The launch of the James Webb Space Telescope (JWST) on Christmas Day made history, representing the most powerful telescope humanity has ever put into space. But, receiving data from the $10 billion NASA telescope is a waiting game that will follow the telescope reaching its destination being brought online and rigorously tested.
“Approximately the first six months after JWST launches will be mostly getting it to L2, unfolding the mirror and the layers of heat shields, and setting up and testing the instruments,” professor of physics and astrophysics at the University of California, Santa Cruz, Joel Primack told Newsweek. “The next months will be devoted to making the first observations, mostly of distant galaxies.”
The first step in the JWST set-up is its journey to the vantage point from which it will observe the Universe, the gravitationally stable point that exists between the sun and the Earth known as the Lagrange Point 2 (L2).
As L2 is located about 930,000 miles from Earth the journey will take the JWST at least 29 days. But, this won’t be an uneventful period for the JWST, as it travels the craft and its mission team will have to perform several important deployments and operations.
JWST mission systems engineer at NASA’s Goddard Space Flight Center, Mike Menzel, explained in a video uploaded to YouTube: “The Webb Observatory has about 50 major deployments.
“And 178 release mechanisms must work to deploy those 50 parts. Every single one of them must work. Unfolding Webb is hands down, the most complicated spacecraft activity we’ve ever done.”
The first of these major milestones have been completed with the unfolding of the five layers of the sun shield.
When the JWST reaches L2 it will undergo months of science and calibration testing. The JWST website echoes Primack’s prediction of a six-month period from launch to the capturing of images but adds that a series of “first light” images may come first.
When these first observations of the Universe actually begin to come through, what will astronomers by using them for, and how do they differ from the observations delivered by the current crop of space and ground-based telescopes?
What Will Astronomers Use the JWST For?
“What JWST will give astronomers is mainly, much better images and spectra of galaxies whose light started toward us more than about 2 billion years after the big bang,” Primack explained.
The reason that the JWST will allow astronomers to look back further in time than previously possible is that it is able to observe the cosmos in infrared regions of the electromagnetic spectrum, at longer wavelengths than its predecessor, the Hubble Space Telescope (HST).
This allows it to see objects at greater distances—and thus further back in cosmic history thanks to the time it takes light to travel to us—than Hubble because very distant objects, like galaxies that existed in the early Universe, undergo a process called redshift.
The wavelength of light from cosmic objects moving away from us is stretched giving it a longer wavelength and lower frequency, moving it towards the red end of the electromagnetic spectrum. That means visible light from stars in distant galaxies is “shifted” down to the infrared region of the electromagnetic spectrum.
Because of the accelerating expansion of the Universe, not only are truly distant objects always redshifted, but the more distant they are, the greater the redshift. This means the optical light from the earliest galaxies and their stars is redshifted to very-long wavelengths.
Primack told Newsweek: “The JWST can see much longer wavelengths of infrared light than HST. With HST we can only see ultraviolet light from such distant galaxies, which redshifts into the visible and near-infrared wavelengths that HST can see.
“Such ultraviolet light is generated by the most massive stars, whose lifetimes are mostly less than about 10 million years, so with HST we mainly see where new stars are forming in such distant galaxies.”
The JWST is so powerful that it will be viewing galaxies as they existed as early as 100 million years after the Big Bang.
This means seeing how our 13.8 billion-year-old Universe was in its infancy.
Primack also points out that the JWST will be vital for investigating the atmospheres around distant exoplanets. This could include spotting complex organic molecules in the atmospheres of these planets outside the solar system, with such molecules possibly indicating the presence of life elsewhere in the Milky Way.