Cosmic eye emerges from exhaustive tests in UK space lab

The sophisticated instrument -- designed to examine the first light in the Universe and the formation of planets around other stars -- was put through its paces inside RAL Space's thermal space test chamber. MIRI contains a camera and a medium resolution integral field spectrograph and coronagraphs and it covers the wavelength range of 5 to 28 microns. This long wavelength range means that MIRI is unique among the Webb instruments because it has to be cooled to 7 Kelvin (minus 266 Celsius), which also brings tough challenges for testing the instrument.

Inside the RAL Space thermal space test chamber specially constructed shrouds cooled to 40K surround the instrument to represent properly the environment and background that the instrument will see in operation on Webb. Simulated stars are used to exercise thoroughly all the different ways in which scientists will use the instrument after launch. The tests were designed to ensure that MIRI can operate successfully in the cold vacuum of space and allow the MIRI scientists to gather vital calibration and baseline data. A team of more than 50 scientists from 11 countries have been working 24 hours a day 7 days a week for 3 months to complete the testing. The instrument has undergone the longest and most exhaustive testing at cryogenic temperatures prior to delivery of an astronomy instrument in Europe. With a total of 86 days at 7 Kelvin this is a significant achievement for the team operating the RAL Space test chamber.

"It is inspiring to see the MIRI working extremely well at its operating temperature after so many years in development. The test campaign has been a resounding success and the whole MIRI team can be very proud of this magnificent achievement" said Gillian Wright, the European Principal Investigator.

"The successful completion of this difficult test program -- involving more than 2000 individual tests -- marks a major milestone for the Webb telescope mission. The MIRI will now be delivered to NASA's Goddard Space Flight Center to join the integration and testing of the observatory's science instrument payload which began this year," said Matt Greenhouse, James Webb Space Telescope Project Scientist for the Science Instrument Payload, at NASA's Goddard, Greenbelt, Md.

The James Webb Space Telescope, a partnership between ESA, NASA and the Canadian Space Agency, is the next-generation premier space observatory, capable of exploring deep space phenomena from distant galaxies to nearby planets and stars. The Webb Telescope will enable scientists to "see the beginning" and study the formation of the Universe and the evolution of our own solar system, from the first light after the Big Bang to the formation of star systems capable of supporting life on planets like Earth. The combination of Webb's unprecedented mirror size, cold temperature and location in space will make it the most powerful space observatory ever, which promises to revolutionise our view of the cosmos.

The Webb Telescope is central to the UK Space Agency's science programme which funds the UK's involvement in the project.

Dr David Parker, Director of Science, Technology and Exploration at the UK Space Agency, said, "MIRI will help unveil the early Universe with un-dreamed of detail; for astronomers, the Webb Telescope will be like a time machine allowing them to view the first stars and galaxies forming when the Universe was very young. It has taken a great deal of hard work and dedication from the European teams and JPL to get MIRI to this important milestone. With the UK playing a lead role in the instrument and the UK Astronomy Technology Centre being the overall European science lead for it, this project is a great example of how the specialist skills of our UK scientists and space companies are being utilised for the biggest and most ambitious international space projects."

The STFC's UK Astronomy Technology Centre (UKATC) is leading the European team developing MIRI in a partnership with NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif. A major part of the UK role is the Assembly Integration and Test (AIV) campaign at RAL Space. MIRI was integrated from key parts that have been developed at institutes across Europe and the USA. Each of these parts of MIRI have already, separately, undergone exhaustive testing to make sure they can survive the rigours of a journey into space and remain operational for the life of the mission. The test campaign at RAL is the only opportunity to ensure that all of the parts of the instrument function together properly and for scientists to obtain critical performance data before the launch. The extensive testing has generated simulated science data which will be used by astronomers in the coming years to develop the calibration software that will be needed when the instrument is in flight.

The MIRI team are now racing to analyse all the data from this huge cryogenic test campaign in parallel with completing the remaining warm testing and preparing the instrument for delivery to NASA's Goddard Space Flight Center. There it will be integrated with the other instruments, the telescope and eventually the spacecraft.

MIRI's ultimate destination is L2 -- a gravitational pivot point located four times further away from Earth than the Moon, on the opposite side of Earth from the Sun. Here it is cool enough for MIRI's instruments to obtain the exquisite measurements that astronomers will use to help decipher the Universe.

Nobel Prize winner, Dr. John Mather, Webb Senior Project Scientist at NASA Goddard said, "Thousands of astronomers will use the James Webb Space Telescope to extend the reach of human knowledge far beyond today's limits. Just as the Hubble Space Telescope rewrote textbooks everywhere, Webb will find new surprises and help to answer questions such as: How did a black hole get to the center of almost every galaxy, and how did it grow? What were the first objects to light up after the Big Bang? How did galaxies like the Milky Way come to their present shapes? When and where were the chemical elements of life synthesized, and how soon could planets and life appear after the Big Bang? How are stars like the Sun and planets like the Earth formed, and how unique is the Earth? Webb is about beginnings, the beginnings of everything."

MIRI will provide enormous increases in sensitivity, spatial and spectral resolution, enabling astronomers to identify the very earliest galaxies. The astronomers who will use MIRI and the Webb telescope are also particularly keen to explore the formation of planets around distant stars. The emission from such events is shrouded by gas and dust in interstellar space. This is not a problem for MIRI, as the infrared light from these objects will penetrate these obstructions and allow MIRI to build up highly resolved images of planetary nurseries in unprecedented detail. With its spectrometer, MIRI could even reveal the existence of water and/or hydrocarbons on these planets or within the planetary debris, paving the way for investigations into the habitability of other planetary systems.