James Webb Space Telescope on Track to Launch Dec. 22

When the James Webb Space Telescope (JWST) was conceived, the first exoplanet had only just been discovered. Now we have thousands of examples of these distant worlds. Luckily, it turns out that even though this instrument was designed for a different era to answer different questions, it is also an excellent tool for advancing exoplanetary science. This week, our newest recruit at PVL considers the upcoming launch of this greatly anticipated new space observatory.
(Above: JWST during testing. Image by Northrop Grumman)

 by Madeline Walters

The James Webb Space Telescope (JWST) is NASA's most powerful space science telescope ever constructed. In partnership with the European Space Agency (ESA) and the Canadian Space Agency (CSA), the telescope will provide improved infrared resolution over Hubble, and will give us a glimpse at some of the most distant objects in the universe, such as potentially habitable exoplanets. Unlike the Hubble telescope, the JWST observes in a lower frequency (higher wavelength) range, allowing it to observe objects that are too old and far away for Hubble to observe. The development for the telescope began in 1996, and the initial launch was planned for 2007, but this ended up being delayed due to cost and construction issues. Now, after many delays, the final launch date has been set for December 22nd. 

One important problem the JWST might help us solve is the issue in figuring out how a specific type of exoplanet, sub-Neptunes, are formed. These planets are larger than Earth and smaller than Neptune, though researchers have found it difficult to understand how they form. The key to understanding the formation of sub-Neptunes is their atmospheres, using a technique called transmission spectroscopy to figure out what an atmosphere is made of based on transmission spectrum patterns. 

Though transmission spectroscopy has been successful for other types of exoplanets, it's difficult to use on sub-Neptunes due to an abundance of aerosols which scatter the light from their stars, making the determination of specific spectra impossible. With the JWST, however, researchers will be able to get a clearer view of these planets, using the telescope's specific frequency sensors to more closely examine the atmospheres. 

One research team will use the JWST's Mid-Infrared Instrument (MIRI) to observe a sub-Neptune, GJ 1214 b, orbiting a nearby red dwarf star. The team plans on observing the system for a continuous 50 hours, around the amount of time it takes for GJ 1214 b to complete a full orbit, and then analyze the collected data to learn about the atmosphere. One way the team will analyse the data is by using transmission spectroscopy, as mid-infrared light shouldn't be scattered in the same way as near infrared light by any of the atmosphere's aerosols. Using the mid-infrared light emitted by the planet due to the absorption and release of radiation from its star, the team will also use thermal emission spectroscopy to learn about the planet's temperature and light reflectivity. Using a technique called phase curve temperature mapping, they will also be able to determine the average surface temperature with respect to longitude using the telescope's sensitive instruments, providing important information about the contents of the planet's atmosphere. 

Due to a delay caused by some vibrations, the launch date of the JWST was moved to December 22nd, though if all goes well, we should be able to watch the launch of the telescope in a few weeks. The revolutionary technology aboard the telescope brings us a new era of space observation and will shed some light on previously unknown cosmic history. Being able to learn more about exoplanets, and unravel secrets about the beginning of time; the JWST will be an extremely powerful tool that helps us answer important questions about the origins of the universe and our place in it.