How we’ll up­grade our bod­ies to colonise the cos­mos

BBC Earth (Asia) - - Front Page -

“with­out the load­ing of grav­ity your skele­ton loses cal­cium and be­comes brit­tle, and your mus­cles de­te­ri­o­rate and shrink”

You might have thought from watch­ing videos of as­tro­nauts aboard the In­ter­na­tional Space Sta­tion (ISS) that space­ships were pretty be­nign en­vi­ron­ments. Float­ing around in mi­cro­grav­ity looks like a lot of fun, and as you’re iso­lated from the rest of the hu­man pop­u­la­tion you’re ef­fec­tively quar­an­tined against catch­ing flu or any other trans­mis­si­ble disease. But in fact, space is pretty harm­ful to the hu­man body. We evolved as so­cial an­i­mals un­der the con­di­tions on the Earth, and trav­el­ling be­yond the planet has a num­ber of neg­a­tive ef­fects on the body and mind.

So what are the main risks en­coun­tered by space­far­ers, and what does the lat­est re­search have to say about how to solve these prob­lems for long-du­ra­tion mis­sions in the fu­ture?


Freefalling around the Earth in or­bit, or coast­ing through in­ter­plan­e­tary space on your way to Mars, gives you the sen­sa­tion of weight­less­ness. You’re still mov­ing un­der grav­ity, but it doesn’t load your body, and this has a whole host of knock-on ef­fects. For ex­am­ple, your in­ner ear can no longer help you ori­en­tate your­self, and the re­dis­tri­bu­tion of bod­ily flu­ids causes your face to puff up and your eye­balls to dis­tort.

But the long-term ef­fects are more con­cern­ing. With­out the load­ing of grav­ity, your skele­ton loses cal­cium and be­comes brit­tle (like with os­teo­poro­sis). Your mus­cles, es­pe­cially those in­volved in sup­port­ing your spine and hold­ing you up­right, de­te­ri­o­rate and shrink. Plus, your heart be­comes weaker when it doesn’t have to pump blood up­wards. While you re­main in a weight­less en­vi­ron­ment, this isn’t too much of a prob­lem – and in some senses your body is be­ing adap­tive in re­mod­elling it­self to life with­out grav­ity – but it can be hugely de­bil­i­tat­ing or dan­ger­ous when you re­turn to the sur­face of the

Earth or any other planet.

In the long-term fu­ture, the so­lu­tion might sim­ply be to gen­er­ate ar­ti­fi­cial grav­ity for your­self on a space­ship. If you ro­tate large sec­tions of a space­craft – giant turning wheels or cylin­ders – you can ex­ploit the cen­tripetal force from the in­side wall that keeps you mov­ing in a cir­cle to cre­ate an ap­par­ent grav­ity. We’re well fa­mil­iar with this idea from sci-fi films like 2001: A Space Odyssey, or more re­cently Pas­sen­gers, but the prob­lem is that the en­gi­neer­ing re­quired to build such a large ro­tat­ing struc­ture in space is pretty chal­leng­ing.

In the shorter term, space­craft might in­cor­po­rate mini-cen­trifuges. These wouldn’t be large enough to walk around or work in­side, but they would fit within the ex­ist­ing struc­ture with just enough space for a sin­gle as­tro­naut at a time. Spin­ning rel­a­tively quickly, these could gen­er­ate ar­ti­fi­cial grav­ity for short bursts while the as­tro­naut ex­er­cises. The idea is that grav­ity could per­haps be dosed in small amounts; just enough to pre­vent the body de­te­ri­o­rat­ing in space. David Green and his col­leagues at King’s Col­lege Lon­don have been work­ing with MIT and the Euro­pean Space Agency (ESA) on an­other so­lu­tion, the ‘grav­ity load­ing coun­ter­mea­sure skin­suit’. This skin­suit looks a bit like a triath­lete’s sleeve­less wet­suit, and

in­cor­po­rates a spe­cific weave of elas­tic ma­te­rial that pro­vides a graded ten­sion be­tween the feet and shoul­ders. This elas­tic load­ing on the body sim­u­lates 1g (Earth’s grav­ity) and is de­signed to help pre­vent stretch­ing of the as­tro­naut’s spine, mus­cle and bone wast­ing. The sci­en­tists are run­ning tests on their skin­suit on Earth, and it was re­cently worn on the ISS by Andreas Mo­gensen, the first Dan­ish as­tro­naut.

What about de­vel­op­ing drugs that could help make ex­er­cise in zero-g more ef­fec­tive or stop mus­cle loss al­to­gether by block­ing the de­gen­er­a­tive process? Nathaniel Szewczyk, at the Uni­ver­sity of Not­ting­ham, has been in­volved in re­search along ex­actly these lines. But rather than ex­per­i­ment­ing on hu­man test sub­jects, he has been us­ing mi­cro­scopic worms.

Caenorhab­di­tis el­e­gans is a ne­ma­tode worm, but it has two dif­fer­ent mus­cle types that are sim­i­lar to the heart mus­cle and skele­tal mus­cles used for move­ment in hu­mans. As C. el­e­gans is such a sim­ple an­i­mal we’ve al­ready been able to work out ex­actly how it de­vel­ops, and we’ve also se­quenced its whole genome. This means that C. el­e­gans is a per­fect test case for help­ing sci­en­tists un­der­stand the ef­fects of mi­cro­grav­ity on an­i­mal bod­ies, and they’ve now been flown on a num­ber of space mis­sions as mi­cro­scopic as­tro­nauts. Szewczyk and his col­leagues have found changes in the cel­lu­lar pro­duc­tion of around 100 pro­teins dur­ing space­flight, many of them in­volved in mus­cle­build­ing. “These ex­per­i­ments with C. el­e­gans in Earth or­bit have en­abled us to track how the ex­pres­sion of dif­fer­ent pro­teins re­sponds to weight­less­ness, and so ex­plore the ge­netic ba­sis be­hind de­te­ri­o­ra­tion of the body’s mus­cles,” he says. “In our cur­rent ESA flight we’re specif­i­cally test­ing a few drugs to see if they can re­duce mus­cle loss in worms.”

So the hope is that in the fu­ture, as­tro­nauts will be able to pop a pill to help pro­tect their heart and mus­cles while in space.

FAR LEFT: The Dainese BioSuit has been de­signed for trips to Mars

LEFT: Dan­ish as­tro­naut Andreas Mo­gensen tries out the ESA skin­suit on the ISS

RIGHT: In 2001: A Space Odyssey, ap­par­ent grav­ity was pro­vided by a ro­tat­ing wheel

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