Lunar Prospector trajectory
Philip Chien (kc4yer@amsat.org)
Sun, 4 Jan 1998 19:14:32 -0400
I'm not sure anybody's going to be able to predict visibility for the Lunar
Prospector launch.
It's a rather unusual trajectory which basically goes straight up from the
launch pad. The first stage does end up in the water though, about 60
miles from the pad. From what a manager told me all three solid stages are
ballistic (e.g. will not reach orbital velocity).
The Orbital Adjust Module (OAM) will put the spacecraft with its apogee
kick motor in to orbit. After separation the OAM will have a retrograde
burn over Hawaii which will reduce the orbital energy enough to assure a
fairly rapid decay. This is the only component of the launch vehicle which
will reach orbit. It's a flat cylinder 2.33 meters in diameter and less
than a meter high. I doubt that this will be very visible due to its size.
The Trans Lunar Injection module (TLI) is a Star 37FM, which is normally
used as the built-in apogee motor for the GPS Block IIR. I saw this stage
with Lunar Prospector in its clean room a couple of weeks ago. It looks
like the TLI is about 2 meters in diameter and about 3 meters tall. It's
covered with black insulating blankets so I doubt it would be very visible.
The TLI is considered to be part of the spacecraft, not part of the launch
vehicle.
The TLI stage sends Lunar Prospector out of Earth orbit towards the moon.
I believe (although have not verified) that it will remain in a very
elliptical Earth orbit which would eventually either reenter or be nudged
in to a solar orbit.
The Lunar Prosepctor spacecraft is *tiny* - you can almost put your arms
around it!
The launch vehicle burnout occurs about 13 minutes after launch. The OAM +
TLI + spacecraft will coast around the earth for 43 minutes before the TLI
and s/c separate from the vehicle over Australia. Half a second after
separation spin rockets on the TLI will spin up the TLI + s/c to 57 RPM.
The TLI then burns to send it and the s/c out of low earth orbit.
It's certainly conceivable that somebody in the right location may be able
to spot one of the launch vehicle stages while it's burning, but that can't
be predicted by a satellite tracking program.
The Lunar Prospector will certainly be the A object from the mission (1998
1A??) and my guess is the TLI stage will get B, and the OAM module will get
C.
Photos of the TLI, spacecraft, and vehicle as it was assembled at the pad
are available at the Kennedy Space Center publisher's photo corner. (go to
http://www.ksc.nasa.gov select public affairs, select photos by index,
select Lunar Prospector.) The webmaster's a good friend so say hi to her
and tell her what a wonderful job she's doing. ;-)
Philip Chien [M1959.05.31/31.145//KC4YER@amsat.org]