[meteorite-list] ESA Tracking Station Establishes Contact With Phobos-Grunt

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 23 Nov 2011 22:12:10 -0800 (PST)
Message-ID: <201111240612.pAO6CAfc027612_at_zagami.jpl.nasa.gov>

http://www.esa.int/esaCP/SEM4NEZW5VG_index_0.html

ESA tracking station establishes contact with Russia's Mars mission
European Space Agency
23 November 2011

On Tuesday, 22 November at 20:25 GMT, ESA's tracking station at Perth,
Australia, established contact with Russia's Phobos-Grunt spacecraft.
Contact with the Mars mission was lost shortly after separation from the
launch vehicle was confirmed on 8 November.

Following liftoff, the spacecraft was injected into low-Earth orbit in
preparation for departure to Mars. Immediately after separation of the
spacecraft and its modified Fregat stage from the launcher, controllers
received signals confirming deployment of the solar panels.

Two automated burns of the Fregat engine were to have taken place beyond
coverage of Russian ground stations, boosting it onto an interplanetary
trajectory for the Red Planet. These failed to happen and contact was lost
from that moment. However, observations showed that the craft was in a
controlled attitude orbiting Earth between about 200 km and 340 km altitude.

ESA responds to Russian request for assistance
 
Upon request from NPO Lavochkin, operator of the mission on behalf of the
Russian space agency, Roscosmos, ESA agreed to do its utmost to attempt
contact using the Agency's ground station network.

Starting on 9 November, and in close coordination with Russian engineers,
ESA made almost daily attempts to contact Phobos-Grunt using numerous
configurations and radio link modes, but to no avail.

A major problem was that the spacecraft's orbit was not accurately known,
whereas ground stations normally require very accurate position information
for pointing due to the antenna size.

In the past few days, ESA's 15 m-diameter Perth dish was modified by the
addition of a 'feedhorn' antenna at the side of the main dish so as to
transmit very low-power signals over a wide angle in the hopes of triggering
a response from the satellite.

The transmit power was reduced in part because the receiver on Phobos-Grunt
is optimised to receive only very weak signals when deep in space.

Perth is ideally located because the satellite's solar panels were
illuminated by sunlight when overhead, giving a power boost to its systems.

ESA station in Australia transmits Russian telecommands
 
On 22 November, the Perth station antenna was pointed toward the
spacecraft's expected orbital position during 20:2120:28 GMT, and
telecommands provided by NPO Lavochkin were transmitted.

"Owing to its very low altitude, it was expected that our station would only
have Phobos-Grunt in view for six to ten minutes during each orbit, and the
fast overhead pass introduced large variations in the signal frequency,"
said Wolfgang Hell, the Phobos-Grunt Service Manager at ESOC.

Hard work pays off
 
Despite these difficulties, it was a success: the signals commanded the
spacecraft's transmitter to switch on, sending a signal down to the
station's 15 m dish antenna.

Data received from Phobos-Grunt were then transmitted from Perth to Russian
mission controllers via ESA's Space Operations Centre, Darmstadt, Germany,
for analysis.

Additional communication slots are available on 23 November at 20:2120:28
GMT and 21:5322:03 GMT, and ESA teams are working closely with Russian
controllers to determine how best to maintain communication with their
spacecraft.

More news will follow as the situation develops.

[NOTE: Images and weblinks supporting this release are available at
http://www.esa.int/export/esaCP/SEM4NEZW5VG_index_1.html ]
Received on Thu 24 Nov 2011 01:12:10 AM PST