NASA to fly 'green' rockets

I have to wonder if this is a good idea, what with so many other green ventures not living up to expectations, this might actually end up getting people killed if it isn’t fully tested before making it into the next manned spacecraft venture.

From the Air Force Office of Scientific Research

AFOSR-funded research key to revolutionary ‘green’ spacecraft propellant

In 2015, NASA, for the first time, will fly a space mission utilizing a radically different propellant — one which has reduced toxicity and is environmentally benign

In 2015, NASA, for the first time, will fly a space mission utilizing a radically different propellant—one which has reduced toxicity and is environmentally benign. This energetic ionic liquid, or EIL, is quite different from the historically employed hydrazine-based propellant, which was first used as a rocket fuel during World War II for the Messerschmitt Me 163B (the first rocket-powered fighter plane).

Within the U.S. space program, hydrazine was used on the 1970s Viking Mars program, and more recently in the Phoenix lander and Curiosity rover Mars missions, as well as in the Space Shuttle’s auxiliary power units. Significantly, monopropellant hydrazine-fueled rocket engines are the norm in controlling the terminal descent of spacecraft. What makes hydrazine desirable as a propellant for this terminal descent role is that when combined with various catalysts, the result is an extremely exothermic reaction that releases significant heat in a very short time, producing energy in the form of large volumes of hot gas from a relatively small volume of hydrazine liquid.

Unfortunately, hydrazine has several significant drawbacks: it is very toxic when inhaled, corrosive on contact with skin, hazardously flammable, and falls short in providing the propulsive power required for future spacecraft systems. In 1998, driven by these challenges, Dr. Michael Berman, a Program Manager at the Arlington, Virginia-based Air Force Office of Scientific Research (AFOSR), the basic research arm of the Air Force Research Laboratory (AFRL), funded Dr. Tom Hawkins of the Propellants Branch, Rocket Propulsion Division at AFRL’s Aerospace Systems Directorate, to find a more benign, yet even more powerful material to replace hydrazine.

This research effort was ultimately associated with a joint government and industry development program, the Integrated High Payoff Rocket Propulsion Technology (IHPRPT) initiative, to improve U.S. rocket propulsion systems. IHPRPT challenged the Department of Defense, the National Air and Space Administration, and the rocket propulsion industry to double U.S. rocket propulsion capability (cost and performance) by 2010. Beginning in 1996, this IHPRPT challenge meant the development of propellants that would provide far greater energy density than current state-of-the-art propellants.

Dr. Hawkins’ interest in EILs began early on in his career beginning at Lehigh University when he worked on advanced propellants for the Strategic Defense Initiative in the 1980s. Knowing the untapped potential of ionic liquids to provide high energy density materials, he embarked on an effort to design and characterize the EIL family. This effort was funded by AFOSR and continues to the present day.

But it was in 2002 that Dr. Hawkins, “…thought we were on the right track when we produced an ionic liquid monopropellant that incorporated an EIL that was investigated under our AFOSR program. This propellant class, known as AF-M315, has an energy density close to twice that of the state-of-the-art spacecraft monopropellant, hydrazine.” With additional support from the IHPRPT program, the Missile Defense Agency (MDA) and related USAF missile programs, a full characterization of one of these new propellants, AF-M315E, was investigated for its overall safety and hazard properties. According to Dr. Hawkins, these safety properties, coupled with the performance of AF-M315E, were “…absolutely outstanding; we found the oral toxicity of AF-M315E to be less than that of caffeine, and its vapor toxicity to be negligible. The vapor flammability of AF-M315E was essentially nil, and this made it difficult to unexpectedly ignite and sustain combustion of AF-M315E—one could even put out small fires with the propellant!”

In 2005 NASA took a keen interest in this very promising alternative to hydrazine and performed further evaluations. Follow on work performed by Aerojet, Inc. brought AF-M315E engine design to a level that was very attractive for a technology transition to the commercial sector. But for that to occur, it was necessary to find a champion to sponsor the flight demonstration that would make AF-M315E spacecraft propulsion an ‘off-the-shelf’ choice for future propulsion systems. NASA became that champion in 2012 with their selection of Ball Aerospace & Technologies Corporation as the lead integrator for the Green Propellant Infusion Mission—a $45 million program that will produce new AF-M315E- based thrusters for NASA’s 2015 spacecraft mission. Additional program team members consist of the Air force Research Laboratory, Aerojet, Inc., the Air Force Space & Missile Systems Center and the NASA/Glenn Research Center.

The field of energetic ionic liquids is the product of AFOSR-sponsored research at AFRL that is changing the landscape of work in the energetic materials community. According to Dr. Hawkins: “The AFOSR- funded program provided the synthesis and characterization work for an EIL that enabled the experimental USAF fuel, AF-M315E, to act as a high-energy density, environmentally benign, easy-to-handle replacement for spacecraft hydrazine fuel.”

Hawkins also noted that twenty years is a well-recognized time period for producing such a revolutionary propellant approach and propulsion system due to the fact that the EIL approach to liquid propulsion is completely different than that of hydrazine, and, most significantly, the performance potentials of EIL-based propellants are not small incremental improvements, but significantly larger than any state-of-the-art propellant. As EIL-based propellants are developed, they will provide lower cost and safer propulsion system operations along with greater mission flexibility and faster mission response times.


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I what way is this Green ? less toxic ? looks like they found a better fuel that HAPPENED to be less toxic to humans … not Green …

Larry Geiger

This is NOT “green”. Good grief. It’s just another advancement in technology, just like hydrazine was in it’s day. There has never been a day when NASA (and all other rocket launching entities) haven’t wanted something “more benign” than hydrazine.
Secondly, almost all propellants that are discharged into the atmosphere from NASA rockets are solid rocket material, and water (LOX and hydrogen engines).


Interesting article, thanks Anthony. It seems as if the inherent properties (stability, energy density) of the fuel are enough to commend it to testing, and the ‘Eco / Green’ label more of a fashion statement….?


Sounds like the stuff is not so much ‘greener’, but a better performer.

M Courtney

It sounds good. Hope it works.
A step-change in technology can only help bring commercial spaceflight closer.
And I still want to go to the moon (no-one has in my lifetime).

Bloke down the pub

Not suitable I know for the purpose outlined above, but a liquid hydrogen / lox engine can already be environmentally friendly.

The navies Russian and American have experience with monopropellants, some of it good, some of it H2O2.

In another century or culture, the press release would have said “More Pleasing to God’s Nostrils”. Same thing here – the PR department is tasked with coming up with a way to make any new development sound as if its in accordance with the dominant cultural memes of the day.


And we still do not know what it actually is so we cannot judge whether it is ”greener”.


I think the point is to reduce the risk of people getting killed. Hydrazine is one of the most dangerous fuels to handle. The quantities employed in RCS or auxillary motors are small, but ground crews have to follow elaborate safety procedures. If it can be replaced thats good without reference to “environment” apart from the working environment.


But more importantly, how will this affect US/Muslim relations?

J. Michael Antoniewicz II

By the article, they’re about 10 years into testing and characterization of the basic formulation.
Now if they could get a Project Morpheus 1.5D vehicle built to test this fuel…. 😉


Over time I became allergic to anything claimed being “green” but this actually looks good. One almost doesn’t want to believe it can be used as rocket fuel.
Hydrazine definitely is a hazardous substance so replacing it by something safer and even more effective would be very nice.


Naaah! The only true green method is to use wind power. (sarc off)


According to Wikipedia, the solution is corrosive and toxic and may be carcinogenic.

Dr. Bob

I have worked with AFRL for 15 years on testing and certification of alternative jet fuels and have found the AF to be very thorough in its evaluation of new fuels and technologies. Here is a paper released by the AF describing some of the tox and performance testing of AF-M315E. I have yet to determine the chemical composition as they seem to want to keep it confidential.
T.W. Hawkins*, A.J. Brand*, M.B. McKay* and M. Tinnirello*
*Air Force Research Laboratory, 10 E. Saturn Blvd, Edwards AFB CA 93524, USA,
What is critical is the specific impulse of the fuel. The lift provided per mass of fuel defines the performance limits of the system.
Time will tell if this is a good move, but it appears to at least be a safe move. Calling it Green though is just a misdirection to give it a good reception in the current political environment.

John M

It may be a better fuel, but to label it as “Green” requires the FTC to review it.
Wonder if they’ve done that?

John from East Lansing

If this pans out, this fuel will be a boon not only to spaceflight, but to aircraft such as the F-16 that uses a Hydrazine-powered APU for emergency power.


I’m not saying there won’t be any future accidents in space exploration, but if and when they do occur, I don’t think it will be due to lack of testing or readiness of their new propellant. If NASA says it’s ready to go in 2015, then I think it will be ready to go. If it’s not ready, I’m sure they would delay it.


Many people believe that it was changing to a green foam on the fuel tank that led to chunks of it breaking off and dooming a shuttle. (Discovery?)

Chuck Nolan

Dr. Bob says:
May 8, 2013 at 6:21 am
I have worked with AFRL for 15 years on testing and certification of alternative jet fuels and have found the AF to be very thorough in its evaluation of new fuels and technologies. Here is a paper released by the AF describing some of the tox and performance testing of AF-M315E. I have yet to determine the chemical composition as they seem to want to keep it confidential.
“It’s people!”
“AF-M315E is people”

Oops, wrong movie plot.


Why are we worried about H2NNH2? It decomposes to things like NH3OH which nature handles just fine. Too much CH3COOH can be deadly too, as is HCl and NaOH. Combine the latter two and you get salt water. Hydrazine toxicity? Duh, but a bogus concern. On the other hand, if you used a propellant based on Hg, THAT would be toxic, and would pose a problem no matter how it transformed in nature (although HgS is one of the least bad choices).


NASA had been working on methane rocket engines for a few years:
(Turn the volume up if you can for the brief video at that link. 🙂 It’s pretty cool.)
Methane might not be “green enough” for some people, but it’s interesting just the same.

When asked about the technical problems with their plans to fly a rocket to the sun, NASA responded that they intended to fly at night.


Right, we don’t want to pollute space. Will we see similar results to changing the shuttles’ freon-installed insulation to “green”, breaking-off stuff?

The new Green?
AF-M315E, is a Hydroxyl Ammonium Nitrate (HAN) fuel/oxidizer blend
Hydroxylammonium nitrate or hydroxylamine nitrate (HAN) is an inorganic compound with the chemical formula NH3OHNO3. It is a salt derived from hydroxylamine and nitric acid. In its pure form, it is a colourless hygroscopic solid. It has potential to be used as a rocket propellant either as a solution in monopropellants or bipropellants.
The compound is a salt with separated hydroxyammonium and nitrate ions.[1] Hydroxylammonium nitrate is unstable because it contains both a reducing agent (hydroxylammonium cation) and an oxidizer (nitrate),[2] the situation being analogous to ammonium nitrate. It is usually handled as an aqueous solution. The solution is corrosive and toxic, and may be carcinogenic. Solid HAN is unstable, particularly in the presence of trace amounts of metal salts.

Ed Fix

If including the word “green” helps them fund development of a radically better rocket propellant that happens to be less toxic and inherently safer than hydrazine, I’m all for it. It’s about time “green” actually did something useful.

Do I understand this correctly? That they’re trying to find a “greener” rocket fuel used in the descent phase? Uh, aren’t all descent phase burns done outside of Earth’s atmosphere?

Ben Wilson

The best I can figure is that the substance doesn’t produce carbon dioxide, thus helping to keep Mars and various asteroids free of greenhouse gases.
Of course, hydrazine (N2H4) doesn’t produce carbon dioxide either, but monomethylhydrazine, and unsymmetrical dimethylhydrazine, both of which are used as rocket fuels, sure do. . . . . .


For ages, the Russians, formerly known as Soviets, use Kerosene and Hydrogen Peroxide for their rockets with great success.
The most environmentally friendly rocket fuel conceivable would be hydrogen peroxide and liquid hydrogen.
But that would be logical, of course…


Or, try steam rockets:
George Stevensons’s “Rocket” instantly springs to mind…


First time NASA went “green”, the Challenger exploded killing all on board.

I can’t think of many candidates for rocket fuel that aren’t some combination toxic, explosive and hazardous.LOX or pure O2, can be pretty bad. If they end up with an improved performance fuel, great. If they want greener rockets, change the surface coating color.

Bill Yarber

Having a fuel with twice the energy density is very important to advancing our space travel programs, all other variables being equal. I hope this succeeds, or leads to future success, but cost per pound of propellant has not been discussed. If it is twice, no big deal. If it is ten times hydrazine, back to the labs!

michael hart

What a tease. So what is the chemical structure of this mono-propellant replacement for hydrazine?
The problem with increasing energy density with mono-propellants is, like overcharging a battery or capacitor, they might produce that energy when you don’t want it. TNT and cordite are also mono-propellants in that sense of the word, but with rather less control.

G P Hanner

The space launch business has been looking for a safer (greener) means of launching rockets for a long time. As the article states, hydrazine is some nasty stuff. By itself it lacks the energy to push a payload into orbit. One of the workhorse space launch systems, the Titan II, uses UDMH and NOX. They are energetic, they are storeable, they ignite when they contact each other, and they are highly toxic.
A major accident happened with the Titan II system at a missile launch silo near Little Rock Arkansas in 1980. The missile eventually exploded and threw the 7 ton (or so) launcher closure door over a quarter mile from the silo. The RV, however, remained intact, just as it had been designed to do. It was the only good thing to happen that day.
BTW, the missile launch crew survived because they were shielded by blast doors that separated them from the missile launch tube.

Pat Frank

Hydroxylammonium nitrate (HAN) is just partly oxidized ammonium nitrate. So, why not just use the latter? Also, if HAN is so great, what about hydrazinium nitrate? It should produce more energy per gram than HAN and has the same advantage of being a solid at RT (no vapor pressure, less toxic) and soluble in all the same solvents.

TomB says, “Uh, aren’t all descent phase burns done outside of Earth’s atmosphere?”
Ah, but does that not mean greener fuel for the little green men?

It is fair to mention a NASA green failure, the Shuttle Challenger. The solid rocket boosters were covered with a rigid foam insulation and were jettisoned after launch. Chunks of a booster debris were recovered my an eco-zeolite and sent to the EPA for analysis. The results showed excessive amounts of a restricted chemical and a Clinton appointed EPA paper pusher forced NASA to delete this chemical. The Shuttle launch schedule was dictated by military satellite payloads with no back-up missile based system. Therefore, NASA was fired to use an altered insulation without adequate testing. Either the spalling insulation itself, or chunks of rapidly forming and spalling ice caused the wing damage, ending in destruction. When the full truth of the myriad of eco-frauds are exposed, humanity will be freed from these Lilliputian green meanie dwarfs.

G P Hanner

I think you are referring to the loss of Columbia. Challenger was desroyed in a main fuel tank explosion about 70 seconds after lift off. That was caused by a leaking O-ring on one of the SRB segments.

Hypergolic green fuels? I vote for Bromine Trifluoride & that nasty green-dyed St. Patrick’s beer.

Also, JC Clark’s Ignition is an excellent thing for any budding fuel researchers to read.


G P Hanner says:
May 8, 2013 at 8:57 am
I watched a History Channel program on that. They showed the removal etc of the war heads and stages of the rocket. The out come I think was to remove all the Titans form the silos.

G P Hanner

Yes. The Titan IIs were all taken off alert by the SALT talks. So were many of the Minuteman missiles. The Titan II was a bargaining chip from the outset because it was the only “heavy throw weight” missile we had. There were 53 of them after the Little Rock episode.
If you want to see a real Titan II missile silo and launch control center you should take a trip to Green Valley, Arizona. It’s about 20 miles south of Tucson. There you will find the Titan Missile Museum. It’s probably the only such museum in existance. Take the Beyond the Blast Doors tour to see the complexity of that thing. Also, volunteer to be the missile crew commander.


If the new fuel is more energetic then it would be “greener” by virtue of the fact that less of it is required to achieve orbit, even if it were as toxic as current fuels. That is a two-edged sword – it also means the payload can be larger and that means more fuel will be burned at low altitude than if the weight of the launch vehicle were reduced by lower fuel weight. Lower weight translates to less trans-atmosphere time due to an increased acceleration rate. Human flight imposes limits on acceleration and so the time to orbit is not likely to change much for those launches.
Regardless of any payload advantages, the waste gases in the trans-atmosphere phase will be less toxic than we currently use and that can’t be a bad thing. I think I’d like to know what happens to it when it precipitates into the ocean and what the linger time is at altitude, though. says, “The results from AF-M315E indicate that a >50% improvement in propulsion system performance over hydrazine is achievable…”
Note that a 50% improvement, while extremely impressive, is not “close to twice that of… hydrazine.”


Well, there ya go. Most people probably don’t appreciate just how natural hydrazine is. The compound – well several different hydrazine compounds – is the primary toxin in many poisonous mushrooms, and for those of precautionary principle bent also occurs in button mushrooms, crimini and others (go ahead and quit eating them, please. More for me). I’ve often wondered if there isn’t some mad researcher out there attempting to genetically engineer a solid rocket booster from fungi by boosting the agaritine to a useful level – agaratine is glutamyl-4-hydroxymethylphenylhydrazine.


Joseph A Olson says:
May 8, 2013 at 9:13 am
…. eco-zeolite….???

A zeolite is an absorbant aluminosilicate mineral. They are widely used as absorbants for various kinds of clean up, waterpurifiers, in fish aquarium filters, and in some cat litter. Zeolites are actually quite useful. What’s an eco-zeolite?

kadaka (KD Knoebel)

From Duster on May 8, 2013 at 11:52 am:

What’s an eco-zeolite?

An eco-zealot that fails to get trapped by human final review after escaping auto-correct/complete.