June 23, 2014
NASA's Mars Curiosity Rover Marks First Martian Year with Mission Successes
NASA's Mars Curiosity rover will complete a Martian year -- 687 Earth days
-- on June 24, having accomplished the mission's main goal of determining
whether Mars once offered environmental conditions favorable for microbial
life.
One of Curiosity's first major findings after landing on the Red Planet in
August 2012 was an ancient riverbed at its landing site. Nearby, at an area
known as Yellowknife Bay, the mission met its main goal of determining
whether the Martian Gale Crater ever was habitable for simple life forms. The
answer, a historic "yes," came from two mudstone slabs that the rover sampled
with its drill. Analysis of these samples revealed the site was once a
lakebed with mild water, the essential elemental ingredients for life, and a
type of chemical energy source used by some microbes on Earth. If Mars had
living organisms, this would have been a good home for them.
Other important findings during the first Martian year include:
-- Assessing natural radiation levels both during the flight to Mars and on
the Martian surface provides guidance for designing the protection needed for
human missions to Mars.
-- Measurements of heavy-versus-light variants of elements in the Martian
atmosphere indicate that much of Mars' early atmosphere disappeared by
processes favoring loss of lighter atoms, such as from the top of the
atmosphere. Other measurements found that the atmosphere holds very little,
if any, methane, a gas that can be produced biologically.
-- The first determinations of the age of a rock on Mars and how long a rock
has been exposed to harmful radiation provide prospects for learning when
water flowed and for assessing degradation rates of organic compounds in
rocks and soils.
Curiosity paused in driving this spring to drill and collect a sample from a
sandstone site called Windjana. The rover currently is carrying some of the
rock-powder sample collected at the site for follow-up analysis.
"Windjana has more magnetite than previous samples we've analyzed," said
David Blake, principal investigator for Curiosity's Chemistry and Mineralogy
(CheMin) instrument at NASA's Ames Research Center, Moffett Field,
California. "A key question is whether this magnetite is a component of the
original basalt or resulted from later processes, such as would happen in
water-soaked basaltic sediments. The answer is important to our understanding
of habitability and the nature of the early-Mars environment."
Preliminary indications are that the rock contains a more diverse mix of clay
minerals than was found in the mission's only previously drilled rocks, the
mudstone targets at Yellowknife Bay. Windjana also contains an unexpectedly
high amount of the mineral orthoclase, This is a potassium-rich feldspar that
is one of the most abundant minerals in Earth's crust that had never before
been definitively detected on Mars.
This finding implies that some rocks on the Gale Crater rim, from which the
Windjana sandstones are thought to have been derived, may have experienced
complex geological processing, such as multiple episodes of melting.
"It's too early for conclusions, but we expect the results to help us connect
what we learned at Yellowknife Bay to what we'll learn at Mount Sharp," said
John Grotzinger, Curiosity Project Scientist at the California Institute of
Technology, Pasadena. "Windjana is still within an area where a river flowed.
We see signs of a complex history of interaction between water and rock."
Curiosity departed Windjana in mid-May and is advancing westward. It has
covered about nine-tenths of a mile (1.5 kilometers) in 23 driving days and
brought the mission's odometer tally up to 4.9 miles (7.9 kilometers).
Since wheel damage prompted a slow-down in driving late in 2013, the mission
team has adjusted routes and driving methods to reduce the rate of damage.
For example, the mission team revised the planned route to future
destinations on the lower slope of an area called Mount Sharp, where
scientists expect geological layering will yield answers about ancient
environments. Before Curiosity landed, scientists anticipated that the rover
would need to reach Mount Sharp to meet the goal of determining whether the
ancient environment was favorable for life. They found an answer much closer
to the landing site. The findings so far have raised the bar for the work
ahead. At Mount Sharp, the mission team will seek evidence not only of
habitability, but also of how environments evolved and what conditions
favored preservation of clues to whether life existed there.
The entry gate to the mountain is a gap in a band of dunes edging the
mountain's northern flank that is approximately 2.4 miles (3.9 kilometers)
ahead of the rover's current location. The new path will take Curiosity
across sandy patches as well as rockier ground. Terrain m
