Many Technical Problems Burden Lunar Base Goal
HOUSTON — Establishing a permanent lunar base in the early 21st Century has become an unofficial goal of America’s space community, but scientists say substantial technical problems have yet to be overcome.
The difficulties range from preventing pollution of the moon’s atmosphere to shielding the base inhabitants from deadly levels of radiation.
At the recent NASA-sponsored “Second Symposium on the Lunar Bases and Space Activities of the 21st Century,” which brought together representatives from NASA, the space-related private sector and academia, scientists expressed optimism about the future of lunar bases.
But they acknowledged that earthlings do not yet have the technical ability to overcome some of the problems.
Proposals currently envisage an initial lunar base of about eight people, but former NASA director Hans Mark told the symposium this could grow to as many as 10,000 by the year 2050.
Whether large or small, the colony presents a threat to the delicate moon environment. Scientists cited a real danger of creating a man-made polluted atmosphere that would diminish the moon’s value for research and astronomy.
The pollution would come from the general hustle and bustle of lunar life which would spread moon dust into the atmosphere, and from the comings and goings of rockets shuttling supplies and people from Earth.
Effect on Atmosphere Noted
During the Apollo missions almost two decades ago, measurements showed that the gases and dust associated with a single landing of the lunar module doubled the mass of the moon atmosphere for months, according to Alan Binder of Lockheed Engineering and Management Services Co. Inc.
Unlike the Earth, where weather and wind currents cleanse contaminants from the air, the moon’s atmosphere is cleared only by solar winds and evaporation.
This works fine for the bit of dust normally rising from the moon’s surface but activity at even modest-size lunar bases would overwhelm these natural forces, according to a study by a University of New Mexico scientific team.
A smoggy “artificial atmosphere” of dust and spent rocket fuel could last hundreds of years, the scientists said.
To reduce pollution, they recommended development of new methods of propulsion, such as electromagnetic launchers or laser systems.
Another major problem confronting lunar base planners is radiation. On Earth, the atmosphere prevents most space radiation from reaching the surface, but on the moon there is no such barrier.
Space travelers, whether living on the moon or flying among the stars, must accept that they will be exposed to radiation levels considered unacceptable on Earth, scientists said.
Annual Limit Five REMS
The exposure limit for people who work around radiation sources on Earth is 5 REMS a year, a REM being a unit by which radiation is measured. By comparison, someone living in Houston is exposed to 0.1 REMS a year or in Denver, 0.2.
During a solar flare on the sun, radiation levels on the moon will reach a lethal 500 REMS, said Stuart Nachtwey of NASA’s Johnson Space Center.
To reduce radiation exposure, lunar base planners say moon residents will live in structures that are either buried beneath the surface or covered with soil.
That will provide sufficient protection indoors, but if the colonists are outside working when a solar flare erupts, they would be in great danger.
The solution lies in either predicting when the flares on the sun occur or shielding the inhabitants at all times.
At present, Nachtwey said, flares cannot be predicted. And, according to Joseph Angelo, director of advanced technology for EG & G Inc., there is no practical way at present to shield space inhabitants when they are not inside.
“The radiation issue will be one of the major issues we’ll have to wrestle with if man is to wander through the solar system as a permanent inhabitant,” said Angelo.
Radiation poses problems in a less obvious way too. The space community hopes that ultimately space colonies will become more like Earth in the sense that men and women can live, get married and have families there.
But, according to Angelo, having children in space may not be feasible.
“You have the problem of fetal development. A fetus in the first three months can be seriously affected by as little as 10 REMS of radiation,” he said. That means the chances for genetic mutations are high, perhaps too high to be acceptable.
Unless the problem is solved, long-term space settlement could be an elusive goal, Angelo said.
One symposium participant, Thomas Ciesla of the space consulting firm Outer Space Environments, said the lunar base may face a problem familiar to any earthling: where to put the trash.
The initial temptation for Moon colonists will be to drop their garbage in the nearest crater, he said.
While that might work for a while, Ciesla said, the inhabitants would soon find that their base, like the early ones in Antarctica, would quickly become ringed by trash.
A better solution, Ciesla said, would be to put their trash in the moon’s perpetual shade areas, which are totally dark and therefore out of sight.
