JWST Getting Closer and Closer to Science Operations

JWST Getting Closer and Closer to Science Operations

The $10 billion James Webb Space Telescope is getting closer and closer to beginning science operations. NASA released another engineering image today to illustrate the clarity JWST will bring to our understanding of the universe, but it is still another two months until everything is ready to deliver scientific-quality data.

Launched on Christmas Day by Europe’s Ariane 5 rocket from French Guiana, the U.S.-European-Canadian space telescope is whetting the appetite of scientists and the public alike with intial images released while it is in the commissiong phase.

Over the past four months, it has successfully reached its destination a million miles from Earth, unfolded in a carefully choreographed sequence, aligned the segments of its primary and secondary mirrors, and cooled down to the very cold temperatures needed for its infrared observations.

Today, NASA, ESA, the Canadian Space Agency (CSA) and the Space Telescope Science Institute (STScI) released an engineering image from the Mid-Infrared Instrument, MIRI, demonstrating how much more crisply it can see the universe compared to the earlier Spitzer space telescope.

Credit: NASA/JPL-Caltech (Spitzer image on the left), NASA/ESA/CSA/STScI (JWST MIRI image on the right)

Both images are of the Large Magellanic Cloud. Spitzer was one of the four Great Observatories launched by NASA in the 1990s and early 2000s to study the universe in the visible (Hubble), gamma ray (Compton), x-ray (Chandra) and infrared (Spitzer) wavelengths. Once called the Space Infrared Telescope Facility (SIRTF), Spitzer was retired in 2020.

Michael McElwain, Webb observatory scientist at NASA’s Goddard Space Flight Center, which manages the JWST program, enthusiastically told reporters today that JWST’s performance is even better than expected — “we basically reached a perfect telescope alignment.” He added that “this is an extraordinary milestone for humanity to have successfully deployed and aligned this large infrared space telescope.”

But it’s not quite ready yet. Another two months of fine-tuning are needed before scientific-quality observations can be made. McElwain said there are about 200 more activities to get through. “While the engineering data that we’ve released is beautiful, there’s more characterization and calibration that we need to do before we’re ready to make science observations.”

JWST has four science instruments:

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

NIRCam, NIRSpec and FGS/NIRSS operate at 40 Kelvin (-387°F/-233°C) and are passively cooled by their exposure to space. MIRI needs to be even colder, 7 Kelvin (-447°F/-266°C), and uses a cryocooler to reach that temperature.

Klaus Pontoppidan, Webb project scientist at STScI, said the first package of science-quality images will be released in mid- July. Those Early Release Observations, or EROs, are specifically intended to demonstrate just what those four instruments can do.

“The EROs is a package of spectacular color images and other data, like spectra. Their objective is to demonstrate at the end of commissioning to the world and to the public that Webb is fully operational and that it produces excellent results. It’s also an opportunity to celebrate the beginning of many years of Webb science.”

The EROs package will “showcase all the four science instruments” and highlight all the Webb science themes from the early universe, to galaxies over time, to the lifecycle of stars, and to other worlds including exoplanets. He declined to say what any of the targets will be for those observations in part because they need to be scheduled once the instruments are ready and in part because “we’d really like it to be a surprise.”

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