Eta Space Develops Cryogenic Propellant Depots for Earth and Space

Eta Space- Lunar Production PlantEta Space, a new space company dedicated to developing advanced cryogenic systems for the modern space and energy age, is celebrating its three-year anniversary in June with milestones scheduled for several key projects. Eta Space is developing LOXSAT, a 135 kg demonstration satellite designed to test critical cryogenic fluid management (CFM) technologies in Earth’s orbit.

Funded as a Tipping Point public-private partner- ship with NASA Space Technology Mission Directorate (STMD), LOXSAT will include 12 individual test objectives to be operated in a microgravity environment for the first time, bringing the Technology Readiness Levels of these systems to TRL7. The demonstrations include zero boiloff storage, propellant densification, pressurization and pressure control, and no vent chilldown and transfer of LOX. The payload will include fluid visualization integrated into the storage tank, enabling validation of zero-g computational fluid models. LOXSAT is scheduled to complete the critical design review in June, a milestone that demonstrates design maturity is sufficient for fabrication and assembly of the payload. LOXSAT is planned to fly on a Rocket Lab Electron rocket in March 2024 on a nine-month mission.  

In parallel with the LOXSAT design work, Eta Space is proud to announce the development of Cryo-Dock™, the world’s first commercial cryogenic propellant depot in Earth orbit. Cryo-Dock is designed to service space- craft stages and orbital transfer vehicles with high-energy liquid oxygen/liquid methane, using a standardized, automated umbilical. Leveraging the successful demonstration of the CFM technologies during the LOXSAT mission, Cryo-Dock will feature full control of the cryogenic propellants in microgravity, including long-term zero boiloff storage and zero-loss chilldown, as well as transfer of the cryogenic propellants. This capability will enable a new era of sustainable space transportation, where spacecraft refueling and reuse will dramatically lower the cost of in-space transportation. 

NASA has awarded another Tipping Point contract to Eta Space for development of a liquid oxygen/liquid hydrogen (LOX/LH2) propellant depot for lunar exploration. The entire system is designed for operation in the extreme environment of the lunar poles, where permanently shadowed regions in craters have been subjected to cryogenic temperatures for millions of years. These cold-trap areas are thought to contain large reserves of volatile elements including water ice, which can be collected, purified and split into its hydrogen and oxygen elements. Eta Space and Skyre are building and testing a ground-based version of a 1/50th-scale Lunar Propellant Production Plant (LP3). Skyre is providing the warm electrochemical systems, while Eta Space is providing the cryogenic components for liquefaction and storage. The long-term goal is production of ten metric tons of LOX/LH2 per month. 

While enabling technology for this sustainable lunar base architecture, the LP3 cycle also has direct applications for “green hydrogen” on Earth. LP3 uses the same process of producing hydrogen from water and solar energy that is the “holy grail” of terrestrial hydrogen energy. However, LH2 production and storage is historically an energy-intensive process, and the ability to liquefy and store large quantities of hydrogen efficiently is a prime goal of Eta Space. While at NASA KSC, founder Bill Notardonato pioneered the concept of Integrated Refrigeration and Storage (IRAS) that allows for direct control over the state of the cryogenic fluid. First working with Dr. Jong Baik at the Florida Solar Energy Center, the IRAS concept was successfully demonstrated on small scales starting in 2004. Later tests culminated in a full-scale demonstration of zero-loss liquid hydrogen storage and transfer and hydrogen densification using an IRAS system for the Ground Operations Demonstration Unit for Liquid Hydrogen at Kennedy Space Center in 2014. This technology is being incorporated into the world’s largest LH2 tank at LC-39B at KSC. Eta Space also operates a small-scale hydrogen liquefier (150 liters) and thermal vacuum chambers to enable testing of materials and components intended for use with LH2.  

Eta Space is leveraging its engineering skills, honed from decades of experience at NASA, to develop a series of in-space cryogenic propellant depots critical to creating a sustainable space program. This experience of using ultrahigh efficiency in cryogenic storage and transfer systems is necessary to help transition the earth to- wards a clean hydrogen energy foundation.

Image: Digital rendering of Lunar Propellant Production Plant. Credit: Eta Space

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