Regards,
Adam

I’ll break out the state vectors a bit more:

1. A spherical post-burn state vector from Emil.
Emil had an Apollo 10 post-mission report with a state vector in it. It turned out this vector also available in other sources I had. It was a moon-centered spherical state vector from after Snoopy “burn to depletion” burn. I don’t know what process produced that vector.

2. A spherical post-burn state vector from the document @BlackProjects tweeted us.
This is from MSC-00126, the Apollo 10 Mission Report. It has a slightly different state vector, also right after the depletion burn.

3. A combination of a pre-burn state vector Emil gave me, with a delta-V vector added to it that Emil gave me.
This is the state vector right before the depletion burn, and then I added the delta-v vector that Emil also gave me.

All 3 of these were state vectors that I assume came from on-board, in that they were the state measured on board the spacecraft during the burn. I’m not sure why there are 2 different vectors, as the sources aren’t given. I do not believe that there is a vector from MSFN tracking. As far as I understand from Chuck and Emil, they didn’t track Snoopy after the burn was complete. The reports do not give the actual source of the data.

I’d say that not only is the data not good enough, I don’t think any data can be good enough to give a definitive solution. In the quick monte-carlos that I did (I’ll have to post some of the graphs of these, they don’t appear to be up here) errors of less than 1 m/sec in delta-v create a huge swatch of possible outcomes 45 years later. The vehicle has made multiple encounters of the Earth-Moon system and has been perturbed in a slightly different way each time. I thought I had posted that stuff here but I don’t see it. Anyway, the trick is that any state vector with any sort of reasonable covariance is going to give a huge swath of possible outcomes.

I am familiar with the Apollo 12 stage. I did a bit of work trying to reconstruct that trajectory back in 2003. They are bigger, and possible easier to see. They are less cool though, just because Snoopy is the only surviving Ascent module that flew.

SRP is tough. All you can really do is estimate some average reflectivity over the known surface area and assume you get some sort of tumbling that averages everything out. I have a guess at the reflectivity and I’ve got the size down fairly well. But, you can turn the SRP on or off, and it doesn’t affect the total spread you get in a monte carlo. I think the best thing we can do is to come up with a spread and try to start scanning the areas in space that correspond to it. In the end, I expect this to look a lot like the asteroid surveys that are being done these days.

So here’s an idea. How about looking for one of the early S-IVBs in lunar orbit? Prior to Apollo 13, when they were all sent crashing into the moon, they were sent into solar orbit just like Snoopy. By my count there should be five of them in solar orbit, from Apollos 8-12 inclusive. (Although Apollo 9 was an earth-orbital mission, its S-IVB was fired out of earth orbit as a test of the restart capability.) You probably know about Apollo 12′s S-IVB coming back in the 2002-2003 timeframe and being temporarily recaptured, so we know we can detect one were it to come close enough.

Alhough the S-IVB is a bigger and brighter target than Snoopy, it is probably also lighter for its size and therefore more subject to the effects of solar radiation pressure. Have you accounted for that in your modeling of Snoopy’s trajectory?

Just to make sure, can you explain each of your state vector sources? I assume that at least one came from Snoopy itself as it propagated its state vector during the burn (perhaps separate ones from AGS and PGNS) and another came from MSFN tracking. Is that right?

A great resource for this type of question is the minor planet center. They address this particular asteroid specifically on their blog here:

http://minorplanetcenter.net/blog/clearing-up-the-fud-on-2012-da14/

For bigger asteroids, the potential for damage is described here:

http://www.astronomynotes.com/solfluf/s5.htm