NASA's tips for revisiting lunar landing sites (someone at NASA has a sense of humour)

Last week I read a document called NASA's Recommendations to Space-Faring Entities: How to Protect and Preserve The Historic and Scientific Value of U.S. Government Lunar Artifacts.

Scientists at NASA wrote the 93-page tome due to interest by new organizations in visiting the moon. Some nations like China and the U.S. are planning lunar missions, but there's also private interest. For instance, the Google Lunar X Prize has 26 teams competing to get a robot to the moon by 2015, have it drive around for 500 metres (or more), and send HD imagery and video back to earth. Winning teams can qualify for $30 million dollars in prizes!

The NASA report - if you can get through all 93 pages - is fascinating. It has all kinds of recommendations for preventing damage to existing moon artifacts. For instance, lunar spacecraft should fly tangentially (aka, beside) existing lunar landing sites instead of over top of them, to avoid kicking up corrosive moon dust or spitting down unburned propellant - either of which could damage the sites and artifacts. Landing too close to a scientific site could cover LRRRs - Laser Ranging Retro-Reflectors - in moon dust. We bounce lasers off LRRRs from the earth and measure how long it takes for the laser to bounce back. This measures the distance between the earth and the moon, and also tests Einstein's Theory of Relativity. These experiments don't work with the mirrors covered in dust!

NASA says that sites of utmost historic importance (Apollo 11 and Apollo 17, the first and last manned visits of the Apollo era) shouldn't be visited at all - they are rightfully considered important milestones for humanity:

"Project Apollo in general, and the flight of Apollo 11 in particular, should be viewed as a watershed in human history and humanity. It was the first instance in human history in which emissaries from this planet visited another body in the solar system. It represented the culmination of years of effort, the significant expenditure of life and resources, and the opening of a new age in human history. The site of that first landing requires preservation; only one misstep could forever damage this priceless human treasure."

NASA says it is permissible to visit the other Apollo sites (12, 14-16). In fact, NASA helpfully supplies a 20-page appendix of items they'd like new moon visitors to study, to determine how they've changed over 40 years on the surface of the moon: thermal paint, gears and dials, bags filled with food and human waste, even the nylon on the iconic lunar American flags. NASA also suggests some experiements, if visitors are so inclined. Here's where they hide their joke (page 52):

"Item J: Push biggest possible rock over edge of crater or rille
Tracks of boulders rolling down slopes have been used to infer geotechnical properties of the surface layer. The large boulder at [lunar site] A17 was sampled because a track implied that it had been part of an outcrop much higher up on the massif. A17 is also the site of an avalanche that is thought to be the result of an (hypothetical) impact on the far side of the massif. Soils that develop on slopes may well be metastable such that avalanches could be easily triggered. Also, it would be fun to push a big rock over a cliff. It is a question whether a rover could push a rock and also observe the descent, but it is worth thinking about." (emphasis added)

Lol, awesome. It's so cool all of this lunar stuff is happening in my lifetime.

NASA Report