The next chapter in cosmic exploration is beginning to take shape: NASA engineers have proposed a space station that, if Congress approves its funding, would begin to orbit the Moon in about a decade. One main goal is to develop the infrastructure and experience of landing humans on Mars one day.
The Deep Space Gateway (DSG) project is likely to be a collaboration between the US UU., Russia and other international partners. It would be located in a lunar orbit about 240,000 miles from Earth, 1,000 times farther than the International Space Station (ISS). This would place it outside the protective magnetic field of the Earth, allowing scientists to measure the effects of deep-space radiation on humans and instruments. The station could also be a relay point for expeditions to the surface of the moon. Plans for humans or robots carrying lunar landers, or both, are still under discussion. NASA officials say that astronauts and construction materials could be transported to lunar orbit in four Orion rocket launches sometime after 2019.
But the proposal has its criticisms. After the space shuttle disaster Columbia in 2003, NASA promised to launch humans separately from the cargo, a principle that the DSG plan seems to violate. Some space policy experts warn that lunar operations are expensive and could be a distraction from Mars rather than a step towards it. Others question whether the planned one-month stays for the new station would teach NASA enough about how the human body responds to deep space, since the trip to Mars requires at least six months. A lunar engineer has expressed concern about intermittent and unpredictable solar storms. Such events could subject astronauts to dangerous levels of radiation in the absence of a shield, such as a thick layer of water, that would have to be incorporated into the design of the space station.
Despite these reservations, many experts agree that the moon could be a crucial training and testing ground, not only for astronauts, but also for Earth-based operations and equipment to support space flights manned "In my opinion, it is clear that you first have to do the lunar exploration," says David Kring, a scientist at the Lunar and Planetary Institute in Houston, who has worked extensively on the planning of the lunar mission. Humans have not landed on the moon since the 1970s. The current generation of space flight engineers needs to learn to work on an extraterrestrial surface, says Kring, "and the best place to do it is in three days."