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K5ARH > SAREX 07.04.97 21:26l 83 Lines 3512 Bytes #-10583 (0) @ AMSAT
BID : STS-83.007
Read: DG5COB GUEST OE7FMI
Subj: STS-83 SAREX Bulletin Number 7
Path: DB0AAB<DB0CRL<DB0TTM<DB0SWR<DB0FP<DB0SON<DB0MAK<OK0PKL<OK0PPR<OK0PRG<
OK0PAB<OH3RBR<VE4KV<WB7AWL<WB0TAX<K5ARH
Sent: 970407/0042z @:K5ARH.#LFT.LA.USA.NOAM #:5410 $:sts-83.007
Silver Spring, Maryland USA
April 6, 1997 @ 2100 UTC
Mission Cut Short
The problems in the fuel cell have been steadily worsening. All three
fuel cells must be operational for the flight to continue. Will
Marchant, KC6ROL, of the AMSAT Development and Operations Team, noted
that the space shuttle is an all-electric vehicle and, unlike most
aircraft, cannot function without electrical power.
Space shuttle managers today decided to cut short the STS-83
Microgravity Science Laboratory-1 (MSL-1) mission because of the
problems with one of the shuttle's three fuel cell power generation
units. In a meeting that concluded at 1400 UTC, NASA's Mission
Management Team (MMT) decided to order the early return due to data
received on fuel cell number 2, which has exhibited evidence of
internal voltage degradation since launch. To ensure the safety of
the crew and Columbia, mission managers decided to reduce power demand
on the degraded cell and to isolate it from the other two fuel cells
which are performing normally. Meanwhile, flight controllers and
engineers on the ground are continuing analysis of fuel cell data in
order to decide whether to shut down the defective unit or to leave it
operating at minimum output in a standby mode.
Columbia is now scheduled to land at 1835 UTC on Tuesday at Kennedy
Space Center. There is no concern for crew safety due to fuel cell
number 2.
Attention has turned to tending with the primary payloads and preparing
for landing. SAREX was turned off and stowed at 1600 UTC.
The shuttle has three fuel cells which use a reaction of liquid
hydrogen and liquid oxygen to generate electricity and produce
drinking water. Although one fuel cell produces enough electricity to
conduct on-orbit and landing operations, shuttle flight rules require
that all three be functioning well to ensure the safety of the crew
and provide sufficient backup capability for the highly dynamic
reentry and landing periods.
The early landing, which is only the third of the shuttle program
behind STS-2 in November 1981 and STS-44 in November 1991, means that
scientists will not be able to perform the majority of the research
planned for the MSL-1 mission. Columbia continues to circle the Earth
in a 188 x 183 statute mile orbit every 90 minutes with all of its
other systems operating normally.
Here is the latest orbital element set for those who are using a
satellite tracking program during this flight.
STS-83
1 24755U 97013A 97096.04854671 .00134457 00000-0 42801-3 0 9058
2 24755 28.4678 304.5233 0003495 348.4889 11.5808 15.90371347 211
Satellite: STS-83
Catalog number: 24755
Epoch time: 97096.04854671 = yrday.fracday
Element set: 905
Inclination: 28.4678 deg
RA of node: 304.5233 deg
Eccentricity: .0003495
Arg of perigee: 348.4889 deg
Mean anomaly: 11.5808 deg
Mean motion: 15.90371347 rev/day
Decay rate: 1.34457E-03 rev/day^2
Epoch rev: 21
Checksum: 331
The Web version of Rise/Set times:
http://www.datasync.com/~nz8c/sarex_passes.html
[Radio amateurs are encouraged to relay these SAREX bulletins to
their local packet BBS as long as the Bulletin IDentification (BID)
is preserved. The BID is the character string beginning with the
dollar sign ($), for example as in "SB SAREX @ AMSAT $STS-83.007"
without the quotation marks.]
Submitted by Pat Kilroy, WD8LAQ for Frank H. Bauer, KA3HDO and the
SAREX Working Group.
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