LISA Pathfinder takes a peek at Earth
5 December 2015ESA’s LISA Pathfinder blasted off on 3 December at 04:04 GMT (05:04 CET) on a Vega rocket that delivered it to a low-Earth parking orbit. From there, the satellite will perform a series of six critical burns with its own propulsion system over the coming week, to raise the highest point of its orbit and eventually start the cruise towards its operational orbit around the Lagrange point L1, 1.5 million km away from Earth towards the Sun.
|A portion of the Earth, its atmosphere and a starry sky above, as seen by LISA Pathfinder's star trackers. Credit: ESA/LPF/Airbus-DS; Acknowledgement to J. Grzymisch & M. Watt|
Since taking over control of the spacecraft after it separated from the upper stage of the Vega launcher, the mission control teams at ESA’s European Space Operations Centre in Darmstadt, Germany, have been checking that the various subsystems on board LISA Pathfinder are working well ahead of the critical orbit raising phase. Among these operations, they also tested the two star-tracker cameras, located below the science module, that are used for navigating the satellite using the stars as reference points.
During the science mission, the images taken by the star trackers are not sent to Earth but processed on board. However, during the commissioning of the spacecraft, the operators are collecting data from the star trackers, and so obtained a one-of-a-kind image – at least for a non-imaging satellite such as LISA Pathfinder.
The image, taken at 19:23 GMT (20:23 CET), shows a portion of the Earth during night time, covered by layers of the atmosphere. Beyond the horizon of our planet, several stars are visible, above as well as through the atmosphere.
“We are extremely happy to see this little souvenir from space, showing that our satellite is alive and well,” says Paul McNamara, ESA’s LISA Pathfinder project scientist.
LISA Pathfinder is a technology demonstration mission that will test instruments and measurement concepts that could be used, in the future, to observe gravitational waves from space. Ripples in the fabric of spacetime caused by accelerating massive bodies, gravitational waves were predicted by Albert Einstein’s General Theory of Relativity but have not yet been directly detected.
The spacecraft is expected to reach its operational orbit in February 2016 and, after final checks, it will begin its six-month scientific mission at the beginning of March.
Acknowledgement: this image was prepared by Jonathan Grzymisch (LISA Pathfinder Control Engineer at ESA) and Mark Watt (Airbus-DS).