On Thu, 01 Aug 2002 15:24:11 -0700, Pierce Nichols
<[EMAIL PROTECTED]> wrote:
> I was speaking specifically about the asteroid flyby mission under
>discussion. That's at least a 13 km/s delta-V, which will require at least
>two stages with current tech and a realistic budget.
One of my assumptions in this discussion is that the organization
contemplating bidding on the mission is some descendant of ERPS, which
already has something close to an SSTO RLV. This outfit is not going
to design a new launch vehicle system just for this mission.
>You know well enough
>that I'm a fairly dedicated heretic when it comes to the whole staging
>question, however :).
I'm fairly agnostic myself. But I put operational, logistical, and
financial considerations on an equal basis with performance
considerations, and single stage wins on the first two, and maybe on
the third as well.
> OTOH, the delta-V requirement for the upper stage goes up. The
>balancing point is intensely dependent on mission and vehicle specific
>parameters. I suspect it's some kind of suborbital, because they eliminate
>the need for a circularization burn or orbital maneuvering fuel aboard the
>lower stage.
You missed the discussion last night. Assume the mission is a flyby
of the rock coming through on the 18th, and the trajectory from
hereabouts is nearly straight up: the rock is going to pass near Vega,
which is almost overhead in the evening this time of year. No circ
burn, and no remote flyback: the first stage can RTLS.
>>(The marketing
>>guy, of course, will say, "We need to practice that anyway. Let's
>>make money at it.")
>
> Actually, that's what the engineering guy says... :). The
>marketing guy sold this mission without inquiring to deeply into the whys
>and wherefores.
Not twice, he doesn't. In fact, I'm not even worried about once.
Recall my assumption that the organization is some descendant of ERPS.
The marketing guy is probably the president of one of the spinoffs,
and a former officer of ERPS. Even if doesn't know the engineering
firsthand, he'll ask, before he sells it.
-R
--
"Sutton is the beginning of wisdom -
but only the beginning."
-- Jeff Greason
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