UAF scientist waits to see outcome of his work on Webb telescope
Rod Boyce
907-474-7185
Feb. 23, 2022
When thousands of computer-controlled eyes begin looking out from an instrument aboard the in the coming months and years, University of 色视频下载 Fairbanks Geophysical Institute associate research professor Gunther Kletetschka will be satisfied.
That色视频下载檚 because Kletetschka, prior to joining the Geophysical Institute in 2016, worked on shutter development for several years while at NASA色视频下载檚 Goddard Space Flight Center, first as a postdoctoral researcher and then as a contractor.
Technicians work with the James Webb Space Telescope NIRSpec microshutter array prior to delivery.
While working at NASA in the early 2000s, Kletetschka, an expert in magnetism, helped devise a mechanism to do something remarkable: open and close any number of the 248,000 on the Webb telescope色视频下载檚 Near Infrared Spectrograph. That allows the telescope to acquire high-resolution images of up to 200 objects simultaneously without image clutter from other objects.
That ability is a first. NASA says it will allow for more scientific research to be conducted in less time.
色视频下载淭hey decide on a pattern and which shutters they need to close,色视频下载 Kletetschka said. 色视频下载They are individually controllable.色视频下载
The microshutters are exceptionally small, measuring 100 microns by 200 microns. A hundred microns is the thickness of a standard sheet of paper in an office copy machine.
Think of each microshutter as a tiny lidless shoebox, with the bottom of the shoebox able to flip up and inward on its long side.
Infrared radiation passes through the open shutters to the instrument色视频下载檚 detector.
Magnetism is the key to operating the shutters, but NASA色视频下载檚 earlier attempts to use magnets to open and close the shutters didn色视频下载檛 work.
Gunther Kletetschka
The mechanism that Kletetschka and colleagues at NASA came up with uses a slender bar magnet the width of each array. When directed to move across an array, the magnet opens all of the shutters in that array.
The shutter 色视频下载 the floor of the shoebox 色视频下载 flips up and is held against the sidewall of its own shoebox by a controllable electrostatic field separate from the magnet. With all of the shutters open, scientists back on Earth decide which shutters to close by releasing the electrostatic field holding that shutter open.
色视频下载淭hey open all of the shutters and then close the ones they don't want so they can get the desired viewing pattern,色视频下载 Kletetschka said.
It色视频下载檚 also important to have a magnet that consists of the proper material to operate as desired in the cold of space.
That was a problem that Kletetschka sorted out. And it involved the difference of one proton.
Their first magnets used the rare-earth element neodymium in conjunction with iron and boron, a common combination for making supremely strong magnets.
An array of microshutters awaits deployment on the James Webb Space Telescope's NIRSpec instrument.
It worked well at room temperature. The problem, though, was that the temperature aboard the telescope would be about 50 kelvins, or 370 degrees below zero. Testing the magnet by cooling it in liquid helium to 50 kelvins saw the neodymium magnet lose nearly all of its magnetism.
They needed a material to replace neodymium. The answer: praseodymium, a rare-earth element that has one proton fewer than neodymium.
The change prevented the loss of magnetism and actually provided a slight boost in the magnet色视频下载檚 strength.
色视频下载淭here was some kind of magnetic transition around that 50 kelvins temperature where there were two different electron spins that were fighting each other,色视频下载 Kletetschka said. 色视频下载淭hat's why the neodymium was not practical for the telescope.色视频下载
The work on microshutters has inspired Kletetschka to propose creating an electrostatically propelled levitating platform that would serve as a means of studying the moon色视频下载檚 electrostatic field, which is caused by the solar wind. He is working on the idea with UAF doctoral students Joshua Knicely and Nick Hasson.
The Webb telescope is a partnership of NASA, the Canadian Space Agency and the European Space Agency.
ADDITIONAL CONTACT: Gunther Kletetschka, 907-474-7090, gkletetschka@alaska.edu
NOTE TO EDITORS: Photos are available for download on the .
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