[meteorite-list] Rosetta Mars Swing-by

[Ron Baalke]

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=40697

Rosetta Mars Swing-by
European Space Agency
23 Feb 2007

The Rosetta swing-by of Mars is the second of four gravity assist 
manoeuvres that are required to place Rosetta on course for 
its final destination: comet 67P/Churyumov-Gerasimenko. The 
closest approach of the swing-by will take place at 01:54 UT, 
25 February 2007, when the spacecraft will pass 250 km above 
the surface of Mars.

Updates on the progress of the flyby can be found on the ESA 
Rosetta Swing-by site.

The Mars swing-by has been setup by two deep space manoeuvres 
on 29 September 2006 and 13 November 2006 and a trajectory control 
manoeuvre on 9 February 2007 to accurately set Rosetta on the 
required swing-by path.

Dates of Assist Manoeuvres

The Mars swing-by has been setup with two Deep Space Manoeuvres 
on 29 September 2006 and 13 November 2006 and a Trajectory Control 
Manouevre on 9 February 2007 to accurately set Rosetta on the 
required swing-by path (see related status reports on the right 
hand side).
Mars Swing-by Details

Event 	                Time (UT)
Occultation Start 	01:52:24
Closest Approach 	01:54:12
Eclipse Start 	        01:54:25
Occultation End 	02:06:50
Eclipse End 	        02:19:10

The time of closest approach is at approximately 01:54 UT, when 
Rosetta is only 250 km above the Martian surface and traveling 
at a speed of over 36 000 kmh-1 relative to Mars. The swing-by 
takes Rosetta over Mars's northern hemisphere, with the point 
of closest approach of a surface position of 298.2° E and 43.5° 
N.

During the swing-by, Rosetta will pass behind Mars, as seen 
from Earth, resulting in a loss of communication for a period 
of 15 minutes, starting 2 minutes before closest approach.

In addition, Rosetta will pass through the shadow cast by Mars 
for a period of 25 minutes and go into eclipse. For this reason 
the spacecraft instruments are not active at closest approach 
- except for the Radio Science experiment. Power will be provided 
by the spacecraft's batteries.

Planned Science Activities

Mars
Between 8 hours and 4 hours prior to closest approach, the orbiter 
instruments will perform targeted observations of the Martian 
surface and the two moons of Mars, Phobos and Deimos.

Because Philae runs off its own separate power supply it is 
possible to have some of these instruments active during the 
eclipse phase. At closest approach the ROMAP and CIVA instruments 
will be operated. ROMAP (Rosetta Lander Magnetometer and Plasma 
Monitor) will take magnetometric measurements from 12 hours 
before to 12 hours after closest approach. CIVA (Comet Nucleus 
Infrared and Visible Analyser) will perform imaging of Mars.

Activity 	Instrument
Mars spectroscopy and imaging of surface and atmosphere 	OSIRIS 
	Orbiter
ALICE 	Orbiter
VIRTIS 	Orbiter
CIVA 	Lander Philae
Investigating the interaction of Mars with the solar wind 	Rosetta 
Plasma experiment 	Orbiter
ROMAP 	Lander Philae
OSIRIS 	Orbiter
Phobos and Deimos imaging 	OSIRIS 	Orbiter
Searching for anomalous accelerations during the swing-by 	

Radio Science experiment
	Orbiter
Investigating the Mars radiation environment 	

Radiation Monitor
experiment
	Orbiter

Jupiter
On 27 February, only a few days after Rosetta's closest approach 
to Mars, NASA's New Horizon spacecraft will perform a swing 
by of Jupiter and afterwards will fly along the planet's magnetotail 
for about 100 days.

Due to Sun illumination conditions, Rosetta will be able to 
observe Jupiter for 4 hours on 28 February and continuously 
after 1 March. Rosetta will make Jupiter observations with the 
ALICE, VIRTIS and OSIRIS instruments.

Pioneer Anomaly
First observed with the NASA Pioneer spacecraft, the anomaly 
represents a deviation in the expected change in spacecraft 
velocity and trajectory against observations. Scientist are 
not certain if the anomaly is caused by an unknown physical 
process, or if it is simply down to the uncertainties in measurements 
and analytical calculations. A test will be carried out using 
a MASER signal sent from the ground based tracking stations.