[amsat-bb] Re: Shuttle question

Ken Ernandes n2wwd at mindspring.com
Fri May 30 06:14:20 PDT 2008

```The Shuttle doesn't have nearly the propellant capacity to match speeds with
AO-40, even if it were in the same orbital plane.  To capture AO-40, it
would need to match AO-40's orbit.  Just to get into the elliptical orbit
and decrease the inclination to 7-degrees is well more thrusting (delta-V)
capacity than the Shuttle has.  Just to put it into perspective it would
need:

1.  Maneuver from a 400-km circular orbit to produce a 1200-km apogee (to
match AO-40's perigee) -- needs ~211 m/sec of delta-V
2.  To perform an apogee boost to match AO-40's semi-major axis and
eccentricity (1200 x 58600-km) -- needs ~2660 m/sec of delta-V.
3.  To perform an apogee plane change would require at minimum a 21.5-degree
inclination, were the Shuttle launched into its minimal 28.5-degree
inclination.  The delta-V for the minimal apogee inclination-only change
would need ~427 m/sec.  For the 51.6 degree ISS inclination (44.6-deg
change), the delta-V would be ~905 m/sec.
4.  Perform terminal rendezvous and capture maneuvers - small in comparison
to the others, so I'll call it free.
5.  After capturing AO-40, the Shuttle would need to de-boost to a low-Earth
orbit (LEO), which requires a perigee braking thrust of another 2660 m/sec.
6.  The Shuttle would then need enough delta-V to de-orbit.

The minimum delta-V in the [optimistic] profile I've described would be 211
+ 2660 + 427 + 2660 = 5958 m/sec, plus de-orbit delta-V.  That's a
significant percentage of what it took to put it in orbit to begin with and
it still would need enough delta-V to de-orbit.  One more piece of bad news:
the astronauts would need to fly through the intense radiation environment
that AO-40 orbits and remain there long enough to perform the maneuvers I've
described and capture AO-40.  That would be a serious health risk at the
very least.

I think you'll agree, after looking at the numbers, that this suggestion is
not feasible.

73, Ken Ernandes N2WWD

-----Original Message-----
From: amsat-bb-bounces at AMSAT.Org [mailto:amsat-bb-bounces at AMSAT.Org] On
Behalf Of Ransom, Kenneth G. (JSC-OC)[BAR]
Sent: Thursday, May 29, 2008 10:11 PM
To: w7lrd at comcast.net; AMSAT-BB
Subject: [amsat-bb] Re: Shuttle question

A few extra pounds could be accommodated on the shuttle if you can get high
enough on the priority list. Much of that space is reserved for critical
components (things so big that only the shuttle can get them there) needed
for ISS. Right now, there are only 11 more shuttle flights (including the
one scheduled to launch this Saturday, May 31) and a couple of those may go
away with the shuttle retirement set for 2010. Getting something boosted
higher would take quite a few more pounds, volume and crew time. The
greatest challenge is getting through the human spaceflight certification
criteria.

It might be worthwhile to explore some of the other launch vehicles that are
a bit less constrained time wise (Progress, HTV, ATV and COTS) and see if a
piggyback payload could be attached and later boosted.  It will still cost
plenty unless the payload has a bank rolled primary objective and amateur
radio happens to fit in the gaps of the design.

Maybe all of the AMSAT's could buy a Progress after it has served it's
purpose and have the Russians boost it to a higher orbit instead of ditching
it afterwards. It comes with solar cells pre-installed ;)

Kenneth - N5VHO

________________________________

From: amsat-bb-bounces at amsat.org on behalf of w7lrd at comcast.net
Sent: Thu 5/29/2008 7:03 PM
To: AMSAT-BB
Subject: [amsat-bb] Shuttle question

Hello
I'm sure this question has been bounced around the BB in past.  I simply
don't recall (senior moment) the results.  With all the TONS of stuff they
regularly pack up there, it seems logical (another senior moment), that an
extra few pounds wouldn't even be noticed, maybe even more than a few
pounds.  Then we can figure a way to get it even higher than the ISS.  Just
thinking of a way to get more of a foot in the shuttle door.
73  Bob W7LRD
Seattle

--
"if this were easy, everyone would be doing it"
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