1 August 2020 | New Scientist | 15THIS year’s hottest destination is
Mars. On 23 July, China launched
the Tianwen-1 mission to the Red
Planet – one of three spacecraft
slated to head there in 2020.
This is China’s second
interplanetary mission, but
the first that the nation has
launched on its own. The
other, Phobos-Grunt, was a
collaboration with Russia that
didn’t make it out of Earth’s
orbit after blasting off in 2011.
The new mission, called
Tianwen-1 – which translates as
“questions to heaven” – consists
of an orbiter, a lander and a
rover, the last of which will be
named via a public competition.
“It’s very ambitious because it’s
a four-part mission: there’s the
launch, getting into orbit, the
landing and the rover, and every
single step has to go right,” says
space consultant Laura Forczyk.
All those steps must work on
the first try, a feat no other space
programme has accomplished
on a Mars mission because of the
difficulty of landing there. “No
planetary missions have ever been
implemented in this way,” wrote
the mission’s scientists in Nature
Astronomy (doi.org/d4vg).
If all goes well, Tianwen-1 will
arrive at Mars in February 2021
and the lander and rover will
touch down two or three months
later. They will take pictures
from the surface, measure the
soil composition, make radar
observations of the planet’s
underground structure and
observe Mars’s magnetic field.Due to the harsh environment
on Mars, the rover is expected
to last about 90 Martian days.
It weighs around 240 kilograms,
about the same as China’s Yutu-
rover, which is currently roaming
the moon. “The Chinese mission
to the far side of the moon has
been hugely successful, so
they’re building on that success
now,” says Forczyk.
The orbiter, which will relay
data from the lander and rover
back to scientists on Earth,
also carries a suite of scientific
instruments. It has two camerasand a spectrometer, which it will
use to create a map of the mineral
composition of Mars’s surface,
as well as radar and detectors to
examine particles in the Martian
atmosphere. It will also look fordeposits of water ice that could
be helpful for future explorers.
Tianwen-1 won’t be alone in
Mars orbit. The United Arab
Emirates has just launched
its first mission to Mars, and
NASA’s Perseverance rover is
set to launch on 30 July. These
missions are all leaving now
because Mars is at its closest point
to Earth, which happens once
every two years. They will arrive
at Mars around the same time
and help us understand the
planet and its history.
“If we learn what Mars is truly
like and how we can operate
there robotically, then those
lessons can be applied to future
CN human missions,” says Forczyk. ❚SABiodiversity
Spiderwebs can
help us monitor
forest life
SPIDERS may build their webs to
catch prey, but trials in Slovenian
forests show they can also serve
as a way for humans to monitor
the biodiversity of ecosystems.
There has been growing interest
in detecting species by collecting
the fragments of DNA they shed in
an environment, a method that can
be less invasive and quicker than
surveying with nets and trays.
Matjaž Gregorič at the Slovenian
Academy of Sciences and Arts
turned to an unusual tool to collect
such environmental DNA: the orb
webs of garden spiders (Araneus
diadematus) and sheet webs of
common hammock-weaving
spiders (Linyphia triangularis).
The webs act as a passive air
filter, capturing DNA from insects,
fungi and bacteria – and providing
an elegant alternative to the air
filtering machines ecologists use,
which need to be powered by heavy
generators (bioRxiv, doi.org/d4xn).
“The results are fantastic,
much more than I hoped for.
From 25 webs, I found [DNA from]50 families of animals: nematodes,
butterflies, moths, wasps, bees,
beetles and flies, everything. The
richness of information surprised
us a lot,” says Gregorič.
He and his colleagues got the
idea from a 2015 trial in a zoo, but
Gregorič says this is the first proofof concept in the wild. The approach
could complement traditional
surveying of pollinators, which
are suffering major declines, or to
detect pests or invasive species.
The use of environmental
DNA to monitor ecosystems is
growing, with the technique being
deployed by regulators in English
rivers and lakes. It doesn’t require
years of taxonomical knowledge
to identify species, which instead
have their DNA matched against
databases. “You don’t have to be
a spider expert to use spiderwebs,”
says Gregorič. ❚
Adam VaughanOrb webs like
these can catch
DNA from
insects in the
surrounding
areaPIX/ALAMY90
Number of Martian days that
China’s rover is expected to lastSpace exploration
Leah Crane
China launches mission to Mars
It is one of three spacecraft heading to the Red Planet this month
The Tianwen-1 mission
includes a Mars lander
and a rover