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Commercial and US Government Launch Vehicles => Other US Launchers => Topic started by: russianhalo117 on 05/03/2013 03:29 am

Title: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: russianhalo117 on 05/03/2013 03:29 am
Green Propellant Infusion Mission (GPIM) LINKS:
LINK 1a: http://www.nasa.gov/mission_pages/tdm/green/gpim_overview.html
LINK 1b: http://www.nasa.gov/centers/glenn/home/index.html
LINK 1c: http://www.nasa.gov/centers/kennedy/home/index.html
LINK 2a: http://www.ballaerospace.com/page.jsp?page=281
LINK 2b: http://www.ballaerospace.com/page.jsp?page=95
LINK 3: http://www.aerojet.com/home.php
LINK 4a: http://www.wpafb.af.mil/AFRL/
LINK 4b: http://www.losangeles.af.mil/library/factsheets/factsheet.asp?id=5318

ARTICLE 1: http://www.nasa.gov/mission_pages/tdm/green/gpim_overview.html
Green Propellant Infusion Mission (GPIM)
 

"There are no passengers on spaceship Earth. We are all crew."
-- Marshall McLuhan, 20th-century Canadian philosopher

Efficiency has long been a key driver in our nation's journey to space. We seek hardware, system and power solutions that optimize performance, giving us the greatest value for our investment. But in the 21st century, additional factors help drive our mission of space exploration -- factors closer to home. Now we seek "green" alternatives to the historically efficient but environmentally hazardous propellants that have seen us to this point in our journey. Toxic, corrosive fuels like hydrazine, which have powered a variety of rockets, satellites and other spacecraft over the years, now are being superseded with new solutions -- ones that improve overall efficiency while also promising safer stewardship of the environment. The era of green propellants is upon us: more powerful, burning cleaner and still safely delivering new generations of explorers to destinations across the solar system.

The Green Propellant Infusion Mission (GPIM) project will demonstrate the practical capabilities of AF-M315E, a high-performance green alternative to hydrazine. This innovative, low-toxicity propellant is expected to improve overall vehicle performance. It boasts a higher density than hydrazine, meaning more of it can be stored in containers of the same volume; it delivers a higher specific impulse, or thrust delivered per given quantity of fuel; and it has a lower freezing point, requiring less spacecraft power to maintain its temperature.

While all rocket fuels can be dangerous to handle without the proper safety precautions, AF-M315E is considerably easier and safer to store and handle than hydrazine, and will dramatically reduce costs and permit shorter launch processing times. NASA and its partners will always maintain the strictest safety standards for storage, transport and use of rocket propellants.

Led by Ball Aerospace Corp. of Boulder, Colo., the Green Propellant Infusion Mission project includes co-investigators from NASA's Glenn Research Center in Cleveland; Aerojet Corp. in Redmond, Wash.; and the U.S. Air Force Research Laboratory at Edward Air Force Base, Calif. Additional support is provided by NASA's Kennedy Space Center, Fla., and the U.S. Air Force Space and Missile Systems Center at Kirkland Air Force Base, N.M.

The GPIM payload is expected to fly to space aboard the Ball Configurable Platform, a compact small satellite set to be launched in 2015.

---------

ARTICLE 2: http://www.ballaerospace.com/page.jsp?page=281
GREEN PROPELLANT INFUSION MISSION (GPIM)

Overview
The NASA Green Propellant Infusion Mission (GPIM) seeks to demonstrate and test the capabilities of a high-performance, non-toxic, “green” fuel on orbit. This the first time the nation will use a spacecraft to test green propellant technology.

The fuel and its accompanying technology offer many advantages for future satellites, including longer mission durations, additional maneuverability, increased payload space, and simplified launch processing.
The propellant for this mission is a Hydroxyl Ammonium Nitrate (HAN) fuel/oxidizer blend, or AF-M315E. Developed by the Air Force Research Laboratory (AFRL), it offers nearly 50 percent higher performance for a given propellant tank volume compared to a conventional hydrazine system. This new, green propellant is less harmful to the environment, increases fuel efficiency, and diminishes operational hazards.

Our Role
The Ball team will develop and fly the GPIM to demonstrate the new fuel and an integrated propulsion system that uses green propellant in space. Once on-orbit, the team will characterize the green fuel’s performance using Ball Aerospace-developed software. Planned on-orbit maneuvers include attitude control demonstrations, spacecraft pointing and hold, thruster performance characterization and mapping, inclination change and orbit lowering.

The GPIM payload will fly aboard the Ball Configurable Platform (BCP) 100 spacecraft bus. The Ball Aerospace-built BCP 100 provides standard payload interfaces and streamlined procedures for short lead-time and affordable access to space. The BCP 100 is ideally suited for scientific, technology development, and risk reduction payloads like the GPIM.

The GPIM will be developed over three years and is expected to launch in 2015.

The Team
Ball Aerospace is the prime contractor for GPIM. A principal investigator from Ball Aerospace will lead the demonstration of the alternative fuel for future space vehicles. GPIM team co-investigators include the Aerojet Corporation, NASA Glenn Research Center, and the U.S. AFRL at Edwards Air Force Base, with additional mission support from the U.S. Air Force Space and Missile Systems Center at Kirkland Air Force Base and NASA's Kennedy Space Center.

Future Applications
In addition to the promise of higher performance for future satellites, the fuel’s exceptional volumetric storage properties is also being examined for military uses such as missile launches and auxiliary power units that currently use hydrazine.
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: spectre9 on 07/09/2013 12:30 pm
Cool video.

I like the FH launch  ;D

http://www.youtube.com/watch?v=0rKYHLAThYc

Hopefully someday we can can toxic hypergol free launches.
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: catdlr on 07/10/2013 11:07 pm
Thruster Testing, Green Propellant Infusion Mission

Published on Jul 10, 2013
Aerojet Rocketdyne highlights preparation and testing of its 22 Newton thruster at its Redmond, Wash. facility . Partnered with Ball Aerospace, Aerojet Rocketdyne has met the first milestone in demonstrating a more environmentally friendly spacecraft fuel by completing an end-to-end checkout of the 22 N thruster required for NASA's Green Propellant Infusion Mission (GPIM). When it flies, the GPIM will demonstrate a high-performance, non-toxic fuel alternative to conventional hydrazine. (Aerojet Rocketdyne )

http://www.youtube.com/watch?v=fBYkhdJC0rw
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: AnalogMan on 07/10/2013 11:47 pm
NASA have just published a NASAfacts sheet for the Green Propellant Infusion Mission Project.  Probably doesn't offer much new, but I did notice the following:

"The Green Propellant Infusion Mission is scheduled to launch aboard a SpaceX Falcon Heavy rocket in late 2015."

http://www.nasa.gov/sites/default/files/files/Green-Propellant-Infusion-Mission-Project_-Fact-Sheet.pdf (http://www.nasa.gov/sites/default/files/files/Green-Propellant-Infusion-Mission-Project_-Fact-Sheet.pdf)
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: russianhalo117 on 07/11/2013 04:26 pm
NASA have just published a NASAfacts sheet for the Green Propellant Infusion Mission Project.  Probably doesn't offer much new, but I did notice the following:

"The Green Propellant Infusion Mission is scheduled to launch aboard a SpaceX Falcon Heavy rocket in late 2015."

http://www.nasa.gov/sites/default/files/files/Green-Propellant-Infusion-Mission-Project_-Fact-Sheet.pdf (http://www.nasa.gov/sites/default/files/files/Green-Propellant-Infusion-Mission-Project_-Fact-Sheet.pdf)
We determined that GPIM is flying in the primary payload slot in the joint DoD/DoC (NASA and NOAA (Sat TBD)) STP-02 mission which is confirmed by participating agencies (SpaceX said that they cannot publicly confirm at this time the payloads selected that were for the 2014 FH Demo Flight or the FH STP-02 flight) launching on the 2015 Falcon Heavy Flight. There has been mention that a test satellite may launch on the 2014 FH Demo flight, but I have not been able to confirm it except that in 2015 it will launch a fully operational demonstration sat on the STP-02 flight. The universal SC bus selected for GPIM was designed to serve as a readily available US equivalent to ESA's Proba SC demonstration series.
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: TrueBlueWitt on 07/12/2013 08:36 pm
I am curious if it's possible to modify older thruster designs to use this safer and higher energy density propellant?  Let's say SpaceX's Draco/Super Draco. 

Also, would this propellant be well suited to a propellant depot architecture?
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: strangequark on 07/12/2013 09:27 pm
I am curious if it's possible to modify older thruster designs to use this safer and higher energy density propellant?  Let's say SpaceX's Draco/Super Draco. 

Also, would this propellant be well suited to a propellant depot architecture?

No. HAN propellants require a catalyst bed, meaning that the design is totally different from existing bipropellant hypergol thrusters like Draco. It is also very different from a hydrazine thruster because the reaction temperature is 2-3 times higher. Hydrazine thrusters are typically made of nickel alloys. HAN thrusters use ceramics and expensive refractory metals like rhenium.

HAN propellants have some shelf-life stability issues that have been one of the major points of focus for developing this propellant type. The understanding of how to stabilize them has improved steadily over the years however, and would probably be fine for any depot with a reasonable throughput. If you're thinking for large scale main propulsion though, HAN would not be a great fuel, as the catalyst bed will result in low T/W for a larger engine. and there's not really any major benefits it would bring to the table over something like Methane/LOX. For refueling satellites, maybe, but the business case is probably weak. I'm not a satellite guy, but I don't think propellant is usually the life-limiting factor.
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: sdsds on 07/13/2013 12:12 am
By way of comparison:
http://www.eads.com/eads/int/en/news/press.20130618_astrium_ecaps_green_propulsion.html
"Astrium and ECAPS develops a new ‘green’ propulsion system"
18 June 2013

The Europeans seem to like ADN (Ammonium Dinitramide). ATK tested that propellant in the U.S. for the Goddard Space Flight Center. How did NASA decide to go with HAN?

And then: are both of these sort of like NOFBx, i.e. are they blends of fuel and oxidizer that somehow stay safe and usable even when mixed together?
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: strangequark on 07/13/2013 12:23 am
By way of comparison:
http://www.eads.com/eads/int/en/news/press.20130618_astrium_ecaps_green_propulsion.html
"Astrium and ECAPS develops a new ‘green’ propulsion system"
18 June 2013

The Europeans seem to like ADN (Ammonium Dinitramide). ATK tested that propellant in the U.S. How did GRC decide to go with HAN?

And then: are both of these sort of like NOFBx, i.e. are they blends of fuel and oxidizer that somehow stay safe and usable even when mixed together?

Yeah, ADN base is very similar. It's less GRC than AFRL. The Air Force has been researching and perfecting HAN based propellants since the early 90s, so it's the most mature system in the US, especially at the contractor in question, which has a strong experience base with the Air Force HAN blends.

These are what are known as "ionic propellants". Basically, they're a combination of water soluble salts in solution. Some of the salts are fuel, some are oxidizer. Pure HAN is an oxidizer. The AF-M315E is a HAN-based mix, with fuel salt, stabilizer, burn rate modifiers, etc. The solvent is water, which is nice because the only volatile given off is water vapor. The mix is also insensitive when not catalyzed. NOFBx is interesting, but I personally find it concerning because of the high vapor pressure (bad for leaks) and the fact that Nitrous-Oxide Fuel Blends are so notoriously explosive. AF-M315E is starting from a much less volatile base, and is the product of much testing over the last two decades.

Something interesting is that these burn much more like solid propellants than traditional liquid propellants. To the point where they do "strand burn" tests with a vial of propellant. They can almost be thought of as a solid propellant that uses water as the binder.
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: spectre9 on 07/13/2013 02:17 am
Awesome post strangequark.

That really helps me understand these new green propellants.
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: ClaytonBirchenough on 07/13/2013 08:22 pm
Planetary body at the end of the video?  ???
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: simonbp on 07/15/2013 03:51 pm
I'm not a satellite guy, but I don't think propellant is usually the life-limiting factor.

For a conventional GEO sat, most of its propellant is used in the GTO -> GEO circularization burn, and the attitude control slowly works through the remainder. So, if you're going to replace hydrazine, you really need to be able to do both.
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: strangequark on 07/15/2013 04:05 pm
I'm not a satellite guy, but I don't think propellant is usually the life-limiting factor.

For a conventional GEO sat, most of its propellant is used in the GTO -> GEO circularization burn, and the attitude control slowly works through the remainder. So, if you're going to replace hydrazine, you really need to be able to do both.

Not quite what I meant. My comment was meaning that I don't know if there would be any market for satellite refueling services.
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: baldusi on 07/21/2013 12:31 pm
I guess most people is interested in the RCS role. Of course that for the GTO it would need to be able to do the kick (about 400N thrust). Unless the set is SEP in which place there's no point on using this.
One part that I find interesting is about processing facilities and cost. Could it be fueled on current facilities? Could new facilities significantly lower the processing cost vis-a-vis an hypergolic?
It would seem, though, that the best candidate for this would be human rated systems. Specially returning ones.
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: strangequark on 07/22/2013 03:12 pm
I guess most people is interested in the RCS role. Of course that for the GTO it would need to be able to do the kick (about 400N thrust). Unless the set is SEP in which place there's no point on using this.
One part that I find interesting is about processing facilities and cost. Could it be fueled on current facilities? Could new facilities significantly lower the processing cost vis-a-vis an hypergolic?
It would seem, though, that the best candidate for this would be human rated systems. Specially returning ones.

There's substantial interest in its role for defense applications.
http://www.prnewswire.com/news-releases/aerojet-demonstrates-innovative-thruster-for-missile-defense-agencys-ncade-program-57514282.html (http://www.prnewswire.com/news-releases/aerojet-demonstrates-innovative-thruster-for-missile-defense-agencys-ncade-program-57514282.html)
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: ClaytonBirchenough on 07/22/2013 09:34 pm
Anybody know the density of the propellant being used? Wikipedia says it's "extremely dense" but doesn't give a number...
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: AnalogMan on 07/22/2013 09:51 pm
Anybody know the density of the propellant being used? Wikipedia says it's "extremely dense" but doesn't give a number...

AF-M315E (HAN based propellant) density is 1.465 g/cm3
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: AnalogMan on 10/06/2015 11:10 am
Green Propellant Infusion Mission Passes Spacecraft Integration Milestone, On Track for 2016 Launch
Oct. 5, 2015 Kim Newton MSFC

The propulsion subsystem for NASA's Green Propellant Infusion Mission has been integrated onto the spacecraft, moving the mission another major step toward scheduled launch in 2016.

GPIM prime contractor Ball Aerospace & Technologies Corp (http://www.ballaerospace.com). in Boulder, Colorado, was able to integrate the green propellant propulsion subsystem in less than two weeks after receiving it from Aerojet Rocketdyne (http://www.rocket.com) in Redmond, Washington. The propulsion subsystem will be the primary payload on the mission’s spacecraft -- a Ball Configurable Platform 100 small satellite. System performance and environmental testing has already begun.

The mission will demonstrate the practical capabilities of a hydroxyl ammonium nitrate based fuel/oxidizer propellant blend, known as AF-M315E, developed by the U.S. Air Force Research Laboratory (http://www.wpafb.af.mil/AFRL) at Edwards Air Force Base in California. It offers higher performance but is safer to handle and easier on the environment or "greener" than traditional chemical fuels such as hydrazine currently used in spacecraft thrusters. It also requires fewer handling restrictions and has potentially shorter launch processing times, resulting in lowered costs.

Because the new propellant provides improved performance and volumetric efficiency compared to hydrazine, more of it can be stored in propellant tanks of the same volume, resulting in a 50-percent increase in spacecraft maneuvering capability for a given volume. It also has a lower freezing point than hydrazine, requiring less spacecraft power to maintain the propellant temperature. These characteristics make it ideal for a wide range of emerging small, deep space satellite missions.

“NASA is always looking for new technologies that also allow us an opportunity to improve safety and cost efficiency,” said Trudy Kortes, program executive for NASA’s Technology Demonstration Missions (http://www.nasa.gov/mission_pages/tdm/main). “GPIM additionally affords us an opportunity to test an environmentally-friendly fuel in space for the first time and there’s nothing more rewarding than a trailblazing mission.”

The GPIM propulsion subsystem on the satellite will be loaded with the low-toxicity AF-M315E propellant before launch. During the 13-month mission, researchers will conduct orbital maneuvers to demonstrate the performance of the propellant during attitude control shifts, changes in orbital inclination and orbit lowering.

“GPIM is the key mission to demonstrate a green monopropellant alternative to hydrazine,” said Jim Oschmann, vice president and general manager of Civil Space and Technology at Ball Aerospace. “Everyone in the industry, from NASA to our industry partners to green propellant suppliers, is eager to see 10 years of American-led research and development realized with this spaceflight mission.”

Three Department of Defense experimental payloads will also fly aboard the Green Propellant Infusion Mission spacecraft, which is scheduled for a launch to low-Earth orbit in 2016 in partnership with the Army Space and Missile Defense Command. Additional team members include the Air Force Space and Missile Systems Center (http://www.losangeles.af.mil/library/factsheets/factsheet.asp?id=5318) at Kirtland Air Force Base, New Mexico, and NASA's Glenn Research Center (http://www.nasa.gov/glenn) in Cleveland, Goddard Space Flight Center (http://www.nasa.gov/goddard) in Maryland and Kennedy Space Center (http://www.nasa.gov/kennedy) in Florida.

The mission is part of a portfolio of technology demonstration flight and ground projects led by NASA teams and industry partners across the country, managed by the Technology Demonstration Missions (http://www.nasa.gov/mission_pages/tdm/main/) program office at NASA's Marshall Space Flight Center (http://www.nasa.gov/centers/marshall/home/index.html) in Huntsville, Alabama.

Technology demonstration missions are sponsored by NASA’s Space Technology Mission Directorate (http://www.nasa.gov/directorates/spacetech/home/index.html) in Washington, which is innovating, developing, testing and flying hardware for use in future missions. NASA's technology investments provide cutting-edge solutions for our nation's future. For more information about the directorate, visit:

http://www.nasa.gov/spacetech (http://www.nasa.gov/spacetech)

For more information about the NASA's Green Propellant Infusion Mission, visit:

http://www.nasa.gov/mission_pages/tdm/green/overview.html (http://www.nasa.gov/mission_pages/tdm/green/overview.html)

For more information about NASA's Technology Demonstration Missions, visit:

http://www.nasa.gov/mission_pages/tdm/main/ (http://www.nasa.gov/mission_pages/tdm/main/)

Photo Caption:  A Ball Aerospace engineer adjusts the thermal insulation on NASA’s Green Propellant Infusion Mission spacecraft bus following integration of the propulsion system.  Credits: Ball Aerospace
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: yg1968 on 03/31/2016 06:07 pm
NASA Spacecraft to Test 'Green' Propellant Passes Major Pre-flight Milestone:
http://www.nasa.gov/mission_pages/tdm/green/green-propellant-test-passes-preflight-milestone.html

Here is some prior articles on the same topic including one on another type of "green" (less-toxic) fuel (LMP-103S):
http://www.nasa.gov/centers/marshall/news/news/releases/2015/new-green-propellants-complete-milestones.html
http://www.nasa.gov/feature/goddard/2016/nasa-goes-green
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: savuporo on 03/31/2016 07:48 pm
Meanwhile, PRISMA with LMP-103S propulsion onboard has apparently performed an orbit lowering maneuver in 2015, thus demonstrating 5 years of operational capability in space.
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: yg1968 on 01/22/2021 01:53 pm
Green propellant successfully demonstrated on NASA mission:
https://spacenews.com/green-propellant-successfully-demonstrated-on-nasa-mission/
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: Comga on 01/23/2021 02:05 am
Green propellant successfully demonstrated on NASA mission:
https://spacenews.com/green-propellant-successfully-demonstrated-on-nasa-mission/ (https://spacenews.com/green-propellant-successfully-demonstrated-on-nasa-mission/)

Sheesh! ::)
An interesting definition of "success"
Six and a half years after the announcement, they declare victory and retreat hastily.

Note that the original plan was to demo four 1 lbf  thrusters for attitude control and a 5 lbf main thruster.
(Gotta love those Imperial units.)
Aerojet could not deliver the larger thruster so a fifth 1 lbf thruster was put in that center position.
(My friend just learned the term RUD.  Aerojet could have taught him that years ago.)
In the meantime, Rocketlab debuted Curie, a 120 N (~27 lbsf ) green monopropellant thruster.
Rocketlab followed that with Hyper-Curie a larger green bipropellant system.
(Anyone know the thrust of the Hyper-Curie engine?)
So whatever was demonstrated by GPIM is now pretty far off the leading edge.

In the article Aerojet talks about getting into the nanosat propulsion game.
Nanosats are commodity items. 
Pricing on all sorts of subsystems that used to cost millions now cost thousands.
Aerojet could not compete with Blue Origin for Vulcan's engine,
How are they going to compete with the large number of low overhead groups also doing nanosat propulsion like nPulsion?

However, NASA got something they value quite highly: a cool acronym - ASENT!
And Ball got sponsored to debut their BCP-100 smallsat.  That went well.

And hey! I know Chris McLean of Ball Aerospace. He's a good guy!  Congrats, Chris.
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: Steven Pietrobon on 01/23/2021 02:37 am
However, NASA got something they value quite highly: a cool acronym - ASENT!

Even cooler when its spelt right! :-) The acronym is ASCENT (Advanced Spacecraft Energetic Non-Toxic).
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: Comga on 01/23/2021 03:13 am
However, NASA got something they value quite highly: a cool acronym - ASENT!

Even cooler when its spelt right! :-) The acronym is ASCENT (Advanced Spacecraft Energetic Non-Toxic).

A long post and THAT’S your comment?

Who really cares?
Unless one agrees that nifty acronyms are more important than developing useful technology.

And Someone Created Even Newer Technology
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: VSECOTSPE on 01/28/2021 01:53 pm
Green propellant successfully demonstrated on NASA mission:
https://spacenews.com/green-propellant-successfully-demonstrated-on-nasa-mission/ (https://spacenews.com/green-propellant-successfully-demonstrated-on-nasa-mission/)

Sheesh! ::)
An interesting definition of "success"
Six and a half years after the announcement, they declare victory and retreat hastily.

Note that the original plan was to demo four 1 lbf  thrusters for attitude control and a 5 lbf main thruster.
(Gotta love those Imperial units.)
Aerojet could not deliver the larger thruster so a fifth 1 lbf thruster was put in that center position.
(My friend just learned the term RUD.  Aerojet could have taught him that years ago.)
In the meantime, Rocketlab debuted Curie, a 120 N (~27 lbsf ) green monopropellant thruster.
Rocketlab followed that with Hyper-Curie a larger green bipropellant system.
(Anyone know the thrust of the Hyper-Curie engine?)
So whatever was demonstrated by GPIM is now pretty far off the leading edge.

It’s worse than that.  SSC developed HPGP, another green propellant, and demonstrated it aboard their Prisma mission way back in 2010.  HPGP has been used by everyone from Skybox to USAF to NASA.

https://en.m.wikipedia.org/wiki/HPGP
https://en.m.wikipedia.org/wiki/Prisma_(satellite_project)

Forget that RocketLab and others have lapped NASA’s agonizingly slow development of GPIM with their own green propellants.  There were demonstrated green propellant alternatives at the time NASA decided to develop GPIM.  There was no need for NASA to blow $50 million on GPIM.  It demonstrated little to nothing that hadn’t already been demonstrated elsewhere in the industry.

Of all the technology gaps NASA STMD needed to be focused on demonstrating over the past decade, green propellant was never one.
Title: Re: Joint Industry/Government Demo Mission: Green Propellant Infusion Mission (GPIM)
Post by: jbenton on 03/03/2021 11:13 pm

...

Of all the technology gaps NASA STMD needed to be focused on demonstrating over the past decade, green propellant was never one.

Fair Point. Given that Congress never gives STMD as much funding as they ask, it's important to make the most of what they have.