JWST instrument flies commercial across Atlantic
BY STEPHEN CLARK
Posted: May 29, 2012
A sensitive infrared camera designed to detect the first light in the universe flew across the Atlantic Ocean in the belly of a jetliner Tuesday, ready to be integrated in the science module of the James Webb Space Telescope for exhaustive testing.
MIRI will be transported by truck to NASA's Goddard Space Flight Center in Maryland, where it will be unpacked and prepared for installation into the telescope's instrument module.
Outfitted with a camera and a spectrometer, MIRI will seek out the first newborn stars formed after the dawn of the universe. Scientists say MIRI is the most sensitive infrared instrument ever built.
In order to observe such faint, distant objects, MIRI must be cooled to 7 Kelvin, or minus-447 degrees Fahrenheit. Infrared detectors need to be colder than the objects they observe in order to see them.
MIRI must be chilled to a colder temperature than the rest of JWST to see the flickers of infrared light as the universe's first stars illuminated more than 13 billion years ago.
The $8.8 billion Webb telescope is scheduled for launch aboard an Ariane 5 rocket in 2018. The observatory, a successor to the lauded Hubble Space Telescope, will be stationed at a point a million miles from Earth.
MIRI, which can observe in wavelengths between 5 and 28 microns, has its own dedicated cooler to achieve its necessary operating temperature.
It is sensitive enough to distinguish the age of ancient light, telling scientists which stars and galaxies formed soonest after the Big Bang.
"We'd like to try and identify very young galaxies, containing some of the first stars that formed in the universe," said Gillian Wright, MIRI chief scientist at the U.K. Astronomy Technology Center in Edinburgh, Scotland.
MIRI does this by resolving dust inside galaxies in the infant universe. Interstellar dust is generated, in part, by exploding stars.
"MIRI provides a diagnostic of whether there has been a previous generation of stars that had gone supernova and created dust," Wright said. "In the first generation of stars there would be no dust or black holes because there hadn't been time to make any."
Scientists will also use MIRI to study disks of debris around newborn stars closer to home, studying the constituent elements and chemicals that form the building blocks of planets.
The Jet Propulsion Laboratory provided MIRI's detectors, software and a cryogenic cooling system. The delivery of MIRI comes at the end of a comprehensive testing campaign, culminating in thermal and mechanical testing at Rutherford Appleton Laboratory in Oxfordshire, United Kingdom.
"The whole team is delighted that our hard work and dedication has resulted in a MIRI instrument that will meet all our scientific expectations," Wright said.
The Fine Guidance Sensor, Near-Infrared Camera, and Near-Infrared Spectrometer - JWST's other three instruments - will be delivered to Goddard beginning later this year.
"It is wonderful to be the first to achieve this major milestone for the JWST project," Wright said. "We can now look forward to significant scientific discoveries when it is launched."
The Fine Guidance Sensor will arrive at Goddard in July. The Canadian Space Agency and Com Dev, its industrial partner, are completing testing of the guidance sensor, which will allow the Webb telescope to acquire and precisely point toward targets.
JWST's Near-Infrared Camera, or NIRCam, will be shipped to Goddard in September, according to J.D. Harrington, a NASA spokesperson.
NIRCam is a joint project between the University of Arizona and the Lockheed Martin Advanced Technology Center in Palo Alto, Calif. Environmental testing is planned before NIRCam's shipment to NASA.
The mission's Near-Infrared Spectrometer, or NIRSpec, is scheduled to be at Goddard by April 2013, Harrington said.
NIRSpec is undergoing a second round of thermal testing at an Astrium facility near Munich.
The instruments will be bolted inside the telescope's Integrated Science Instrument Module, or ISIM, in a clean room at Goddard. The ISIM is a specially-designed chassis to support JWST's science sensors.
"The JWST project is looking forward to receiving MIRI," said Matt Greenhouse, the ISIM project scientist at NASA. "The delivery of MIRI will mark the start of ISIM integration, a major milestone for NASA on the way to completion of JWST by 2018."
Engineers at Goddard are refining procedures for putting together the ISIM and science instruments. Technicians have practiced with models of the payloads to prepare for integration of the flight instruments.
Each component of the telescope, including the instruments and mirrors, is going through cryogenic testing individually, but the first time the telescope's optics will be collectively strained to their operating temperature -- an unimaginably crisp minus 387 degrees Fahrenheit -- will be in 2015 inside a massive cooling chamber at the Johnson Space Center in Houston.