NEARLY two years after President George Bush made a return to the moon a key objective, NASA has come up with an outline of where on the moon astronauts might land. Its list of 鈥渉igh priority鈥� landing sites unveiled on 19 September reveals not only the diversity of the lunar surface, but also the conflicting motivations that fuel the drive to return to Earth鈥檚 companion in space.
鈥淲e convened a large group of lunar scientists and asked them what the sites of interest were,鈥� said NASA administrator Michael Griffin as the list was announced. 鈥淭hey ranged from the poles to the equator.鈥�
The choices include old favourites like the Mare Tranquillitatis to new ones on the far side of the moon. 鈥淭hey indicate a variety of scientific and operational challenges,鈥� says planetary scientist Paul Spudis of Johns Hopkins University in Laurel, Maryland.
Advertisement
鈥淧eople think we have been there and done that, but there is so much we don鈥檛 know about the moon鈥�
One motivation for returning to the moon is quite simply to learn more about it. Sites chosen for this purpose include the geologically diverse Aristarchus plateau, which was the likely target of the cancelled Apollo 18 mission. Other sites (see Map) would never have been accessible to the Apollo landers because they are too far from the lunar equator.
But besides the sites that promise to reveal secrets of the moon鈥檚 geological history, there are others that are valuable for the resources that might support future human efforts on the moon and beyond. 鈥淭o my mind, the interesting question is: do you focus on science or do you focus on developing the moon for some other purpose,鈥� says Michael Duke, a lunar resources expert at the Colorado School of Mines in Golden, Colorado.
That question could affect not only the selection of landing sites but the number of sites that astronauts ultimately visit. A scientific survey would most likely benefit from sampling as diverse a set of locations as possible. But the goal of using the moon as a staging post for voyages across the solar system, which is also part of the Bush vision, may push NASA towards establishing a moon base. That would require repeated visits to the same location.
Whether lunar science or interplanetary travel turn out to be the driving force, the sites chosen for the next generation of lunar visitors will be strongly influenced by a trio of powerful satellites heading to the moon in the next few years. India鈥檚 Chandrayan-1, Japan鈥檚 Selene and NASA鈥檚 own Lunar Reconnaissance Orbiter are all scheduled for launch by 2008. Together they will map the lunar surface from above with vastly improved resolution, and help to clarify key questions such as whether or not there is a significant quantity of ice at the lunar poles.
But for many lunar scientists, the landing site hardly matters. It is getting there that is all-important. 鈥淧eople think we have been there and done that, but there鈥檚 so much we don鈥檛 know about the moon,鈥� says Mark Robinson of Northwestern University in Evanston, Illinois. 鈥淔or at least the first few years you鈥檙e going to get good science no matter where you land.鈥�
