NASA developing a new, eco-friendly propellant

[Frida Space]

In less than a year from now, NASA will launch the GPIM (Green Propellant Infusion Mission) smallsat. It will be the first satellite to use a new propellant developed by the Air Force's Research Laboratory called AF-M315E and based on hydroxylammonium nitrate (NH3OHNO3). While common hydrazine is both toxic and corrosive, AF-M315E is neither of those. In fact, it is also more efficient and 40% denser, giving a 50% increase in maneauverability for a given tank volume. Also, the fact that it is neither toxic nor corrosive means it can be stored, handled and used much more easily and quickly, possibly reducing launch processing times and costs. Finally, its freezing point is much lower than that of hydrazine, meaning that it doesn't have to be heated as much to remain liquid while in space. The only major problems that I see is that it has a higher combustion temperature, which requires stronger metals, and obviously that it hasn't been tested a lot yet, but I hope that will change soon.

The new propellant was developed by the US Air Force, but GPIM's propulsion system, featuring 5 x 1 N thrusters, has already been fully built by Aerojet Rocketdyne and given to Ball Aerospace, which will build and assemble the satellite and all subsystems (including 3 scientific instruments) for NASA.

I'd put a few links if they weren't all giving 404s right now.

What do you guys think of this "eco-friendly" propellant? Here are a few pics from Aerojet Rocketdyne and Ball Aerospace:

[Bill Phil]

Eco friendly? It hardly sounds like it.

This is biprop, right? If so, what's the Oxodizer?

What's the exhaust?

How is it produced?

There are more factors to consider before it should be labeled Eco friendly.

[Hcube]

Eco friendly? It hardly sounds like it.

This is biprop, right? If so, what's the Oxodizer?

What's the exhaust?

How is it produced?

There are more factors to consider before it should be labeled Eco friendly.

Uh i thought it was monoprop like the hydrazine, with the propellant being activated with a catalyser (iridium or so). I don't know about the exhaust, but since it is to be used in space... who cares ? I'd say the point is to avoid having toxic materials during launch...

[smjjames]

I'm with Bill Phil here, in what way are they claiming that it's ecofriendly?

[Sampa]

I'm guessing that it is a relative term. I think he meant a more eco-friendly fuel than is used currently.

[Frida Space]

Yes, thanks, "eco-friendlier" would have been better. However, it' is completely not toxic nor corrosive, which in my opinion is a very big leap towards a fully green propellant.

And yes, this is a monopropellant.

[tater]

If it doesn't reduce the cost per kg to orbit, we shouldn't waste a penny on it.

[Frida Space]

I'm with Bill Phil here, in what way are they claiming that it's ecofriendly?

Look at how that researcher is handling it: not even a mask to protect her mouth or nose. Hydrazine, instead, is extremely toxic and corrosive: it can damage skin, lungs, liver and even the CNS. I call that eco-friendlier

- - - Updated - - -

If it doesn't reduce the cost per kg to orbit, we shouldn't waste a penny on it.

I'm not sure how much it costs, however being denser it means that, for the same tank volume, you could store 40% more in it. Adding to that its higher efficiency, you should be getting a lot more delta V out of it = smaller rockets = less expensive launches. *i think*

[SAI Peregrinus]

It's hardly non-toxic. The exhaust is, but the fuel/oxidizer itself isn't. The MSDS has more info. NEVER trust the press release or the stock photo.

[Kaos]

It is less toxic than hydrazine (which by itself is not a complicated goal to achieve). It is more efficient (also not that complecated). But it is presumably not more complicated to handle than hydrazine (which is the interesting part). I think it is a good idea, but one should not expect too much. It is only a little step, but a step in a good direction.

[Kryten]

If it doesn't reduce the cost per kg to orbit, we shouldn't waste a penny on it.

Handling a material as toxic as hydrazine or it's derivatives isn't exactly cheap. Just take a look at the suits they need to fuel a sat with the stuff;

http://www.arianespace.com/images/missionup-dates/2015/1265-lg.jpg

[AngelLestat]

Yes, thanks, "eco-friendlier" would have been better. However, it' is completely not toxic nor corrosive, which in my opinion is a very big leap towards a fully green propellant.

And yes, this is a monopropellant.

Then change all words of propellant for monopropellant

If it were only a green propellant, we already have one.. oxygen+hydrogen.

[SAI Peregrinus]

Handling a material as toxic as hydrazine or it's derivatives isn't exactly cheap. Just take a look at the suits they need to fuel a sat with the stuff;

http://www.arianespace.com/images/missionup-dates/2015/1265-lg.jpg

The MSDS for this "green" propellant recommends respiratory protection if working indoors. And the MSDS I found is for 24% aqueous solution, not the pure stuff you'd use for rocket fuel.

Acute Tox. - Acute toxicity

Aquatic Acute - Acute aquatic toxicity

Aquatic Chronic - Chronic aquatic toxicity

Eye Irrit. - Eye irritation

H302 - Harmful if swallowed.

H310 - Fatal in contact with skin.

H311 - Toxic in contact with skin.

H315 - Causes skin irritation.

H319 - Causes serious eye irritation.

H334 - May cause allergy or asthma symptoms or breathing difficulties if inhaled.

H335 - May cause respiratory irritation.

H400 - Very toxic to aquatic life.

H410 - Very toxic to aquatic life with long lasting effects.

Resp. - Sens. Respiratory sensitisation

Skin Irrit. - Skin irritation

STOT SE - Specific target organ toxicity - single exposure

Fatal in contact with skin. The specific target organ toxicity is for the lungs. And the "very toxic to aquatic life with long lasting effects" bit certainly isn't that "green".

That said, the exhaust IS nicer than that of Hydrazine. Nowhere near as much ammonia.

[shynung]

If it were only a green propellant, we already have one.. oxygen+hydrogen.

Depends on where the hydrogen comes from. Methane reformers produce carbon monoxide as a byproduct (which usually gets thrown away). Water cracking plants are cleaner locally, but gobbles a lot of energy; the pollution comes from the generators that power it.

Real 'green' propellant exists, though: compressed nitrogen gas, as a monopropellant. As you've probably guessed, the exhaust is nothing but nitrogen gas, completely safe, nontoxic, and noncorrosive. However, the specific impulse is pathetic, so it's only used for special applications, such as EVA jetpack propellant.

[GoSlash27]

Umm... If it's intended to be fired in space, then it doesn't matter how "eco- friendly" the exhaust is.

Best,

-Slashy

[shynung]

Umm... If it's intended to be fired in space, then it doesn't matter how "eco- friendly" the exhaust is.

Best,

-Slashy

Sure. But eco-friendliness of the unfired propellant translates directly to safety concerns when handling it. In this case, propellants that attack the human hide less vigorously is seen as desirable.

[GoSlash27]

Sure. But eco-friendliness of the unfired propellant translates directly to safety concerns when handling it. In this case, propellants that attack the human hide less vigorously is seen as desirable.

This is true, but the unfired propellant isn't eco-friendly or less hazardous.

Best,

-Slashy

[RainDreamer]

I think we should use nuclear thermal propulsion instead - nothing dangerous as exhaust. But I guess people never even consider nuclear energy to be anything close to eco-friendly.

[tater]

Recast the OP as a safety/handling issue, and sure, safer is better. "Green" is so vague as to be useless. If handling is cheap enough to affect overall costs, it should show up in the data. If it is cheap enough to justify, including dev costs (amortized), then it is competitive.

NASA buys propellant, and handles it. Safety is a legit issue, as is Isp. How their supplier makes it, etc? Not their problem as long as it meets the required specs, I don't think they should be wasting money on it, let the private sector come up with it if it is a cost effective product. If it's not cheaper, launches simply move someplace cheaper.

[Kryten]

This has nothing to do with launches, the issue is replacing hydrazine and derivatives as propellant in satellite and small upper-stage thrusters. The actual volumes involved are tiny, and the direct cost would be lost in the noise.

[cryogen]

I dug up some data.

The specific impulse is 266s, compared to 242s for monopropellant hydrazine. (They don't specify the assumptions for this figure).

It's still much worse than storable bipropellants, like hydrazine / N₂O₄ (344s?). So I'm not sure how useful this really is. It could replace small RCS thrusters, but it doesn't look viable for main propulsion (i.e., apogee thrusters on GEO comsats), which is where most of the hydrazine actually goes.

http://www.nature.com/news/green-fuels-blast-off-1.13603

https://en.wikipedia.org/wiki/Green_Propellant_Infusion_Mission

Edited August 22, 2015 by cryogen

[tater]

This has nothing to do with launches, the issue is replacing hydrazine and derivatives as propellant in satellite and small upper-stage thrusters. The actual volumes involved are tiny, and the direct cost would be lost in the noise.

Again, recast the OP as safety. "Green" for tiny volumes is similarly lost in the noise (assuming you can even define green in a meaningful way such that the error bars are not larger than the signal for this application).

Isp still matters, even from a "green" context, because you need dv in the end, and any reduction means more green propellant required, and more booster propellant to get it where it needs to be.

Years ago at the U, there were kids who successfully protested the use of styrofoam coffee cups in favor of reusable ceramic mugs for food service. I asked the guy with the petition how the energy budget compared given the commercial dishwasher required, plus the impact of caustic detergents and water use, and how this demonstrated that ceramic was superior... I got the blank stare you'd expect. I told him they might be right about the cups, but no one could make an informed decision if they didn't "show their work." It was a demand over the heads of the poly sci and art history majors driving the petition

I'm all for better stuff, but it needs to be demonstrated that it is superior, and that there is a need.

[RuBisCO]

Is not the other green monopropellent that been in development Nitrous Oxide Fuel Blends?

http://www.firestar-tech.com/NOFBX-MP.html

[SciMan]

True, but that stuff is more dangerous to handle no matter how non-toxic it is.

Because it's basically a fuel-oxidizer stored in a single tank, it's quite unstable.

To quote the wikipedia article linked by RuBisCO:

"Recent work on the decomposition of nitrous oxide has raised concerns about the safety risks of mixing hydrocarbons with nitrous oxide. By adding hydrocarbons, the barrier to an explosive decomposition event is lowered significantly."

In other words, it's more likely to explode compared to keeping the fuel and oxidizer separate until they're in the combustion chamber of the engine.

Nobody likes uncommanded explosions in rockets IRL.

[jwenting]

NASA has a very eco-friendly propulsion mechanism, compressed hot air. They produce the hot air in bulk in their headquarters, all the now need is a compressor and some insulated pipes to get it to the launch facilities without cooling.