[AR] Re: Human rated propellants, was: Australian peroxide death

  • From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
  • To: Arocket List <arocket@xxxxxxxxxxxxx>
  • Date: Sun, 23 Jun 2019 12:17:39 -0400 (EDT)

On Sun, 23 Jun 2019, John Dom wrote:

There is a sort of beetle capable of producing concentrated peroxide in tiny bladders "onboard", next decomposing it and use it as a boiling spray (for defence ?). I saw them at in the London zoo once. Puff, puff!

Yes, the bombardier beetles. (There are a number of different species.) Not only does the peroxide decompose, but the resulting oxygen oxidizes an organic fuel in the liquid -- it's a mixed monoprop. Yes, it's for defence; in addition to the spray being boiling hot, it contains irritant compounds. It can kill other insects, and feel like a bite or sting to larger creatures.

This reminds me of a question posed a few decades ago on AR as to why
evolution never designed rocket propulsion for, say, trees to launch
themselves to space.

It would have to confer a big survival advantage of some kind to be worth the energy expenditure of building up a large mass of high-energy propellant. And early low-performance versions would also have to show significant advantage, perhaps of a different kind (e.g., small, crude wings may have helped small fast-running bipeds balance themselves), since evolution tends to proceed in small steps rather than big jumps. (Larry Niven's "stage trees" were the descendants of a bioengineered species, not the result of natural evolution.)

Evolution does do some weird things; would you believe levitating spiders? <https://www.cell.com/current-biology/fulltext/S0960-9822%2818%2930693-6?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982218306936%3Fshowall%3Dtrue>

Henry

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