Frontier teamed with Astrobotic Technology, Inc. of Pittsburgh, Pa. to win the award and will provide five DSE thrusters under the program for use in Astrobotic’s Peregrine lunar lander planned for launch at the end of 2020. During a future technology demonstration mission (TDM), the DSE thrusters will be integrated into a propulsion system provided by Dynetics of Huntsville, Ala. for trans-lunar injection, several lunar orbit insertion (LOI) decelerations, a breaking maneuver, and finally a powered descent to the lunar surface.
A Peregrine lunar lander flight mock-up. (Image source: Astrobotic Technology)
The propellant that the DSE thruster utilizes – MON-25/MMH hypergolic bipropellant – was key for the award selection.
MON-25/MMH may seem like a mouthful until you describe it as "monomethyl hydrazine (MMH) with a solution of 25% mixed oxides of nitrogen (MON)," or nitric oxide in dinitrogen tetroxide/nitrogen dioxide.
But please, please keep reading.
Basically, the nitric oxide is an oxidizing agent (makes sense) that also reduces MMH’s freezing point – in this case, -67 degrees Fahrenheit. For perspective, NASA typically uses hypergolic bipropellants with a MON-3 which freezes as five degrees Fahrenheit. All margins taken into account, the DSE is capable of operating at a wide propellant temperature range – between -22 to 122 degrees Fahrenheit – while a similar existing thruster may operate with propellant at temperatures between between 45 to 70 degrees Fahrenheit.
And because MON-25 propellants operate at lower temperatures, less power is needed for propellant conditioning for in-space propulsion applications, especially long duration and/or deep-space missions.
This is a potential windfall, since science missions require spacecraft propulsion systems that have that Dan Goldin seal of approval: high-performance, lightweight, compact, highly-matured, low-cost, with a short development time.
(It may sound like a tall order, but then again, all transportation solutions are bound by mass, power, and cost. And it gets even more stringent the higher of the ground you go.)
Unlike similarly classed, currently available heritage thrusters, the DSE uses improved designs, modern materials, and advanced manufacturing processes. The lower power rate for the DSE’s propellant conditioning trickles down to battery and solar panel mass reduction and then to a lighter, simpler, more robust, and more flexible design.
And baselining against those heritage thrusters, in this case from the Missile Defense Agency (MDA), NASA’s Marshall Space Flight Center proved the benefit during a 2017 hot-fire test. Even more, they found that DSE thruster tech could be applied to improve existing MDA hardware.
DSE thruster development work horse hardware in vacuum test. (Image source: NASA)
“The DSE thruster fills a significant need in the commercial marketplace. Potential uses include long-duration science missions to asteroids, Mars, Europa and other exomoons, and lunar landers, as well as short-duration missions for the Missile Defense Agency (MDA),” says Sharad Bhaskaran, Mission Director at Astrobotic.
All-in-all, its adaptable for spacecraft main propulsion, reaction control systems, and lander descent and ascent. The reduced system weight and volume increases available payload mass and/or acceleration capability, potentially expanding launch vehicle applications.
For Astrobotic, the DSE thruster means that the company can accommodates multiple customer payloads on a single Peregrine launch at an industry-defining low price of $1.2 million per kilogram. So far, they have 12 company deals for its first Moon mission and 130 customer payloads in the pipeline.
[This Friday post is part of our “Composite coverage: real lightweight stuff” series and a departure from SAE International’s traditional reporting approach. Let us know if you like our fun, conversational, and most likely irreverent coverage of legitimate news and notable events.]
William Kucinski is content editor at SAE International, Aerospace Products Group in Warrendale, Pa. Previously, he worked as a writer at the NASA Safety Center in Cleveland, Ohio and was responsible for writing the agency’s System Failure Case Studies. His interests include 'literally anything that has to do with space,' past and present military aircraft, and propulsion technology. And also sportscars.
Contact him regarding any article or collaboration ideas by e-mail at email@example.com.
Continue reading »