NASA’s James Webb Space Telescope will see the first galaxies to form after a major explosion, but to do so its first tools need to be cold – really cold. On April 7, Webb’s Mid-Infrared Instrument (MIRI) – a joint venture between NASA and ESA (European Space Agency) – reached a maximum operating temperature below 7 kelvins (minus 447 degrees Fahrenheit, or minus 266 degrees Celsius). Along with Webb’s three other instruments, MIRI first cooled in the shadow of a sunshield the size of a Webb tennis court, descending to about 90 kelvins (minus 298 F, or minus 183 C). But getting down to less than 7 kelvins required an electric cryocooler. Last week, the team passed a landmark challenge called the “sting point,” in which the tool went from 15 kelvins (minus 433 F, or subtract 258 C) to 6.4 kelvins (minus 448 F, or subtract 267 C).
The project manager said
“The MIRI cool team has put a lot of hard work into developing a small point process,” said Analyn Schneider, MIRI’s project manager at NASA’s Jet Propulsion Laboratory in Southern California. “The team was happy and nervous going into the important work. It has finally become a textbook for the process, and the cool performance is much better than expected. ”
MIRI detects long wave infrared wavelengths
Low temperatures are necessary because all four Webb devices receive infrared light – waves that are slightly longer than human eyes can see. Remote galaxies, stars hidden in the dust, and planets outside our solar system all emit infrared light. But so do other warm things, including Webb’s electronics and optics hardware. Cooling down the four metal receivers and the surrounding hardware suppress that infrared release. MIRI gets a longer infrared wave length than the other three tools, which means it needs to be even cooler.
Another reason why Webb detectors need to be cold is by pressing something called a dark current, or electric current created by the vibration of the atoms in the receivers themselves. The black stream mimics the true signal on the receivers, giving the false impression that they are being struck by light from an external source. Those false alarms can swallow up the real signs that astronomers want to discover. Since the temperature is a measure of how fast the atoms in the detector vibrate, lowering the temperature means less vibration, which means that the dark energy is reduced.
MIRI Skills
MIRI’s ability to detect long-distance infrared is also very sensitive to black matter, so it needs to be cooler than other devices in order to completely eliminate that effect. In all degrees the temperature of the metal rises, the dark energy rises by about 10 degrees.
When the MIRI reached 6.4 kelvins freezing, scientists began a series of tests to make sure the machines were working as expected. As a physician looking for any signs of illness, the MIRI team looks at the data describing the life of the metal, and then gives the tool a series of instructions to see if it can perform the functions correctly. This landmark event is the culmination of the work of scientists and engineers in many institutions beyond JPL, including Northrop Grumman, the cryocooler builder, and NASA’s Goddard Space Flight Center, which oversees the integration of MIRI and cooler throughout the experiment. .
The project scientist said
“We spent years practicing at that time, following the instructions and checks we made at MIRI,” said Mike Ressler, a MIRI project scientist at JPL. “It was like a movie script: All we had to do was write and practice. When the test data came in, I was happy to see it look as expected and that we have a healthy tool. ”
There are still many challenges the team will have to face before MIRI begins its scientific career. Now that the tool is at working temperature, team members will take star-studded photographs and other known objects that can be used to measure and evaluate the performance and function of the tool. The team will make these arrangements in line with the ratings of the other three tools, bringing the first scientific photos of Webb this summer.
“I am very proud to be part of this team of enthusiastic, enthusiastic scientists and engineers from all over Europe and the U.S.,” said Alistair Glasse, a MIRI scientist at the UK Astronomy Technology Center (ATC) in Edinburgh, Scotland. “This time is our ‘fire test’ but it is already clear to me that the personal ties and mutual respect we have built over the years are what will make us go through the next few months to provide the best tool. the international community of astronomy. ”
More about Mission
The James Webb Space Telescope is an international program led by NASA and its partners, ESA and the Canadian Space Agency.MIRI was developed with a 50-50 collaboration between NASA and ESA. JPL leads U.S. efforts of MIRI, and the international association of European astronomical institutions donates ESA. George Rieke and the University of Arizona lead the MIRI science team. Gillian Wright is the chief investigator of MIRI European.LaszloTamas with UK ATC heads the European Consortium. The development of the MIRI cryocooler was led and managed by the JPL, in partnership with Northrop Grumman in Redondo Beach, California, and NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
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