From: yee@trident.arc.nasa.gov (Peter E. Yee)
Subject: NASA Daily News for 07/31/92 (Forwarded)
Apparently-To: sci-space-news@ames.arc.nasa.gov
Followup-To: sci.space
Organization: NASA Ames Research Center, Moffett Field, CA
Date: Fri, 31 Jul 1992 18:29:43 GMT

	Daily                News
Friday, July 31, 1992  24-hour audio service at 202/755-1788

 % Atlantis launches at 9:56 am to start Tethered Satellite mission;
 % European Retrievable Carrier to be deployed tomorrow morning;
 % Tethered Satellite System check out is Sunday, deploy is Monday;
 % Oshkosh Air Show begins today,  NASP 50-foot mockup featured;
 % Marshall to host Space Station Freedom users conference next week;
 % STS-47 flight crew inspects Endeavour & Spacelab-Japan experiments.

Like clockwork, Atlantis lifted off this morning right on time at 9:56
am EDT to begin the STS-46 mission.  The ascent into exceptionally
clear Florida skies was absolutely nominal.  First and second stage
performance were right on the money.  Atlantis is now in a circular
267-statute-mile-high orbit.  The flight crew will spend the afternoon
activating the European Space Agency's European Retrievable Carrier
spacecraft and then deploy it from the payload bay early tomorrow
morning.  On Sunday, the STS-46 crew will begin to carry out a series
of experiments with the Tethered Satellite System.  The Italian-built
TSS satellite will be deployed on Monday.  This will be the first time
a satellite has ever been deployed on a long tether in space.  The
Tethered Satellite will be extended to a distance of 12-1/2 miles from
Atlantis.

Mission commander for this flight is Loren Shriver, who is making his
third shuttle flight.  Pilot is first-timer Andy Allen.  Mission
specialists for the flight are NASA astronauts Marsha Ivins, making her
second flight, and Jeff Hoffman and Franklin Chang-Diaz, both making
their third flights, and ESA astronaut Claude Nicollier, making his
first flight.  Franco Malerba, Italian Space Agency, is the payload
specialist for this mission, his first flight.

The Tethered Satellite System will be used in a series of tests to
determine if it is feasible to use such a system for generating
electricity for such structures as Space Station Freedom.  When the
Tethered Satellite is fully deployed, the combination of Tethered
Satellite and shuttle orbiter, both connected by the electrically-
conducting tether, will be acting as an electrical generator as they
move in orbit through the Earth's magnetic field lines.  The expected
voltage potential between the two spacecraft is on the order of 5,000
volts.

The mission is scheduled for 6 days, 22 hours and 11 minutes with a
planned end-of-mission landing at the Kennedy Space Center's Shuttle
Landing Facility on Friday, August 7.  This is the 12th flight for
Atlantis, which last flight was the Atlas-1 mission this past March and
April.

* * * * * * * * * * * * * * * *

The Experimental Aircraft Association Fly-In opens in Oshkosh,
Wisconsin, today, and will stay open through next Friday, August 7.
The NASA pavilion will feature a 50-foot-long mock-up of the National
AeroSpace Plane which was designed and built by students at Mississippi
State University.  The NASA exhibit will also focus on the Agency's
work in the area of high-speed civil transport.  The two-trailer Space
Station Freedom habitation and laboratory module exhibit will also be
parked by the NASA pavilion.  The space station display allows visitors
to walk through high-fidelity mockups of the U.S. habitation and
laboratory modules.

* * * * * * * * * * * * * * * *

NASA will hold the first Space Station Freedom Utilization Conference
next week in Huntsville.  The purpose of the conference, set for Monday
through Thursday, August 3 through 6, is to inform potential
researchers about Freedom capabilities, plans and opportunities for
research and to provide an open forum for exchange of information and
ideas between space station managers and potential space station
investigators.  As part of the forum, experienced researchers who have
flown equipment aboard Spacelab will describe their experiences and
learned lessons.  Further information on the conference can be obtained
from Barry Epstein, NASA Headquarters, 202/453-8203, or Deb Gilman, BDM
International, at 202/479- 5250.

The seven astronauts scheduled to fly aboard Endeavour for its
September Spacelab-Japan science mission, Wednesday inspected the
Spacelab module and conducted their final pre-launch inspection of the
module's experiment racks.  The crew entered Endeavour and then using
the airlock tunnel, crawled into the Spacelab for their inspection.
The next milestone for that mission is expected to occur mid-August
when Endeavour is moved from the Orbiter Processing Facility to the
Vehicle Assembly Building.

* * * * * * * * * * * * * * * *

In yesterday's edition it was not made clear why "star calibrations and
momentum wheel desaturations" are necessary for Magellan if it is not
actively mapping Venus.  The nominal Magellan orbit consists of two
major elementsPa Venus-facing portion and an Earth-facing portion.
Magellan maneuvers back and forth during each orbit to accommodate the
Venus- facing requirement for radar mapping and the Earth-facing
requirement for transmission of the radar data.  Magellan uses three
reaction wheels, or gyroscopes, to control the spacecraft's attitude in
relation to Venus.

There is one reaction wheel for each of the spacecraft's three axes P
yaw, pitch and roll.  To counteract a spacecraft motion in one of these
axes, the gyro for that axis is spun up.  The reaction wheels, driven
by electric motors, are used to store momentum while they are
spinning.  During each orbit, Magellan's thruster motors are fired to
counteract the torque being applied to the spacecraft as the gyroscopes
are then despun.  Despinning eliminates momentum which had been stored
during the orbit.  This process is referred to as "momentum wheel
desaturation."

During this same orbital period, Magellan uses its onboard star
trackers to look at the position of two stars and compare their
location with its onboard star map.  This allows the attitude and
guidance system to maintain a fix relative to Venus.  These two
operations are executed routinely each orbit.  During Magellan's
current operating sequence, the radar instrument and data recording
systems are not being used while Jet Propulsion Laboratory flight
controllers determine the best procedure for using the spacecraft's
high-rate data transmitter system.

There are several sections of the planetary surface which have not yet
been mapped and JPL Magellan controllers are fine tuning procedures
which will be used later this summer to ensure that data of those
regions are transmitted with the least likelihood of noise or other
problems corrupting the data.  In the meantime, Magellan's orbital
housekeeping functions such as star calibrations and gyro despinning
continue nominally.

Here's the broadcast schedule for Public Affairs events on NASA Select
TV.  Note that all events and times may change without notice, and that
all times listed are Eastern.  Live indicates a program is transmitted
live.

Friday, July 31, 1992
Live    6:00 am  Launch coverage of Atlantis for STS-46 Tethered Satellite and
                 Eureca deploy mission begins from KSC.
Live    9:56 am  Scheduled launch of Atlantis for STS-46 mission. 
       10:09 am  Replay of launch videos.
Live   11:00 am  Post-launch press conference from KSC.
Live    1:01 pm  Tethered Satellite System structure check, from Atlantis.
Live    5:26 pm  TSS retention latch function check, from Atlantis.
Live   10:23 pm  Unberthing of the European Retrievable Carrier, from Atlantis.

Saturday, August 1, 1992
Live   12:40 am  Eureca solar array and antenna deploy, from Atlantis.
Live    3:51 am  Eureca release from payload bay, from Atlantis.
Live    9:00 am  Mission status briefing, from JSC.
        9:30 am  Replay of Flight Day 1 activities.
       11:30 am  Replay of Flight Day 2 activities.

Sunday, August 2, 1992
Live    7:51 am  Cabin TSS operations, from Atlantis.
Live    2:51 pm  TSS science operations, initial beam emission test, from
                 Atlantis.
Live    3:30 pm  Mission status briefing from JSC.
Live    4:16 pm  TSS science operations, orbiter fluorescence observations,
                 from Atlantis.
       11:30 pm  Replay of Flight Day 3 activities.

Monday, August 3, 1992
Live   11:41 am  Pre-deploy operations for Tethered Satellite System, from
                 Atlantis.
Live   12:50 pm  Tethered Satellite System boom extension, from Atlantis.
Live    2:29 pm  Tethered Satellite System deploy and flyaway, from Atlantis.
Live   10:00 pm  Mission status briefing from JSC.
       11:30 pm  Replay of Flight Day 4 activities.
  
This report is filed daily at noon, Monday through Friday.  It is a
service of NASA's Office of Public Affairs.  The editor is Charles
Redmond, 202/453-8425 or CREDMOND on NASAmail.  NASA Select TV is
carried on GE Satcom F2R, transponder 13, C-Band, 72 degrees West
Longitude, transponder frequency is 3960 MegaHertz, audio subcarrier is
6.8 MHz, polarization is vertical.
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