27 July 2019 | New Scientist | 39>Clockwise (from top
left): Tracy Caldwell
Dyson, Naoko
Yamazaki, Dorothy
Metcalf-Lindenburger
and Stephanie Wilson
on the International
Space Station in 2010“ None of these
differences affects
an individual’s
ability to perform
as an astronaut”
has an effect on any individual’s ability to
perform as an astronaut.
“About the only thing that is impactful in
terms of being able to perform your duties
is really the difference between men and
women in their susceptibility to cancer from
radiation,” says Dorit Donoviel at Baylor
College of Medicine in Houston, Texas, who
co-wrote the review’s executive summary.
Women are more likely to develop such
radiation-based cancers than men, even in
the comparatively low-radiation environment
of Earth’s surface. Up on the International
Space Station (ISS), far from Earth’s protective
magnetic field, such a variation could be a
cause for concern.
This doesn’t mean women shouldn’t be
going into space, just that they might need
more protection, either in the form of bulkier
spacesuits or by limiting their time outside
a spacecraft. “We are working to reduce the
radiation risk for all astronauts by developing
countermeasures,” says Donoviel. On long-
term missions, protection barriers could be
built out of materials already in space, like
clay from asteroids, she says.
Since that review was published five years
ago, most of these conclusions have held up,
says Donoviel, but more research is needed.
A sample size of 171 men and 30 women, the
number of people who had spent time on
the ISS by the time the study was published,
is both too small and too skewed to come to
any meaningful conclusions.
Even less well understood is the question
of reproductive health. Most of the findings
we have come from animal studies, and are
scant and often conflicting. Research on
men suggests sperm count and testosterone
levels decrease in space, but return to normal
120 days after returning to Earth. For women,
though, there is simply no long-term data
available about menstruation or ovulation,
says Varsha Jain, a gynaecologist at King’s
College London.
That lack of knowledge comes, in part,
because astronauts find it easier to take
contraceptives to avoid menstruating inNASA