HWM Singapore – August 2019

FEATURE

PICTURE

NASA,

SPACEX

WHATHAPPENS TO

THEHUMAN BODY INSPACE?

 But even if we pull off amazing feats
of engineering and devise a  awless
system to get humans to Mars, there’s
still one very pesky problem. The human
body just wasn’t built to exist for long
periods in a zero-gravity environment
bombarded by cosmic radiation.
“The NASA Twins Study: A
multidimensional analysis of a year-long
human space ight” is a cross-disciplinary
study of the long-term eff ects of space
on the human body. The study was
just published in the April 2019 issue of
Science, and it is a one-of-a-kind study,
conducted on identical twin astronauts
Scott and Mark Kelly. Scott Kelly spent
an entire year aboard the International
Space Station between 2015 and 2016,
while his twin Mark remained on
Earth as a control.
Over the course of 25 months, the
brothers submitted to the collection
of a multitude of biological samples, in
addition to a battery of cognitive and

physical assessments. The idea behind

the study was to determine what exactly

happens to the human body after

prolonged periods in space, and by

extension, assess the dangers of long-

term space habitation.

The answer is pretty simple. The

human body does not like space. As

adaptable as we are, cosmic radiation

wrecks havoc on our DNA, leading to

scary changes that scientists are only

beginning to understand. Scott Kelly

lived in space for a year, and it’s diffi cult

to extrapolate what would happen to

Mars colonists who would be exposed to

far more radiation. What’s more, the ISS

orbits low enough to still be protected

by Earth’s magnetic  eld, even if the

astronauts are exposed to more radiation

than someone on Earth because they’re

above the planet’s atmosphere.

A crew journeying to Mars would

have to contend with eight times more

radiation than Scott Kelly. While the

study ultimately concluded that it was

still possible to sustain human health

for a year-long space ight, longer space

missions are an entirely diff erent ball

game, and round trips to Mars could

take up to three years.

TWISTED CHROMOSOMES

Space sure did a number on Scott’s

DNA. Sections of his chromosomes were

inverted or translocated, which possibly

ended up aff ecting gene expression as

well. The study found that over 10,000

genes in Scott’s genome were activated in

space, no doubt a response to stressors

like lift-off and zero gravity.

And even though 91.3 percent of

these genes whose expression changed

in space returned to normal within six

months of Scott returning to Earth, a full

811 genes never did. More worryingly,

Mark Kelly (left) and Scott Kelly (right)

are identical twin astronauts who took

part in a study to examine the long-term

eff ects of space ight.

International Space Station.

42 HWM | AUGUST 2019