Using LIBS in Autonomous Robots to Explore Geomaterial Composition in Space Exploration
Credit: DLR, German Aerospace Center. DLR’s LRU2 robot during the ARCHES space mission simulation on Mount Etna
LIBS, or Laser-Induced Breakdown Spectroscopy, has rapidly yielded valuable data in a recent demonstration of autonomous robots designed to explore foreign celestial bodies, such as the Moon. At the foot of Mount Etna, an active volcano in Italy, a space mission simulation was performed using several robots to navigate and map their surroundings and collect and analyze rock samples.
A modular LIBS instrument developed by Dr. Susanne Schroeder and colleagues from the DLR Institute of Optical Sensor Systems can be coupled to the robotic arm of one of DLR’s Lightweight Rover Units (LRUs) to determine the elements contained in a sample. The LIBS instrument, contained in a lightweight box, can be chosen by the robot from a set of tools and other modular instruments. It is then carried as a ‘backpack’ on the rover and placed onto a rock of interest in the target area. The chosen optics focus the laser at a fixed distance of about 7 cm from the instrument where some rock material is vaporized and turned into a small plasma. The plasma emission is subjected to spectral analysis, and the results are sent to the control center to determine the elemental composition.
MicroJewel DPSS Laser for LIBS
Dr. Schroeder and her team chose Quantum Composers’ MicroJewel for its compact size, low power consumption, and ease of integration with other commercially available components. Already in use in lab experiments for years, the MicroJewel performed reliably in field tests, despite environmental conditions.
The payload box that houses the LIBS instrument, including the MicroJewel Nd:YAG laser, spectrometer, and microcontroller, currently weighs about 1 kg and scans the LIBS’ targets at sampling rates of up to 30 Hz. The spectrometer covers wavelengths of 550-770 nm, allowing for the detection of rock-forming elements such as silicon, calcium, sodium, and potassium, as well as minor and trace elements such as hydrogen and lithium, and emission of nitrogen.
Current components should allow for further reduction of payload mass and volume for future missions. The MicroJewel today takes only a fraction of the available footprint on the LRU. Though the MicroJewel is designed for operating conditions of 15-30 degrees Celsius, using it in extraterrestrial environments would require active temperature control customizations to the instrument to maintain a suitable operating environment.
LIBS: Celebrating 10 Years in Space
LIBS has now been in use in space exploration for a decade with the ChemCam instrument on NASA’s Curiosity rover on Mars (Maurice et al., 2016). The successful operation of the LIBS instrument in the most recent ARCHES demonstration mission helped to achieve the mission goals and shows the importance of this technique to current and future space missions. On Earth, these autonomous robots, equipped with LIBS instrumentation, could also prove beneficial for tasks in places too dangerous for humans to work.
Preparing for exploration of the Moon and other celestial bodies will require a further reduction of payload, adaption to the specific spacecraft, shock testing, and temperature control. As Dr. Schroeder’s team prepares for future LIBS instrumentation on Moon-analogue and Mars-like scenarios, space-ready laser spectroscopy may provide important elemental analysis of rock or soil composition in planetary in-situ exploration.
Learn more about the MicroJewel.