The Mid-Infrared Instrument (MIRI) is one of four scientific instruments on the James Webb Space Telescope (JWST)
observatory, scheduled for launch in 2018. It will provide unique capabilities to probe the distant or deeply dust-enshrouded
regions of the Universe, investigating the history of star and planet formation from the earliest universe to
the present day. To enable this the instrument optical module must be cooled below 7K, presenting specific challenges
for the environmental testing and calibration activities.
The assembly, integration and verification (AIV) activities for the proto-flight model (pFM) instrument ran from March
2010 to May 2012 at RAL where the instrument has been put through a full suite of environmental and performance tests
with a non-conventional single cryo-test approach.
In this paper we present an overview of the testing conducted on the MIRI pFM including ambient alignment testing,
vibration testing, gravity release testing, cryogenic performance and calibration testing, functional testing at ambient and
operational temperatures, thermal balance tests, and Electro-Magnetic Compatibility (EMC) testing. We discuss how
tests were planned and managed to ensure that the whole AIV process remained on schedule and give an insight into the
lessons learned from this process. We also show how the process of requirement verification for this complex system
was managed and documented. We describe how the risks associated with a single long duration test at operating
temperature were controlled so that the complete suite of environmental tests could be used to build up a full picture of