Questions tagged [monopropellant]

A propellant that does not require an oxidizer, it can be used alone. An exothermic reaction is started with a catalyst or by heating. Hydrazine is the most common such fuel. New ones are in development.

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If high-test peroxide is most stable when pure, why are most uses of it in rocketry at lower concentrations?

Per the Wikipedia article for High-test peroxide: Hydrogen peroxide becomes more stable with higher peroxide content. For example, 98% hydrogen peroxide is more stable than 70% hydrogen peroxide. ...
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Could New Horizons' thrusters' ISP be as low as 157 sec?

A discussion below How much of a deep space spacecraft's structural mass is useless dead weight after launch? Any plans to shed it in the future? has lead to https://nssdc.gsfc.nasa.gov/nmc/...
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How much hydrazine does an Iridium satellite start with? How much does it use per year?

Iridium satellites use hydrazine and the spacecraft are expected to last at least 15 years. How much hydrazine do Iridium satellites start with, and if possible, roughly do they use per year?
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Does peroxide spontaneously decompose when introduced into hot combustion chambers?

I understand that hydrogen peroxide (HTP) can be decomposed into superheated steam and oxygen using a catalyst, but I haven't been able to find any information on whether or not it will decompose in ...
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Why does New Horizons have ~2 kg of unusable “trapped” hydrazine?

The 2018 arXiv preprint The New Horizons Kuiper Belt Extended Mission by the New Horizons team says in section 6, pp. 21-22: Nevertheless, throughout the 2020s, there is significant potential for ...
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What's up with the lack of subminiature chemical rockets?

Not long ago, I was researching the scaling of converging-diverging de Laval nozzles to subminiature (1.5 mm throat diameter) dimensions for a non-rocket application, and later on studied the ...
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When would the density Isp product be an important performance metric of a propellant?

The quote NASA is testing hydroxylammonium nitrate in space which is expected to perform 50% better than standard propellants and can be allowed to freeze (hydrazine must be kept liquid). LMP-103S ...
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Why would it be “less bad” for hydroxylammonium nitrate monopropellant to freeze than for hydrazine?

Answers to Is it bad if hydrazine freezes on a spacecraft? Is it always kept as liquid, or can it be safely allowed to freeze and then thawed when needed? explain that while the freezing of hydrazine ...
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How do long range space probes adjust trajectory?

More specifically, after the main launch adjustments have been made using the primary boosters and temporary adjusting propellants how might even the slightest trajectory and orientation corrections ...
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How much fuel is left in InSight?

InSight probably landed with some fuel margin. Unless it was vented/burned on landing (maybe not a bad idea considering potential leaks down the road), is there some left ? Do we know the ISP of ...
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Why is hydrazine used in arcjet thrusters?

Most arcjet thrusters seem to use hydrazine or ammonia, with some research being done on hydrogen and water arcjets. I know hydrazine is easily catalyzed into exothermic decomposition, and it and its ...
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Is there a known way a nuclear heating device could move around in the CO$_2$ deposit on Mars? [closed]

What would be an easier way to start terraforming Mars than evaporizing the CO$_2$ deposit near the south pole ? An autonomous nuclear heating device of about 1000 kg for instance, that landed on ...
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What “green” propellant powers Curie, the engine on RocketLab's payload kickstage?

Upon news of RocketLab's successful flight of the Electron launch vehicle, it was announced that not only had they deployed the three onboard payloads into the desired orbit, they had done so using a ...
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Why is the Otto II monopropellant fuel not used in spaceflight applications?

Is anyone familiar with the chemical/thermodynamic properties of Otto II fuel (a monopropellant used in torpedoes)? It is composed of nitrated propylene gycol with a couple additives that make it non-...
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Where are the “World's First Space Engines” now?

From the Wikipedia article Pioneer P-30: At an altitude of about 370 km (230 mi), the first stage separated from the second stage. When the second stage was ignited, telemetry showed abnormal burning,...
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How was the Stabilo crewed re-entry vehicle supposed to work? A tractor engine with four nozzles?

ARCA Space's webpage for the Stabilo program has a description and an image. Hydrogen peroxide monopropellant? Reaction closer to the crew than the nozzle? With thrust at the top, it seems that ...
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Would (theoretically) metastable solid metallic hydrogen even need an oxidizer?

In this answer there is discussion of some research on the potential, future use of a solid metallic hydrogen phase that would be metastable at ambient pressure as a rocket propellant. The work is ...
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What was the result of the propellant predictions in the last chapter of “Ignition!”?

In John D. Clarke's Ignition! (1972), the author spends the last chapter making predictions about the future of liquid rocket propellants. I thought these were very interesting, but I realize the book ...
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Is Landsat-7's propellant resupply port “robot-ready”? (Restore-L mission)

update 2020-11-20: OSAM-1 (Formerly Restore-L) Continues to Make Progress, Fuel Tank Installed note: the recent 2019 news Northrop's satellite refueling spacecraft launches on October 9th which is ...
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Density impulse of monopropellant hydrazine?

I only found sources (like this ) giving impulse density of hydrazine used as a bipropellant in conjunction with various oxidizers, but I was unable to find any that would give me density impulse of ...
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Thrust/weight ratio of monopropellant thruster engine

Doing some digging online, but I was unable to come up with an answer to this... What are ballpark thrust-to-weight ratios for typical hydrazine monopropellant thrusters? I'm looking for a value that ...
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Is there a derivative of LMP-103S, called LMP-103, that has even higher performance?

I found this PDF while searching for any and all info related to LMP-103S, which you can read more about in my related question. In the PDF, if you scroll down to page 4, you will find a chart ...
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Is LMP-103S truly a viable replacement for Hydrazine?

LMP-103S is the name of a new monopropellant, tested on the PRISMA mission in 2010. It's main ingredient is ADN (Ammonium Dinitramide), a strange chemical invented in the 70's in USSR and ...