Lmao, what are some hypergolic propellants that aren't toxic? They're insanely reactive by their very nature, that means they will react and fuck with anything that's alive. They're intrinsically incredibly toxic.
There are, after all, some chemicals that explode shatteringly, some that flame ravenously, some that corrode hellishly, some that poison sneakily, and some that stink stenchily. As far as I know, though, only liquid rocket fuels have all these delightful properties combined into one delectable whole."
Isaac Asimov, from the leading words to John D. Clark's "Ignition!"
While technically true, in rocketry - where the term was born - "hypergolic" mostly mean "of hydrazine family", which are (almost all extremely) toxic.
So it's a moot point to talk about the fine print. What was meant is that SpaceX doesn't pollute the land with poisonous fuel of the Starship, and the one argument is that the fuel isn't poisonous to begin with.
(And I'd really like to know what kind of additive would be in liquid methane - medium cryogenic - which Musk hopes to keep adding on Mars and which is toxic.)
That being said, there are plenty of propellants used as part of hypergolic combinations that aren't toxic. For example, oxygen, used as part of the hypergolic ignition system for SpaceX's merlin engines.
Merlin engines combine TEA-TEB with liquid oxygen to start the engines but do not use TEA-TEB as a propellant. TEA-TEB also spontaneously ignites with air; that shit is insane but you deliberately chose not to mention TEA-TEB because you know TEA-TEB would fuck you up (presuming you could even consume it without catching fire first!) Leaving out such a pertinent detail leaves it hard to believe you're not arguing in bad faith.
Why are we even talking about hypergolic propellants? Because a fear mongering comment upthread suggested that rocket propellants are extremely toxic. Scratch hyperbolic propellants off the list and what are you left with? Kerosene, methane, hydrogen, and oxygen. None of these present a significant toxicity threat, the worse of them is kerosene which can contaminate the soil and groundwater but all of the others vaporize harmlessly. So the fear monger was trying to cash in on the toxic reputation of hypergolic propellants to insinuate that Starship presents such a threat itself. This is complete nonsense, a bad faith argument that even a single minute of research can refute.
No, I said they use liquid oxygen as a propellant, and they use liquid oxygen as a hypergolic. The fact that this doesn't make LOX a hypergolic propellant is precisely my point.
> TEA-TEB also spontaneously ignites with air
> you know TEA-TEB would fuck you up
EXACTLY. Hypergolic is a property of the combination of chemicals, toxicity is a poroperty of a single chemical. Air is non toxic no matter what you combine it with. TEA-TEB is toxic no matter what you combine it with. Air being hypergolic with TEA-TEB does not suddenly make it toxic, nor does it suddenly make TEA-TEB non-toxic.
I'm not arguing in bad faith, you just are fundamentally misunderstanding what point I am trying to make, which again is that hypergolicity != toxicity. No more, no less.
> Scratch hyperbolic propellants off the list and what are you left with? Kerosene, methane, hydrogen, and oxygen.
You are repeating the misunderstanding about hypergolicity. Scratch propellants that can be used in hypergolic combinations off the list and you have nothing. Scratch hypergolic propallant COMBINATIONS off the list, and you still have non-hypergolic combinations of all those highly toxic propellants. Methane and oxygen are both non-toxic, but that has nothing to do with the fact that they need an ignition source to burn with one another.