The Green Propellant Infusion Mission (GPIM) was a NASA technology demonstrator project that tested a less toxic and higher performance/efficiency chemical propellant for next-generation launch vehicles and CubeSat spacecraft.[4][5][6] When compared to the present high-thrust and high-performance industry standard for orbital maneuvering systems, which for decades, have exclusively been reliant upon toxic hydrazine based propellant formulations, the "greener" hydroxylammonium nitrate (HAN) monopropellant offers many advantages for future satellites, including longer mission durations, additional maneuverability, increased payload space and simplified launch processing.[4][5][7] The GPIM was managed by NASA's Marshall Space Flight Center in Huntsville, Alabama, and was part of NASA's Technology Demonstration Mission Program within the Space Technology Mission Directorate.

Green Propellant Infusion Mission (GPIM)

Artist's rendering of GPIM on Earth orbit
Mission type	Technology demonstrator
Operator	NASA
COSPAR ID	2019-036D
SATCAT no.	44342
Website	www.ball.com/aerospace/programs/gpim
Mission duration	Planned: 14 months[1] Final: 1 year, 3 months, 19 days
Spacecraft properties
Bus	BCP-100
Manufacturer	Ball Aerospace
Dry mass	158 kg (348 lb)
Start of mission
Launch date	25 June 2019, 06:30 UTC[2]
Rocket	Falcon Heavy
Launch site	Kennedy Space Center, LC-39A
Contractor	SpaceX
End of mission
Disposal	Deorbited
Decay date	14 October 2020[3]
Orbital parameters
Reference system	Geocentric orbit
Regime	Low Earth orbit
Perigee altitude	710 km (440 mi)
Apogee altitude	724 km (450 mi)
Inclination	24.0°

The Green Propellant Infusion Mission launched aboard a SpaceX Falcon Heavy rocket on 25 June 2019, on a test mission called Space Test Program 2 (STP-2).[8] The cost of the program was projected to be US$45 million.[9]

Development

Propellant

Hydroxylammonium nitrate molecule (NH₃OHNO₃) is a dense energetic ionic liquid

The propellant for this mission is hydroxylammonium nitrate (NH₃OHNO₃) fuel/oxidizer blend, also known as AF-M315E.[6][10] Preliminary data indicates that it offers nearly 50% higher performance for a given propellant tank volume compared to a conventional monopropellant hydrazine system.[4][6][10] The Green Propellant Infusion Mission sought to improve overall propellant efficiency while reducing the toxic handling concerns associated with the highly toxic propellant hydrazine.[5][11] The new propellant is an energetic ionic liquid. Ionic liquids are salt compounds in a liquid form whose molecules have either a positive or negative charge, which bonds them together more tightly and makes the liquid more stable.[12]

This new propellant is also expected to be significantly less harmful to the environment.[6] It is called a "green" fuel because when combusted, AF-M315E transforms into nontoxic gasses.[12] The AF-M315E propellant, nozzles and valves are being developed by the Air Force Research Laboratory (AFRL), Aerojet Rocketdyne, and Glenn Research Center, with additional mission support from the USAF Space and Missile Systems Center and NASA's Kennedy Space Center. The Air Force licensed AF-M315E production to Digital Solid State Propulsion (DSSP) to supply the propellant to government and commercial customers.[13]

Following the success of GPIM, the AF-M315E propellent was renamed ASCENT (Advanced Spacecraft Energetic Non-Toxic) in preparation for commercial use and production.[14]

Satellite

The GPIM system flew aboard the small Ball Configurable Platform 100 (BCP-100) spacecraft bus.[6][11] Aerojet Rocketdyne was responsible for the development of the propulsion system payload, and the technology demonstration mission employed an Aerojet-developed advanced monopropellant payload module as the sole means of on-board propulsion.[10]

Scientific payload

The Defense Department's Space Experiments Review board selected three payloads to be hosted aboard GPIM:

• An Air Force Academy instrument to characterize Earth's ionosphere and thermosphere.
• A Naval Research Laboratory instrument to measure plasma densities and temperatures.
• An Air Force Institute of Technology instrument that will test space collision avoidance measures.[15] Over the course of its mission, GPIM uses these instruments to monitor space weather and continuously track its own position and velocity.[1]

Applications

Once proven in flight, the project presents AF-M315E/ASCENT propellant and compatible tanks, valves and thrusters to NASA and the commercial spaceflight industry as "a viable, effective solution for future green propellant-based mission applications".[7][11] According to NASA, the new propellant will be an enabling technology for commercial spaceports operating across the United States "permitting safer, faster and much less costly launch vehicle and spacecraft fuel loading operations."[5] The combined benefits of low toxicity and easy open-container handling shorten ground processing time from weeks to days, simplifying the launching of satellites.[5] The new fuel is 50% denser than hydrazine,[16] meaning more of it can be stored in containers of the same volume. It also has a lower freezing point, requiring less spacecraft power to maintain its temperature.[7]

In addition to its use on lighter satellites and rockets, the fuel's exceptional volumetric storage properties is also being assessed for military uses such as missile launches.[6]

See also

References

External links

• Spores, Ronald A.; Robert Masse, Scott Kimbrel, Chris McLean (15–17 July 2013), "GPIM AF-M315E Propulsion System", 49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit (PDF), San Jose, California, USA{{citation}}: CS1 maint: multiple names: authors list (link)