[meteorite-list] 'Mount Sharp' on Mars Links Geology's Past and Future (MSL)

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.cfm?release=2012-090
  
'Mount Sharp' on Mars Links Geology's Past and Future
Jet Propulsion Laboratory
March 28, 2012

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 .

D.C. Agle 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle at jpl.nasa.gov

2012-090