Astronomers Prepare to Turn Webb Telescope Toward Nearby Super-Earths
The James Webb Space Telescope (JWST) has been in space for about six months, which is just a fraction of the time NASA spent designing and building it. All that effort is about to pay off, though. Webb will begin science operations this summer, and some of its first targets will be a pair of nearby exoplanets. These planets, 55 Cancri e and LHS 3844 b are in a category of larger rocky exoplanets known as super-Earths. Webb could provide scientists the best view yet of terrestrial planets outside of our solar system.
NASA designed the JWST as a follow-up to the hugely successful Hubble Space Telescope. While Hubble needed a service mission after launch to work correctly, Webb appears to be a prime example of optical perfection. NASA reports the telescope’s instruments are “diffraction-limited,” which means it’s as good as it can possibly be given the size of the mirror.
So far, we’ve only seen a few test images from Webb, but they already show how much more powerful it is than past instruments. That could be a boon to the study of exoplanets, which are too dim to be observed in detail. However, Webb has a much larger mirror than even Hubble, and it can peer deeply into the infrared part of the light spectrum. That could allow it to collect data from 55 Cancri e and LHS 3844 b like never before.
55 Cancri e orbits a binary star about 41 light years away and is believed to be eight times Earth’s mass. This solar system is home to five known exoplanets, and 55 Cancri e is the innermost. It completes an orbit of the stars once every 18 hours, and scientists believe its surface is molten. However, observations show that heat is distributed away from the sunward side of the alien world. That might be because 55 Cancri e has a thick atmosphere that moves heat around, or it could effectively rain lava across the surface. Researchers will use the Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) to capture thermal emission spectra from 55 Cancri e in hopes of identifying the mechanism for heat bleed.
The other target, LHS 3844 b, is a slightly cooler super-Earth that is only about 30 percent more massive than our planet. It also has a short orbital period (11 hours), but the star (48 light years away) is smaller and cooler than our own. Data from the Spitzer telescope suggest it has no atmosphere, but that could make it easier to gather data on its composition. Thermal emission spectra could be compared to known rocks, and if the planet is volcanically active, Webb might even be able to detect trace gasses expelled from inside the planet.
Astronomers believe getting this data from Webb will help us better understand the nature and evolution of Earth-like planets across the galaxy. There are more than 5,000 known exoplanets, so taking a look at two of them with Webb is just the start.