24 | New Scientist | 4 July 2020
Up close with the Red Planet
We once thought Mars had canals built by an advanced society. We have come
a long way since then and there is still much to discover, finds Leah CraneViews Culture
NASA
/JPL-CALTECHNASA’s Perseverance
rover will soon look for
signs of life on MarsBook
The Sirens of Mars:
Searching for life
on another world
Sarah Stewart Johnson
Allen LaneIF YOU look up on a clear night,
you might spot a light brighter
than all the others, not twinkling
like a star, but floating serene
and reddish-tinged in the sky.
Across history, many have gazed
at Mars and imagined what its
distant shores might hold. Some
have even sent spacecraft up
there to find out.
In her book The Sirens of Mars,
Sarah Stewart Johnson tells the
story of the Red Planet and those
who have sought to understand
it, from Herodotus and Euclid
to NASA and its Curiosity and
Perseverance rovers, with the
author herself slotted in between.
The tale begins before Mars
was even understood to be a
place, when it was just a light
in the sky. It then moves on to
when scientists thought that
Mars could be truly the twin of
Earth, when apparent lines on
its surface were taken to be the
canals of an advanced society.
Even after discovering they
weren’t canals, people still
thought they could be signs
of vegetation, the signature
of a green and thriving planet.
At the point Stewart Johnson
reaches the first space missions
to fly by Mars and their failures
to spot any obvious signs of life,
the disappointment is palpable.
The narrative feels as if it is
building towards a big revelation,
maybe even the discovery of living
organisms on Mars. Those who
have studied the planet for a long
time know intimately the roller
coaster of emotion it has caused.Stewart Johnson has made Mars
her life’s work. She is from a space-
loving family, making her career
choice seem inevitable. The book
is part memoir, part history, part
education, and the three flow
together so smoothly you might
not even realise how much you
are learning about Mars.At one point, she describes
crater walls as “reveal[ing] layers
that had been stacked like the
pages of a closed book, one
moment in time pressed close
against the next”. She manages to
press moments in time together
as closely as the sedimentary rocks
on Mars, revealing its history just
as the rocks do.
As much as that history
contains many disappointments,from the revelation that the
canals of Mars aren’t real to
the understanding that there is
unlikely to be life on the surface,
it is also optimistic. There are
many joyful moments, such as
when scientists realised that Mars
might not be quite as arid and dead
as we once thought, but rather it
has water hiding everywhere.
Those moments are what propel
the story forward and what drives
Stewart Johnson to keep travelling
to some of the most extreme and
barren environments on Earth to
grasp at the possibility that there
may yet be life on Mars that looks
nothing like it does here on Earth.
“We are still struggling to contend
with the truly alien, to recognize
and interpret signs of ‘life as we
don’t know it’, ” she writes.
The Sirens of Mars comes at an
exciting time: Mars researchers
have more information now
than at any other point in history,
and NASA’s Perseverance rover,
scheduled to launch this month,
will surely bring a wave ofdiscoveries when it collects rock
and soil samples in its search
for signs of ancient life. Yet as
the interest in Mars grows, with
many nations and companies
working on missions to its surface,
researchers’ efforts to understand
it become increasingly urgent.
As Stewart Johnson writes: “The
next decades are thus critically
important for the search for life
because the window to explore an
untrammeled planet – a pristine
record of the past – is closing.”
In the end, the book tells you
what anybody who has studied
science learns as they move from
one school year to the next: the
more we know, the clearer it is that
what we thought we knew before
was wrong. However, as Stewart
Johnson so clearly describes, the
journey of understanding where
we were wrong propels us ever
forward to explore. ❚“ Mars may not be quite
as arid and dead as
we once thought, but
rather it has water
hiding everywhere”