The problems of flying to Mars
Comment envoyer une mission habitée vers Mars ?
Depuis le début des années 1960, l’envoi d’une mission habitée vers Mars constitue l’un des enjeux majeurs de l’exploration spatiale. Grâce aux engins automatisés, nous disposons aujourd’hui de nombreuses données sur la planète rouge. Mais si la perspective d’envoyer des hommes sur Mars semble plus proche que jamais, les défis à relever pour accomplir cet exploit restent colossaux.
Sending people to Mars is a daunting prospect. It would take astronauts at least nine months to get there, they might spend a year on the planet itself, and they would then spend another nine months on the journey home. During that time they would be exposed both to high radiation levels and to the increasingly irritating tics and habits of their fellow crew. It is hard to say which of these would be more likely to result in someone’s death.
2. But though the scientific value of such a mission is questionable, as a propaganda stunt it would be unequalled. America’s space agency, NASA, is therefore looking into ways of preserving both the physical and the mental health of putative Martian voyagers.
THE TWIN STUDY
3. One such effort is the NASA Twin Study, full results of which are to be published in the next few months. The NASA Twin Study took advantage of identical-twin astronauts Mark and Scott Kelly. Scott was launched to the International Space Station in 2015 for a 12-month tour as station commander. Mark remained on Earth for the same period. Both men gave regular samples of blood, urine and so on for scientific analysis. Both also undertook batteries of physical and mental tests. Not knowing exactly what might change in the men’s bodies, ten teams of researchers spread across America combed through the samples and results to track as many molecular, cognitive and physical changes as possible.
4. As Chris Mason of Weill Cornell Medical College said at this year’s AAAS meeting, these teams found lots of surprises. Dr Mason compared the operation of Scott’s genes with those of his brother back on Earth. Genes in Scott’s body associated with the immune system, he found, became highly active. This was also true of the cellular machinery associated with repairing DNA. “It’s almost as if the body is in high alert,” he said, which would not be surprising given the stresses of space flight. Another surprising observation was the presence of a lot of mitochondrial fragments in Scott’s blood. Mitochondria are
tiny structures within a cell which release energy from sugar. They tend to get into the bloodstream only when cells are damaged or dying of stress.
5. From Scott’s point of view, the good news is that almost all of the thousands of changes catalogued in his body reverted to normal soon after he returned to Earth. This suggests that, for the most part, a healthy human body recovers well from the stress of space flight. In the coming years NASA is planning dozens more long-duration tests on people, including tracking astronauts heading to the moon in preparation for future trips to Mars.
TEAMWORK
6. Understanding how teams function, how they go wrong and how to prevent social problems will be a critical element of any successful mission to Mars. Such a mission might involve half a dozen people, perhaps from different cultures, cooped up together for some three years in a space no bigger than a typical family home. There would be no emergency-escape strategy. One of the attempts being made to model these conditions is that of Noshir Contractor, a behavioural scientist at Northwestern University, in Illinois. As he told the meeting, he has been studying the dynamics of groups of people isolated for long periods in the Human Exploration Research Analogue, a facility at the Johnson Space Centre in Houston, Texas. Here, volunteers are locked away for up to 45 days at a time on mock space missions. They are poked and prodded, physiologically and psychologically, and monitored day and night.
SEND IN THE CLOWN
7. Something researchers have already learned from these experiments is that certain personality characteristics are essential to helping groups work well together. A good group needs a leader, a social secretary, a storyteller and a mixture of introverts and extroverts. Intriguingly, by far the most important role seems to be that of the clown. According to Jeffrey Johnson, an anthropologist at the University of Florida who has spent years examining relations between people in Antarctic crews overwintering at the South Pole, the clown is not only funny, he is also smart and knows each member of the group well enough to defuse most of the tensions that might arise during long periods of close contact. This sounds rather like the role of a jester in a royal court. The clown also acts as a bridge between different groups of people. In groups that tended to fight most or to lose coherence, Dr Johnson found, there was usually no clown.
For the most part, a healthy human body recovers well from the stress of space flight.
8. Building a perfect team for a long mission to Mars will not be easy, says Dr Contractor, and there is much to learn yet. But if human beings are ever to travel to other parts of the solar system, then understanding the behaviour of those who will be crewing the hardware should make a successful voyage far more likely.