For the Max Planck Institute for Solar System Research (MPS) and for the German Aerospace Center (DLR), Cassidian Optronics GmbH has developed and manufactured a highly efficient laser source for the first European laser altimeter, the BepiColombo Laser Altimeter (BELA). Following successful qualification, the flight unit of the laser has now been delivered and, after being integrated into the BELA instrument, it should take off for Mercury in 2016 on board the European Space Agency’s “Mercury Planetary Orbiter” satellite. One important goal of the “BepiColombo” mission is to completely record the topography of the planet Mercury over the course of a year.
After swinging into orbit around Mercury, under the influence of harsh environmental conditions, the BELA instrument will produce high precision measurements of the distance between the satellite and the surface of the planet, from which the shape of Mercury’s landscape can be reconstructed. The precise alignment and stability of this high-performance laser is of particular importance for laser altimetry. With an extensive test programme, Cassidian Optronics has ensured that all of the critical optical and electronic components will work perfectly despite the extreme loads that they will be subjected to.
The satellite will take about four years to fly to Mercury. After reaching Mercury orbit, the laser will start to send very intense pulses of light lasting only a few thousand millionths of a second to Mercury’s surface. Each second, ten pulses will be emitted from a height of about 1,000 kilometres down to hit the surface of the planet. The pulses will be reflected back to the satellite where they will be received and analysed. The received laser pulses will still be strong enough so that, from the time taken for the round trip, the height of the ground on Mercury can be calculated with a precision of less than a metre.
While developing this laser, Cassidian Optronics was able to make use of its many years of experience with military lasers and laser range-finding equipment as well as experience from previous space projects. Amongst other things, this includes mirrors for the European Space Agency’s GAIA mission as well as spectrograph components for the James Webb Space Telescope (JWST).
Date: Dec 17, 2013