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No. 90 - Earth Swing-by Activities
19 November 2007
Report for the Period 10 November - 16 November 2007
During the reporting period Rosetta successfully went through the second Earth Swing-by manoeuvre that boosted the spacecraft towards a new and bigger orbit around the Sun. The period was characterised by intense flight operations preceding and following the closest approach that was on the 13 November at 20:57:23 UTC when Rosetta flew at an altitude of ca. 5300 km over the South Pacific.
No correction manoeuvres were needed in the days preceding the swing-by. Orbit determination and manoeuvre optimisation performed after the swing-by confirmed the need for a small correction. In order to optimise the fuel consumption the manoeuvre will be split in two legs (one to be performed on the 23 November, the second in February 2008).
Several instruments have been operating during the reporting period producing a significant amount of science data, now being processed by the PI teams.
At the end of the reporting period (DOY 320) Rosetta was at 1.75 million km from Earth (0.011 AU); one-way signal travel time was 6 seconds. The distance to the Sun was 145.65 million km (0.98 AU).
The Earth Swing-by phase will continue now with the remaining payload operations and the first trajectory correction manoeuvre planned for 23 November. The intense navigation campaign will finish shortly after.
The mission control teams are now planning check-out and tests in preparation of the Asteroid fly-by of September 2008.
Earth Swing-by 2
On DoY 317 at 20:57:22.964 UTC Rosetta flew at an altitude of 5294.852 km over the surface of the Earth for its 2nd swing-by. Rosetta will swing-by again the Earth on 13 November 2009 for its 3rd and last swing-by on its way to comet 67P/Churyumov-Gerasimenko.
The Rosetta Earth swing-by has also been characterised by warning and alarms regarding potential hazards for the Earth coming from an asteroid that would fly only 5600 km over the Earth surface in the night of 13 November. It is interesting to note that this hazard was Rosetta approaching the Earth and the high-quality of the orbit determination of these alert centers.
In the night of the swing-by the mission control team at ESOC was also informed of an object following Rosetta on a very similar orbit and coming from Mars (as Rosetta). Further analysis revealed in this case that the object was an asteroid with an Apollo-type orbit.
Using data up to the end of the NNO pass on 11 November, the orange cross and surrounding 3-sigma error ellipse show the current estimate in the B-plane. The location is 5.0 km from the optimum target.
The target location corresponds to a perigee altitude of 5299.5 km (relative to the Earth's equatorial radius). The estimate corresponds to an altitude of 5294.7 km with a 3-sigma uncertainty of 1.5 km.
The associated 3-sigma error ellipse is not shown because it would be too small to see clearly. Its semi-major axis is about 10 m and its semi-minor axis is less than 5 m.
The final estimate corresponds to a perigee altitude of 5294.852 km (relative to the Earth's equatorial radius). The 3-sigma uncertainty of this result is 7 m.
The time of closest approach was 20:57:22.964 UTC on 13 November. The 3-sigma uncertainty of this result is less than 0.005 seconds.
Apollo Type Asteroid
Last Update: 20 November 2007For further information please contact: SciTech.firstname.lastname@example.org
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