NASA's rover Curiosity successfully carried out a highly challenging landing on Mars early Monday, transmitting images back to Earth after traveling hundreds of millions of miles through space in order to explore the Red Planet.
The $2.6 billion Curiosity made its dramatic arrival on Martian terrain in a spectacle popularly known as the "seven minutes of terror."
This jaw-dropping landing
process, involving a sky crane and the world's largest supersonic
parachute, allowed the spacecraft carrying Curiosity to target the
landing area that scientists had meticulously chosen.
The mission control in
NASA's Jet Propulsion Laboratory in California burst into cheers as the
rover touched down. Team members hugged and high-fived one another as
Curiosity beamed back the first pictures from the planet, some shed
tears.
"The successful landing
of Curiosity -- the most sophisticated roving laboratory ever to land on
another planet -- marks an unprecedented feat of technology that will
stand as a point of national pride far into the future," President
Barack Obama said in a statement congratulating the NASA employees who
had worked on the project.
The scientific community reacted to the achievement with a mixture of elation and relief.
"Rationally I know it was
supposed to work all along, but emotionally it always seemed completely
crazy," said James Wray, assistant professor at Georgia Institute of
Technology, who is affiliated with the science team of Curiosity. "So to
see all those steps being ticked off and actually working, it's a huge
relief."
The initial images the
SUV-sized rover sent back to Earth were black and white and grainy, but
one showed its wheel resting on the stony ground and the vehicle's
shadow appeared in another. Larger color images are expected later in
the week, NASA said.
The spacecraft had been
traveling away from Earth since November 26 on a journey of
approximately 352 million miles (567 million kilometers), according to
NASA.
Curiosity, which will be
controlled from the Jet Propulsion Laboratory, has a full suite of
sophisticated tools for exploring Mars. They include 17 cameras, a laser
that can survey the composition of rocks from a distance and
instruments that can analyze samples from soil or rocks.
The aim of its work is "to assess whether Mars ever had an environment able to support small life forms," NASA says.
Curiosity's first stop
is Gale Crater, which may have once contained a lake. After at least a
year, the rover will arrive at Mount Sharp, in the center of the crater.
The rover will drive up the mountain examining layers of sediment. This
process is like looking at a historical record because each layer
represents an era of the planet's history, scientists say.
The phenomenon of
sedimentary layers is remarkably similar to what is seen on Earth, in
California's Death Valley or in Montana's Glacier National Park, says
John Grotzinger, chief scientist of the Mars Science Laboratory mission.
Rocks and minerals found
on Earth are different than on Mars, but the idea of a mountain made of
layers is familiar to scientists. Unlike on Earth, however, Mars has no
plate tectonics, so the Martian layers are flat and not disrupted as
they would be on Earth. That also means that Mount Sharp was formed in a
different way than how mountains are created on Earth -- no one knows
how.
In these layers,
scientists are looking for organic molecules, which are necessary to
create life. But even if Curiosity finds them, that's not proof that
life existed -- after all, these molecules are found in bus exhaust and
meteorites, too, says Steve Squyres, part of the Mars Science Laboratory
science team.
If there aren't any
organics, that may suggest there's something on the planet destroying
these molecules, said Wray, of Georgia Tech. But if Curiosity detects
them, Wray said, that might help scientists move from asking, "Was Mars
ever habitable?" to "Did Mars actually host life?"
Curiosity's mission is
also significant in an era when NASA's budgets are shrinking and China
is becoming more ambitious in its space exploration program.
"I feel like it's a
signal that we have the capability to do big and exciting things in the
future." said Carol Paty, assistant professor at Georgia Tech's School
of Earth and Atmospheric Sciences. "You can't not be excited."
Liquid water is not
something scientists expect to be apparent on Mars because the planet is
so cold and dry, Squyres said. If the planet does harbor liquid water
today, it would have to be deep below the surface, perhaps peeking out
in a few special places, but not likely to be seen by Curiosity, Squyres
said.
It's hard to know how
long ago liquid water would have been there because there's no mechanism
to date the rocks that rovers find on Mars, Squyres said.
Evidence from the
spacecraft NASA has sent to Mars so far suggests that the "warm and wet"
period on Mars lasted for the first billion years of the planet's
history.
"In order to create
life, you need both the right environmental conditions -- which includes
liquid water -- and you need the building blocks from which life is
built, which includes organics," Squyres said. The Mars Science
Laboratory is a precursor mission to sharper technology that could do
life detection, Grotzinger said.
There aren't specific
molecules that scientists are looking for with Curiosity. The attitude
is: "Let's go to an interesting place with good tools and find out
what's there," Squyres said.
Curiosity is supposed to
last for two years on Mars, but it may operate longer -- after all,
Spirit and Opportunity, which arrived on Mars in 2004, were each only
supposed to last 90 Martian days. Spirit stopped communicating with NASA
in 2010 after getting stuck in sand, and Opportunity is still going.
"You take what Mars
gives you," said Squyres, also the lead scientist on the Mars
Exploration Rover Mission, which includes Spirit and Opportunity. "If we
knew what we were going to find, it wouldn't be this much fun."
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