Laurence Malcom
Since its launch in 2021, the James Webb Space Telescope (JWST) has removed every target NASA has set for it. It’s fully exposed, perfectly aligned and patrols a Sun-Earth L2 point at a moderate 6K. Now, NASA has released the first gorgeous, crystal clear images from Webb. They compare what the Spitzer and Webb Space Telescopes see when they look at the same spot in the sky. The difference is amazing. Web visibility makes Spitzer look like a VHS tape.
At a press conference Monday, Webb Project scientists broke down the telescope’s mission milestones so far. And the news is all good! The shiny new telescope is in its final stage of operation, as it calibrates and tests its instruments before it goes into operation. Last week, Webb began testing his precision five-layer sunscreen with a series of micro-cycles. Now is the time to bring the four science telescope instruments into collective harmony. First in line is MIRI, Webb’s middle infrared eye.
MIRI, a joint project between NASA and ESA, is Webb’s “coldest instrument.” The telescope must be extremely cold precisely because it sees infrared radiation. If it were warmer than fifty degrees Kelvin or so (-369 farahanheit), its radiant infrared glow would blind it. But there is another reason for its thermal intensity.
Webb has to keep his hardware cool enough to suppress something called the “dark stream”. NASA explains that the dark current is the electric current generated by the vibration of atoms in the detectors themselves. It can simulate much of the ambient energy inside the ping detector for a real photon. MIRI is wonderfully sensitive, so it is susceptible to false positives from the dark current.
First photos from Webb’s camera roll
These first images from the Web show our neighboring galaxy, the Large Magellanic Cloud. Images tuned to 8.0 μm show a gentle infrared glow from clouds of polycyclic aromatic hydrocarbons (PAHs). These organic molecules are sometimes called the “building blocks of life.”
The Large Magellanic Cloud thrives in clarity as this image transitions from what Spitzer saw to what Webb saw.
Webb is designed and built to capture the faintest glow of residual warmth from things like planets, stars, and gas clouds. As it searches for such long wavelengths of light, it can peer straight through obscured expanses of cold dust and debris.
JWST is often mentioned on the same page as Hubble and Spitzer, two of NASA’s Big Four observatories. These powerful space telescopes are designed to soar above the light pollution, interference and atmospheric haze that defy ground-based observatories. Webb, like Spitzer, sees mostly in the infrared, where Hubble can pick up the visible spectrum and some near ultraviolet radiation.
But the James Webb Space Telescope absolutely blows Spitzer when it comes to image quality. Webb focuses on his giant, flawless mirror by machining with nanometer precision. That’s why it produces images with such elegant clarity.
Orbital dynamics
In a restricted three-body system, such as the Sun, Earth, and a space telescope, there are five points of orbital equilibrium, which we call Lagrangian points. NASA loves Lagrange points. Of all the gin joints in all cities around the world, Webb orbits in L2, and his causes have everything to do with orbital dynamics.
JWST is stationed at Earth-Sun L2 point. This means that the Earth is always directly between the telescope and the sun. Thus, the telescope enjoys a permanent midnight in the deepest part of the Earth’s cold shadow.
But there is another reason why Webb is in place at L2. L4 and L5 are shallow gravitational wells in which orbital debris accumulates. In turn, L2 removes itself; It throws matter at the slightest disturbance. That’s why Webb is in orbit About L2, rather than just spinning around L2 itself. That way, she doesn’t have to deal with a constant barrage of debris.
But don’t let that make you think that L4 and L5 are places to avoid. Outside of JWST, NASA uses other Lagrange points from the Earth and the Sun to do all kinds of science. For example, the SOHO orbital vehicle Watching the solar wind from L1. And the scientific reward does not stop at the Earth’s orbit. All other planets in the solar system have their own L1-L5 points with respect to the Sun. Since the same rules of gravity apply there, it’s easy to use Lagrange points as a “gravity slingshot” for a deep-space probe. NASA’s ongoing Lucy mission has sent a probe to the Trojan asteroids, which live in Jupiter L4 and L5.
Pictures: NASA/JPL-Caltech (Spitzer), NASA/ESA/CSA/STScI (Webb).
