NASA’s Treasure Map for Water Ice on Mars – Jet Propulsion Laboratory

NASA has big plans for returning
astronauts to the Moon
in 2024, a stepping stone on the path to sending humans
to Mars. But where should the first people on the Red Planet land?

A new paper published in Geophysical Research Letters will
help by providing a map of water ice believed to be as little as an inch (2.5
centimeters) below the surface.

Water ice will be a key consideration for any potential
landing site. With little room to spare aboard a spacecraft, any human missions
to Mars will have to harvest what’s already available for drinking water and
making rocket fuel.

NASA calls this concept “in situ resource
utilization,” and it’s an important factor in selecting human landing
sites on Mars. Satellites orbiting Mars are essential in helping scientists
determine the best places for building the first Martian research station. The
authors of the new paper make use of data from two of those spacecraft, NASA’s
Mars Reconnaissance Orbiter (MRO) and Mars Odyssey orbiter, to locate water ice
that could potentially be within reach of astronauts on the Red Planet.

“You wouldn’t need a backhoe to dig up this ice. You
could use a shovel,” said the paper’s lead author, Sylvain Piqueux of
NASA’s Jet Propulsion Laboratory in Pasadena, California. “We’re
continuing to collect data on buried ice on Mars, zeroing in on the best places
for astronauts to land.”

Buried Treasure on
Mars

Liquid water can’t last in the thin air of Mars; with so
little air pressure, it evaporates from a solid to a gas when exposed to the
atmosphere.

Martian water ice is locked away underground throughout
the planet’s mid-latitudes. These regions near the poles have been studied by
NASA’s Phoenix lander, which scraped up ice, and
MRO, which has taken many images from space of meteor impacts that have
excavated this ice
. To find ice that astronauts could easily dig up, the
study’s authors relied on two heat-sensitive instruments: MRO’s Mars Climate
Sounder and the Thermal Emission Imaging System (THEMIS) camera on Mars Odyssey.

Why use heat-sensitive instruments when looking for ice? Buried
water ice changes the temperature of the Martian surface. The study’s authors
cross-referenced temperatures suggestive of ice with other data, such as
reservoirs of ice detected by radar or seen after meteor impacts. Data from
Odyssey’s Gamma Ray Spectrometer, which is tailor-made for mapping water ice
deposits, were also useful.

As expected, all these data suggest a trove of water ice
throughout the Martian poles and mid-latitudes. But the map reveals
particularly shallow deposits that future mission planners may want to study
further.

Picking a Landing
Site

While there are lots of places on Mars scientists would
like to visit, few would make practical landing sites for astronauts. Most
scientists have homed in on the northern and southern mid-latitudes, which have
more plentiful sunlight and warmer temperatures than the poles. But there’s a
heavy preference for landing in the northern hemisphere, which is generally
lower in elevation and provides more atmosphere to slow a landing spacecraft.

A large portion of a region called Arcadia Planitia is the
most tempting target in the northern hemisphere. The map shows lots of blue and
purple in this region, representing water ice less than one foot (30
centimeters) below the surface; warm colors are over two feet (60 centimeters)
deep. Sprawling black zones on the map represent areas where a landing
spacecraft would sink into fine dust.

What’s Next?

Piqueux is planning a comprehensive campaign to continue
studying buried ice across different seasons, watching how the abundance of
this resource changes over time.

“The more we look for
near-surface ice, the more we find,” said MRO Deputy Project Scientist
Leslie Tamppari of JPL. “Observing Mars with multiple spacecraft over the
course of years continues to provide us with new ways of discovering this
ice.”

JPL manages the MRO and Mars Odyssey missions for NASA’s Science
Mission Directorate in Washington. Lockheed Martin Space in Denver built both orbiters.
JPL built and operates the Mars Climate Sounder instrument. THEMIS was
built and is operated by Arizona State University in Tempe. The Gamma Ray
Spectrometer was built and is operated by the University of Arizona in Tucson.

News Media Contact

Andrew Good
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-2433
andrew.c.good@jpl.nasa.gov

Alana Johnson
NASA Headquarters, Washington
202-358-1501
alana.r.johnson@nasa.gov

2019-245