Is life possible on other planets? The US space agency NASA plans to send its next rover to Mars in 2020 in an effort to answer this question. Seven unique instruments will be aboard that will help explore the planet better than ever before. One of the most exciting is the MOXIE (“Mars Oxygen ISRU Experiment”), with ISRU standing for “In-Situ Resource Utilization.” The experiment will attempt to extract oxygen from the carbon dioxide of the Mars atmosphere by electrolysis for the first time. MOXIE uses a solid oxide electrolysis (SOXE) stack developed by the US company OXEon Energy. On its journey through space, the stack will be exposed to extreme conditions: it must not only withstand the vibrations of the rocket launch and the landing impact, but also function in temperatures ranging from – 55 °C to over 800 °C. To maintain the high efficiency of the stack over the duration of the mission, OXEon utilizes special glass-ceramic sealants from SCHOTT.
During production of the SOXE stack, the glass powder is melted to form a permanent hermetic bond between the oxide ceramic electrolyte and metal interconnect of the cell. The sealing glass is formulated to match the exact coefficient of thermal expansion of the metals and ceramics, creating an uncompromising seal bond that remains stable even when temperatures shift. This is necessary to prevent uncontrolled that are switched in series as part of a stack are electrically isolated by the alkaline-free glass, even at high temperatures.
“The extreme temperatures and high forces present a special challenge for the MOXIE,” explains Dr. Jens Suffner, Technical Sales Manager at SCHOTT Electronic Packaging. “Many types of glass turn soft and elastic at temperatures of 500 °C and higher.” To prevent this, SCHOTT uses special sealing glasses with defined crystalline phases. This keeps the glass seal gas-tight and in place with sufficient strength, even under the harsh conditions present on Mars.
If the MOXIE is successful, it might revolutionize human exploration on Mars. The breathable air needed for a manned space mission could be directly generated on site. The created oxygen will also be used as the oxidant for the production of rocket fuel. This would solve an essential part of the challenge for enabling a return flight. So far, the road to the red planet has been viewed as a one-way street.
