Re: Rocket Science
Posted: Wed Mar 25, 2026 5:13 pm
Sent by email from GW Johnson 2026/03/25
There are thrusters that use NTO and one of the hydrazines at Isp close to 300 s, or catalyst decomposition of only hydrazine at smthat at or below Isp 200 s. Monopropellant is lower isp but simpler, and lighter weight because there is only one tank. Nobody uses hydrogen peroxide anymore, because it is NOT long-term stable in storage at the high peroxide concentration that you really need (above 85%). These thrusters get used in satellites for years at a time to maintain attitude control and make minor orbit changes.
There are also ion thrusters that can do the same job, at far higher Isp (2000+ s), but with heavier electrical gear to accelerate the particles. They are extremely low thrust, but over long periods of time at the far-higher Isp you can make major orbit changes. All of these use gaseous xenon (or something very similar) stored in sample gas pressure bottles, and fed out through a pressure regulator to maintain constant thruster feed pressures. Iodine is a solid candidate, but hasn't really been used yet. You would heat t to move it from the container to the thruster gear.
The storable liquids include H2O2, IRFNA, and NTO as oxidizers, and multiple hydrazines plus kerosene as the fuels. The hydrazines are fully hypergolic with any of those oxidizers, kerone is IFFY with H2O2 and IRFNA, and not hypergolic at all with NTO.
The hazards of handling hydrazine are modest, about like handling anhydrous ammonia: a corrosive and a suffocant. The hazards of handling kerosene are low: a mild toxicity if ingested, plus a fire hazard. The hazards of handling H2O2 are a corrosive action plus a suffocant, plus the explosion hazard if kept at high strength for too long. That occurs erratically, with only a subtle warning: bubble formation and mild temperature rise, only in the minutes or hours before it explodes. Easy to miss the signs. The hazards of handling IRFNA are mostly that it is a strong acid corrosive, plus the fire hazard if it contacts a fuel material. There is some serious toxic effect, too, since it is nitric acid with a dash of water and a dash of NTO in it. That's what makes it reddish and expelling clouds of very toxic reddish vapors. NTO is the worst one: extreme toxicity as well as a corrosive effect. The stuff has poisonous effects that extend to behaving like nerve gas. You must wear a sealed suit with its own breathing supply, to get anywhere near it.
The solid propellants have their own hazards and characteristics, but are nowhere near as dangerous as those storable oxidizers, or any of the cryogenics. That is why only solid propellants are now used for the weapons troops handle in the field anymore.
GW
There are thrusters that use NTO and one of the hydrazines at Isp close to 300 s, or catalyst decomposition of only hydrazine at smthat at or below Isp 200 s. Monopropellant is lower isp but simpler, and lighter weight because there is only one tank. Nobody uses hydrogen peroxide anymore, because it is NOT long-term stable in storage at the high peroxide concentration that you really need (above 85%). These thrusters get used in satellites for years at a time to maintain attitude control and make minor orbit changes.
There are also ion thrusters that can do the same job, at far higher Isp (2000+ s), but with heavier electrical gear to accelerate the particles. They are extremely low thrust, but over long periods of time at the far-higher Isp you can make major orbit changes. All of these use gaseous xenon (or something very similar) stored in sample gas pressure bottles, and fed out through a pressure regulator to maintain constant thruster feed pressures. Iodine is a solid candidate, but hasn't really been used yet. You would heat t to move it from the container to the thruster gear.
The storable liquids include H2O2, IRFNA, and NTO as oxidizers, and multiple hydrazines plus kerosene as the fuels. The hydrazines are fully hypergolic with any of those oxidizers, kerone is IFFY with H2O2 and IRFNA, and not hypergolic at all with NTO.
The hazards of handling hydrazine are modest, about like handling anhydrous ammonia: a corrosive and a suffocant. The hazards of handling kerosene are low: a mild toxicity if ingested, plus a fire hazard. The hazards of handling H2O2 are a corrosive action plus a suffocant, plus the explosion hazard if kept at high strength for too long. That occurs erratically, with only a subtle warning: bubble formation and mild temperature rise, only in the minutes or hours before it explodes. Easy to miss the signs. The hazards of handling IRFNA are mostly that it is a strong acid corrosive, plus the fire hazard if it contacts a fuel material. There is some serious toxic effect, too, since it is nitric acid with a dash of water and a dash of NTO in it. That's what makes it reddish and expelling clouds of very toxic reddish vapors. NTO is the worst one: extreme toxicity as well as a corrosive effect. The stuff has poisonous effects that extend to behaving like nerve gas. You must wear a sealed suit with its own breathing supply, to get anywhere near it.
The solid propellants have their own hazards and characteristics, but are nowhere near as dangerous as those storable oxidizers, or any of the cryogenics. That is why only solid propellants are now used for the weapons troops handle in the field anymore.
GW