As­tro­phys­i­cal Fit­ness

Air & Space Smithsonian - - Front Page - BY GUY GUGLIOTTA

Where does it hurt? Af­ter a long visit to space, ev­ery­where.

A YEAR IS A LONG TIME TO SPEND as a hu­man satel­lite cir­cling Earth in zero grav­ity. But if as­tro­nauts didn’t like it, they wouldn’t sign up, right? “Don’t get the idea that there was a short­age of can­di­dates,” says Scott Kelly, a short guy with a shaved head and a stocky build. “A lot of peo­ple wanted to do it.”

And Kelly won the prize. In late March, he and cos­mo­naut Mikhail Kornienko will fly to the In­ter­na­tional Space Sta­tion, or­bit­ing 230 miles above Earth, and re­main aboard for a full year. Four Rus­sians have al­ready spent an un­in­ter­rupted year in space, but none since Mir in 1999. Kelly will be the first Amer­i­can to do it. Hav­ing logged a cu­mu­la­tive six months in space on three prior mis­sions, he will re­turn to Earth with more than 500 days in or­bit.

That fame may come with a price. Back­aches, bone loss, lousy sleep, loss of bal­ance, headaches, mus­cle atro­phy, nau­sea, ra­di­a­tion ex­po­sure, rashes: There is al­ready a well-thumbed com­pen­dium of woes that have plagued vis­i­tors to space. Says Kelly, “You feel bad for a month, and I’ve never felt com­pletely nor­mal.” For as­tro­nauts, phys­i­cal discomfort is an oc­cu­pa­tional hazard scarcely worth men­tion­ing when set along­side the un­par­al­leled high of be­ing in space. But when does that discomfort be­come too much?

NASA, its Rus­sian coun­ter­part Roscos­mos, and the other sta­tion part­ners want to know what would hap­pen to your body and mind if you were to travel to Mars—a round trip ex­pected to take nearly three years. (That’s an es­ti­mated six months’ tran­sit time in each di­rec­tion, plus 18 to 20 months on Mars or or­bit­ing it while wait­ing for it to re­align with Earth.) A full year in space does a bet­ter job im­i­tat­ing the ef­fects of so long a jour­ney than the cur­rent six­month sta­tion so­journs. The idea is to see if peo­ple who stay in space longer get beat up worse, or if the harm oc­curs mainly in the early part of the mis­sion.

Sticks and Kid­ney Stones

NASA has deemed some of the usual sus­pects to be un­der con­trol, at least for six-month In­ter­na­tional Space Sta­tion mis­sions. Two and a half hours of ex­er­cise per day ap­pears to halt the bone loss and mus­cle atro­phy. Drugs con­trol nau­sea, and oint­ment helps the rashes. There are sleep­ing pills and pain pills.

But for a Mars mis­sion, NASA has iden­ti­fied 32 “ma­jor” risks to hu­man health and per­for­mance. These in­clude ev­ery­thing from ra­di­a­tion poi­son­ing, which will take a lot more than a se­ries of year-long ISS vis­its to un­der­stand, to on­board fires or loss of cabin pres­sure, which are mostly about bad luck.

NASA’S Hu­man Re­search Pro­gram, based at Hous­ton’s John­son Space Cen­ter, stud­ies the other stuff: “Are there trou­bling trends out there?” asks Mark Shel­hamer, the Re­search Pro­gram’s chief sci­en­tist. (There are.) “Is there a smok­ing gun?” he asks. (Maybe.) NASA sci­en­tists hope Kelly’s year-long ISS mis­sion—and another five af­ter that—will help them to find out.

First are the “per­ni­cious” things, Shel­hamer says. Some as­tro­nauts get post-flight kid­ney stones, and “the preva­lence is trou­bling.” The in­ci­dence was higher af­ter six-month ISS mis­sions than af­ter twoweek Space Shut­tle de­ploy­ments. Kid­ney stones, as any­one who has ever had one knows, are no fun.

High con­cen­tra­tions of cal­cium ox­alate in the blood­stream cause stones to form in the kid­neys. Bone loss might be the cul­prit, but NASA’S cur­rent best guess is that the high level of car­bon diox­ide in the ISS air sup­ply is to blame: It’s 10 to 20 times what we breathe on Earth.

“CO2 is acidic,” Shel­hamer says. “One way your body deals with it is by buf­fer­ing your blood­stream with cal­cium.” If a lim­ited time in space causes kid­ney stones, more time might make them more likely.

Also on sci­en­tists’ to-do list are what Shel­hamer calls “prov­ing neg­a­tives.” Have the prob­lems of bone loss, dif­fi­culty with bal­ance, and mus­cu­lar atro­phy truly been solved? Longer flights of­fer re­searchers the chance to find out.

Most im­por­tant, how­ever, are the po­ten­tially dan­ger­ous im­pon­der­ables—“the things we don’t feel good about,” as Shel­hamer puts it—whose causes and ef­fects re­main un­clear. In par­tic­u­lar, pathogens and the hu­man im­mune sys­tem in­ter­act dif­fer­ently in mi­cro­grav­ity. “Some pathogens in­crease in vir­u­lence, and some don’t,” Shel­hamer says. “Some as­pects of the im­mune sys­tem de­te­ri­o­rate, some don’t.” The great fear is that at some point the “lines cross”: A pathogen be­comes stronger as an im­mune re­sponse grows weaker. “We haven’t seen it yet, but will we see it af­ter eight months?”

The Vi­sion Thing

The high­est-pri­or­ity prob­lem, how­ever, is im­paired vi­sion, a con­di­tion that re­turn­ing crew mem­bers have re­ported with in­creas­ing fre­quency. One U.S. as­tro­naut dis­cov­ered dur­ing reen­try that he couldn’t read the check­list for land­ing. (For­tu­nately, crew mem­bers know the pro­ce­dures vir­tu­ally by heart.) For years, re­searchers have re­garded the vi­sion prob­lems and other mi­cro­grav­ity ef­fects as mi­nor and usu­ally rev­ersible. On Earth, grav­ity pulls flu­ids to a per­son’s lower body. In space, flu­ids float upward

with a num­ber of un­pleas­ant ef­fects. Any­one who has seen as­tro­nauts on TV no­tices their swollen faces. Fluid mi­gra­tion is also a likely cause of headaches. Eye­sight is so of­ten im­paired that the sta­tion stocks a sup­ply of drug­store glasses with dif­fer­ent mag­ni­fi­ca­tions.

Un­der­stand­ing the ef­fects of space travel is com­pli­cated by the pa­tient pop­u­la­tion be­ing stud­ied. Most as­tro­nauts are be­tween 35 and 55 years old, clus­ter­ing in their early to mid-40s, the age when a per­son’s eye­sight usu­ally heads south. For a long time, any oc­u­lar discomfort as­tro­nauts re­ported in or­bit seemed to van­ish once they came home.

And then it didn’t. “Right now we have cir­cum­stan­tial in­for­ma­tion” from as­tro­nauts re­port­ing vi­sion im­pair­ment, usu­ally far­sight­ed­ness, “that has lin­gered,” Shel­hamer says. “You have it af­ter [a stay of] six months. Maybe it’s no worse af­ter a year, but we don’t know that.”

Vi­sion, in part, is what got Kelly the cov­eted po­si­tion as America’s first year-round as­tro­naut. The can­di­date had to have com­pleted a previous space sta­tion mis­sion, had to have served as a mis­sion com­man­der, had to be a qual­i­fied space­walker, and had to have been free of se­ri­ous vi­sion prob­lems. “That cut it down to three or four peo­ple,” Kelly says. “And one of them is my backup.”

Kelly ac­knowl­edges that he, like most as­tro­nauts, has had “vi­sion is­sues” on all three of his flights. In 1999 he was 35 and had “bad mid­dle vi­sion” for a while. Eight years later, when he com­manded STS 118, he was al­ready wear­ing read­ing glasses. And in 2010-2011, his eye­sight “gen­er­ally changed in a neg­a­tive way” while he was aboard the space sta­tion, but cor­rected three months af­ter his re­turn. At present, Kelly, who turns 51 on Fe­bru­ary 21, wears glasses for dis­tance.

Kornienko, 54, is also a space sta­tion vet­eran and a space­walker with only four fewer days in or­bit than his crew­mate. Drafted out of high school into the Soviet army, he be­came a para­trooper, then served as a Moscow po­lice­man while he went to en­gi­neer­ing school. He joined the cos­mo­naut corps in 1998, the same year Kelly be­came an as­tro­naut. He does not wear glasses, Kelly says, but may use con­tact lenses.

Since vi­sion im­pair­ment came to the at­ten­tion of re­searchers, sci­en­tists have floated sev­eral the­o­ries as to its cause: Blood­stream tox­ins might put pres­sure on the eye. Im­proper tech­nique dur­ing ex­er­cise ses­sions might in­crease fluid pres­sure in the brain. And as al­ways, ra­di­a­tion re­mains a sus­pect.

But NASA’S work­ing hy­poth­e­sis is that when weight­less­ness dis­places fluid sur­round­ing the brain, some of the ex­cess mi­grates down the op­tic nerve sheath un­til it presses into the back of the eye. This can have grim im­pli­ca­tions: “The bo­gey­man is whether [a pro­longed in­crease in cra­nial pres­sure] is go­ing to cause other neu­ral im­pacts—to fine mo­tor co­or­di­na­tion, headaches, mem­ory,” Shel­hamer says. If it does, “you’ve got a se­ri­ous, se­ri­ous prob­lem.”

The need for re­search into fluid dis­place­ment is so ur­gent that space agency sci­en­tists will use the Kel­lyKornienko mis­sion to be­gin a “fluid shifts” study,

in which sev­eral sta­tion as­tro­nauts will un­dergo reg­u­lar test­ing to de­ter­mine the root cause of vi­sion im­pair­ment and what­ever other health im­pli­ca­tions fluid dis­place­ment might have.

Glas­nost

One wel­come re­sult of the study will be a re­newal of true part­ner­ship aboard the space sta­tion. Ever since it was fin­ished, “there’s been the U.S. seg­ment and the Rus­sian seg­ment,” notes John B. Charles, as­so­ci­ate man­ager of NASA’S Hu­man Re­search Pro­gram for In­ter­na­tional Sci­ence. The Amer­i­cans do their ex­per­i­ments and the Rus­sians do theirs. “The Cana­di­ans and the Ja­panese pretty much stick with us, and the Euro­peans go back and forth,” Charles says, adding that NASA would like to see that di­vi­sion of la­bor end. The agency plans to join with Roscos­mos and the other part­ners in as­tro­naut health ex­per­i­ments that in­volve ev­ery­one.

But the en­dur­ing mis­match be­tween Amer­i­can and Rus­sian re­search tech­niques re­mains a chal­lenge: The Rus­sians don’t mea­sure all of the same things Amer­i­cans mea­sure, and don’t use the same terms. Both na­tions, over the past 50 years, have changed test pro­to­cols, hard­ware, and soft­ware; have added or aban­doned tests; and have headed off in new re­search di­rec­tions. As a re­sult, sig­nif­i­cant chunks of space sci­ence have fallen into a dis­con­nected data hodge­podge.

Fur­ther­more, to pro­tect as­tro­nauts’ pri­vacy, the U.S. has a wall be­tween flight doc­tors and re­searchers, for­bid­ding sci­en­tists to use con­fi­den­tial clin­i­cal data in their stud­ies and for­bid­ding doc­tors from tap­ping sci­en­tists for in­for­ma­tion on their pa­tients. But “on the Rus­sian side, clin­i­cians and re­searchers work side by side,” Charles re­marks. “Some­times they are the same per­son.” (Charles points out he and his col­leagues are work­ing on how to minimize that “wall” and col­lect more use­ful data, while still obey­ing fed­eral laws and NASA poli­cies pro­tect­ing con­fi­den­tial­ity.)

Fi­nally, un­like the Amer­i­cans, Rus­sian re­searchers don’t use what Shel­hamer calls “pop­u­la­tion-based medicine”: gath­er­ing data from lots of sub­jects, ana- lyz­ing it, and draw­ing con­clu­sions. In­stead, he says, they do per­son­al­ized medicine: “They look at each cos­mo­naut as a case study,” Charles ex­plains. “Their re­search tells them ev­ery­thing they need to know about that cos­mo­naut, but it’s not the sta­tis­ti­cally based data we are ac­cus­tomed to us­ing.”

Shel­hamer sees the value of both method­olo­gies. “Who’s to say which is the more re­al­is­tic ap­proach?” he asks. “We try to find an av­er­age, but if we’re send­ing six as­tro­nauts to Mars, maybe it’s bet­ter to know ev­ery­thing about each per­son.”

RE­SEARCH INTO FLUID DIS­PLACE­MENT IS SO UR­GENT THAT SPACE AGENCY SCI­EN­TISTS WILL USE THE KELLY-KORNIENKO MIS­SION TO BE­GIN A “FLUID SHIFTS STUDY,” IN WHICH SEV­ERAL STA­TION AS­TRO­NAUTS WILL UN­DERGO REG­U­LAR TEST­ING TO DE­TER­MINE THE ROOT CAUSE OF VI­SION IM­PAIR­MENT.

One in­sight into per­son­al­ized medicine may come from an ex­per­i­ment com­par­ing Scott Kelly to his twin brother and fel­low as­tro­naut Mark. (Mark Kelly left the corps af­ter his wife, former Con­gress­woman Gabrielle Gif­fords, was shot in the head by a would-be as­sas­sin in 2011.) NASA de­cided to un­der­take the study af­ter Scott Kelly asked the brass what he should say if re­porters asked him whether he and Mark would be com­pared. NASA turned the idea into what Hu­man Re­search Pro­gram bio­chemist Craig Kun­drot de­scribes as a “pi­lot project” de­signed to get “some in­ter­est­ing data points” by “mak­ing Mark the con­trol for Scott.” Sci­en­tists will mon­i­tor the broth­ers down to the molec­u­lar level, com­par­ing their DNA, RNA, pro­teins, me­tab­o­lites, and gut mi­cro­biomes, among other things. They’ll study macro phe­nom­ena too: fluid shifts, walk­ing per­for­mance, jump­ing per­for- mance, cog­ni­tion, and im­mune sys­tems. Both Kellys got flu shots last fall, and both will re­ceive fre­quent and com­pre­hen­sive phys­i­cal ex­am­i­na­tions for the du­ra­tion of the mis­sion.

In an el­e­gant co­in­ci­dence, Mark Kelly re­tired with 54 days in space. Scott, if all goes ac­cord­ing to sched­ule, will spend 540 days, out­fly­ing Mark in space by ex­actly one or­der of mag­ni­tude.

Space Crazy

The last im­pon­der­ables are the psy­cho­log­i­cal stresses: long tran­sits, phys­i­cal con­fine­ment, lim­ited con­tact with fam­ily, no chance for emer­gency evac­u­a­tion. Repli­cat­ing these con­di­tions will be prob­lem­atic: The mis­sion is only a year long, the as­tro­nauts un­der study are ex­posed to a chang­ing cast of char­ac­ters, and they are in low Earth or­bit, only a Soyuz ride away from home. Still, sci­en­tists see testable pos­si­bil­i­ties in a year-long mis­sion. For the last decade, NASA as­tro­nauts have kept di­aries for the “ISS jour­nals project,” and even though “touchy-feely is not a virtue” for the as­tro­naut corps, Shel­hamer says, the di­arists have a lot to say about col­leagues, the work­load, sleep­less­ness, and other ir­ri­ta­tions that the pub­lic knows lit­tle about. The jour­nal en­tries have helped re­searchers un­der­stand the im­por­tance of com­mu­nal rit­u­als such as meal­time: When one ISS crew tapped the spe­cial sup­plies ear­marked for in­com­ing re­place­ments, “the new guys were fu­ri­ous,” Shel­hamer says.

And while as­tro­nauts un­der­stand they must get along with crew­mates, the same is not true of mis­sion con­trol—a fre­quent fo­cus of an­i­mos­ity. The story of the Sky­lab crew who balked at their work­load in 1973 is le­gendary. Less widely known is the 2010-2011 ex­per­i­ment wherein Rus­sia’s In­sti­tute for Biomed­i­cal Prob­lems ran a 520-day Mars mis­sion sim­u­la­tion for six crew mem­bers–three Rus­sians, two Euro­peans, and one Chi­nese. Univer­sity of Penn­syl­va­nia be­hav­ioral sci­en­tist David F. Dinges ran a study us­ing a ques­tion­naire that cap­tured any dis­agree­ment as per­ceived by the as­tro­naut. The par­tic­i­pants re­ported five times as many con­flicts

THE LAST IM­PON­DER­ABLES ARE THE PSY­CHO­LOG­I­CAL STRESSES: LONG TRAN­SITS, PHYS­I­CAL CON­FINE­MENT, LIM­ITED CON­TACT WITH FAM­ILY, NO CHANCE FOR EMER­GENCY EVAC­U­A­TION. REPLI­CAT­ING THESE CON­DI­TIONS WILL BE PROB­LEM­ATIC DUR­ING A YEAR-LONG MIS­SION WITH A CHANG­ING CAST OF CHAR­AC­TERS IN LOW EARTH OR­BIT.

with mis­sion con­trol as with other as­tro­nauts.

Two spe­cific ar­eas of in­quiry in­ter­est Shel­hamer. So far Jour­nals Project leader Jack Stuster has not de­tected an across-the-board “third-quar­ter ef­fect” in the psy­ches of as­tro­nauts. “It’s like when you’re in col­lege,” Shel­hamer says. “For the first two years it’s new and fun, and for the last year you’re fo­cused on the fin­ish line. Trou­ble comes in the third quar­ter, when it’s ‘I still have so far to go.’ If we ex­tend the mis­sion to a year,” he won­ders, will dis­il­lu­sion­ment set in?

Dinges has de­signed a four- minute test to as­sess stress lev­els among as­tro­nauts, made up of a three-minute “psy­chomo­tor vig­i­lance test” cou­pled with a one-minute “vis­ual ana­log rat­ings” of the sub­ject’s level of stress, de­gree of fa­tigue, and qual­ity of sleep, among other fac­tors.

Dur­ing six-month mis­sions the re­sults re­sem­ble “a cu­bic curve,” Shel­hamer says, with stress ris­ing as the cube of elapsed time, “an ex­tremely trou­bling trend. If there’s an ac­cel­er­a­tion, we’re go­ing to have to do more re­search to fig­ure out what to do about it.”

Dinges says the stress rat­ings gen­er­ally “started out low-mod­er­ate and got higher,” but when he looked at in­di­vid­u­als, he saw that only half the as­tro­nauts re­ported in­creased stress. “We’ve known for a long time that some peo­ple de­te­ri­o­rate faster than oth­ers,” Dinges says. “Vul­ner­a­ble peo­ple are vul­ner­a­ble.”

Even so, “there were cor­re­lates,” Dinges says. High stress lev­els among ISS crew mem­bers “cor­re­lated with poor sleep qual­ity, phys­i­cal ex­haus­tion, and the work­load. This looks very phys­i­o­log­i­cal, not men­tal.”

And there is a fi­nal im­pon­der­able: “No­body un­der­stands the phys­i­o­log­i­cal cost of the mis­sion,” Dinges says. “You have work­load creep, in­ad­e­quate sleep, con­fine­ment, and iso­la­tion. But you also have nu­tri­tion is­sues, low oxy­gen, high CO2, bone and mus­cle atro­phy.” And then there are the “more oc­cult is­sues” like fluid shift to the brain.

“It’s un­likely that there’s some­thing meta­phys­i­cal or psy­cho­log­i­cal as­so­ci­ated with this,” Dinges says. “We want to know if there is a phys­i­o­log­i­cal trig­ger: Are some peo­ple cop­ing bet­ter, or are they blessed with phys­i­cal char­ac­ter­is­tics that en­able them to han­dle it more eas­ily?”

Space, ev­ery­one agrees, can be nasty. It will likely be nas­tier for a year than for six months. Mul­ti­ply­ing that time by a fac­tor of 2.5 or three as we reach for Mars might make all those de­pri­va­tions worse.

But for as­tro­nauts, thriv­ing amid ad­ver­sity is part of the job de­scrip­tion.“we love a chal­lenge,” Kelly says. “We love chal­leng­ing en­vi­ron­ments.”

An air­tight can bound for Mars ought to do the trick.

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