MELFI, the Minus Eighty degrees Celsius Laboratory Freezer for ISS is the first of the freezers provided by the European Space Agency (ESA) as Laboratory Support Equipment for the International Space Station (ISS). Three freezers will ensure the continuous cold chain for transporting biological samples between the Ground Laboratories and the ISS.The first MELFI Flight Unit was delivered to NASA in 2002 and is scheduled for next Space Shuttle flight in 2006 to be installed in the International Space Station.The second MELFI Flight Unit was delivered at NASA-KSC in 2004 for JAXA, the Japanese Space Agency.While the technology for this kind of freezer was qualified with the first unit, the production phase of the two following units and the operations using the first unit have brought some know-how for the long term life of the system. The cooling engines for the different units confirmed how challenging the technology was.The second unit had to follow a complementary verification campaign for the requirements specific to the JEM, the Japanese Module in ISS. The specificities of the JEM module, compared to the USLAB were analyzed and adaptations were found to keep all MELFI Units compatible of both ISS modules. Some improvement on the thermal control was first necessary to extend the working domain of the MELFI, and then an extended test campaign has confirmed the compatibility with both JEM and USLAB.Because the freezers are the only payloads flying active inside the MPLM (Logistics Module), MELFI units followed the verification of the MPLM interfaces for an active flight, including software interfaces, electrical power quality and water cooling loop. The results have confirmed the acceptable margins between both sides for the ascent and descent phases.Repeated test sessions using both the NASA PRCU (Payload Rack Check Unit) and the PTCS (Payload Test and Checkout System) have confirmed that both units are ready for flight. This paper presents the different steps of MELFI development leading to the availability of the MELFI units ready for use inside MPLM and inside the ISS, including the JEM..
