ISS Science Operations Weekly Status Report 30 Jan 2002
Operations continued on the slow fractal sample initiated earlier this month
by the Experiment on Physics of Colloids in Space (EXPPCS) science team.
The first attempt at mixing a colloid with a salt to initiate fractal gel growth
began Jan. 16. Although all mechanical components worked properly, a tiny rubber
valve that had been clamped closed failed to unseal after unclamping during
the mixing operation. A second mix of the salt with the colloid was successful
and clustering of the colloids was immediately detected. The clumping of the
colloids to form a gel is continuing normally, the science team reported. The
team completed a 12-hour run on Sunday and a 24-hour run on Tuesday. The next
test is scheduled for Friday, Feb. 1. Scientists hope the fractal network will
eventually span the entire sample cell to form a gel as they continue to record
the process.
Fractal research is expected to continue for eight weeks. A fractal is something
that appears to have the same structure under different degrees of magnification.
One example is the coastline of a continent. Maps showing 25 miles or 250 miles
of coastline will appear somewhat similar in the apparent amount of roughness.
Scientists are interested in studying the fractal structure of this colloid
gel, which is 99.992 percent water and only 0.008 percent colloid. Among their
questions is whether something with so little material will be able to form
a gel. They are also studying aging of the gel.
Fractal gels are of interest to manufacturers and materials specialists on
Earth. A primary mechanism for degradation of motor oil is the formation of
fractal clusters of soot. Another example is the aging and spoilage of food.
Fractal gels are also found in a specialized material known as aerogel, which
is only 0.5 percent solid and possibly the best thermal insulator known. EXPPCS
is managed by NASA’s Glenn Research Center in Cleveland. The principal investigator
is David Weitz of Harvard University.
“The fundamentals of fractal structures are well understood, but the
applications of these amazingly low density materials is poorly understood
and relatively untapped,” said Art Bailey, senior scientist with the
colloids experiment with Harvard University. “The research we are conducting
to explore the limits of fractal behavior will play a role in the expanding
the areas of application beyond petrochemicals and food.”
Astronauts Dan Bursch and Carl Walz on Saturday, Jan. 26, tested themselves
with a lung function experiment called Pulmonary Function in Flight (PuFF).
PuFF studies possible changes in lung function due to microgravity inside the
Space Station, as well as the low pressure environment of the space suits used
aboard the Station. The test followed Bursch’s spacewalk last Friday and served
as Walz’s regular monthly test.
On Tuesday, Jan. 29, the crew collected background radiation readings of the
radiation badges with the EVA Radiation Monitoring (EVARM) experiment.
The badges are stowed in pockets in astronauts’ cooling undergarments to measure
radiation dosages at specific areas of the body. Bursch on Tuesday also logged
in diet and other data for the Renal Stone experiment, which is testing
a possible preventative for kidney stone formation in space. He and Walz are
performing the second session of the experiment this week.
The Active Rack Isolation (ARIS) team is working to learn the cause
of a broken pushrod on the experimental vibration dampening device. Bursch
reported a noise on Thursday, Jan. 24, during crew sleep. He later determined
that the pushrod on the upper right side of EXPRESS Rack 2 was broken. It is
one of eight pushrods designed to keep the rack and delicate microgravity experiments
inside isolated from vibrations caused by crew movement, equipment vibration
and other disturbances. The science team is working with Station controllers
to remove and replace the broken pushrod with a spare today (Jan. 30). The
crew is being consulted on details of the damage. On-orbit inspection with
close-up photos may reveal more. A pushrod also broke during Expedition Three
due to a loose nut designed to hold it in place, but Bursch and Walz reported
Saturday that it was tight when they inspected it. Expedition Three Commander
Frank Culbertson, who performed the pushrod repair on his expedition, talked
with the current crew on Tuesday to pass on his experience.
Planners have moved up operations with the Earth Knowledge Acquired by Middle
School Students (EarthKAM) one week early to Monday, Feb. 4, to allow for
a full four-day operation without communications outages expected during the
original operating period. EarthKAM allows middle school students to send photography
targets to a camera onboard the Station to support a variety of classroom studies.
Since Expedition Three, several new schools in the United States have joined
the program as well as school in Germany.
Recent photos of Materials International Space Station Experiment (MISSE)
show that one of the samples may be peeling off. More photos may be taken during
a February spacewalk to learn more. MISSE is a suitcase-sized package of experimental
spacecraft materials.
The list of sites for the Crew Earth Observations photography research
this week include ice in the South Sandwich Islands, industrialized Southeast
Africa, brush fires and smoke in Angola, water levels in Lake Eyre in Australia,
and Patagonian glaciers in Chili.
