Breathing on Mars

NASA is preparing for human exploration on Mars. The Mars 2020 rover mission will try to convert carbon dioxide into breathable oxygen for the first time ever. Highly temperature resistant sealing glasses from SCHOTT are being used in the rover’s electrolysis cells to help carry out its mission, even in the extreme conditions on the planet.

NASA is preparing for human exploration on Mars. The Mars 2020 rover mission will try to convert carbon dioxide into breathable oxygen for the first time ever. Highly temperature resistant sealing glasses from SCHOTT are being used in the rover’s electrolysis cells to help carry out its mission, even in the extreme conditions on the planet.

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.

SCHOTT uses special sealing glasses with defi ned crystalline phases.
Highly temperature-resistant sealing glass from SCHOTT protects the electrolysis cell.

How MOXIE works

MOXIE uses a solid oxide electrolysis (SOXE) stack developed by OXEon Energy for converting CO2 to O2. Its working elements consist of stacked scandia-stabilized zirconia electrolyte-supported cells that are coated with a catalytic cathode on one side and an anode on the other. These are separated by expansion-matched interconnects that direct the source, exhaust, and produce gases to and from their respective manifolds and are sealed by SCHOTT’s highly temperature-resistant glass-ceramic that provides electrical insulation, leak-tightness and mechanical stability.

When CO2 flows over the catalytic cathode surface under an applied electrical potential, a reaction occurs and it is electrolyzed. The CO is exhausted and the oxygen ion electrochemically driven through the SOXE electrolyte to the anode where it is oxidized. The O-atoms combine to produce the gaseous O2, which is then released from the anode cavity at a proportional rate. The reaction chemistry uniquely determines both the minimum electrical current and CO2 flow required to produce O2 at a given rate.

August 6, 2018

Contact

Kevin Waxman
Electronic Packaging
SCHOTT North America, Inc.

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