The Mysterious 30 Year Journey of Apollo 12

[catdlr]

an 24, 2023
Let's talk about Apollo 12 and its incredible 30-year journey through space. In September 2002, astronomers discovered what they first thought was an asteroid, but would soon find out it was the  Saturn V  third stage that launched the Apollo 12 astronauts to the Moon. This rocket left Earth in 1969 and returned to Earth 30 years later. But what happened in the meantime? In this video, we look at how one tiny error in the Apollo 12 mission sent this rocket stage on a 30-year trip through space!

[Comga]

This was a favorite discovery when it happened. 

It is difficult to make these videos for general audiences, and then have them land in front of a well educated group like NSF, so they can be excused for some simplifications.

A detail that was left out is the non-Keplerian trajectory.
As I recall, the second curiosity, after the shock of finding an object in a distant Earth orbit, was that its trajectory was odd.  It deviated from what would have been predicted for a solid body orbiting the Earth and the Sun.  The key was realizing that its density was low.  It was more influenced by the solar wind and light pressure than would be assumed for an asteroid that corresponded to its brightness.
So the realization was that it was of anomalously low density. 

Then when the spectrum matched that of white paint, it was realized that it was a tank, a rocket body, much smaller than when it was assumed to be an asteroid, which are all dark.  That matched the expected density.

What I did not recall from the time and learned from the video was the interaction with the Lagrange (la-granj, not la-graenj) point.  This was years before weak stability trajectories, “interplanetary highways”, were explored and exploited, like that in use right now by Hakuto-R.  Its discovery may have contributed to this field of flying to these complex balance points and efficiently sliding out to a goal with little delta-V.

[leovinus]

We are still learning about "funny" orbits in the solar system. Cruithne, Earth's second moon, was only discovered in 1997 with a horseshoe orbit.

[edzieba]

We are still learning about "funny" orbits in the solar system. Cruithne, Earth's second moon, was only discovered in 1997 with a horseshoe orbit.

Whilst Cruithne and similar co-orbiting objects share an orbital period close to Earth's, it'd be an extreme stretch to call them 'moons' when they don't even hang out inside Earth's Hill sphere (let alone orbit it).

[Harry Cover]

What I did not recall from the time and learned from the video was the interaction with the Lagrange (la-granj, not la-graenj) point. 

Yes - la grange, not la grandjeu.    (grandjeu sounds like grand Dieu !  - Great God !)

Fun fact: Lagrange derives from la grange, which in french exactly means: the barn.

https://en.wikipedia.org/wiki/Joseph-Louis_Lagrange

In consequence I think the astrodynamicists like Edward Belbruno or the late Robert Farquhar (and many others) should be called "barnstormers" - like the daredevil aviators from the 1920's.

[Robspace54]

I could not determine which S-IVB this image is of, but I imagine that the AS12 S-IVB paint would have yellowed from long exposure to solar UV.

[saturnapollo]

Apollo17.

[Comga]

I could not determine which S-IVB this image is of, but I imagine that the AS12 S-IVB paint would have yellowed from long exposure to solar UV.

Regardless of which Apollo mission this stage is from, the photo would have to have been taken shortly after it was jettisoned.
This photo was not taken from astronautical distances decades after the mission.
It is not if the Apollo 12 third stage after it’s travels around the Sun.

[AS_501]

Would that the Apollo 12 S-IVB could be retrieved to study the long-term exposure to the space environment away from the Earth and Moon.  The observed effects would be different in some ways from LDEF or the Apollo LM descent stages.