NASA and other space agencies have started planning a return to the Moon under the mandate given by President George W. Bush. A new, more versatile Space Transportation System will be needed, and calls for proposals are now out. The first landings will probably be more like the Apollo ones but in time it is hoped that a permanent (or at least long term) lunar base will be established where astronauts can subsist and explore for extended stays.
Four things are essential in making a safe, flexible base:
a means of replenishing oxygen;
water;
souurce(s) of power;
suitable shielding from extralunar radiation.
Oxygen, in principle, can be extracted from the lunar silicate minerals but a reliable, practical means of obtaining this is yet to be worked out (in May 2005, NASA issued a Call for Proposals for innovative solutions). Water can, in part, be recycled from sources (such as astronaut urine) brought with the explorers. But, if substantial water is found near the polar regions, extraction should not be too difficult - so the base would likely be located at high latitudes.
Power requirements can be met with nuclear generators and/or with efficient solar arrays.
Shielding may prove difficult since the base units (presumably separate from the landing craft) need to be made of light materials. Still, as experience is gained, that should aid in selecting radiation-absorbing outer components of the base.
There is another strong argument for selecting polar regions for the base besides the water potential. Placing astronomical observatories at either or both poles would allow almost ideal observing conditions (better than the present Hubble Space Telescope since systems and components would be state-of-the-art). Nearly all of both celestial hemispheres would be accessible, whereas locating an observatory at lower latitudes would have result in some light interference from earthshine (light reflected from the Earth). But exploration would be curtailed somewhat by dependence on a polar station.
The establishment of a Moon base will be a giant step in mankind's renewal of space exploration. Among its benefits, it could serve as the launching site for a trip to Mars. On September 18, 2005 NASA made its first public announcement of how its approach to how the Moon landings (and probably Mars afterwards) will be made. There is a striking similarity to the Apollo approach in that landing craft will be on a large multistage rocket, with the main thrust section falling back to Earth after sending the manned vehicle on its journey. This vehicle and a companion for sending material to build a lunar base is shown at the right, with other existing vehicles side by side for comparison. NASA Lunar Flight Plan.
Ambitious and exciting as this master plan appears to be, there are many obstacles that could delay or even cancel its execution, including consequences from the current global financial problems. The earliest readiness date for a landing is set at 2018. A crew of 4 will descend on the Crew Exploration Vehicle (CEV) and stay for (at least) a week. Over time, the stay will be longer as the astronauts build a lunar base capable of sustaining the mission for weeks to months. This will provide the needed experience for prolonged missions that would take place on Mars at a later time. When the crew returns to Earth in the detached capsule, it will have the capability of landing either on land or at sea. If no serious damage occurs, the CEV can be used up to 10 flights.
An estimated cost for the first landings is $104 billion dollars. The estimated cost for the International Space Station is $100+ billion. These budgets are likely to be exceeded, since as a rule, such estimates are nearly always low. Additional money must be appropriated if the undetaking is to happen. Budgetary deficits (exacerbated in 2005 by the Katrina disaster and the current finacial meltdown) can affect the schedule. Some monies will become available for the program after the Space Shuttle program is retired in 2010. But, NASA, and even its critics, together recognize that a Moon exploration resumption followed by Mars exploration (which would gain from the lunar experiences) may be vital to keeping the American space program healthy enough to press forward, rather than wither and diminish by loss of dedicated personnel.
And America is now in a space race with China who have announced that they plan to buld a Moon base by 2025. Perhaps the renewed competition will spur both nations into acting sooner rather than later, and those of us who watched the Moon landings in the 60s and 70s may see the dream of manned space exploration rekindled in our lifetimes.
