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Re: (meteorobs) Pegasids and ZHRS

This is a bit off-topic, but kinda interesting in that I bet few of us were
aware of this application for such a machine. I wasn't, but it makes sense
now...

At 04:40 AM 1999-07-12 -0400, you wrote:
>        One more thought...does it really cost "tens of millions" just
>to send up an SR-71 for one flight?  That sounds a tad expensive for any
>aircraft, but I'm no pilot...

I'm not, either; I was guessing, but I'm sure that the cost is in that
range: that is, far more than a million dollars for a simple local test
flight (a "local" test flight to a SR-71 is one over the same continent or
hemisphere, BTW). If you don't know:

The SR-71 is essentially a rocket plane burning very esoteric liquid fuel;
I remember reading once that as a SR-71 takes off, you can follow it down
the runway by the wisps of steam rising from the spilled fuel leaking from
the fuselage tanks which spills over the wing surfaces. You should be able
to find detailed data about the aircraft on the web or at your local book
store; but basically, its engines perform as inefficient jets below about
50,000 feet, and convert into ramjets (I think) above 50,000 feet altitude.
It cruises at something like Mach 4 or 5, possibly faster; i.e., four or
five times the speed of sound. We don't hear sonic booms from them because
they're too high (around 120,000 feet altitude, I believe) by the time they
break the sound barrier, and the pilots probably don't kick the throttle
until they're out over water. 

The SR-71 (I think there were about a dozen of them operable simultaneously
at one time; today, I think there are only a half dozen still flyable) is
used for all kinds of tasks, of which 99% are probably classified. But
published accounts I've seen include things like making very rapid runs
over certain "hot spots" on other continents when our intelligence agencies
just HAVE to have some kind of quick "look-see" after a crisis breaks out
somewhere and a satellite isn't readily available; the SR-71 carries
cameras of all kinds. 

It's a gigantic and fantastic airplane. I can see that they would use it to
attempt to collect atmospheric samples after a bolide explodes because it
flies so fast that it could probably be over New Zealand within, say, a
couple of hours or maybe less, I dunno. And it flies so high and fast that
by the time radar detects it (which most air-defense radars can't anyhow
due to limited range), it's gone. The SR-71 was actually officially retired
from the US Air Force many years ago; there's a replacement which
name/nomenclature I cannot recall at the moment. I'm probably incorrect;
but I thought that I read that the replacement aircraft is the faster
non-space vehicle in the world at something close to Mach 10.

When the SR-71 lands, the pilot cannot leave the aircraft for up to 15 to
30 minutes because the skin of the aircraft is too hot to touch due to the
hypervelocity speeds attained in flight (same thing goes for the Space
Shuttle, BTW: if you ever watched one land at Edwards, you probably
wondered what took so long for the crew to exit the space craft).

So, if you think of the intensive maintenance required to keep a multi-Mach
aircraft operating (did I also read that the engines have to be completely
rebuilt after EVERY flight, or was it just after every THREE flights??),
plus the incredible fuel expense, plus the cost of the pilot's years of
training and experience, plus the cost of the maintenance crew's training
and experience, then I doubt that my guess at "tens of millions per flight"
is all that far off.

I guess the question has to be "Why would someone consider the explosion of
a bolide to be that interesting??". I dunno; perhaps, in the case of the
New Zealand "incident", there may have been sufficient uncertainty about
whether the fireball was really a bolide, or some unexpected re-entering
space craft; for example, how about an ex-USSR nuclear-powered satellite??
I can easily understand that if there was a suspicion that such a satellite
re-entered and exploded in the atmosphere so close to ground, there would
be considerable concern about how much, and what kind of, debris remained
in the atmosphere, and how "hot" (radioactive) it might be.

Remember: I'm making a lot of guesses at a lot of the above.

SteveH
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