Tuesday, April 12, 2011

The MELFI Shuffle: Contingency Planning for Preserving Samples

The International Space Station is a unique laboratory, due to its microgravity environment, but it still shares similarities with Earth-bound research facilities. Both perform experiments as part of their research goals, yielding various samples from which they collect data towards results. These samples can require preservation in refrigerators and freezers. A recent malfunction of a Minus Eighty-Degree Laboratory Freezer for ISS, or MELFI, on the space station, however, brought to light one of the main differences between this orbiting lab and its Earthly counterparts-refrigeration repair companies do not make house calls in space.

The malfunction of the MELFI flight unit two has been an ongoing challenge for the space station. In October of 2009, and twice in December 2010, the unit experienced an automatic shutdown due to difficulties with the Electronics Units or EUs. The nonfunctioning EUs all returned to Earth for ground teams to identify the exact cause of trouble. The first EU returned to Earth for study on STS-131/19A, while the remaining two returned on STS-133/ULF-5 in March 2011. The first malfunction was linked to the motor drive electronics, a subassembly of the EU. The parts were replaced and the repaired EU is scheduled to return to the space station on STS-134/ULF-6 in late April 2011. The other two EUs are currently undergoing testing and the motor drive electronics appear functional, which indicates the malfunction is in the remaining parts of the EU.

No comments: