All_About_Space_-_Issue_94_2020

During your timein space,do

you feel anysignificant changes

to your body?

It’sfunny;someofthechangeswerea littleinsidiousandsome

wereveryimmediate.Obviouslywhenwegetintocontinuous

microgravity,whichhappensrightaftermainenginecut-offat

eight-and-a-halfminutesafterlaunch,I thinkI waslaughing

morethananythingelse,asitwassodifferentthanstanding

ontheground.

Wealsohaddifferentphysiologicalchangesthathappenedfairly

immediately.Youstartfeelinga littlebitoffullnessinyourhead.

Somepeoplegetnauseatedimmediately;withmeitwaskindofa bit

moreinsidious.Mostofushaditinjustthatperiod,atleastthefirst

dayortwo,andsomeneveractuallygotoverit.Thisisbecauseyour

bodyisjustconfused.Yourvestibularsystemisaccustomedtohaving

fluidssettleinthesemicircularcanals[inyourears],butitjustnever

does,asthef luidsjustf loataroundinthere.

I’mcuriousastohowlongittookmetogrowaboutfive

centimetres[2inches]taller.Butwedidmeasureourselvesseveral

daysintothef lightandeveryoneofushadgrowna fewcentimetres.

I grewasmuchasfivecentimetres.Withoutgravitycontinuously

pullingthroughourspines,ourbodiesgetlonger.Thereareother

effectsalso,likevisioncanshift.Someastronautsexperiencedvision

shiftsbyuptothreedioptres,I understand.

GregoryH.JohnsonisaformerNASAastronautwho

flewasapilotontwoSpaceShuttlemissions,STS-123

andSTS-134

Whenyou

takeaway

gravity,

yourbody

takestimeto

adjusttothe

conditions

Firstly,bystudyingthem,weareessentiallystudyingfragmentsthatcouldhaveendedup

asplanets,sowecanbetterunderstandhowtheplanetsformedandhowtheyevolved.

Near-EarthasteroidsaremuchclosertotheEarth,sowecanstudythemingreaterdetail.

Thesecondreasonispracticality.Near-Earthasteroidscanpotentiallycollidewiththe

Earth.TheMoon,justnexttotheEarth,iscompletelypockmarkedbyimpactcraters.The

smallestasteroidswillburnintheEarth’satmosphere,sotheyarelessdangerous.However,

becauseoftheirinherentmotionandbecausetheyfallintotheEarth’sgravity,asteroidshit

theEarthatveryhighspeed– atleast40,000kilometres(25,000miles)perhour,over

ten-timesfasterthana bullet– sotheirimpactsreleasea lotofenergy.Roughly,theimpact

ofa ten-metre(33-foot)asteroidproducesthesamequantityofenergyastheHiroshima

bomb.Studyingnearbyasteroidshelpstoprepareagainstimpacts:ifwehaveenough

time– manyyears– toprepare,theasteroidcouldbedeflected,completelyavoidingthe

collision.Ifthatisnotpossible,knowingthesize,compositionanddensityofthe

asteroidwillhelppredicthowbadtheimpactwillbe,andtoprepareforit.

ESA© DrOlivierHainautisaEuropeanSouthernObservatoryastronomer

Not only is

there scientific

benefit, there is

also the matter

of safety

SOLARSYSTEM

Why doweneed toobserve

nearby asteroids?

SPACE EXPLORATION

© NASA

ASK

Our experts answeryourquestions