BOULDER, Colorado - Ground
controllers today successfully performed a major maneuver of NASA's Mars
Reconnaissance Orbiter (MOR)--an "end game" tactic that puts the orbiting probe a step
closer to studying the red planet with its entire suite of science sensors.
For
months, the MRO has been aerobraking--using the
friction of the planet's thin atmosphere to slow the craft. That technique
saves on onboard propellant.
The
decision to exit aerobraking was made early today, noted James Graf, MRO
Project Manager at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. The burn gets MRO out of the atmosphere, with two more maneuvers scheduled over
the next two weeks before the spacecraft achieves its science-gathering orbit,
he told SPACE.com.
Spacecraft
engineers and navigation experts exploited MRO's Trajectory Correction Maneuver
(TCM) thrusters, said Wayne Sidney, MRO Flight Engineering Team Lead for
Lockheed Martin Space Systems, the firm that designed and built the spacecraft
in neighboring Denver, Colorado.
Heavy lifting
"I
am greatly relieved that the aerobraking phase is over," Graf explained. "All
of aerobraking, but in particular the last demanding week, is dangerous and it
is great to have it behind us."
Graf
saluted a combined JPL and Lockheed Martin Space Systems team that "performed
fabulously over the last six months as did the spacecraft." With the heavy
lifting of aerobraking behind MRO operators, he said, the spacecraft team is
moving on into the transition phase events, which include the commissioning of
MRO instruments.
This
upcoming phase has its own set of challenges for the team, Graf observed,
including the deployment of the Shallow Subsurface Radar (SHARAD) antenna and
the lid for the Compact Reconnaissance Imaging Spectrometers for Mars (CRISM),
he said.
"The
engineering images returned from these instruments at the end of the month
should be astounding," Graf predicted.
Sidney told SPACE.com
that regular MRO burns over the last six months were on the order of seconds.
The burn today lasted several minutes, he said, "the biggest burn just with
these TCM engines."
The
burn was executed on-time and performance was perfect, Sidney said. "The
spacecraft is in great shape. Aerobraking is now officially over."
There's
still more nudging to do with MRO over the next few months, fine-tuning tweaks
that push the probe into a final, desired orbit. The mission's main science
observations are scheduled to begin in November, after a period of intermittent
communications while Mars passes nearly behind the Sun.
Rock-solid, well behaved
Overall,
MRO is in excellent health, Sidney explained. However, one nagging item cropped
up a few weeks ago. A radio frequency switch to flip between MRO's high and
low-gain antennas is stuck. A tiger team of experts is investigating the issue,
trying to ascertain the root, probable cause of the problem.
"If
we don't get the switch unstuck we've lost some redundancy...but we still have
the capability to communicate over the low and high-gain antennas using the
other transmitter," Sidney explained. At this point in MRO's aerobraking
campaign, "everything else has been really rock-solid, right on...and gone really
well. It has been a remarkable spacecraft. Very well behaved," he added.
Dipping
in and out of the martian atmosphere, MRO has seen very few surprises. A worry
for aerobraking specialists is encountering dust storm activity that can mix
things up in the atmosphere, playing havoc with the delicate,
spacecraft-slowing maneuvers.
"The
atmosphere has been very cold and clear the whole six months as we hoped it
would be," Sidney said.
Launched
in August 2005, MRO swung into an elongated orbit around Mars in March of this
year.
The
$750 million MRO mission is designed to contribute to several science
objectives: Determine whether life ever arose on Mars; characterize the climate
and geology of Mars; as well as prepare of eventual human exploration of the
red planet.
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