The fact that many tonnes of spacecraft and rocket-body debris have been crashed onto the Moon is not widely known, even among the community of space professionals (that is, engineers, scientists, and other individuals engaged in space-related activity as a profession). Moreover, the majority of those who know about the impacts fail to recognize them as a problem. If it was not considered pollution in the 1960s, they ask, why should it be now? After all, the Moon's surface shows the result of meteor impacts that have occurred throughout geological time. What difference will a few more make?

Even the most hardened space environmentalist (should such an individual exist) might concede that a few spacecraft impacts on a body the size of the Moon have a relatively small effect, certainly compared with the megaton boulders that formed the impact craters we see from Earth. But simply ignoring them sets a dangerous precedent for the future of lunar exploration.

It is clear from the table of impacts that the practice of intentionally crashing spacecraft on the Moon did not cease with the Apollo impacts of the 1970s. Japan's Muses A/Hiten spacecraft crashed in 1993, and the impact of its sister craft Hagoromo is assumed, whereas as recently as 1999 NASA decided to target Lunar Prospector at the Moon's south pole.

In fact, when all of the spacecraft, propulsion units, and related debris that have landed or crashed onto the Moon are considered, the total number exceeds 80,7 and amounts...