A unique levitation furnace that flew on the Space Shuttle in 1998 is being eyed for upgrades to fly on future Shuttle and International Space Station missions.
"TEMPUS on MSL-1 provied it was operationally reliable," said Dr. Ivan Egry, the project scientist at the German Space Agency (DLR). "I am really surprised at how much scientific data we are still squeezing out of it."
Egry spoke Tuesday morning to the third Biennial Microgravity Materials Science Conference sponsored by NASA.
TEMPUS - built by the DLR and used jointly by DLR and NASA - is the German acronym for containerless electromagnetic processing in weightlessness. That, simply put, is what TEMPUS does. An electromagnetic coil inside the TEMPUS facility positions metal samples with about 1/1,000th the force needed on the ground to work against gravity and keep the samples from touching the container walls. A second coil pumps in radio wave energy - a bit like a microwave oven - to melt the sample.
This approach is vital in a number of research areas because touching the container walls will instantly cool the sample and levitation on the ground often involve forces great enough to disturb the sample. Scientist don't want either to happen when they are trying to make precise measurements of fundamental properties that can help them refine manufacturing processes on Earth.
TEMPUS flew on the Microgravity Sciences Laboratory-1 mission in 1998, and on the second International Microgravity Laboratory (IML-2) in 1994. Data are still being analyzed, but Egry gave a preview Tuesday, including benchmark data that will let scientists correct the surface tension measurements for one type of metal, and make the first-ever reliable viscosity measurements.
"Many things were surprising," Egry said when asked about the data from TEMPUS. Among them were the first experimental measurements of the electrical conductivity of cobalt-palladium in both its liquid and solid states.
TEMPUS demonstrated its value by making repeat measurements that matched very closely with one another. Consistency is crucial when one is trying to establish basic physical properties. For example, one line of experiments involved cooling metals, such as zirconium, far below their normal freezing point and then recording the point where they froze, how much heat they gave off, and other details. The zirconium sample was put through 120 melt/freeze cycles.
"It's relly amazing to see how one undercooling cycle follows the other," Egry said as he showed a graph showing precise repeatability in the data.
All told, the MSL-1 mission hosted 22 experiments comprising 197 hours of test run and 437 melting cycles.
Spurred by this success, DLR is looking at adapting TEMPUS to fly on Spacehab, and to incorporate better sample handling and video capabilities, and a broader temperature range. DLR also is looking at an Advanced TEMPUS that would allow scientists to replace samples in orbit - so the furnace would not have to be brought back - and add other improvements to enhance the science.