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The Minus Eighty degrees Celsius Laboratory Freezer for ISS (MELFI) is a freezer that has been delivered to NASA as Laboratory Support Equipment (LSE) by ESA. One of the main concerns during the development of MELFI has been first the intrinsic thermal performance of the system, and, second, the thermal performance once on orbit. From the beginning the differences between the thermal performance on orbit and on ground were estimated through thermal analyses of the sub-systems to predict the behavior on orbit, and specific tests on ground simulating as far as possible a non-convective environment. The results were used to define the criteria for the performance to be obtained on ground, which would ensure the compliance with requirements on orbit. The complete verification campaign has demonstrated that the system is capable of giving the performance imposed by the criteria on ground for all mission aspects, including samples cooling down and protection during power-off.

The Minus Eighty degrees Celsius Laboratory Freezer for ISS (MELFI) will be the first freezer to be delivered to NASA as Laboratory Support Equipment (LSE) by ESA. Among the MELFI thermal requirements, the rapid freezing of samples to a required temperature and the low power consumption that limits MELFI performance during re-cooling phases after power off, are ones of the most critical. This paper will present the thermal activities, which led both to a verification of those requirements and to a complete thermal characterization of MELFI.

The Minus Eighty degrees Celsius Laboratory Freezer for ISS (MELFI) is a freezer that will be delivered to NASA as Laboratory Support Equipment (LSE) by ESA. A first qualification test campaign was conducted with the DM (Development Model) Brayton Sub-System (BSS) installed in MELFI QM (Qualification Model) rack. This test campaign gave a lot of information on MELFI thermal system behaviour. Nevertheless, the lessons learned from these first performance tests raised questions about the tests to be performed with MELFI first flight model. Thus, this paper will present the qualification test results, the observations made after these tests and, in the light of these remarks, the logic followed to completely redefine the thermal test plan in order to fully cover the verification of the thermal requirements before MELFI first flight.

The first Flight Unit of the Minus Eighty degrees Celsius Laboratory Freezer for ISS (MELFI) has been delivered to NASA as Laboratory Support Equipment (LSE) by ESA, and is presently waiting for the next available Space Shuttle flight to be installed in the International Space Station. The second Flight Unit is under preparation to be delivered at NASA-KSC in 2004 for JAXA, the Japanese Space Agency. Compared to the first unit, the acceptance of this second unit imposes the verification of requirements specific to the JEM, the Japanese Module in ISS. The specificities of the JEM module, compared to the USLAB were analysed and adaptations were found to keep all MELFI Units compatible of both ISS modules. The most important difference between JEM and USLAB is the water-cooling system, which has a much larger flow and inlet temperature ranges in JEM.