The pioneering camera and spectrometer for the James Webb Space Telescope — the gigantic successor to the Hubble Telescope — is about to receive its first taste of the harsh conditions of space, without even leaving the UK.
The sophisticated instrument — designed to examine the first light in the Universe and the formation of planets around other stars — will shortly be put through its paces in the space test chamber at the Science and Technology Facility Council’s Rutherford Appleton Laboratory (RAL). The tests include ensuring it can survive the vibrations of a rocket launch and operate successfully in the cold vacuum of space.
The journey to space began a few months ago when the flight model of MIRI was integrated at RAL, from key parts that have been developed at institutes across Europe. Each of these parts of MIRI have already, separately, undergone exhaustive mechanical and thermal testing to make sure they can not only survive the rigors of a journey into space, but also remain operational for the life of the mission. Now the whole instrument will be tested using specially designed facilities developed at RAL to simulate the environment that the instrument will experience once in space.
“Bringing the Flight Model MIRI to readiness for the testing is the culmination of several years hard work and dedication from the teams all around Europe along with the efforts from our US colleagues. The fact that we are now at that point is testament to the tremendous team spirit in the MIRI Consortium and there will be many people waiting to hear the test results” said John Thatcher, the MIRI European project manager from Astrium Ltd.
Dr. David Parker, Director of Space Science and Exploration for the UK Space Agency, said, “MIRI is in for a tough old time in this mock space environment but we’re confident that this unique instrument is up to the job.”
He added, “With the UK playing a lead role in the instrument and the UK Astronomy Technology Centre being the overall science lead for it, this project is a great example of how the specialist skills of our UK scientists and space companies are being utilized for the biggest and most ambitious international space projects.”
The Webb telescope represents the next generation of space telescope and, unlike its predecessor Hubble, it will have to journey far from home. With a prospective launch date in 2014 its ultimate destination is L2, a gravitational pivot point located 1.5 million kilometers away, on the opposite side of the 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.
“The first tests we will do simulate the ‘shake, rattle and roll’ that MIRI will see when the Ariane 5 rocket lifts off from South America on the JWST launch,” explained Nigel Morris, the RAL MIRI manager. “My team at RAL have constructed a specific test facility that will operate inside our main thermal vacuum chamber and simulate the extremely cold environment that the instrument will experience once in space,” he added. The facility will also cool MIRI itself down even further to its -266.5 degrees C operating temperature and allow the scientists to make their first measurements to calibrate the instrument.
One of the jewels in MIRI’s crown is the potential to observe star formation that has been triggered by an interaction between galaxies. Conventionally, the emission from such events is shrouded by gas and dust in interstellar space. This is not a problem for MIRI, as it’s extremely low temperature (colder than the temperature on Pluto) will allow it to penetrate these obstructions.
Following completion of the tests, MIRI will be shipped to the Goddard Space Flight Center in the US, next year, when the instrument will be integrated with the other instruments, the telescope and eventually with the spacecraft.
When MIRI eventually reaches its sheltered position, located four times further away from the Earth than the Moon, scientists can begin probing the Universe’s secrets, including its earliest days. “We’d like to try and identify very young galaxies, containing some of the first stars that formed in the Universe,” says Gillian Wright, European Principal Investigator for MIRI based at the UK Astronomy Technology Centre.
The astronomers who will use MIRI and the Webb telescope are also particularly keen to explore the formation of planets around distant stars, another area where dust penetration becomes important. “MIRI is absolutely essential for understanding planet formation because we know that it occurs in regions which are deeply embedded in dust,” said Wright. MIRI’s beam width of 6 microns allows the instrument to image 30-35 Astronomical Units (AU) of a protoplanetary disc. With most such discs thought to be hundreds of AU across, MIRI can build up highly resolved mosaics of these planetary nurseries in unprecedented detail. With its spectrometer, MIRI could even reveal the existence of water and/or hydrocarbons within the debris, paving the way for investigations into the habitability of other planetary systems.
