Putting together the Webb telescope’s mid-infrared eyes - Ars Technica

There is more than one reason why the Mid-Infrared Instrument (MIRI) on board the James Webb Space Telescope (JWST) is considered to be pioneering.

To reach these wavelengths, MIRI had to be kept the coldest of any instrument on JWST, meaning it essentially set the requirements for the telescope's cooling system.

Some people at NASA looked at the block diagram of our management structure and said it will never work," professor George Rieke, who leads the science team of MIRI, recalled.

Although everything eventually fell into place, there were moments when professor Gillian Wright, who is the European principal investigator for MIRI, harbored some nervousness.

By the time we started developing MIRI, the military had moved to other types.

He said the MIRI team had to work with the manufacturer to recover a key step in building the detectors.

According to Wright, the cooler had the potential to put the MIRI project at risk.

Initially, the MIRI team had designed a thermos-like container filled with liquid hydrogen to keep the instrument cool.

However, this system, which could cool MIRI for five to 10 years, weighed a lot.

It was a risk because the technology development started about five years behind the rest of the telescope," Wright said.