A new Cryogenic Workshop and NASA’s 4-K Cooler contribution

A new cryogenic workshop, the first gathering of all the main parties in the newly reformulated X-IFU cooling chain, took place January 31st through February 2nd in Toulouse, at CNES. The main participants included representatives from:

• ESA, who is responsible for the passive cooling of the X-IFU from room temperature to 50 Kelvin;
• NASA’s Goddard Space Flight Center who is now responsible for the cryocooler that will provide cooling at 4.5 Kelvin (and 20 Kelvin) from 50-Kelvin; 
• CEA Grenoble who are responsible for the adiabatic demagnetization refrigerator for cooling from ~ 4.5 Kelvin to 50 mK;
• Added Value Solutions (AVS) in Spain, who are responsible for providing the X-IFU cryostat;
• IRAP and CNES who are responsible for the definition of all X-IFU interfaces and requirements, and for the management and development of the entire program, the assembly integration and testing, as well as the definition of all interfaces associated with the X-ray microcalorimeter array detection chain within this cooling system.

Cryogenic Workshop and NASA’s 4-K Cooler contribution

For the U.S. 4.5 Kelvin cryocooler, there are a number of different options involving various different U.S. companies that already have space-flight heritage and high technical readiness levels (TRL) of the critical components such as the compressors and heat exchangers. There is a plan for a number of these companies to be partially supported by NASA to develop a demonstration model (DM) of the main thermo-mechanical parts of the cryocooler. Subsequently there will be a downselect to a single company to provide the engineering and flight models after mission adoption. The details of the statement of work and requirements for this DM to be considered sufficiently high TRL at mission adoption was a key topic of discussion. The request for proposals for the DM will be released in the near future. Paul Whitehouse from NASA led a lively discussion on how some of the various cryocooler options might be mechanically integrated with the pay-load compartment (PLC), the cryostat, and with the V-grooves needed for passive cooling. 

It was a very successful first meeting that included friendly and constructive discussions amongst all parties, working towards better definition of this new cooling system design. Numerous critical questions were raised and discussed that were critical for each of the partners to enable them to subsequently further develop their respective contributions.

One of the newer members of the detection chain remarked about halfway through this meeting, “Is this typical for an Athena meeting that so many technical topics get discussed without coming to final conclusions?” Fortunately, the final day of the meeting saw key leaders for ESA, NASA and CNES really pull together all the key topics that had been discussed during various parts of the meeting into a critical action item list that included actions to most of the teams present. This list has now set the cooling chain team on a clear course (and with a clear schedule) to the conclusion of all the design development and the evolution of all requirements for all the key systems.

Simon BANDLER
Project manager for the U.S. contribution to the X-IFU