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Comment by marktangotango | Hacker News Reader

Does any one know what the toxic propellants are (the Briz-m upper stage)?

Edit: "burning storable propellant combination of nitrogen tetroxide as oxidizer and unsymmetrical dimethyl hydrazine as fuel. The engine had a specific impulse of 328.1 seconds and was designed for eight firings during a mission. "[1]

[1] http://www.russianspaceweb.com/briz.html

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Hydrazine is so handy as a rocket fuel. It's room temp, stable, hypergolic, plenty of energy, it can even be a monopropellant. But it's also corrosive, extremely toxic (even in the low-ppm range) and also carcinogenic. It's easily absorbed as a vapor and through the skin, and it'll kill you before you can smell it. There's good reason to not use the stuff in large quantities or in systems that are likely to be handled by humans for more than tanking it up.

And nitrogen tetroxide ain't no picnic either. It's happy to fume, and those fumes will corrode your lungs and you won't know it. Then several hours or even days later, you're dead of pulmonary edema.

LOX and kerosene are mother's milk in comparison.

I work in rocket propulsion research and have worked with, and around, both of these propellants, and I think you exaggerate to the point of being incorrect. You can smell hydrazine long before it's dangerous - it smells a bit fishy, somewhat like ammonia. It has to get really quite bad before your body-mounted gas alarms tell you that you're above recommended limits.

I'm more worried by NO2 but as a fume it's bright orange so one can normally see a cloud of it coming and make plans to head somewhere not downwind. If you do get caught by some, protocol is to lie with your head at the bottom of an inclined plane for several hours, so the the fluid can drain out of your lungs (and you call an ambulance of course).

When propulsion tests are happening on site we keep emergency breathing apparatus under our desks incase there's a containment failure and we need to get out. Usually though we just test when the wind direction would take anything away from the office/workshop.

I'm not bothered about kerosene but I have a healthy respect for LOX; it's as easy to kill yourself with it as with hydrazine. Where breathing apparatus and chem suits will keep you safe from hydrazine pretty much, LOX doesn't forgive any dirtiness, grease, human hair, or the wrong choice of o-ring material, especially when pumped at high speeds and pressures. Different risks but LOX is arguably more likely to bite you.

Here's an often-cited LOX safety video of the sort you probably couldn't make today:

https://www.youtube.com/watch?v=QioE_OX4vP8

After reading the precautions you folk take - I hardy think the OP is exaggerating. Emergency breathing apparatus under our desks pretty much sums it up. With respect.

We use hydrazine in US rocketry, too. As nasty as the stuff is, if I were still in the missile business, I'd use it. It's a strong, well-proven technology.

Yes, Russia used it in their long- and medium-ranged ballistic missiles. After a series of agreements between the US and Russia were reached both countries agreed to reduce their arsenal ( https://en.wikipedia.org/wiki/START_I ). As a result Russia has an excessive amount of Hydrazine in storage. It's expensive to store it because it's a very toxic and corrosive substance. At the same time it's pretty difficult to get rid of it.

At least in case of Angara they burn it at a high altitude.

>Yes, Russia used it in their long- and medium-ranged ballistic missiles.

oh, yea, donning these suits (during summer sunny day) before [imaginary] filling up your missile. Whatever militaristic enthusiasm, if any, we may have harbored (ROTC students, so not much to start with (ROTC in Russia is a way to avoid military, not to get into it:)), it'd definitely disappear half way through it and that even without having the real dangerously toxic and corrosive stuff present.

The Briz upper stage is an existing design, it wasn't purpose built for Angara, it's been flying with various other rockets.

Storable propellants are good for upper stages that need to do long coast periods and many stops and starts. Apollo used them.

But there are multi-restart versions of lox-hydrogen stages. The RL-10 engine in Delta and Atlas can do it.

We shouldn't indefinitely rely on strong, well proven technologies if those have known serious drawbacks.

Even now there are alternatives. IMO, better ones.

The US space shuttle also used hydrazine (not for primary propulsion, obviously) which is why it was met with people wearing hazmat suits on the runway.

That reads like a who's who of Pipeline's "not going to work with" segment.

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