The Green Propellant Infusion Mission (GPIM) was a

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedi ...

technology demonstrator project that tested a less toxic and higher performance/efficiency chemical propellant for next-generation launch vehicles and

CubeSat A CubeSat is a class of miniaturized satellite based around a form factor consisting of cubes. CubeSats have a mass of no more than per unit, and often use commercial off-the-shelf (COTS) components for their electronics and structure. CubeSat ...

spacecraft. When compared to the present high-thrust and high-performance industry standard for

orbital maneuvering system In spaceflight, an orbital maneuver (otherwise known as a burn) is the use of propulsion systems to change the orbit of a spacecraft. For spacecraft far from Earth (for example those in orbits around the Sun) an orbital maneuver is called a ' ...

s, which for decades, have exclusively been reliant upon toxic

hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazin ...

based propellant formulations, the "greener" hydroxylammonium nitrate (HAN)

monopropellant Monopropellants are propellants consisting of chemicals that release energy through exothermic chemical decomposition. The molecular bond energy of the monopropellant is released usually through use of a catalyst. This can be contrasted with bipro ...

offers many advantages for future satellites, including longer mission durations, additional maneuverability, increased payload space and simplified launch processing. The GPIM was managed by NASA's

Marshall Space Flight Center The George C. Marshall Space Flight Center (MSFC), located in Redstone Arsenal, Alabama ( Huntsville postal address), is the U.S. government's civilian rocketry and spacecraft propulsion research center. As the largest NASA center, MSFC's first ...

in Huntsville, Alabama, and was part of NASA's Technology Demonstration Mission Program within the Space Technology Mission Directorate. The Green Propellant Infusion Mission launched aboard a

SpaceX Space Exploration Technologies Corp. (SpaceX) is an American spacecraft manufacturer, launcher, and a satellite communications corporation headquartered in Hawthorne, California. It was founded in 2002 by Elon Musk with the stated goal of ...

Falcon Heavy Falcon Heavy is a partially reusable heavy-lift launch vehicle that is produced by SpaceX, an American aerospace manufacturer. The rocket consists of two strap-on boosters made from Falcon 9 first stages, a center core also made from a Falc ...

rocket on 25 June 2019, on a test mission called Space Test Program 2 (STP-2). The cost of the program was projected to be .

Development

Propellant

The propellant for this mission is hydroxylammonium nitrate () fuel/oxidizer blend, also known as AF-M315E. Preliminary data indicates that it offers nearly 50% higher performance for a given propellant tank volume compared to a conventional monopropellant

system. The Green Propellant Infusion Mission sought to improve overall propellant efficiency while reducing the toxic handling concerns associated with the highly toxic propellant

. The new propellant is an energetic

ionic liquid An ionic liquid (IL) is a salt in the liquid state. In some contexts, the term has been restricted to salts whose melting point is below a specific temperature, such as . While ordinary liquids such as water and gasoline are predominantly made of ...

. 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. This new propellant is also expected to be significantly less harmful to the environment. It is called a "green" fuel because when combusted, AF-M315E transforms into nontoxic gasses. The AF-M315E propellant, nozzles and valves are being developed by the

Air Force Research Laboratory The Air Force Research Laboratory (AFRL) is a scientific research organization operated by the United States Air Force Materiel Command dedicated to leading the discovery, development, and integration of aerospace warfighting technologies, p ...

(AFRL),

Aerojet Rocketdyne Aerojet Rocketdyne is an American manufacturer of rocket, hypersonic, and electric propulsive systems for space, defense, civil and commercial applications. Headquartered in Sacramento, California, the company is owned by Aerojet Rocketdyne Hold ...

, and

Glenn Research Center NASA John H. Glenn Research Center at Lewis Field is a NASA center within the cities of Brook Park and Cleveland between Cleveland Hopkins International Airport and the Rocky River Reservation of Cleveland Metroparks, with a subsidiary facil ...

, with additional mission support from the

USAF The United States Air Force (USAF) is the Aerial warfare, air military branch, service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part ...

Space and Missile Systems Center Space Systems Command (SSC) is the United States Space Force's space development, acquisition, launch, and logistics field command. It is headquartered at Los Angeles Air Force Base, California and manages the United States' space launch ...

and NASA's

Kennedy Space Center The John F. Kennedy Space Center (KSC, originally known as the NASA Launch Operations Center), located on Merritt Island, Florida, is one of the National Aeronautics and Space Administration's (NASA) ten field centers. Since December 196 ...

. The Air Force licensed AF-M315E production to

Digital Solid State Propulsion Digital Solid State Propulsion (DSSP) is an aerospace company developing microthruster propulsion technology for small satellites. DSSP's technology utilizes Electric Solid Propellants (ESPs) to enable small satellites to make orbital maneuver ...

(DSSP) to supply the propellant to government and commercial customers. Following the success of GPIM, the AF-M315E propellent was renamed ASCENT (Advanced Spacecraft Energetic Non-Toxic) in preparation for commercial use and production.

Satellite

The GPIM system flew aboard the small Ball Configurable Platform 100 (BCP-100)

spacecraft bus A satellite bus (or spacecraft bus) is the main body and structural component of a satellite or spacecraft, in which the payload and all scientific instruments are held. Bus-derived satellites are opposed to specially produced satellites. Bus-d ...

was responsible for the development of the propulsion system payload, and the technology demonstration mission employed an Aerojet-developed advanced

payload module as the sole means of on-board propulsion.

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 The thermosphere is the layer in the Earth's atmosphere directly above the mesosphere and below the exosphere. Within this layer of the atmosphere, ultraviolet radiation causes photoionization/photodissociation of molecules, creating ions; the th ...

. * 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. Over the course of its mission, GPIM uses these instruments to monitor

space weather Space weather is a branch of space physics and aeronomy, or heliophysics, concerned with the time varying conditions within the Solar System, including the solar wind, emphasizing the space surrounding the Earth, including conditions in the m ...

and continuously track its own position and velocity.

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". 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." The combined benefits of low toxicity and easy open-container handling shorten ground processing time from weeks to days, simplifying the launching of satellites. The new fuel is 50% denser than hydrazine, meaning more of it can be stored in containers of the same volume. It also has a lower

freezing point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depe ...

, requiring less spacecraft power to maintain its temperature. 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.

References

External links

* {{DEFAULTSORT:Green Propellant Infusion Mission Monopropellants NASA space probes Rocket fuels Rocket propellants Spacecraft propulsion SpaceX payloads contracted by NASA Spacecraft launched in 2019 Spacecraft which reentered in 2020 SpaceX commercial payloads