[AR] Re: Falcon 9 flight today
- From: Ben Brockert <wikkit@xxxxxxxxx>
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Mon, 7 Oct 2013 17:38:20 -0600
John,
Henry noted that much of the venting was LOX, rather than most.
Hopefully someone with experience in orbital decay behavior, like TVA
or the boffins on SeeSat, will look at the TLEs over time and be able
to make an educated guess as to how much propellant is left on the
stage.
I don't know if it was his intention, but Henry's parenthetical could
be read as implying that LOX venting is the less interesting part of
the propellant venting process, whereas I find the idea of a cloud of
light blue oxygen snow to be kind of amazing. It also needs to be kept
in mid for any suborbital rockets that vent propellant to minimize
landing mass; without attention to the pressure drops it would be
possible to instead just freeze a mass of LOX in the tank.
Ben
On Mon, Oct 7, 2013 at 3:27 PM, <JMKrell@xxxxxxx> wrote:
> Ben,
>
> Henry notes that most of the venting is LOX. Ionizing radiation quickly
> converts oxygen to monatomic radicals. Monatomic oxygen does etch the
> surfaces of satellites as they pass through the cloud, but this is a
> nuisance compared to shrapnel from a ruptured tank. The pressurizing gas in
> the RP-1 tanks is vented, but little RP-1. Venting tons of RP-1 would pose a
> coating hazard to satellite optics and sensors. Upon venting most of the
> RP-1 solidifies like your YouTube example and then sublimes at a very slow
> rate.
>
> John Krell
>
> In a message dated 10/7/2013 12:58:05 P.M. Pacific Daylight Time,
> wikkit@xxxxxxxxx writes:
>
> On Mon, Oct 7, 2013 at 1:43 PM, Henry Spencer <henry@xxxxxxxxxxxxxxx> wrote:
>> Vented propellant would be a hazard to other traffic only if that other
>> traffic passed very close to the venting stage soon after venting. The
>> vented propellant spreads out fast, and eventually blends into the
>> surrounding atmosphere. (Note also that much of what is vented from a
>> Falcon upper stage is LOX.)
>
> There would have been a small impulse if something flew through the
> cloud when it was dense, just as one of the schemes for deorbiting
> space junk is to put up a suborbital cloud of dense dust in front of
> the junk. I don't have software that could search for conjunctions in
> any reasonable amount of time, though.
>
> The LOX would have contributed to the particle cloud with the RP-1.
> Pulling vacuum on liquid nitrogen will create solid nitrogen, as can
> be demoed in the lab: http://www.youtube.com/watch?v=sy1_R2u1UKk Same
> is true for oxygen. The oxygen ice crystals wouldn't last long in
> sunlight, but it wouldn't have gone straight to gas from the rocket.
>
> Ben
>
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