For the last 4 months, until May 27th, an armless, legless torso has been aboard the International Space Station, so that scientists could learn more about the space radiation that presents a challenge to having a human presence in space.
The torso provided a real-world confirmation that the computer models previously used to look at space radiation were accurate, so now they can be confident in using the models to plan future space missions.
“Short lunar missions are fine,” [Francis] Cucinotta [of NASA's Johnson Space Centre] says, “but living in a lunar habitat for 6 months starts to be problematic. We’re going to have to do a really good job with radiation shielding and perhaps medical countermeasures to have 6-month missions.”
Mars will be even tougher, these models suggest. Some scenarios call for missions that would last 18 months or more. “Right now there’s no design solution to stay within safety limits for such a Mars mission,” Cucinotta says. “Putting enough radiation shielding around a spacecraft would make it far too heavy to launch, so we need to find better lightweight shielding materials, and we probably need to develop medical techniques to counteract damage to cells caused by cosmic rays.” He notes that one of the biggest obstacles to progress in this area is “uncertainty in the types of cell damage deep cosmic ray exposure can cause. We still have a lot to learn.”