Zeolite Crystal Growth (ZCG) Furnace Results

Results

The ZCG
mission 8A experiment was completed on May 6, 2002—a day earlier than
originally planned. After a brief loss of signal, the ground operators detected
anomolous temperature readings inside the furnace. They rebooted the hardware,
returning both central processing units to normal function. To avoid any
more temperature cycling problems and possible damage to the samples, however,
the science team decided to end the experiment and power down the hardware.
The ground operators are using the down time to run diagnostics and prepare
the hardware for the new experiment samples to be delivered on STS-111.

This
latest batch of experiment samples were delivered in April by STS-1. On
Monday, April 22, Expedition 4 Flight Engineer Carl Walz reactivated the
furnace and mixed the autoclaves to begin the experiments. ZCG is the
first payload to receive full-time support from the Active Rack Isolation
System (ARIS), a system that reduces vibration like shock-absorbers
on a car. ARIS underwent thorough testing throughout Increments 2, 3 and
4, and went online in April.

The Expedition 4 crew
installed the ZCG hardware in EXPRESS Rack 2
on December 29, 2001, and completed tests of the system’s function, including
remote links, on February 8, 2002.

Space
grown zeolite crystals have proven to be larger and better-ordered than
Earth-grown crystals. Theoretically, it is possible to grow crystals in
microgravity that are 500 to 1000 times larger than terrestrially-grown
crystals. Zeolite A crystals grown during USML-1 achieved 96 percent area
and 175 percent volume increases over Earth grown samples, and approached
theoretically perfect aluminum/silicon ratios.

Applications

Zeolite
materials have great potential for commercial applications. Their shapes
form complex, open frameworks that act as absorbents or filters, and they
can be used in diverse ways: as absorbents for oil spills; to control
household odors; to filter ammonia from municipal wastewater; and as a
growth medium for hydroponic horticulture. They have been suggested as
nuclear waste scavengers and quantum confinement hosts for semiconductor
materials. Larger, better-constructed crystals, made possible by space-based
facilities, are more suitable for research and use in commercial materials.

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