[meteorite-list] Orbit-Raising Commands Fail to Budge Phobos-Grunt

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 30 Nov 2011 08:28:51 -0800 (PST)
Message-ID: <201111301628.pAUGSp0c023335_at_zagami.jpl.nasa.gov>

http://www.spaceflightnow.com/news/n1111/29phobosgrunt/

Orbit-raising commands fail to budge Phobos-Grunt probe
BY STEPHEN CLARK
SPACEFLIGHT NOW
November 29, 2011

Plagued by an undiagnosed problem that stranded it in Earth orbit,
Russia's Phobos-Grunt Mars mission remained quiet Tuesday after renewed
attempts to coax the craft back into contact with ground controllers.

European Space Agency officials transmitted signals to raise
Phobos-Grunt's orbit Tuesday in hopes it would allow greater
communications opportunities at a higher altitude, according to the
agency's Twitter page.

The ploy didn't work, and the probe remains in a low-altitude orbit less
than 200 miles above Earth.

Outfitted with a feedhorn antenna designed to attenuate the power of its
radio signals, ESA's Perth ground station heard signals from
Phobos-Grunt twice last week.

Perth's 49-foot dish antenna received limited telemetry from the
spacecraft. ESA passed the data to engineers with NPO Lavochkin, the
probe's prime contractor.

Details on communications attempts have come exclusively from ESA.
Roscosmos, the Russian space agency, has not released an update on
Phobos-Grunt since Nov. 24.

The Perth facility only has between six and eight minutes each time
Phobos-Grunt flies overhead in sight of the station, providing limited
windows for transmitting commands and receiving data.

Officials hoped raising the craft's orbit would lengthen communications
passes and give engineers a better chance of recovering the mission, but
the commands didn't work Tuesday.

ESA said Russia requested more orbit-raising commands to be transmitted
Tuesday night and Wednesday morning. The outcome of those attempts will
be known later Wednesday.

Engineers are adding a feedhorn antenna to ESA's tracking site at
Maspalomas in the Canary Islands. The feedhorn device was added to
ground stations to reduce the power of signal transmissions because
Phobos-Grunt's computers may think the craft is on the way to Mars, when
radio signals from Earth would be weaker than in orbit.

Phobos-Grunt was designed to release a Chinese orbiter around Mars, then
touch down on the Red Planet's rocky moon Phobos and collect samples. It
carries a return vehicle to shepherd the soil of Phobos back to Earth
for analysis.

Phobos-Grunt has been stuck in its low-altitude orbit since liftoff Nov.
8. A rocket pack attached to the spacecraft was supposed to fire twice
to accelerate the probe toward Mars, but neither firing occurred as
planned in the hours after launch.

Without data to assess the 29,000-pound craft's health, Russian
engineers were left in the dark about why the burns failed. Russia
enlisted help from ESA and NASA to contact the probe, but NASA's deep
space antenna in Goldstone, Calif., never received a signal.

NASA's deep space network stopped listening for Phobos-Grunt on Tuesday
to prepare for Saturday's launch of the Mars Science Laboratory.

Because Phobos-Grunt's altitude is so low, experts say the fuel-laden
craft will succumb to the affects of drag and fall back to Earth early
next year. Nicholas Johnson, NASA's chief orbital debris expert, said
the re-entry may occur in late January or February, but a specific time
period won't be known until much later.

If Russia is unable to regain control of the spacecraft, it would plunge
into the atmosphere uncontrolled with a full load of propellant.
Received on Wed 30 Nov 2011 11:28:51 AM PST