Sky & Telescope - August 2021 - 9

ZHURONG: CNSA; BLACK HOLE: LAUREN FANFER /
OHIO STATE UNIVERSITY
SPACE
Firsts for China at Mars
and in Low-Earth Orbit
TOUCHDOWN! On May 14th China's
rover, named Zhurong for a mythical
god of fi re and war, landed at the southern
edge of Utopia Planitia on Mars.
As of press time, the China National
Space Administration has pronounced
the landing successful but has not yet
released images of the landing site.
China is the fi fth nation to attempt
a soft landing on Mars and the third
to succeed (though the Soviet Union's
Mars 3 lander stopped functioning
shortly after setting down).
The rover is part of the Tianwen 1
( " questions to heaven " in Chinese)
mission, which also includes an orbiter
and landing platform that accompanied
the rover to the surface. The mission
launched in July 2020 (S&T: July 2020,
p. 22) and arrived in orbit around Mars
in February 2021.
The rover entered the Martian atmosphere
protected behind a heat shield,
before discarding it and deploying a
large parachute. Retrorockets slowed
it further, and autonomous hazard
avoidance guided the spacecraft on fi nal
approach. The orbiter served as a communications
relay during the landing,
and the European Space Agency and
Argentina have also assisted in tracking
the mission.
Zhurong's primary mission is set for
at least 90 sols, or about three months.
The solar-powered rover is equipped
An artist's concept shows the Chinese rover perched atop the landing platform at the southern
edge of the plains of Utopia Planitia. It will roll down the ramp to begin exploration.
with six science packages, including a
laser spectrometer, a climate weather
package, a magnetometer, imagers,
and ground-penetrating radar. Besides
studying Martian regolith and geology,
magnetic fi elds, and its weather
and climate, Zhurong will also search
for subsurface water ice. That " ground
truth " will put data collected by the
Tianwen 1 orbiter into context. The
orbiter is designed to operate for at least
a Martian year, or 687 days.
The successful landing closely follows
another accomplishment: On April
29th, China launched the fi rst section
of its Tiangong ( " heavenly palace " )
space station. The core module, Tianhe
( " harmony of the heavens " ), is the fi rst
of three parts, which together have a
nominal lifetime of 10 years. Two other
pieces, the Wentian and Mengtian
experiment modules, are due to launch
by early 2022. Tianhe is already scheduled
to accept Tianzhou cargo vehicles
and crewed Shenzhou spacecraft in May
and June, respectively.
Due to U.S. technology trade restrictions,
China has been conspicuously
absent from the International Space
Station, which has hosted a continuous
human presence in space since 2000. It
remains unclear whether China plans
to maintain a permanent presence on
the station, or if crews will rotate out in
temporary expeditions.
DAVID DICKINSON
cal about the purported evidence for
" non-interacting " low-mass black
holes, in which there's no mass transfer,
accretion disk, or X-ray emission
to support the claim. Other claims of
nearby black holes have not stood the
test of time (e.g., S&T: Aug. 2020, p. 8).
In the case of the " Unicorn, " van den
Heuvel thinks that what appears to be
an invisible black hole could actually be
a close pair of low-luminosity stars too
faint to see.
One explanation for the light variations from
the red giant star V723 Monocerotis is that it
has a distorted shape due to the tidal pull of a
3-solar-mass black hole companion, as shown
in this artist's concept.
Then again, if V723 Monocerotis
does orbit a bona fi de black hole, it
would be the smallest one found so far,
part of a rare class of low-mass black
holes. Filling this " mass gap " would
shed light on black hole formation.
GOVERT SCHILLING
sk yandtelescope.org * AUGUST 2021
9

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Sky & Telescope - August 2021

Table of Contents for the Digital Edition of Sky & Telescope - August 2021