NASA’s massive new space telescope is getting colder and colder.
as long as James Webb Space TelescopeNASA officials write that the slow cooling process is coming to an end RenewThere is no set schedule for when all components of the observatory will meet operating temperatures. That’s because most of the phase of the telescope’s months-long operating period goes back to physics, as mission managers wait for the mirrors to naturally cool to temperature to allow alignment to continue.
All observatory instruments are at final temperature, including the mid-infrared instrument (MIRI), which is very sensitive to heat and receives help from cryogenics to stay within 7 degrees Kelvin (minus 447 degrees Fahrenheit or minus 226 degrees Celsius). Webb needed to maintain very cold temperatures in order to detect infrared light at the wavelengths it emitted.
The mirror “isn’t there yet,” Jonathan Gardner, deputy chief scientist for the Web project, said in an update published Thursday (April 21).
Live update: NASA’s James Webb Space Telescope Mission
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That was because the eighteen hexagons of the primary mirror, as well as the secondary mirror, were all made of beryllium and plated with gold. “At very cold temperatures, beryllium has a long thermodynamic time constant, which means it takes a long time to cool or heat up,” explains Gardner.
Since then, the $10 billion telescope has started to cool off launch It’s December 25, 2021, says Gardner, and he’s making good progress so far. All parts of the main mirror are below the 55 K mark (minus 360 degrees Fahrenheit or minus 218 degrees Celsius) required to run MIRI. More cooling “will only increase the performance,” Gardner said.
Of the 18 primary mirrors, only four are above the 50 K mark (minus 370 F or minus 223 C). Since all of these sections have some mid-infrared radiation reaching the MIRI detectors, the agency said, officials would prefer to cool them by an additional 0.5 to 2 Kelvin before starting the next phase of alignment.
Gardner notes that this temperature can vary. The telescope and sun visor work together when the telescope is pointed at an object. There is “a small amount of residual heat,” he says, which can travel through the five-layer sun visor to the main mirror depending on what angle the visor is against the sun, or its position.
“Because the temperature of the mirror portion changes very slowly, its temperature depends on the average position over several days,” he said. In fact, Webb spent most of the commissioning period pointing to the poles of the ecliptic, or the plane where Planet-planet tata surya revolves around the sun.
This polar position, says Gardner, “is a relatively hot position.” But he added that this was temporary. “During scientific operations, starting this summer, the telescope will have an even distribution of the signal across the sky. The average heat input for the warmer part of the mirror is expected to decrease slightly, and the mirror will be slightly cooler.”
Immediately after the start-up, Gardner added, the team plans to test Webb’s ability to go from a “hot situation” to a “cold situation.” This process of heat flow “will tell us how long it takes the mirror to cool or heat up when the observatory is in this position for a certain period of time.”
Gardner said Webb’s trip still needed to be completed sometime in June. “Is Webb at his final temperature? The answer is roughly,” he concluded.
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