ISS Science Operations Weekly Status Report 24 Jan 2002
The Experiment on Physics of Colloids in Space (EXPPCS) team
has expanded its research from studying colloid behavior to building “fractal
structures” with them.
The ground-based science team this week continued its fractal test run aboard
the Space Station that began on Jan 16 and will continue for five weeks. The
fractal sample being studied is a gel made from colloids. It is made mostly
of liquid but with enough binding material to prevent it from flowing. Gelatin
is a common example. 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 colloids experiment team last week concluded its 120-hour reexamination
of the crystallization of the AB6 binary colloid, then conducted a successful
follow-up 24-hour run and were successful in obtaining high quality data. The
experiment has been extended from Expedition Four to Expedition Five.
The Active Rack Isolation System ISS Characterization Experiment (ARIS-ICE)
ground team continued testing the experimental ARIS vibration dampening device
during the past week. Located in EXPRESS Rack 2, ARIS is designed to protect
delicate microgravity experiments from vibrations caused by crew motion, operating
equipment, etc. The experiment was launched in April 2001 on the 6A Shuttle
flight. Although not completed, ARIS-ICE has to date spent over 10 successful
months on the Station, logged more than 2,300 hours on the ground station console,
transmitted more than 15,000 commands from ground to the Station to conduct
more than 1,446 ARIS-ICE on- orbit tests.
The experiment has helped enhance the vibration dampener’s performance by improving
the power umbilical design, validating its performance over a wide frequency
range and resolving several other technical issues. On Tuesday, Jan. 22, the
crew began tests in which they use a small hammer to tap on the Station’s Z-panel
containing power, data, fluid and other utility umbilical lines into the EXPRESS
Rack 2, while the ground team measures the dampener’s response. Those tests
will continue through the end of the month. The science team would like more
data synchronized with crew exercise periods and exercise equipment.
On Saturday, Jan. 19, the crew during their normal maintenance checks noticed
and removed an ice buildup in the Biotechnology Refrigerator containing
several cell science samples processed earlier in the mission and now awaiting
transfer to Earth.Locations on a list of possible targets for the Crew Earth
Observations program during the past week have included ice fields in the
South Sandwich Islands, Reunion Island in the Indian Ocean where a major volcanic
eruption was occurring on the island east of Madagascar, a severe tropical cyclone
in the Indian Ocean , smog in southeastern Africa’s industrialized heartland
of the Vaal River, Patagonian ice fields in Chile, American Samoa’s reefs and
coral structures, and the Marquesas Islands.
Flight Engineers Dan Bursch and Carl Walz performed their Crew Interactions
surveys on Wednesday, Jan. 23.
Also on Wednesday, the Expedition Three team was reunited during a teleconference
for a post-mission debriefing with the Expedition Three crew in Houston. The
science team uses these meetings to get feedback on procedures and improve instructions,
planning and timelines for future missions.
Thursday, Jan. 24, is expected to be a light duty day for the crew in preparation
for a Russian EVA scheduled for Friday. On Saturday, Jan. 26, Bursch will follow
up his scheduled Friday spacewalk with a lung function test with the Pulmonary
Function in Flight experiment. Walz also will perform PuFF for his regular
monthly test.
