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Questions tagged [hydrazine]

Hydrazine is an inorganic compound used as a monopropellant.

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3answers
3k views

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?

After having read this answer I wondered what happens if hydrazine freezes. It looks like it is "normal" and not like water, in the sense that it contracts when freezing, unlike water which expands ...
21
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1answer
899 views

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 ...
4
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1answer
843 views

Why does Juno use “mixed oxides of nitrogen” oxidizer for propulsion? Which ones?

In the recent Spaceflight 101 article Rocket Burn postponed for NASA’s Juno, to remain in elongated Jupiter Orbit until December it says: Juno uses a bi-propellant main propulsion system with ...
2
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1answer
286 views

Why Was DARPA's Orbital Express Refueling Program Discontinued?

From 2006-2008 DARPA ran a program called Orbital Express(wikipedia link) which was "a safe and cost-effective approach to autonomously service satellites in orbit." The program had several goals: ...
22
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2answers
7k views

Why did SpaceX choose to use Hydrazine over newer “green” propellants for Dragon 2?

Firstly, I understand the need to use hypergolics over cryogenics as part of Dragon 2's abort and landing sequence - they provide "instant on" thrust and are throttlable with very wide margins (...