Lunar Orbiter 1 - first U.S. spacecraft to orbit the Moon

[Secular_Response]

I just stumbled across this fascinating Wikipedia article on Lunar Orbiter 1 and thought it was worth sharing. There are plenty of details, enough so that a simulated mission could be easily accomplished. There's even a link to a pdf of the 1967 NASA performance report.

Some interesting facts:

- Earth parking orbit Aug. 10, 1966 at 19:31 (UTC). The Trans lunar injection burn occurred at 20:04. Nicely timed - only 33 minutes before TMI.

- Took the first two pictures of the Earth ever from the distance of the Moon. 1,2

- Crashed into the Moon's far side on October 29, 1966 on its 577th orbit. Running low on RCS fuel. Not kidding.

http://en.wikipedia.org/wiki/Lunar_Orbiter_1

[deadshot462]

Those look like Jeb's sunglasses in that middle sphere, maybe it's the window he was looking out from.

Explains a lot.

[PakledHostage]

What I found even more interesting was the related article about the Lunar Orbiter Image Recovery Project. I guess this was big news in some circles a few years back, but I don't remember hearing about it.

You've got to admire the LOIRP team's dedication! It would have been so easy to give up.

[BeefTenderloin]

How did it's orbit degrade when there was no atmosphere?

[Vanamonde]

Atmosphere is the main cause of orbit decay, but not the only one. Solar wind also has a small but cumulative effect. And at least in the case of Mars, the density of the planet varies so much that gravity is actually a little stronger at some points in an orbit, so spacecraft there must continually adjust their trajectories to maintain a steady orbit. I imagine tidal effects also come into play.

[PakledHostage]

I understood from the article that they intentionally crashed Lunar Orbiter 1 into the dark side of the Moon because it was low on fuel and to free up radio bandwidth for the Lunar Orbiter 2 probe.

The Moon also causes orbital perturbations because its gravitational field is not uniform. Check out NASA's current GRAIL mission for more on this. The Wikipedia article about the GRAIL mission may not be the definitive source, but it is a good place to start.