It's crunch
time for NASA's Mars
Reconnaissance Orbiter, a massive spacecraft bearing down on the red planet
for a March 10 arrival after seven months of spaceflight.
The orbiter
is set to fire its thrusters at 4:25 p.m. EST (2125 GMT) Friday in a maneuver
that, researchers hope, will put MRO in orbit around Mars to study the planet's
atmosphere, water history and identify landing sites for future missions.
"The
mission is entering a very dangerous phase for the next several days," said Fuk
Li, NASA's Mars exploration directorate chief at the Jet Propulsion Laboratory
(JPL) in Pasadena, California. "We've sent four missions that we intended to
orbit Mars [in 15 years] and only two have succeeded...for us those are
sobering numbers."
MRO is
expected to conduct a 27-minute thruster burn to place it in an elliptical
orbit around Mars. Flight controllers will be in contact with the spacecraft
for the maneuver's first 21 minutes before MRO swings behind the planet's
southern hemisphere to complete the orbit insertion burn. The spacecraft is
expected to reestablish contact with Earth at 5:16 p.m. EST (2216 GMT), mission
managers said.
"For the
last six minutes we are essentially in white knuckle time," said James Graf,
MRO project manager at JPL, during a Wednesday press conference. "If we don't
get several of those last minutes, we will not be able to get into Mars orbit."
But so far,
the $720 million MRO mission has performed flawlessly.
The probe's
310-million mile (498-million kilometer) flight has been so precise since its
Aug. 12, 2005 launch that flight controllers cancelled the last two of four
planned course corrections, saving precious fuel for the orbiter's mission in
Mars orbit, Graf said. Its Optical Navigation Camera, a new imager designed to
compare Mars' two moons Phobos and Deimos with background stars to determine
MRO's position, has already proven itself useful and achieved one of several
technology demonstrations slated for the mission, he added.
MRO will
join two other NASA orbiters - Mars Global
Surveyor and Mars
Odyssey - currently circling Mars, as well as the space agency's Spirit and Opportunity rovers
crawling across the planet's surface. Europe's Mars
Express probe is also orbiting the planet.
But MRO
outstrips all three orbiters in size and camera resolution and is expected to
lay the foundation for future Mars missions.
"We're
bringing more capability to the planet," said Richard Zurek, MRO's project
scientist at JPL, adding that the probe's science package will help researchers
learn more of the water story on Mars. "What we're really doing now is establishing the background
environment that we have to deal with when we plan future missions."
MRO carries
six primary instruments to study Mars, including the High-Resolution Imaging
Science Experiment (HiRISE) camera that can collect more data in a single image
than NASA's twin Mars rovers sent
home during their first 90 days, mission managers said.
During its two-year science mission, subsurface radar will probe for underground
water and ice, while other instruments hunt for water-related minerals and
study the Martian atmosphere. A suite of three cameras will also pick out
potential landing sites for future spacecraft.
Normal
science operations will begin this fall after MRO completes about seven months
of aerobraking
maneuvers, which use atmospheric drag to slow and shape the spacecraft's orbit,
to reach its final orbit, mission managers said. The first of 550 aerobraking passes is scheduled for later this month, and each pass will allow researchers to map the density of the Martian atmosphere, they added.
"There are waves
in the atmosphere just like there are waves in [Earth's] ocean," Zurek said.
"Knowing about these variations helps us plan our aerobraking process."
NASA will
broadcast a pre-orbit insertion MRO mission briefing on NASA TV at 12:00 p.m.
EST (1700 GMT) on March 10. Live coverage of MRO's Mars arrival begins at 3:30
p.m. EST (2030 GMT). You are invited to follow the mission's progress via SPACE.com's
NASA TV feed available here.
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