16 Scientific American, July 2019
HUMANS IN SPACE
Astronaut Scott Kelly describes
the hardships of life in space
Scott Kelly is the first American to spend
almost a year in space. The nasa astronaut
lived for a record 340 days onboard the In
ternational Space Station (ISS) from 2015 to
- Like other astronauts, he endured the
stresses of microgravity, cosmic radi a tion
and “headward fluid shift,” in which blood
and tissue fluid collect in the head. But Kel
ly’s experience was unique in that research
ers painstakingly documented his physiolo
gy and cognitive performance while in or
bit—and simultaneously monit ored his
identical twin brother, Mark Kelly, as an
The nasa Twins Study, a ground break
ing analysis of the effects of life in space, was
published in April in Science. It revealed
that Kelly underwent changes (which his
twin did not experience) in his eyes, carot
id artery, DNA expression and cognitive
performance during the mission. Most
measurements returned to preflight levels
after he returned to Earth—although some
of his cognitive scores worsened. scientific
american spoke with Kelly about the study,
the difficulties of prolonged space flight and
the implications for future longterm mis
sions. An edited excerpt follows.
— Jim Daley
What were the biggest physiological
challenges you faced in orbit?
That headward fluid shift is the worst in
the beginning. Your body adjusts to it
over time, but it never adjusts completely.
I always felt pressure in my head. Another
thing that varied from high to too high
was the carbon dioxide. When it was at its
lowest, it was 10 times what it would be
on Earth. When it was at its highest, it was
about 30 times what it is on Earth. It would
burn your eyes. I was able to tell what the
CO 2 level was pretty accurately without
having to look at the measurement.
EDITORS’ NOTE: According to a 2012 nasa
study, the ISS functions at higher than nor-
mal concentrations of CO 2 “out of opera-
tional necessity,” but research supports
these levels as safe.
What physical changes did you
experience back on Earth?
In the absence of gravity, not only is your
heart less fit, but your veins and arteries are
also not as strong. And once you get back
to Earth, all the blood just wants to pool in
your legs. That lasted for weeks. I would
stand up, and my legs would swell up like
water balloons. I had rashes and hives on
my skin whenever it had any pressure on
it: on my butt, the back of my legs, my el
bows. That was surprising. I was sore.
I was tired for a long time. From a mental
state, your schedule is so tightly controlled
onboard the ISS—then, when you get back,
you don’t have anyone telling you what to
do anymore. You feel a little lost for a bit.
When you don’t have that structure, it’s
kind of hard to be motivated at first.
A “click and drag” intelligence
test predicts realworld success
Imagine playing Scrabble without being
able to rearrange the tiles on your rack or
designing a building without sketching ideas
or making models. Such a thought exercise
shows the importance of environmental in
teraction in human thinking. But many cog
nitive tests meant to predict realworld
achievement measure only what people can
process inside their head. A new type of IQ
test that lets takers “externalize” their prob
lemsolving predicts school grades better
than the original version it was based on,
a recent study found.
In a common IQ test called Raven’s Pro
gressive Matrices, each question shows
participants a threebythree grid of shapes
in which one is missing and asks them to
select a shape that best completes the
overall pattern. In the updated version, they
must first arrange the eight other shapes
into a coherent pattern by clicking and
dragging them on a computer screen.
The new test’s creators gave 495 Dutch
university students either the old or new
assessment. Their scores on the original
test correlated with their exam grades,
but scores on the clickanddrag test pre
dicted grades even better—by one mea
sure more than twice as well as the origi
nal version, according to the study, which
was pub lished in the February issue of
Nature Human Behaviour.
The researchers also tracked people’s
movement of shapes during the test and
found that those who performed best
tended to exhibit flurries of activity, with
lulls in between. The study authors suspect
that rather than randomly moving shapes
until they fit a pattern, successful students
were forming ideas, testing them and then
pausing to reflect before trying a new one.
Question in the style of a static Raven’s
Progressive Matrices test.
Onboard the International Space Station:
nasa astronaut Scott Kelly in July 2015.