STS-94 Day 13 Highlights
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- On Sunday, July 13, 1997, 7:15 a.m. CDT, STS-94 MCC Status Report # 24
- Three fourths of the way through its 23rd voyage in space, Shuttle
Columbia continues to perform near flawlessly while payload
controllers collect volumes of data from experiments being conducted
by the seven astronauts on the Microgravity Science Laboratory
- Commander Jim Halsell, Pilot Susan Still, Mission Specialist Don
Thomas and Payload Specialist Greg Linteris are on duty throughout the
morning and early afternoon overseeing orbiter systems and science
investigations while the remaining three crew members - Payload
Commander Janice Voss, Mission Specialist Mike Gernhardt and Payload
Specialist Roger Crouch rest.
- The Combustion Module continues to be the focus of attention as the
astronauts and investigators research methods that could improve
fire-fighting techniques on Earth as well as improve the operation and
efficiency of combustion engines while reducing air pollution.
- Halsell, Still Thomas and Linteris were interviewed by the ABC Radio
Network just before 7 a.m. today discussing these and other mission
- Voss, Gernhardt and Crouch have begun shifting their sleep schedules
slightly later each day to prepare for Thursday's planned landing back
at the Kennedy Space Center.in Florida. After handing control of the
flight over to Halsell and the Red team about 1:30 this morning, the
Blue team turned in for an eight hour sleep period set to end with
wakeup at about 12:30 this afternoon.
- On Sunday, July 13, 1997, 8:00 a.m. CDT, STS-94 Payload Status Report # 20
reports: (MET 11/18:58)
- During the past 24 hours, researchers aboard Columbia have gained
yet a better understanding of what makes certain types of heat
transfer devices fail in space. They also pushed the envelope of
knowledge of combustion by setting a fire at the lowest atmospheric
pressure yet this mission and "giving birth to twin droplets of flame
in an unplanned experiment. Meanwhile, researchers in the Spacelab
Mission Operations Control set an all-time record for the number of
commands issued to experiments aboard a Spacelab mission.
- At 5:25 p.m. CDT Saturday night, the 25,838th science command was
sent to the shuttle breaking a 1994 record and demonstrating the high
pace of research activities aboard Columbia.
- Saturday morning, Payload Specialist Dr. Gregory Linteris resumed
work on the Droplet Combustion Experiment, burning a drop of heptane
fuel at one-quarter of the atmospheric pressure on Earth. It left
- "It was a superior burn," said Dr. Fred Dryer of Princeton
University in Princeton, N.J.. "This is the first time we've been
successful with a quarter-atmosphere burn. It is the most difficult
condition (to achieve a burn) -- the lowest pressure of this kind that
we've been trying to obtain science for. It's always hard to do
science at extremities. It was very gratifying."
- So successful was the experiment run that two additional tests were
dropped from the schedule. "The one run defined all the science we
needed," said Dryer. "Additional experiments this morning just are not
necessary. We will conserve fuel for future runs."
- The Droplet Combustion Experiment is providing researchers with
fundamental knowledge of the burning process and may provide a method
for verifying which complex, chemical model accurately describes the
process. It may also lead to cleaner and safer ways to burn fuels.
- Later Saturday, Mission Specialist Janice Voss again set up the
Droplet Combustion Experiment for three more runs. Igniting a
3-millimeter fuel droplet in the chamber filled with normal air.
- "On the ground, there have been a lot of studies on heptane. But
all have been less than 2 millimeters in diameter," said the study's
lead investigator, Dr. Forman Williams of the University of California
at San Diego. "This is the first complete burn of a 3-millimeter
diameter heptane droplet." Forman was also excited "because in the
atmosphere of normal air, we were able to observe a fuel droplet that
burns for a longer period of time." Additionally, as a fuel droplet
burned in a spherical shape, the heat dissipated outward, and actually
extinguished the flame before all the fuel vapor was completely burned
away. This gave researchers a very pure look at the combustion
- Also Saturday, Mission Specialist Dr. Donald Thomas began what would
be eight hours of highly successful combustion tests in the Middeck
Glovebox -- a facility that allows the crew to handle, transfer and
manipulate experiment hardware and materials not approved for use in
the open Spacelab. The Spacelab crew has now performed more than 100
tests runs in the Glovebox -- twice as many as expected.
- In a novel twist to this experiment, scientists decided to run a
test using two droplets instead of one. This provided a bonus to
researchers as they observed the interaction of the
droplets. Dr. Williams, the experiment's principal investigator,
called the view of the two droplets "the most beautiful set of twins
I've ever seen." Information from the study is expected to help
improve theoretical models of combustion.
- Saturday evening and Sunday morning, Mission Specialist Voss set up
the flame ball -- or Structure of Flame Balls at Low Lewis-number --
experiment for another series of test in the Combustion Module. She
used a fuel mixture of hydrogen, oxygen and sulfur hexafluoride at one
atmospheric pressure. Voss sparked the fuel mixture in the test
chamber, producing a burning ball of flame. Upon a reburn attempt,
another flame ball was ignited.
- The flame ball study, lead by Dr. Paul Ronney of the University of
Southern California in Los Angeles, is designed to show under what
conditions a stable flame ball can exist and if heat loss is
responsible for the stabilization of the flame ball during burning.
The experiment also examines how various mixture properties, such as
fuel/oxidizer concentrations and temperature, affect the flame-ball's
stability and existence.
- Ronney said that from this experiment, "we can learn the burning
limits of fuel mixtures. It gives us an idea of just how lean a fuel
can be -- and still burn." He said the results of this experiment may
lead to leaner-burning fuel on Earth. "That would mean better gas
mileage and less auto emissions," said Ronney. Other benefits include
improved fire safety for future spacecraft.
- Saturday afternoon, Payload Specialist Dr. Roger Crouch set up the
Capillary-driven Heat Transfer Device in the Middeck Glovebox. The
study examines the device's ability to transfer heat away from a
particular location. In the future, these devices may be used to
transfer heat from electrical equipment to radiators on spacecraft.
The benefits of these systems are that they weigh less than
conventional units because they operate on evaporation and
condensation, and are more economical because they do not require
power. This study has already provided insight into how these devices
work and is offering explanations as to why they occasionally fail in
- The experiment's lead investigator, Dr. Kevin Hallinan of the
University of Dayton, Ohio, said, "As a result of today's tests, we've
been able to characterize boundaries of what we call unstable
operations which accelerates this transition to this failed -- or
- "We've seen the same failure mechanism that we've also seen
previously. But today we were able to characterize the conditions
that cause a violent instability in the evaporator portion of the
device. This instability immediately causes the entire device to
fail. So we now effectively understand another 'failure mechanism'
and are closer to our goal of understanding why the Capillary-driven
Heat Transfer devices have failed in space yet succeed in 1-G (on the
ground). We are confident new designs can be rendered that will
- Coming up later today, Payload Specialist Dr. Gregory Linteris will
continue combustion test runs -- observing the structure of flame
balls -- as other members of Columbia's crew start the Coarsening in
Solid-Liquid Mixtures experiment. The goal of this investigation is
to examine the solidification process for the development of stronger
alloys and new manufacturing processes.
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