'Mount Sharp' on Mars Links Geology's Past and Future

MEDIA RELATIONS OFFICE
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D.C. Agle 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov

News feature: 2012-090 March 28, 2012

'Mount Sharp' on Mars Links Geology's Past and Future

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2012-090&cid=release_2012-090

One particular mountain on Mars, bigger than Colorado's grandest, has been beckoning
would-be explorers since it was first sighted from orbit in the 1970s. Scientists have
ideas about how it took shape in the middle of ancient Gale Crater and hopes for what
evidence it could yield about whether conditions on Mars have favored life.

No mission to Mars dared approach it, though, until NASA's Mars Science Laboratory
mission, which this August will attempt to place its one-ton rover, Curiosity, at the foot of
the mountain. The moat of flatter ground between the mountain and the crater rim
encircling it makes too small a touchdown target to have been considered safe without
precision-landing innovations used by this mission.

To focus discussions about how Curiosity will explore the mountain during a two-year
prime mission after landing, the mission's international Project Science Group has
decided to call it Mount Sharp. This informal naming pays tribute to geologist Robert P.
Sharp (1911-2004), a founder of planetary science, influential teacher of many current
leaders in the field, and team member for NASA's first few Mars missions. Sharp taught
geology at the California Institute of Technology (Caltech), in Pasadena, from 1948 until
past his retirement. Life magazine named him one of the 10 best college teachers in the
nation.

"Bob Sharp was one of the best field geologists this country has ever had," said Michael
Malin, of Malin Space Science Systems, San Diego, principal investigator for two of
Curiosity's 10 science instruments and a former student of Sharp's.

"We don't really know the origins of Mount Sharp, but we have plans for how to go there
and test our theories about it, and that's just how Bob would have wanted it," Malin said.

Caltech Provost Edward Stolper, former chief scientist for the Mars Science Laboratory,
said, "For much of his more than 50 years at Caltech, Bob Sharp was the central figure
in its programs in the geological and planetary sciences. One of his major contributions
was the building of a program in planetary sciences firmly rooted in the principles and
approaches of the geological sciences.

"Moreover, through his own work on the Jet Propulsion Laboratory's early missions to
Mars and the work of others that he influenced, he also had a major influence on
planetary science and exploration at JPL. Recognition of this remarkable scientist and
leader by the naming of Mount Sharp is highly fitting, and I hope it will serve to
perpetuate his legacy."

The Mars Science Laboratory spacecraft was launched Nov. 26, 2011, bound for
landing beside Mount Sharp inside Gale Crater on the evening of Aug. 5, PST (early
Aug. 6, EST and Universal Time). The mission will use Curiosity to investigate whether
the area has ever offered environmental conditions favorable for fostering microbial life,
including chemical ingredients for life and energy for life.

Mount Sharp rises about 3 miles (5 kilometers) above the landing target on the crater
floor, higher than Mount Rainier above Seattle, though broader and closer. It is not
simply a rebound peak from the asteroid impact that excavated Gale Crater. A rebound
peak may be at its core, but the mountain displays hundreds of flat-lying geological
layers that may be read as chapters in a more complex history billions of years old.

Twice as tall as the sequence of colorful bands exposed in Arizona's Grand Canyon, the
stack of layers in Mount Sharp results from changing environments in which layers are
deposited, younger on top of older, eon after eon, and then partially eroded away.

Several craters on Mars contain mounds or mesas that may have formed in ways
similar to Mount Sharp, and many other ancient craters remain filled or buried by rock
layers. Some examples, including Gale, hold a mound higher than the surrounding
crater rim, indicating that the mounds are remnant masses inside once completely filled
craters. This presents a puzzle about how environmental conditions on Mars evolved.

"This family of craters that were filled or buried and then exhumed or partially exhumed
raises the question of what changed," said Ken Edgett of Malin Space Sciences,
principal investigator for one of Curiosity's instruments. "For a long time, sedimentary
materials enter the crater and stay. Then, after they harden into rock, somehow the rock
gets eroded away and transported out of the crater."

Some lower layers of Mount Sharp might tell of a lake within Gale Crater long ago, or
wind-delivered sediments subsequently soaked by groundwater. Orbiters have mapped
water-telltale minerals in those layers. Liquid water is a starting point in describing
conditions favorable for life, but just the beginning of what Curiosity can investigate.
Higher layers may be deposits of wind-blown dust after a great drying-out on Mars.

"Mount Sharp is the only place we can currently access on Mars where we can
investigate this transition in one stratigraphic sequence," said Caltech's John
Grotzinger, chief scientist for the Mars Science Laboratory. "The hope of this mission is
to find evidence of a habitable environment; the promise is to get the story of an
important environmental breakpoint in the deep history of the planet. This transition
likely occurred billions of years ago -- maybe even predating the oldest well-preserved
rocks on Earth."

Possible explanations for how erosion shaped the mountain after layers were deposited
include swirling winds carving away the edges, and perhaps later wet episodes leaving
channels down the sides and fresher sediments on the crater floor. Clues about those
episodes present Curiosity with other potentially habitable environments to investigate.

The Mars Science Laboratory is managed by NASA's Jet Propulsion Laboratory in
Pasadena, Calif., a division of Caltech. For more information, visit:
http://www.nasa.gov/msl .

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