After one week orbiting Earth, heading to L1


Since LISAPathfinder launch, on Thursday December 3rd 2015, teams from the European Space Observations Centre (ESOC) in Darmstadt are working day and night to ensure the orbital operating steps. As illustrated in the figure, these maneuvers consist in correcting the path and increasing by successive pushes the  altitude of the apogee, that is to say, the point on the orbit which is farthest from the Earth . Each time the engine of the propulsion module is activated for several tens of minutes.

Just after the launch the apogee was at an altitude of 1,540km. The first push took place Saturday 07/12/2015 at 5:02 with an increase in speed of 393 m/s which rose the apogee at 3,392km. Then the same day another push at 17:20 rose the apogee at 7.105 km (+ 552 m/s). Then, Tuesday 08/12/2015, two new pushes allowed to reach orbits with apogees at 14,488 km (+ 603 m/s) and then 44,526 km (+ 807 m/s). And the fifth push was operated on 10/12/2015 at 0:34 with an increase in speed of 398 m/s which rose the apogee to 129,122 km.

Finally after running tests on its performance, the engine was activated  on Saturday 12 at 5:18 during 6 minutes to make the final push (+ 234 m/s). This allowed to eject LISAPathfinder outside the Earth’s orbit and to put the satellite on its trajectory towards the Lagrangian point L1. We will have now nearly fifty days to cover the 1.5 million kilometers from the Earth to L1.

Have a good journey LISAPathfinder, arrival late January 2016!

Antoine Petiteau


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