The James Webb Space Telescope has been deployed. So, what's next for the largest observatory outside the planet?
This new generation of observatories is getting closer to the point of observation and entering the preparation period for main mirror and instrument testing.
NASA's James Webb Space Telescope is fully unfolded with artistic illustrations. After the observatory is deployed, there is more work to be done before it begins to study the universe. (Image source: ESA)
The configuration of the James Webb Space Telescope has only just begun.
On Saturday, January 8, the new observatory, the largest space telescope to date, successfully opened the last main lens, a mission that NASA has described as one of the most complex space deployments ever settled. As a next step, the Weber working group will work on aligning the telescope with the target while launching the key components of the observatory into practical work.
The Weber Space Telescope is expected to reach the "insertion position" on Jan. 23 and then ignite the engine to glide to a "parking space" about 930,000 miles (1.5 million kilometers) from Earth — the second Lagrange point. If it can successfully reach the ideal location, it will be able to achieve long-term residence with minimal energy consumption due to its perfect straight line arrangement with the Sun, Earth and Moon.
Related knowledge: Ideally, two objects in the same orbit rotate at the same period, and the gravitational force of the two celestial bodies is balanced at the Lagrange point, so that the third object is relatively stationary to the first two objects.
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But the ground control team has to do more than just simulation exercises, and much of the complex commissioning work has yet to be done, and NASA specifically pointed out that in the next few weeks, calibrating the lens and preparing the instrument is a key part of the focus.
NASA's James Webb Space Telescope engineering team celebrates the opening of the main mirror at the Space Telescope Science Institute in Baltivan, Maryland, On January 8, 2022 (Credit: NASA/Bill Ingles)
On Saturday, January 8, John Duning, deputy manager of the Weber program at NASA's Goddard Space Flight Center, told reporters at a press conference at the Weber Control Center, a space telescope science institute in Baltimore, Maryland, that team members would synchronize 18 lenses to "basically a mirror" over the next 15 days in preparation for engine ignition.
Duning also added: "The working group plans to start launching the relevant instruments for the Weber Space Telescope around next week. When Weber enters the second Lagrange point, the internal temperature will reach extremely low values, and engineers will fully activate the various instruments. ”
The second Lagrange point is the ideal location for Weber to conduct a deep space probe. Being far from the sun and equipped with a hood, Weber will work in the dark environment necessary for thermally tracked infrared observations. Infrared wavelengths allow telescopes to penetrate dust and observe the internal structure of young exoplanets, or distant galaxies, to understand the formation and evolution of the universe.
According to NASA, Weber is equipped with four scientific instruments — a near-infrared camera, a near-infrared spectrometer, a mid-infrared imaging spectrometer, and a combined finely guided sensor and spectrometer — that allow it to be observed in the visible, near-infrared, and mid-infrared (0.6 to 28.5 micron) regions.
"Each instrument has a unique set of operating rules," Denin says, "and once a certain temperature is reached inside, it will be a challenge to (calibrate) them to ensure consistency." ”
Lee Feinberg, component manager of the Godard Weber Optical Telescope, explained at a press conference that the main mirror adjustment will be launched on January 11. Due to the intense pressure at launch, the main mirror is temporarily folded, so it takes 10 to 12 days to "push all the lenses forward about half an inch for fine optical calibration."
The basic calibration period is expected to last 3 months, thus preparing for the emission of the "first light", when the telescope will take the first test image, which is also a step in the calibration work. NASA suggested that because the telescope has not been fully aligned, the first images will most likely be pasted out, and the completion of accurate configuration depends on more imaging effect confirmation and instrument testing.
This image shows the trajectory of the James Webb Space Telescope near the second Lagrange point (Image: NASA)
"The entire calibration process for the telescope takes about 120 days, so the calibration completion date is initially set around April 24, depending on the actual progress of the entire commissioning process," Dening said. “
Dening added that the overall commissioning of the telescope will be completed simultaneously with various instrument control teams, who will "turn on different instruments and ... These instruments are then used to calibrate the telescope to further refine the telescope's functions."
There has been some historical sensitivity to the fact that space telescopes take blurry images. In 1990, the Hubble Space Telescope launch incident was a sensation, but due to engineering failures, the backhaul image was blurred like the telescope suffered from myopia, and had to be followed up with correction work. Hubble operates in low-Earth orbit, which astronauts can maintain and upgrade via the space shuttle, while the webb telescope's remote operation makes it hopeless and can only be accurately calibrated by remote operation.
Jane Rigby, a Weber project scientist at NASA's Goddard Space Flight Center, told reporters: "We started to shrink the mirror surface from the millimeter level, and we are trying to shrink them to a size smaller than the coronavirus, to tens of nanometers." ”
"It's a very time-consuming process. Everyone knows the first picture we took... The telescope isn't ready to be used out of the box. The first photo will be ugly and blurry. We're going to have 18 of these little images all over the sky, and we're going to drive them into a telescope.
"I like to think that the 18 mirrors we have now are all like little heroines, doing their own thing, singing their own songs, no matter what tune they are using," Rigby continued, "we have to make them work like choruses, which is an orderly and laborious thing." ”
At the end of the commissioning, Rigby said the team plans to roll out a set of "stunning images" that showcase the telescope's capabilities. The images have yet to be released to the media, but Rigby said their goal will be to "showcase four scientific instruments and really surprise everyone."
Officials revealed at a press conference that the first images will include stars (checked for precise alignment) and the Large Magellanic Cloud (which assesses the telescope's ability to present luminosity shadows or inherent brightness), among others.
After the test, which will take about six months, there will be a five-month initial science operation period consisting of the Early Release Science Program, which will cover six broad categories from planet formation to stellar physics.
BY：Elizabeth Howell
FY：Astronomical volunteer team
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