[AR] Re: Falcon 9 flight today
- From: JMKrell@xxxxxxx
- To: arocket@xxxxxxxxxxxxx
- Date: Wed, 9 Oct 2013 18:18:42 -0400 (EDT)
In a message dated 10/9/2013 12:37:23 P.M. Pacific Daylight Time,
henry@xxxxxxxxxxxxxxx writes:
On Wed, 9 Oct 2013 JMKrell@xxxxxxx wrote:
> My data lists RP-1 vapor pressure at <2 Torr @20C.
That's still quite a bit, if it's driving steady flow out a vent.
> In the earth's shadow, space is very cold.
Space has no temperature; things in space have temperature determined by
the combination of heat inflow and outflow. Things exposed only to black
sky can get very cold, but when half the sky is full of warm Earth, that's
actually fairly hard to arrange. Witness the way infrared-astronomy
satellites prefer high orbits, Lagrange points, or even Earth escape
trajectories.
In any case, what matters for this is not the coldest part of the orbit,
but the warmest part. Rates of evaporation, sublimation, melting, etc.
scale so strongly with temperature that the net rate is driven almost
entirely by the peak temperature, not by the lowest or even the average.
Correct, evaporation rates are peak temperature driven. Mass transport
under vacuum is differential temperature driven, Boltzmann equation.
Henry Spencer
henry@xxxxxxxxxxxxxxx
(hspencer@xxxxxxxxxxxxx)
(regexpguy@xxxxxxxxx)
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