[meteorite-list] Rosetta Correctly Lined Up for Critical Mars Swingby

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 15 Feb 2007 13:21:48 -0800 (PST)
Message-ID: <200702152121.NAA09672_at_zagami.jpl.nasa.gov>

http://www.esa.int/esaCP/SEMKRCO2UXE_index_0.html

Rosetta correctly lined up for critical Mars swingby
European Space Agency
15 February 2007

ESA mission controllers have confirmed Rosetta is on track for a
critical 250-km Mars swingby on 25 February. Engineers have started
final preparations for the delicate operation, which includes an
eclipse, a signal blackout, precise navigation and complex ground tracking.
 
Rosetta is scheduled to make its closest approach to Mars at 02:57 CET
on Sunday, 25 February, using the Red Planet as a gravitational brake to
reduce speed and alter trajectory as part of the spacecraft's complex,
10-year, 7.1-thousand-million-kilometre journey to comet
67P/Churyumov-Gerasimenko.
 
"Last Friday's engine firing went well. On Tuesday, we confirmed the
spacecraft is on nominal track for the swingby. There is currently no
need for additional engine burns, so the next manoeuvre slot, planned
for the weekend, has been cancelled," said Paolo Ferri, Rosetta Flight
Director, speaking at ESOC, ESA's Space Operations Centre in Darmstadt,
Germany.
 
Communications blackout, eclipse as Rosetta passes behind Mars
 
Later today, the Flight Control Team is scheduled to begin charging
Rosetta's batteries for the planned 25-minute eclipse during the
swingby. During the eclipse, Rosetta's solar panels will be shadowed
from sunlight by Mars, and all but essential systems will be turned off
or placed into low-power modes.

Rosetta's original trajectory and engineering design did not include an
eclipse, but unavoidable launch delays forced the trajectory to be
replanned. Mission controllers working on Rosetta have spent months
carefully planning and testing a low-power configuration which will
allow the spacecraft to safely operate on batteries.
 
Further, ground controllers expect to lose contact with Rosetta for a
tense 15-minute occultation, or blackout, starting at 03:14 CET on 25
February, as Rosetta passes behind Mars with respect to ground stations
on Earth.

At closest approach, Rosetta will skim by Mars in a spectacular passage,
a mere 250 km above the Red Planet. At this time, ESA's Mars Express
will be some 11 042 kms away from Rosetta, while NASA's Mars
Reconnaissance Orbiter will be about 7172 kms distant.
 
ESA-NASA cooperation for deep-space tracking
 
The intensive swing-by activities at ESOC have included a comprehensive
tracking campaign to carefully plot Rosetta's position and trajectory.

Ranging and Doppler measurements from DSA 1, ESA's deep-space tracking
station at New Norcia, Australia, have been augmented by data from
NASA's DSN deep-space network. Both networks are using Delta DOR (Delta
Differential One-Way Ranging) technology to precisely locate and track
the spacecraft.
 
Delta DOR uses two widely separated ground antennas to simultaneously
track a spacecraft and measure the time difference between signals
arriving at the two stations. ESA first used the sophisticated technique
to track Venus Express in 2006.
Received on Thu 15 Feb 2007 04:21:48 PM PST