craters should look like: about 20m in diameter, very bright from the young age, and elongated in the east-west direction because of the shallow impact from the east. I'd have to check, but I think some had rays projecting to the west.

Only LRO's narrow-angle camera has sufficient resolution, and I don't know how completely they've mapped the equatorial band where these unknown sites have to be. You could use the products of the Lunar Orbiter Image Recovery Project to confirm that a crater didn't exist before the Apollo landings.

Eagle would probably be easier to find than Orion. Apollo 11 used a very low inclination lunar orbit so you'd only have to search a very narrow strip along the lunar equator. I would pay special attention to the eastern slopes of mountains within the latitude range.

You might be able to interest schoolkids in a project like this. Whoever's lucky enough to find each site would probably become instantly famous.

[onebigmonkey]

Have you compared it with the known impact craters from the other LMs?

Have you looked at the (pre-Apollo) Lunar Orbiter Image Recovery Project images of the same area?

I've looked at all the available orbiter images but the LOIRP hasn't published many of Orbiter IV, which has the best coverage of this area (Palus Putredinis). There doesn't appear to be much there in the ones that are available on the Apollo Image Atlas, but the level of detail isn't enough to be conclusive.

The crater itself is bigger than those calculated for ascent module impacts, but that will of course depend on the substrate impacts. There is a clear directional component to the ejecta.

Going back to my comment in the OP about finding Apollo 13's SIV-B crater in an Apollo 14 image, you can imagine my disappointment at finding the same conclusions in Apollo 16's PSR! It would still be nice to show that the Apollo 12 photographs of the same spot don't show it!

[GoneToPlaid]

Unfortunately this crater is visible in Apollo 15 panorama camera images AS15-P-9382 and 9387. Also the bearing of its ejecta butterfly is wrong. But it is a very good example of a shallow angle impact of a small meteoroid.

[onebigmonkey]

Unfortunately this crater is visible in Apollo 15 panorama camera images AS15-P-9382 and 9387. Also the bearing of its ejecta butterfly is wrong. But it is a very good example of a shallow angle impact of a small meteoroid.

And as they were taken during Rev 16 that would pretty much eliminate it

Ah well...nice dream...

[bknight]

Do you think that there may have been a transposition error in the reported impact site?

[raven]

A very neat crater all the same. Obviously very fresh, relatively speaking. I wonder how old it is?