Sky & Telescope - July 2020 - 23

ext year, Earth invades Mars. Launch opportunities to
Mars only happen once every 26 months, and during
the next window - which spans this July and August -
three spacecraft are set to begin their journeys. If everything
goes well, in early 2021 they'll deliver two orbiters, a lander,
and two rovers to Mars, joining the six orbiters, one lander,
and one rover that already operate there.
Robotic spacecraft have orbited Mars continuously since
1997. The numerous missions have produced global maps of
albedo, topography, and composition, ﬁnding evidence for
abundant shallow subsurface ice and a distant past of longterm environments suitable for life. NASA seeks to take the
next step with its Perseverance rover, going beyond the search
for habitable environments to the search for life itself.
Perseverance won't launch alone. Two other launches
represent efforts to expand the exclusive club of agencies that
have achieved successful missions at Mars beyond NASA,
ESA, and India. The United Arab Emirates will launch an
orbiter to Mars, and China's plans are even more ambitious.
Both missions, if successful, would mark historic ﬁrsts for
their respective countries.

selected for safety more than science. The orbiter has a hefty
payload, including two cameras and a spectrometer for
surface mapping, a radar instrument for detecting subsurface water ice, and a magnetometer and particle analyzer for
studying the space environment.
The 240-kilogram, solar-powered rover is twice as heavy
as China's lunar rovers and a third the mass of Spirit and
Opportunity, but it's only a quarter of Perseverance's weight.
It carries ground-penetrating radar, a multispectral camera, weather instruments, and a magnetic-ﬁeld instrument.
The nominal mission is 90 Martian days, but if the Chinese
q DESCENT Retro rockets will help slow the lander once parachutes
and air cushions (not seen here) have already been deployed.

TR ACKS: N ASA / JPL- CA LTECH / MSSS; L A NDER /ROV ER
A ND SOL A R PA NELS: XINHUA NE WS AG ENCY (3)

China's Aspirations
China's bold plans for its ﬁrst Mars mission involve an
orbiter, lander, and rover. No other agency has attempted
more than an orbiter on its ﬁrst mission. China has already
demonstrated capability for deep-space navigation with
Chang'e 2, which it piloted out of lunar orbit and on to a
rendezvous with asteroid 4179 Toutatis. China also placed
a lander and rover on the Moon on its ﬁrst attempt with
Chang'e 3 (S&T: June 2020, p. 34).
However, landing on Mars is far more difﬁcult than
on the Moon because of the planet's atmosphere, which
is thick enough to burn up an incoming spacecraft with
frictional heating (therefore requiring an aeroshell and
heat shield for entry) but too thin to slow a spacecraft by
parachute alone (therefore requiring both parachutes and
landing rockets).
Like the Viking missions did, China's Mars mission (provisionally designated Huoxing 1, or "Mars 1") will probably
place the entire spacecraft stack in orbit and then use the
orbiter to perform reconnaissance of landing sites. The landing site will be in one of two northern-hemisphere regions

MARS

tq CHINA'S MISSION At left, an artist's
concept of China's
Mars mission shows the
rover ready to roll. Solar
panels are folded up on
the rover's back and will
unfold upon deployment (below).

s k y a n d t e l e s c o p e . o r g * J U LY 2 0 2 0

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Sky & Telescope - July 2020

Table of Contents for the Digital Edition of Sky & Telescope - July 2020