Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/DAILY_1/930319.DFC

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=--=--=START=--=--= NASA Spacelink File Name:930318.REL

3/18/93:  PRELIMINARY RESULTS FROM ATLAS 1 (STS-45)

NASA Facts
National Aeronautics and Space Administration
Washington, D.C. 20546

Preliminary Results from ATLAS 1

        The first Atmospheric Laboratory for Applications and Science (ATLAS 1)
conducted 14 investigations in atmospheric science, solar science, space plasma
physics and astronomy.  The 13 instruments were carried aboard two Spacelab
pallets or mounted on the payload bay walls of the Space Shuttle Atlantis,
which was launched March 24, 1992 and landed April 4, 1992.

        The data from these investigations will be used in several ways.  The
six ATLAS core instruments and the co-manifested Shuttle Solar Backscatter
Ultraviolet Experiment (SSBUV), will be reflown periodically to provide
"snapshots" the Earth's atmosphere and the Sun at different points of the 11-
year solar cycle.

        ATLAS 1 obtained substantial volumes of data that will help scientists
better understand the chemistry of the atmosphere, the energy output of the
sun, the behavior of high-energy particles as they reach the atmosphere and the
structure of the universe.

        In addition, data from several ATLAS 1 instruments, which are precisely
calibrated before and after flight, will be compared to observations from
similar instruments aboard free-flying satellites.  This will help insure the
accuracy of a large portion of the data that is the ultimate product of NASA's
Mission to Planet Earth, a comprehensive research program that takes advantage
of the perspective from space to study the Earth as a global environment
system.

        Though data analysis continues, some preliminary results are available.
Data will continue to be refined and results published in scientific journals.
A special section of Geophysical Research Letters, a journal of the American
Geophysical Union, devoted entirely to ATLAS 1 results, is scheduled for
publication in spring 1993.

Atmospheric Science

Atmospheric Trace Molecule Spectroscopy (ATMOS):

Showed increases in hydrogen fluoride and hydrogen chlorideQcompounds involved
in ozone depletionQfrom the instrument's 1985 flight aboard Spacelab 3.  These
increases are consistent with predictions of computer models and with
measurements of surface concentrations of chlorofluorocarbons, which are the
sources of the chlorine and fluorine in the stratosphere.

        ATMOS obtained more than 9,300 spectra in 53 orbital sunrises and 41
sunsets.  The instrument made 30 coincident measurements with the HALOE
instrument aboard the Upper Atmosphere Research Satellite (UARS), 24 coincident
measurements with UARS' CLAES instrument and 14 coincident measurements with
the SAGE II instrument aboard the Earth Radiation Budget Satellite (ERBS).  The
formal comparison and analysis of data between the ATMOS and UARS science teams
will begin in 1993.

Atmospheric Lyman-Alpha Emissions (ALAE):

Expanded our knowledge about how chemicals mix in the regions above our
atmosphere by improving upon previous measurements of hydrogen and deuterium.

        ALAE observed deuterium as far down as approximately 50 miles (80
kilometers), the bottom of the atmospheric region known as the thermosphere.
This measurement represents an important advance over ALAE's measurements on
Spacelab 1 in 1983, in which atomic deuterium could not be detected below
approximately 70 miles (110 km).  ALAE also obtained measurements of hydrogen
and deuterium in the exosphere and interplanetary medium.

          The results from the Earth's upper atmosphere can also be compared to
similar measurements made in the atmospheres of Venus and Mars to help us
better understand the differences between the atmospheres of the planets.

Grille Spectrometer (Grille): Observed 10 trace atmospheric gases, including
carbon dioxide, ozone and chemicals involved in stratospheric ozone depletion.
Initial analysis shows an increase in hydrogen chloride from the mid-1980s,
compared to ATMOS data from Spacelab 3.  GRILLE obtained 89 observations
ranging from 1 degree South to 33 degrees South. An additional measurement was
made at 29 degrees North on the ninth (extra) day of the mission.  Data also
were compared with those from Grille's first flight, aboard Spacelab 1 in 1983.

Imaging Spectrometic Observatory (ISO):

Obtained the first complete spectral map of the ionosphere, thermosphere and
mesosphere (altitudes between 40 and 240 miles).  ISO also made the first
space-based measurement of the hydroxyl radical (OH, a key intermediate of the
chemistry affecting ozone levels in the mesosphere and stratosphere) between
approximately 40 and 50 miles (70-80 km) Together with measurements from ALAE,
MAS, ATMOS, and GRILLE, these data will form a comprehensive set of mesospheric
chemistry data that can be used to validate computer models.

        ISO also made the first comprehensive spectral survey of mesospheric
airglow, the faint glow that emanates from chemical reactions in the upper
atmosphere.  The airglow data can be used to help evaluate computer models of
the atmosphere.  ISO also made the first dayglow profiles of an electronically
excited form of atomic nitrogen, which may improve our understanding of nitric
oxide in the thermosphere and the critical role it plays in the chemistry in
the upper atmosphere.

Millimeter-Wave Atmospheric Science (MAS):

Refined our knowledge of the atmosphere with measurements of ozone, chlorine
monoxide and water vapor that were consistent with existing models and previous
observations.  Day-night, latitudinal and vertical variations in ozone and
water vapor were as expected.  The MAS data show significant variations in
ozone across longtitudes at approximately 60 degrees latitude and 18 miles (30
km) altitude.  This is consistent with data from the Total Ozone Mapping
Spectrometer (TOMS) aboard NASA's Nimbus 7 satellite.

        The MAS measurements are also being compared to ground- based microwave
measurements to improve validation and interpretation.  MAS measurements will
be compared to those from instruments aboard the Upper Atmosphere Research
Satellite (UARS) to better assess the MAS and UARS measurements.

Shuttle Solar Backcatter Ultraviolet Experiment (SSBUV):

Indicated, through comparisons of SSBUV data with the Solar Backscatter
Ultraviolet Experiment (SBUV-2) instrument aboard the NOAA-11 weather
satellite, that the SBUV-2 instrument has continued to degrade at its shortest
wavelengths as expected.  Subsequent analysis will allow science teams to
compare SSBUV's ozone data with NOAA-11's and refine the latter's data.

        Other results indicate that SSBUV's sensitivity over most of its
wavelengths was comparable to that seen in SSBUV's previous flight (August
1991), and that comparisons of solar measurements between these two flights was
quite good at most wavelengths.

        SSBUV obtained ozone profiles and total ozone amounts during 34 orbits.
For six additional orbits, the instrument observed upper stratospheric ozone
distributions with a higher resolution across Earth's latitudes.  The
instrument also obtained solar ultraviolet measurements on seven orbits, and
there were four in-flight calibrations to assess instrument performance.

Solar Science

Active Cavity Radiometer Irradiance Monintor (ACRIM) and the
Measurement of the Solar Constant (SOLCON):

Obtained data on the solar constant that are still being analyzed and compared
to several similar instruments, including the ACRIM instrument onboard UARS and
to the Earth Radiation Budget Experiment (ERBE) onboard the Earth Radiation
Budget Satellite (ERBS).  SOLCON data show strong evidence for solar variation
during the mission (higher solar levels during the first and fourth solar
pointing period than the second and third).  The expected correlation between
total solar output and the number of sunspots was observed.

Solar Spectrum Measurement (SOLSPEC) and the Solar Ultraviolet
Spectral Irradiance Monitor (SUSIM):

Obtained measurements of the sun's ultraviolet energy.  Results are being
compared with those obtained from the previous flights of these instruments
aboard Spacelab 1 and Spacelab 2, respectively.  Preliminary comparisons
indicate relatively good agreement between the two flights for both
instruments.

        Once final analysis of the SUSIM data are completed, the results will
be compared with the SUSIM instrument flying aboard UARS. These highly
calibrated instruments are an important check on solar ultraviolet data because
the harsh environment of space significantly degrades instruments on
free-flying satellites.  While these instruments are designed with onboard
calibration lamps to correct for instrument degradation, the confidence gained
by having an independent instrument available for comparison is critical, given
the importance of ultraviolet radiation in creating and destroying ozone.

Space Plasma Physics

Atmospheric Emissions Photometric Imaging (AEPI):

Succeeded in several different areas.  By observing the formation and changes
in airglow (high- energy particles) around the shuttle, AEPI will help answer
questions about the energetics and dynamics of the mesosphere.  These
measurements are important in their own right and also will better define the
science objectives of the proposed Thermosphere-Ionosphere-Mesosphere
Energetics and Dynamics (TIMED) mission.

        AEPI also observed the artificial auroras created by the SEPAC
instrument.  By knowing the energy levels and electric currents of these beams,
and then observing the beams' behavior and lifetimes, the AEPI team will be
able to better understand how natural aurorae behave and the structure of the
Earth's magnetic field.  The AEPI-SEPAC experiments also proved the technology
of beam formation and the detection of subsequent aurora.

Energetic Neutral Atom Precipitation (ENAP):

Using the ISO instrument, studied emissions from neutral atoms (not
electrically charged) atoms that reached the upper atmosphere.  Emissions from
several chemicals were observed, and quantitative information on the magnitude
of these emissions was obtained.  These data are particularly important for
understanding emissions at low- to mid-magnetic latitudes.  Thermospheric
modelers will use the data to better understand the effect of neutral atom
precipitation on the chemistry of thermosphere and ionsphere.

Space Experiments with Particle Accelerators (SEPAC):

Created and observed several artificial auroras, allowing scientists to observe
the structure of the Earth's magnetic field.  Together, data from SEPAC and
AEPI showed the size and intensity of the artificial auroras and determined the
cause of their shape.  Correlative measurements made from the ground in Peru
detected disturbances associated with the SEPAC plasma contactor beam.  The
SEPAC investigation will provide significant amounts of data that will help us
better understand the structure of the Earth's magnetic field and the behavior
of high-energy particles from space as they reach the field.

Astronomy

Far Ultraviolet Space Telescope (FAUST):

Observed 22 fields and detected 4,976 objects.  Data anlyzed to date include
images from the north galactic pole and the galactic and extragalactic
background, as well as of the broad structural characteristics of galaxies.
Data on far ultraviolet emissions of the Earth were also obtained, as was
information about the magnitude of a potential Shuttle effect on astronomical
observations.  Astronomical data have been compared to that from other
spacecraft for particular objects; a good correlation between the flux observed
by FAUST and that from the International Ultraviolet Explorer (IUE) satellite
was obtained.

        FAUST data also indicated that the orbital night at ATLAS 1's
approximately 180-mile altitude becomes sufficiently dark that astronomical and
geophysical observations can be made to low light levels.  A faint far
ultraviolet glow seen when looking down at the Earth has been shown to be of
terrestrial origin and not due to shuttle glow.

March 1993
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
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=--=--=START=--=--= NASA Spacelink File Name:930319.REL

3/19/93:  PEARSON ANNOUNCES SHUTTLE PROGRAM ADJUSTMENTS

Ed Campion                      March 19, 1993
Headquarters, Washington, D.C.



RELEASE:  93-49


     NASA's Associate Administrator for Space Flight Jeremiah W. Pearson today
announced that Leonard Nicholson is leaving his current position as Space
Shuttle Program Manager to take over the key Johnson Space Center, Houston,
position of Acting Director of Engineering. As a result of this action,
Brewster Shaw, currently Deputy Director Space Shuttle Operations will take
over the duties formerly performed by Nicholson in the position of Director
Space Shuttle Operations.

     JSC Director Aaron Cohen has assigned current Director of Engineering
Henry Pohl to a new position on his staff, where he will be responsible for
leading JSC's support of the agency's effort to redesign the space station.
Pohl will spearhead the center's efforts and serve as a focal point for JSC
support to Assistant Deputy Administrator Joseph Shea, who was appointed by
NASA Administrator Daniel S. Goldin to oversee the redesign.

     Shaw will move from Kennedy Space Center to JSC. In addition to his
current duties, he will direct the day-to-day management and execution of the
Shuttle program, including detailed program planning, scheduling and Shuttle
systems configuration management.

     As Acting Director of Engineering at JSC, Nicholson will be responsible
for managing the work of eight functional divisions and providing support to
program and project offices for current and future space flight programs
assigned to JSC, including the Shuttle and space station.  JSC's Engineering
Directorate also performs complete in-house design, development and testing of
certain Government-furnished equipment and maintains expertise in test
facilities and computational complexes.

     JSC Flight Crew Operations Director David Leestma has appointed Astronaut
Linda Godwin, Ph.D. to replace Col. Loren Shriver as Deputy Chief of the
Astronaut Office. Shriver is being reassigned to the Space Shuttle Program
Office to assist in the management of this program.

     "I'm very pleased to make these appointments" said Pearson. "These are
extremely talented individuals whose knowledge and experience in space flight
make them excellent choices for these key positions."

     Nicholson, Shaw and Shriver are expected to assume their new duties
following Shuttle Mission STS-57, in late April. Pohl will assume his new
duties immediately and Deputy Engineering Director Max Engert will manage
day-to-day operations of the organization until Nicholson is free to take over.
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
=--=--=-END-=--=--=

=--=--=START=--=--= NASA Spacelink File Name:930319.SHU

KSC SHUTTLE STATUS 3/19/93


            SPACE SHUTTLE DAILY STATUS-STS 55
                  Friday, March 19, 1993


George H. Diller
Kennedy Space Center



Vehicle: OV-102/Orbiter Columbia    Mission: STS-55
Current location: Pad 39-A          Orbital altitude: 184 sm
Payload: Spacelab D-2               Inclination: 28.45 degrees
Launch date: March 22  9:51 a.m.    Landing: KSC 3/31
Mission duration: 8 days 22 hours   Crew size: 7


STS-55 IN WORK:

- installation of aft compartment flight doors
- aft compartment confidence test
- aft compartment positive pressure leak check
- checkout of flight controls


STS-55 WORK SCHEDULED:

- pyrotechnic initiatior checks 8 a.m. Saturday
- load cryogenics reactants starting Saturday at 12 Noon


STS-55 WORK COMPLETED:

- aft compartment closeouts complete
- checkout of navigational aids complete


SPECIAL TOPICS: (STS-55)

     The launch of Columbia was postponed 24 hours after a planned launch of an
Air Force Delta II rocket at Complex 17 was scrubbed due to high winds.  The
countdown clock at Complex 39 is currently in a 24-hour hold at T-35 hours and
will resume counting at midnight tonight.  The launch window on Monday opens at
9:51 a.m.  EST. A second launch opportunity is available on Tuesday if
necessary.



Predicted weather conditions at 9:51 a.m. on Monday:

Clouds:  3,000 scattered cumulus/stratocumuls  50% sky coverage
        10,000 scattered altocumulus  50% sky coverage
        25,000 broken cirrostratus  65% sky coverage

Temperature:  73 degrees
Relative Humidity: 68%
Winds: SE/12-20 knots
Visibility: 7+ miles

Probablity of violating tanking constraints: 0%
Chance of meeting launch weather criteria:  70%
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
=--=--=-END-=--=--=

=--=--=START=--=--= NASA Spacelink File Name:6_2_2_43_10.TXT

STS 55 COLUMBIA/SPACELAB D-2 PROCESSING HISTORY

George H. Diller                               March 19, 1993
Kennedy Space Center


KSC Release No. 26-93



     Processing of the Space Shuttle Columbia began after the KSC landing of
Columbia's previous mission, STS-52. The orbiter was towed to bay 2 of the
Orbiter Processing Facility (OPF) on Nov. 1, 1992 for deservicing and
preparations to reconfigure its payload bay for the STS-55 mission.

     The Spacelab D-2 experiments arrived at KSC in July 1992 to begin
integration into the Spacelab racks.  Installation of the racks into the
laboratory module followed in September. The Mission Sequence Test which
replicates the mission activities, including flight crew participation, was run
last November.

     The Spacelab D-2 laboratory module was installed into the payload bay of
Columbia on Jan. 11, 1993 while the orbiter was in the OPF. An Interface
Verification Test (IVT) between the Spacelab and Columbia was conducted on Jan.
16 to verify all connections.

     Meanwhile, in the Vehicle Assembly Building (VAB), build-up of the solid
rocket boosters on mobile launcher platform 3 occurred in November and December
of last year.  The external tank arrived at KSC by barge on Sep. 29, 1992, and
was transferred to a test cell in the VAB for checkout and final preparations.
It was mated to the solid rocket booster stack on Jan. 12, 1993.  The external
tank/solid rocket booster stack was fully assembled and tested by Jan. 12.



     After 77 work days in the OPF, Columbia was transported to the VAB on Feb.
2 and mated to the awaiting external tank/solid rocket booster stack.  The
two-day Shuttle Interface Test to verify vehicle connections began on Feb. 5.
Rollout of the Space Shuttle Columbia from high bay 3 of the VAB to Launch Pad
39-A occurred on Feb. 7.

     During launch preparations at the pad, a question arose as to whether the
correct set of turbine blade tip seal retainers had been installed inside main
engine liquid oxygen high pressure turbopumps.  As a result, a precautionary
decision was made to replace these pumps.  On Feb. 14 work began to changeout
the turbopumps from each of the three main engines and installation was
completed by Feb. 25.

     Another unplanned event at the pad involved a ruptured hydraulic line in
the aft main engine compartment.  This occurred on March 2 during the Flight
Readiness Test and a decision was made to remove and inspect all 12 hydraulic
lines in the aft.  Nine lines were re-installed in addition to three
precautionary new lines.  This work was finished on March 9, and the Flight
Readiness Test was completed on March 10.

     As of March 21, a total of 41 work days will have been spent at the launch
pad creating 123-work-day flow for STS-55 processing activities.
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
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=--=--=START=--=--= NASA Spacelink File Name:6_2_2_43_8.TXT

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STS-55 TV SCHEDULE REV
STS-55 TV SCHEDULE A

     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
=--=--=-END-=--=--=

=--=--=START=--=--= NASA Spacelink File Name:6_2_2_43_9.TXT

STS-55 COUNTDOWN EVENTS SUMMARY


SPACELINK NOTE:  The launch has been postponed until Monday, March 22, 1993.


Mitch Varnes                               March 18, 1993
Kennedy Space Center



KSC Release No. 27-93


STS-55 LAUNCH COUNTDOWN TO BEGIN AT 4 P.M. EST TODAY


The countdown clock for the STS-55 flight of the Space Shuttle Columbia is
scheduled to begin at 4 p.m. (EST) today at the T-43 hour mark.  The countdown
includes 24 hours and 52 minutes of built-in hold time leading up to the
opening of the launch window at 9:52 a.m. (EST) on Sunday, March 21.

At the start of the countdown, the launch team in firing room 1 of the Launch
Control Center will verify that the Shuttle vehicle is powered up and that the
data processing system and backup flight control system are operating.  Flight
software stored in the orbiter's twin memory banks will be reviewed, computer
controlled display systems will be activated, and the backup flight system
general purpose computer will be loaded.

Preparations also start at the liquid oxygen and liquid hydrogen storage farms
for loading the external tank with super cold, or cryogenic, propellants.
Orbiter navigation aids are turned on and tested, and the inertial measurement
units are activated.

In parallel with these activities, the launch team prepares for loading
Columbia's onboard fuel cell storage tanks with liquid oxygen and liquid
hydrogen reactants.  Also performed at the start of the countdown is the final
stowage, microbial sampling and water level adjustment of the crew waste
management system.

At T-27 hours, the countdown will enter its first built-in hold.  This 4-hour
hold extends from 8 a.m. until noon on Friday, March 19.  When the countdown
resumes, the launch pad will be cleared of all personnel in preparation for
loading the onboard fuel cell storage tanks.

Servicing of the liquid oxygen and liquid hydrogen fuel cell supply tanks is
scheduled to start at the T-25 hour mark.  Servicing activities take
approximately five hours.

When servicing of the fuel cell tanks has been completed, the pad will be
reopened for normal work.  Shortly thereafter, the countdown will enter the
second planned hold.  During this fourhour hold at the T-19 hour mark, the
orbiter mid-body umbilical unit used to load the super cold fuel cell reactants
into the orbiter will be demated.  This hold will extend from 8 p.m. until
midnight on Friday, March 19.

When the countdown resumes, technicians will complete final vehicle and
facility closeouts and begin activating the orbiter's communications systems
and configuring Columbia's cockpit for flight.  The main propulsion system and
shuttle main engines will also be readied for cryogenic loading.

The orbiter's flight control system navigation aids and communications systems
will be activated and switches in the cockpit will be configured for loading of
the external tank.  The stowable mission specialist seats will be installed in
the flight deck and along the middeck.

The countdown will enter the next built-in hold at T-11 hours at 8 a.m. on
Saturday, March 20.  During this hold, time critical equipment will be
installed in the orbiter's cockpit and the inertial measurement units will be
activated and warmed up.  At about 11 a.m., the rotating service structure will
be moved away from the vehicle to the launch position.  This hold is scheduled
to last 11 hours and 32 minutes, or until 7:32 p.m. on Saturday.

At T-9 hours, the onboard fuel cells will be activated and the launch team will
begin evacuating the blast danger area at T-8 hours, or about 8:32 p.m. on
Saturday. At this time, final stowage of items into the crew module will occur
and the joint heaters on the solid rocket boosters will be activated.  At T-7
hours, 30 minutes, the flow of conditioned air through the orbiter's payload
bay will be switched to gaseous nitrogen in preparation for loading the
external tank with super-cold liquid propellants.

The inertial measurement units will transition from the warm up stage to the
operate/attitude determination mode at T-6 hours and 45 minutes.  At T-6 hours,
a steering check of the orbital maneuvering system engines will be performed.


The countdown will enter another planned built-in hold at the T-6 hour mark at
approximately 12:32 a.m. on Sunday. During this one-hour hold, final
preparations for loading the external tank will be completed and a pre-tanking
weather briefing will be conducted.

Chilldown of the main propulsion system and loading of cryogenic propellants
into the external tank will commence at the T-6 hour and counting mark at 1:32
a.m.  Sunday. This fueling operation will be concluded by 4:32 a.m., at the
start of the T-3 hour hold.

The T-3 hour hold is two hours in duration.  During this time, the ice
inspection team will perform a survey of the tank's outer insulation and the
closeout crew will begin configuring the crew module and white room for the
flight crew's arrival.  Liquid oxygen and liquid hydrogen will be in a stable
replenish mode during this time to replace the propellant that "boils" off.

The astronauts are scheduled to be awakened at 4:42 a.m. on Sunday.  Their
pre-flight meal is scheduled at 5:12 a.m.

After completing their meals, the crew will receive a briefing on weather
conditions at the Kennedy Space Center and at the contingency Shuttle landing
sites.

The astronauts will be outfitted in their partial pressure suits before leaving
the Operations and Checkout Building at about 6:37 a.m.  They will arrive at
Launch Pad 39-A's white room at about 7:07 a.m.  At the launch pad, closeout
personnel will assist the crew with their entry into Columbia.

Just prior to the T-1 hour mark, the test team and the flight crew will get
another weather update, including observations from astronaut Hoot Gibson, who
will be at KSC and flying in a Shuttle Training Aircraft.

The last two built-in holds will be 10 minutes in duration and will occur at
the T-20 minute mark or at 9:12 a.m. and at the T-9 minute mark or at 9:33 a.m.
During the final hold, readiness polls are taken by the NASA test director, the
Shuttle launch director and the Mission Management Team chairman.  A final "go
for launch" will be given upon the successful completion of these pre-launch
polls.

Milestones after the T-9 minute mark include start of the ground launch
sequencer at T-9 minutes and counting; retraction of the orbiter access arm at
T-7 minutes, 30 seconds; start of the orbiter's auxiliary power units at T-5
minutes; pressurization of the liquid oxygen tank at T-2 minutes, 55 seconds;
pressurization of the liquid hydrogen tank at T-1 minute, 57 seconds; and the
electronic "go" to Columbia's onboard computers to start their own terminal
countdown sequence at T-31 seconds.  A "go for main engine start" will be given
at about T-10 seconds, and Columbia's three main engines will start at T-6.6
seconds.  Solid rocket ignition and lift-off occurs at T-0.








COUNTDOWN MILESTONES

Launch - 3 Days (Thursday, March 18)

Perform the call-to-stations at T-43 hours.  Begin check out of the backup
flight system and review flight software stored in mass memory units and
display sytems.  Load backup flight system software into the orbiter's fifth
general purpose computer.

     Begin stowage of flight crew equipment.  Inspect the orbiter's mid and
flight decks and remove crew module platforms.  Start external tank loading
preparations.


Launch - 2 Days (Friday, March 19)

     Enter first planned built-in hold at T-27 hours for a duration of 4
hours.  Activate orbiter's navigation system.

     Resume countdown.  Start preparations for servicing fuel cell storage
tanks and begin final vehicle and facility closeouts for launch.

     Clear launch pad of all personnel and load liquid oxygen and liquid
hydrogen reactants into the orbiter's fuel cell storage tanks.

     Enter second planned built-in hold at T-19 hours for four hours.



       After the loading operation, the pad will be reopened for normal work
and orbiter and ground support equipment closeouts will resume.

      Demate orbiter mid-body umbilical unit used during fuel cell loading.
Resume countdown.  Activate orbiter communications systems and prepare Shuttle
main engines for propellant tanking and flight.


Launch - 1 Day (Saturday, March 20)

      Install mission specialist seats in crew cabin.  The tail service masts
on the mobile launcher platform will be closed out for launch.


     Enter planned hold at T-11 hours (5 a.m.) for a duration of 13 hours and
32 minutes.


     During this hold, the orbiter's inertial measurement units will be
activated and kept in the "warm up" mode and film will be installed in the
numerous cameras on the launch pad.  In addition, safety personnel will conduct
a debris walkdown and the pad sound suppression system water tank will be
filled.

     The rotating service structure will be moved to the park position during
this hold at 11 a.m.  Perform orbiter ascent switch list in crew cabin.

      Resume countdown at 6:32 p.m.  Install time critical flight crew
equipment and perform the pre-ingress switch list.  Start fuel cell
flow-through purge.

     Activate orbiter fuel cells.  Configure communications at Mission Control
in Houston for launch.  Clear the blast danger area of all non-essential
personnel and switch orbiter purge air to gaseous nitrogen.

     Enter one-hour planned built-in hold at T-6 hours (11:32 p.m.).


               Launch Day (Sunday, March 21)

     Resume countdown.  Launch team verifies there are no viola- tions of
launch commit criteria prior to cryogenic loading of the external tank.  Start
loading the external tank with cryogenic propellants.



     Complete filling the external tank with its flight load of liquid hydrogen
and liquid oxygen propellants.  Perform open loop test with range safety and
conduct gimbal profile checks of orbi- tal maneuvering system engines.

     Perform inertial measurement unit preflight calibration and align Merritt
Island Launch Area (MILA) tracking antennas.


     Enter two hour hold at T-3 hours.  Closeout crew and ice in- spection team
proceeds to launch pad.

     Resume countdown at T-3 hours (5:32 a.m.) Complete closeout preparations
in the white room and cockpit switch configurations.  Crew departs astronaut
quarters at Operations and Checkout Build- ing for the pad.



     Flight crew enters orbiter.  Astronauts perform air-to-ground voice checks
with Mission Control in Houston. Close orbiter crew hatch.  Begin range safety
final network open loop command check, perform hatch seal and cabin leak
checks, begin the inertial measurement unit preflight alignment and range
safety closed loop test.  The white room is closed out and the closeout crew
moves to fallback area.  Primary ascent guidance data is transferred to the
backup flight system.

     Enter planned 10-minute hold at T-20 minutes.

     Resume countdown.  Transition orbiter onboard computers to launch
configuration and start fuel cell thermal conditioning.  Close orbiter cabin
vent valves.  Backup flight system transitions to launch configuration.


     Enter planned 10 minute hold at T-9 minutes.


     Resume countdown.



Start automatic ground launch sequencer (T-9 minutes).
Retract orbiter crew access arm (T-7:30).
Start mission recorders (T-5:30).
Start APU's. Arm SRB and ET range safety safe/arm devices (T-5).
Start liquid oxygen drainback (T-4:55).
Start orbiter aerosurface profile test (T-3:55).
Orbiter transfers to internal power (T-3:30).
Start MPS gimbal profile test (T-3:30).
Pressurize liquid oxygen (LO2) tank (T-2:55)
Retract gaseous oxygen vent arm (T-2:55).
Fuel cells to internal reactants (T-2:35).
Pressurize liquid hydrogen (LH2) tank (T-1:57).
Deactivate SRB joint heaters (T-1:00).
LPS go for start of orbiter automatic sequence (T-0:31 seconds).
Start SRB gimbal profile test (T-0:6.6).
SRB ignition and liftoff (T-0).
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
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=--=--=START=--=--= NASA Spacelink File Name:6_8_3_4_58.TXT

MAGELLAN STATUS 3/19/93

Magellan Status


Status Report of Magellan for Friday, March 19, 1993:

1.  The Magellan spacecraft is operating normally, performing a desat on every
orbit and a starcal every other orbit.  The High Gain Antenna is kept pointed
toward Earth (except during the starcal) in order to acquire gravity data,
especially around periapsis.  Engineering telemetry is being received at 1200
bps.

2.  The Magellan Project continues to implement the plan to collocate 50 MESUR
members on the second floor of Bldg. 230, while minimizing impact to MGN
preparations for TEX and LMGT. About half of the offices being vacated by MGN
team members have been cleared, and the remaining moves will be complete by
March 31st.  Significant amounts of excess paper have been eliminated, and
unneeded equipment has been surplused.

3.  Several members of the Magellan science team were in Houston, Texas, this
week for the Lunar and Planetary Science Conference. An Exhibit of Magellan
results was presented, as well as technical papers.

4.  Magellan completed its 7000 orbit of Venus shortly before midnight (PST) on
Tuesday, We are now 67 days from the end of Cycle-4 and the start of the
Transition Experiment.
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
=--=--=-END-=--=--=