All of the modes James Webb instruments will use to study the universe
With the James Webb Space Telescope now fully aligned and capturing crisp images, the team has moved on to getting its instruments calibrated. While this process is ongoing, NASA has shared an update about the 17 different modes that will be possible using Webb’s four instruments, with examples of what kind of scientific research will be possible with each.
As the engineers work on calibrating Webb’s instruments, they will check through each of the 17 modes and make sure it is ready for science operations to begin this summer.
Near-Infrared Camera (NIRCam) modes:
- Imaging. This instrument takes pictures in the near-infrared wavelength, and will be Webb’s main camera function. It will be used to take images of both individual galaxies and deep fields, such as the Hubble Ultra-Deep Field.
- Wide field slitless spectroscopy. This mode, in which light is split into different wavelengths, was originally intended just for aligning the telescope, but scientists realized they could also use it for science-related tasks such as observing distant quasars.
- Coronagraphy. Some sources of light, like stars, are very bright and glare from them covers up fainter light sources nearby. This mode places a disk to block out a bright light source so dimmer objects can be seen, such as exoplanets orbiting around bright stars.
- Time series observations – imaging. This mode is used to observe objects that change quickly, like magnetars.
- Time series observations – grism. This mode can look at light coming through the atmosphere of exoplanets to learn about what the atmosphere is made up of.
Near-Infrared Spectrograph (NIRSpec) modes:
- Multi-object spectroscopy. This instrument is outfitted with a special microshutter array, in which thousands of tiny windows, each around the width of a human hair, can be opened or closed individually. This allows the instrument to observe up to 100 objects at the same time, meaning it can collect data far faster than previous instruments. It will be used to capture deep field images like one of a region called the Extended Groth Strip.
- Fixed slit spectroscopy. Instead of looking at many targets at once, this mode uses fixed slits for very sensitive readings for individual targets, such as looking at light from sources of gravitational waves called kilonovas.
- Integral field unit spectroscopy. This mode looks at light coming from a small area instead of a single point, which allows researchers to get an overall look at objects such as distant galaxies that appear larger due to an effect called gravitational lensing.
- Bright object time series. This mode allows researchers to look at objects that change quickly over time, such as an exoplanet in a full orbit of its star.
Near-Infrared Imager and Slitless Spectrograph (NIRISS) modes:
- Single object slitless spectroscopy. This mode blurs out light from very bright objects so researchers can look at smaller objects, like rocky Earth-like plants in the TRAPPIST system.
- Wide field slitless spectroscopy. This type of spectroscopy is used to look at the most distant galaxies, like those we don’t yet know about.
- Aperture masking interferometry. This mode blocks out light from some of the 18 segments of Webb’s primary mirror to allow high-contrast imaging, like looking at a binary star system where stellar winds from each star are colliding.
- Imaging. This mode is a backup for the NIRCam imaging that can be used when the other instruments are already in use. It will be used to image targets like a gravitationally lensing galaxy cluster.
Mid-Infrared Instrument (MIRI) modes:
- Imaging. MIRI works in the mid-infrared wavelength, which is useful for looking at features like dust and cold gas, and will be used on such targets as the nearby galaxy Messier 33.
- Low-resolution spectroscopy. This mode is for looking at faint sources, like an object’s surface to see its composition, and will be used to study objects like a tiny moon orbiting Pluto called Charon.
- Medium-resolution spectroscopy. This mode is better for brighter sources, and will be used to look at targets like the disks of matter from which planets form.
- Coronagraphic imaging. Like NIRCam, MIRI also has cornographic modes that can block out bright sources and which will be used to hunt for exoplanets around the nearby star Alpha Centauri A.
To see the progress being made on getting all 17 of these modes ready, you can follow along using the Where is Webb tracker, which shows deployment status as each mode is ready for operations.
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May 14, 2022 at 10:00AM