Sky & Telescope - July 2020 - 27

N ASA / JPL- CA LTECH

Similar Rovers, Divergent Approaches
Perseverance looks a lot like its predecessor, Curiosity. But
its instruments are new, and its mission has different goals.
Curiosity was, literally, a Mars Science Laboratory, performing sensitive analyses on rock samples within its belly
while on the Martian surface. By contrast, Perseverance has
no such interior lab. Instead, it will obtain and document
samples for future return to Earth for deeper analysis.
Perseverance will be the heaviest rover ever to land on
Mars: At 1,050 kilograms, it's 17% heavier than Curiosity. Much of that weight is in instruments. Compared with
Curiosity, Perseverance has upgraded science cameras (now
with zoom capability!) and weather sensors. Its arm-mounted
Planetary Instrument for X-ray Lithochemistry (PIXL)
improves on Curiosity's element-sensing Alpha Particle X-Ray
Spectrometer. The wide-ﬁeld-of-view engineering cameras
Perseverance will use for navigating its environment are dramatically better than Curiosity's. And its ground-penetrating
Radar Imager for Mars's Subsurface Experiment (RIMFAX) is
a dramatic upgrade of underground imaging technology.
Of all of the new instruments, perhaps the most exciting are the two Raman spectrometers: one in the rover's
mast-mounted SuperCam and one mounted at the end of
the robotic arm called the Scanning Habitable Environments
with Raman and Luminescence for Organics and Chemicals
(SHERLOC). Raman spectrometers allow sensitive detection
of carbon-containing compounds - including ones of biological interest. SuperCam, which also encompasses an upgraded
version of Curiosity's ChemCam rock-zapping laser, will
help the Perseverance team determine which rocks might be
biologically interesting from a distance. SHERLOC will obtain
close-up, high-resolution images of rock targets using a copy
of the Curiosity Mars Hand Lens Imager.
For this mission to be successful, it's not only the landing
that must go well. Perseverance will stress the aging network

u A LOAD TO CARRY
Perseverance will carry
23 cameras, including
seven specifically for scientific purposes, and a
sample-caching system,
which will package and
lay aside samples for a
later mission to pick up
and carry home. It also
carries five instruments
designed to explore the
history of water and
chemistry in the ancient
lake basin.

NASA's Perseverance represents a dramatic
shift in Mars exploration strategy.
of NASA's data-relay orbiters. Curiosity already routinely uses
ESA's ExoMars Trace Gas Orbiter for communications. This
takes a little pressure off of Mars Odyssey and Mars Reconnaissance Orbiter, and it also provides ESA with valuable
experience in data relay for their future ExoMars lander.
Relief in the form of a new NASA orbiter that's capable of
providing communications relay for landed missions will not
arrive at Mars until at least 2027.

Perseverance: Sample Grabber
Perseverance will land in nearly the same way that Curiosity did. On February 18, 2021, during local afternoon, it will
enter the atmosphere and begin its "7 minutes of terror." A
heat shield will slow its descent, then a parachute will slow
it further. Finally, it will lower itself gently to the surface
on cables attached to a rocket-powered jetpack, cutting the
cables after touchdown to allow the jetpack to ﬂy away and
land at a safe distance.
Engineers have upgraded the landing technology with
terrain-relative navigation: The spacecraft has extra cameras
and onboard processing capability to ﬁgure out where hazardous spots like big rocks and sand traps lie within the landing
ellipse, and it can steer around them to land on a safe spot.
By 2021, we may have three simultaneously operating
weather stations on Mars: Curiosity, Insight, and
Perseverance all carry meteorological experiments.
Perseverance also has an instrument that will test
ways to generate oxygen from Mars's thin carbon
dioxide atmosphere.

SUPERCAM
MASTCAM-Z
SHERLOC
RIMFAX

MEDA

PIXL

MOXIE

ROBOTIC ARM

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