STS-75 Day 2 Highlights
Back to STS-75 Flight Day 01 Highlights:
- On Friday, February 23, 1996, 7 a.m. CST, STS-75 MCC Status Report # 02
- Setting up shop was the order of business aboard Columbia overnight
and early Friday as the seven astronauts split into three shifts to
support the many experiments scheduled throughout the 14-day mission.
- Much of the astronauts' time was spent verifying the health of the
Tethered Satellite System in anticipation of its scheduled deployment
Saturday afternoon. The 1,400 pound satellite will be deployed to a
distance of almost 13 miles while it remains attached to its support
structure in the orbiter's payload bay by a pencil-thin cable. TSS
deployment is currently scheduled for Saturday at 2:37 p.m. Central
- Before turning in for his first on-orbit sleep period, Mission
Specialist Jeff Hoffman tested the latching mechanisms that secure the
satellite atop its docking ring on an extendable boom structure.
These latches will be released just prior to the start of the six hour
process to reel out the satellite.
- The crew also checked out and activated several other experiments that
will be carried out after the Tethered Satellite is retrieved Monday.
A glovebox device on the middeck was set up and will be used later in
the flight to conduct combustion experiments in an enclosed
- The astronauts also activated the Commercial Protein Crystal Growth
experiment designed to grow nearly perfect crystals for study back on
Earth for the possible development of better pharmaceuticals.
- Columbia will remain in a near circular 160 nautical mile orbit for
most of the mission, circling the Earth every 90 minutes to provide
the crew with views of a sunrise and sunset 16 times each day.
- On Friday, February 23, 1996, 6 a.m. CST, STS-75 Payload Status Report # 01
reports: (0/15:42 MET)
- Mission Specialist Claude Nicollier, Payload Commander Franklin
Chang-Diaz and Payload Specialist Umberto Guidoni started their duty
shifts by activating the Shuttle Electrodynamic Tether System (SETS),
the Deployer Core Equipment (DCORE), the Tethered Satellite System
(TSS) carriers and the TSS deployer. The SETS investigation, by
Dr. Brian Gilchrist of the University of Michigan, will study the
electrical characteristics of the Tethered Satellite System and also
will explore the use of space tethers as science tools. The Core
experiment, by Dr. Carlo Bonifazi of the Italian Space Agency, will
demonstrate the ability of a tethered system to produce electricity.
- In addition to increasing understanding of physical processes in the
near-Earth space environment, these studies will help provide
explanations for events witnessed elsewhere in the solar system, such
as the formation of comet tails and the bursts of radio "noise"
detected from Jupiter. Tether science research will allow scientists
to conduct unique, new types of electrical experiments and to develop
new and promising tether applications in space technology.
- Mission Specialist Jeffrey Hoffman then tested the Tethered
Satellite System reel motor assembly and the Satellite restraint
latches. These latches, which worked very well, will release the
Tethered Satellite on Saturday, allowing the satellite to be reeled
out to its maximum deployment of twelve miles (20.7 kilometers),
making the Tethered Satellite-Shuttle system the longest electrically
conductive object ever flown in space.
- Nicollier and Chang-Diaz also checked out the Tether Optical
Phenomena (TOP) experiment and the computers associated with
deployment of the Tethered Satellite. The experiment, conducted by
Dr. Stephen Mende of Lockheed Martin, will provide visual data that
will aid scientists in answering a variety of questions concerning the
Tethered Satellite's objectives during its flight in Earth orbit.
- The Marshall-managed Tethered Satellite System Reflight (TSS- 1R)
mission is a reflight of the Tethered Satellite System (TSS-1), which
was flown on the Space Shuttle in July/August 1992. Building on the
knowledge gained on the first Tethered Satellite mission about tether
motions, the Tethered Satellite System will circle the Earth, placing
the tether well within the electrically charged layer of the
atmosphere known as the ionosphere. There, a satellite attached to
Columbia by a thin conducting tether will be deployed into the
ionosphere from the Shuttle payload bay, providing scientists with
unique experimental opportunities.
- The United States Microgravity Payload (USMP-3), also managed by the
Marshall Space Flight Center, soon will have completed its first 24
hours in orbit, nestled safely within the confines of the Shuttle
Columbia's cargo bay. Mission Specialist Maurizio Cheli activated the
payload's support equipment, and Chang-Diaz turned on the experiments
in the cargo bay.
- Following the successful power-up of the experiments onboard,
science teams located at Marshall's Spacelab Mission Operations
Control Center began remotely monitoring and interacting with the
Microgravity Payload. The USMP-3 experiments are designed to increase
scientists' understanding of materials science and condensed matter
physics. These experiments include the MEPHISTO directional
solidification furnace, the Advanced Automated Directional
Solidification Furnace (AADSF), the Isothermal Dendritic Growth
Experiment (IDGE) and the Critical Fluid Light Scattering Experiment,
- Working in Columbia's cabin, Chang-Diaz examined the Middeck
Glovebox Facility while Nicollier activated the Commercial Protein
Crystal Growth experiment. The glovebox, managed by the Marshall
Space Flight Center, is a contained work area where crew members will
conduct three combustion investigations that would be impractical and
potentially hazardous if performed outside the glovebox in the open
cabin environment. These experiments include the Forced-Flow
Flamespreading Test and Comparative Soot Dynamics, developed by Kurt
R. Sacksteder and Dr. David L. Urban, both of the Lewis Research
Center, and the Radiative Ignition and Transition to Spread
Investigation, developed by Dr. Takashi Kashiwagi of the National
Institute for Standards and Testing. The Protein Crystal Growth
investigation will process nine different proteins for the development
of new therapeutic treatments for infections, human cancers, hormone
disorders and Chagas disease.
- On Friday, February 23, 1996, 4:30 p.m. CST, STS-75 MCC Status Report # 03
- Although running into tethered satellite computer problems that
remain under investigation by flight controllers and scientists,
Columbia's crew pressed ahead this afternoon with checkouts and
preparations for a Saturday deploy of the satellite.
- The tethered satellite itself was powered up and appears to be in
excellent condition. However, activation and checkout of the
satellite-related experiments that are mounted in Columbia's cargo
bay fell behind schedule when a computer relay for data and commands
experienced problems. The Smart Flexible Multiplexer Demultiplexer
(SFMDM), or "Smartflex", as the computer relay is called, was
switched to a backup component after experiencing an apparent overload
when some of the cargo bay experiments were first powered up.
- The backup "Smartflex" equipment is working well, but controllers are
evaluating its performance for several hours before attempting to
repower the cargo bay-mounted satellite experiments and put further
demands on the unit. At this point, there is still enough time prior
to Saturday's planned 2:37 p.m. satellite deploy to reactivate
those experiments and perform all needed checkouts and fine-tuning.
Flight controllers currently plan to begin those procedures this
evening aiming toward an on-time satellite flyaway.
- In addition to the computer relay trouble, the crew reported apparent
balky processing by an onboard laptop computer used as one method of
displaying information from the satellite experiments. The Portable
General Purpose Support Computer (PGSC) was switched for a backup
laptop computer by the crew, and the data connections to the computer
ports also were switched to backup ports. However, the apparent slow
processing persisted. Flight controllers are evaluating the cause of
the trouble, and any impact it may have on the planned operations.
- The "Smartflex" must be operating for a deploy of the tethered
satellite since it provides data and commands to the satellite-related
experiments and equipment in the cargo bay. Communications and
commanding of the satellite itself during deploy, however, is done by
a radio link to Columbia.
- On Friday, February 23, 1996, 6 p.m. CST, STS-75 Payload Status Report # 02
reports: (01/03:42 MET)
- At the end of the first flight day, STS-75 crew members aboard the
Space Shuttle Columbia were continuing predeployment checkout and
activation of the Tethered Satellite System (TSS), a cooperative
venture between NASA and the Italian Space Agency. The satellite,
attached to the Shuttle by a pencil-thin tether, is being readied for
deployment to a distance some 12.5 miles (20.7 kilometers) above the
orbiter. This upward deployment, planned for Saturday afternoon, will
begin a series of electrodynamic investigations using the
Shuttle-tether-satellite system as it moves at 17,000 miles per hour
through Earth's magnetic field lines to produce electrical current and
- Crew members methodically stepped through detailed troubleshooting
procedures for three of 18 TSS on-board computers. The smart flexible
multiplexer/demultiplexer or relaying computer, called "smartflex,"
which sends crew commands to the tethered satellite and collects some
science data, experienced timing errors, causing it to automatically
switch over to its backup system. The backup system appears to be
operating well and the timing errors of the smartflex computer are
continuing to be investigated.
- Payload Specialist Dr. Umberto Guidoni and Mission Specialist Jeff
Hoffman changed out the Data Display and Control System (DDCS), a
laptop computer that graphically displays TSS data, because it was
operating at a low performance level. The backup computer was
successfully booted, but readings showed that it also was operating
sluggishly. Since the smartflex and DDCS computers are linked, flight
controllers are checking to see if these problems may be related.
- When activated, the data acquisition and control assembly computer
that monitors various TSS parameters gave normal readings except for
tether length. A reading of 76 feet (23 meters) was shown when it
should have been zero. The system was later reset to zero and the
computer responded correctly. This reading will be rechecked after
the boom on which the satellite is mounted is extended in preparation
- Meanwhile, Payload Commander Franklin Chang-Diaz continued science
activation procedures in an effort to keep the satellite deployment
timeline on track. Science activities completed to this point include
activation of the Shuttle Electrodynamic Tether System ion and
electron sensors, as well as activation and checkout of the TSS
Deployer Core Equipment and Satellite Core Equipment hardware,
including the electron guns used to eject the tether current back into
the ionosphere at the orbiter. Also, activation and checkout of the
satellite and its three investigations were completed. These include:
Research on Electrodynamic Tether Effects, which measures electric
fields; Research on Orbital Plasma Electrodynamics, which measures
ions and electrons; and Magnetic Field Experiment for TSS Missions,
which measures magnetic fields. Baseline data were collected both
about the charged particle environment of Columbia's cargo bay, as
well as the effect of dynamic "noise" produced by activities such as
thruster firings and water dumps to see how these vibrations are read
by the satellite's sensors.
- One of the unique features of this complex research flight is that
the seven-member international crew is working in three staggered
shifts instead of the normal two. This allows the crew to operate a
suite of instruments designed to gather real-world information about
how conducting tethers might be used to generate electrical power for
spacecraft and to learn to control tethers in space. Ground-based
researchers stationed at Spacelab Mission Operations Control also hope
to validate theories that could lead to numerous future applications
of tethers in space. Such possibilities range from positioning
scientific research platforms downward into regions of Earth's
atmosphere that are too high for science balloons and too low for
remote sensing satellites, and to use the force created by current
flow in a tether to reboost spacecraft as their orbit decays due to
atmospheric drag, thereby saving fuel.
- Another unique feature of the tethered satellite mission is that the
science investigations all work together to give researchers an
integrated picture of system performance and to characterize the
charged particle environment in and around the Shuttle orbiter, which
acts as an integral part of the overall tethered system. The tethered
satellite is coated with an electrically conducting paint. The tether
that secures it to Columbia's cargo bay has a copper core and is
covered by Teflon and Kevlar, the material used in bullet- proof
vests, to shield the tether from the harsh space environment.
Scientific instruments are housed in the upper half of the satellite,
and on the Mission Peculiar Equipment Support Structure that is
attached to the Spacelab platform in the cargo bay. Three ground
tracking stations located along the Shuttle's flight path will collect
additional science data during the tether mission.
- Meanwhile, data is being received by experiments that make up the
third United States Microgravity Payload (USMP-3), awaiting its turn
as the primary payload after TSS operations are completed. In fact,
"the best images ever sent down" of dendrites were reported by Dr.
Martin Glicksman, principal investigator of the Isothermal Dendritic
Growth Experiment (IDGE). Dendrites are microscopic tree-like
structures formed by molten materials as they solidify into the
familiar materials used for everyday products ranging from aluminum
cans to airplane turbine blades.
- Overnight, crew members will continue activating and calibrating TSS
systems and experiments, and making other preparations for tomorrow's
satellite deployment and the beginning of 20 hours of science data
Go to STS-75 Flight Day 3 Highlights: