Sky and Telescope - November 2017 - 18

The Next Space Sprint

(continued from page 15)
Australia, but ancient stromatolites date as far back as 3½
billion years, leaving behind a structure, trapped organics,
and unusual chemical isotopes that together cannot easily be
explained without life having been present.

p LIFE FROM MARS? These globule structures in the meteorite ALH
84001 are similar in texture and size to some made by bacteria on Earth.
However, life isn't required to explain their formation.
u CACHE CLOSEUP The Mars
2020's CacheCam provides a
top-down view into the rover's
sample tube.

t NASA'S MARS 2020 Based on the
Curiosity rover design, Mars 2020 is
about 3 meters long and 2.2 meters
tall (10 feet and 7 feet, respectively),
and it weighs less than a compact car.

p NAVIGATING OBSTACLES These images provide an example of
what the navigation camera aboard NASA's 2020 rover sees. On the left
is a pile of rocks as seen by the rover, from 15 meters (roughly 50 feet)
away. The right-hand picture shows how camera data reveal the pile's
3D contours. Using the 3D information, the rover team can plan precise
travel and arm movements.

N O V E M B E R 2 0 17 * S K Y & T E L E S C O P E

Loaded up with a panoply of instruments, the car-sized Mars
2020 rover should be able to detect any stromatolite-like Martian biosignatures. The most prominent of these instruments
from the outside will be the rover's eyes: Mastcam-Z and
Supercam, perched on a mast 2 meters above ground level. The
former can take high-deﬁnition video, panoramic color, and
3D images of the Martian surface and features in the atmosphere. "Mastcam-Z will play a major role in helping to select
the samples, as well as helping to characterize the geology and
geological context of the landing site," says Mastcam-Z principal investigator Jim Bell (Arizona State University).
Meanwhile, Supercam will dissect organic compounds from
a distance, identifying the chemical and mineral makeup
of targets as small as a pencil point from 7 meters away.
Supercam does this in part by using Raman spectroscopy - a
technique whereby laser light is shone on a sample and the
scattered light offers information about molecular vibrations
inside the material, which scientists interpret to identify the
sample's makeup. This versatile instrument also performs color
imaging and visible and near-infrared spectroscopy.
Although used in chemistry labs across the world for
decades to analyze the ﬁngerprints of molecules, Raman
spectroscopy is a new technology for the surface of Mars.
And Mars 2020 will actually be carrying two of these
spectrometers: Supercam on the mast and SHERLOC
(Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) on the robotic arm's
turret. Also out on a turret is PIXL (Planetary Instrument
for X-ray Lithochemistry), an X-ray spectrometer. It identiﬁes chemical elements at a tiny scale. Both instruments are
cutting-edge and are what geologists utilize when hunting for
signs of past life in ancient rocks here on Earth.
Two other Mars 2020 instruments, from Spain and Norway, respectively, will contribute weather measurements and
ground-penetrating radar. There's even one - MOXIE (Mars
Oxygen In-Situ Resource Utilization Experiment) - aiming
to produce oxygen from the Martian carbon-dioxide atmosphere. In future crewed missions, a MOXIE-like device could
produce oxygen for propellant off the surface or for breathing.
But what has caused the most controversy and excitement
is a new system for caching Mars rocks. "The rover might
not be able to detect deﬁnitive biosignatures on its own,"
says Horgan. "Hence a core part of this mission is a followon sample return." The Mars 2020 rover will collect and
hermetically seal about 30 tubes of surface material that its
scientists deem likely to contain signs of life. These pencilsize samples will be left on the surface in a "depot" ready to
be collected in the future.

ME TEORITE: N ASA; SA MPLE VIE W: N ASA / JPL- CA LTECH; ROV ER: N ASA; ROCKS: N ASA / JPL- CA LTECH

Caching In

Sky and Telescope - November 2017

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