The Space Technologies group of Laser Zentrum Hannover is developing a laser suitable for use in outer space as part of the ExoMars-Mission. The laser will be used to help establish if there is any form of life on the planet.
The first European Mars Rover on a joint mission of the American and European space agencies NASA and ESA will take off in 2018. The 250kg Rover will roll over the surface of Mars at a speed of 100m per hour. While doing so, it will inspect the surface and gather up ground and rock samples, some of them up to 2m deep. The main goals of the ExoMars mission are to search for traces of former or present life on the earthlike planet, and to prepare for the arrival of a manned Mars landing.
One of the central analytical instruments on the ExoMars Rover is MOMA. The Mars Organic Molecule Analyser will help with the complicated search for traces of life, by identifying organic materials and analysing it. If organic molecules like hydrocarbons are found, this might mean they might point to possible forms of life on Mars.
One of the core components in the MOMA is a laser desorption mass spectrometer (LD-MS) suited to travel in space, which includes a diode-pumped, solid-state laser in the UV spectrum. Using laser desorption, it is possible to bring non-vaporisable molecules in a gas phase, and make them slightly ionised, so they can be detected in a mass spectrometer. To achieve this, a compact, pulsed laser with a radiation wavelength of 266nm is needed, with a laser pulse energy of more than 250µJ. Such a laser system, which is also suitable for travel in space, is currently not available.
The core job of the LZH is to develop and construct the actual solid-state laser head. The technical requirements for use in outer space are very high. Dr Jörg Neumann, project leader at the LZH explains: 'The high temperature changes between night and day on Mars are a real problem. On top of that come the mechanical vibrations on the way to Mars and cosmic, ionising radiation. The real challenge is, that the laser must be rugged enough to withstand these elements, but at the same time light, small and compact.'
Scientists in the Laser Development Department are working on a passively Q-switched Nd:YAG oscillator, which is pumped longitudinally using optical fibres. With the help of non-linear crystals, the infrared light of the oscillator is transformed into ultraviolet light. Thermal controls guarantee that this system functions despite changing surrounding temperatures.