Liftoff! NASA’s Webb Space Telescope on Its Way to L2

Liftoff! NASA’s Webb Space Telescope on Its Way to L2

The James Webb Space Telescope was lofted into space today to begin a month-long journey to its destination a million miles from Earth. Once there, it will observe the universe in infrared wavelengths, revealing the earliest era of the universe when galaxies were being formed. It has taken many more years and billions of dollars than planned to get to this point, but scientists are confident the knowledge gained from its discoveries will be well worth it.

JWST is a joint program among NASA, the European Space Agency and the Canadian Space Agency.  Collectively they have spent about $10 billion so far and NASA expects to spend about $1 billion more for 5 years of operations. If all goes well, it could operate for another 5 years after that, but eventually will run out of fuel needed to maintain its orbit around the Sun-Earth Lagrange Point-2 (SEL-2), its vantage point for studying the universe.

The telescope is not designed to be serviced like the Hubble Space Telescope, which is nearby in Earth orbit, but it is conceivable that someday a robotic refueling system might be developed to travel there and fill the tank to keep it operating even longer.

ESA provided today’s launch at no cost to NASA as part of its contribution to the mission. Launch on Europe’s Ariane 5 rocket from Kourou, French Guiana was at 7:20 am ET.

Liftoff of the James Webb Space Telescope on an Ariane 5 rocket from Kourou, French Guiana, December 25, 2021. Screengrab.

JWST is a 6.5 meter diameter telescope, too big to fit inside the Ariane 5 rocket’s fairing, so it had to be folded. Over the next month it must unfold itself and perform several course corrections, a nerve-wracking period of time NASA calls 29 Days on the Edge.  The telescope has 344 single point failures, 80 percent of which are associated with deployment.

Illustration of the James Webb Space Telescope in its operational configuration, with its 18-segment gold-plated mirror atop the sunshield, which protects the telescope from the light and heat of the Sun. Credit: NASA

The first critical event, deployment of the solar array that powers the telescope, took place about 30 minutes after launch, a little earlier than planned and within view of a camera on the Ariane 5’s upper stage that was sending back video (albeit choppy) of JWST after it separated and was flying free. It was a pleasant surprise to be able to see that happen live.

The next major step is a course correction later today, 12.5 hours after launch.

But that is just the beginning. JWST prime contractor Northrop Grumman has a video showing the carefully choreographed deployment sequence that must follow. NASA has a “where is Webb?” website to keep everyone up to date on how it’s going.

The 6,161 kilogram (13,583 pound) telescope has four instruments to study the universe, including our own solar system and galaxy, in the infrared, which allows it to peer back in time to the beginning of the universe 13.8 billion years ago.

The Near-Infrared Camera (NIRCam) was provided by the University of Arizona, the Near-Infrared Spectrograph (NIRSpec) by ESA, and the Mid-Infrared Instrument (MIRI) jointly by NASA and the European Consortium (led by the U.K.) with ESA. Canada provided the Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph (FGS/NIRISS).

To be able to detect infrared (heat) signatures, the instruments must be very cold. MIRI will operate at 7 degrees Kelvin (-447°F/-266°C). The others operate at 40° K (-387°F/-233°C).

With its 6.5 meter (21.3 feet) diameter mirror, JWST is the largest space telescope ever built and is 100 times more sensitive than Hubble, which has a 2.4 (7.8 feet) meter diameter mirror and instruments that observe primarily in visible light wavelengths.

Now that it is in space, JWST is operated by the Space Telescope Science Institute in Baltimore, MD, which already operates Hubble. Scientists will use it to make observations that will tell the story of the early universe, seeing the first stars and determining how galaxies formed. Thomas Zurbuchen, the head of NASA’s Science Mission Directorate, compares it to filling in missing pages in a photo album. Studies of cosmic background radiation reveal the universe just after the Big Bang. Images from Hubble and data from other telescopes that observe in x-ray and other wavelengths, tell the story of later times. What’s missing are the universe’s “childhood” years. That is the gap JWST will fill.

That is just one area of inquiry, though. More than 4,000 planets have been detected around other stars — exoplanets — and JWST will study the constituents of their atmospheres, which could indicate whether life might exist there. Other scientists want to study planets in our solar system, though they have to be careful not to point the telescope toward objects that are too bright. Basically, JWST will be able to study everything from the beginning of the universe to today and scientists are eager to get started.

They must remain patient for a while yet, though. It will take a month for JWST to reach L2, then about five more months for the telescope and the instruments to cool down to operating temperatures and the 18 mirror segments to be adjusted properly. NASA will be getting telemetry and test data throughout this period, but expects the first usable science image six months from now.

NASA spent $8.8 billion developing JWST, and plans to spend another $900 million for 5 years of operations, bringing the total U.S. cost to $9.7 billion. Canada spent $200 million Canadian ($160 million U.S.) and ESA’s cost is about 700 million Euros ($860 million), though ESA accounts for costs differently so that figure is not directly comparable to NASA’s (European scientists’ salaries are paid by their home institutions, for example, not by ESA).

JWST is billions over budget and years late. Congress imposed an $8 billion development cost cap on the program after yet another overrun in 2010-2011, but had to raise it to $8.8 billion in 2018 when even more problems arose. The project retained congressional support over all those years because the scientific breakthroughs it promises are “worth the wait.”  Now it is time for JWST to deliver.

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