James Webb Space Telescope Set to Study Two Strange Super-Earths

James Webb Space Telescope Set to Study Two Strange Super-Earths thumbnail


Space agency officials promise to deliver geology results from worlds dozens of light-years away

An artist’s concept of the exoplanet 55 Cancri e, an extremely hot rocky planet almost twice the diameter of Earth that will soon be scrutinized by the James Webb Space Telescope. Credit: Mark Garlick/Science Photo Library/Alamy Stock Photo

The James Webb Space Telescope plans to explore strange, new rocky worlds in unprecedented detail.

The telescope’s scientific consortium has an ambitious agenda to study geology on these small planets from “50 light-years away”, they said in a statement Thursday (May 26). The new observatory will have to do a lot of work, and should be completed in a few weeks.

Rocky are harder to see than gas giants with current telescope technology. This is due to their smaller size and relative brightness next to a star. But Webb’s powerful mirror and deep-space location should allow it to examine two planets slightly larger than Earth, known as “super-Earths.”

While neither of these worlds are habitable, they could be used as a starting point for future deep-dive studies of other planets. The two planets Webb officials highlighted include the super-hot, lava-covered 55 Cancri e, and LHS 3844 b, which lacks a substantial atmosphere.

55 Cancri e orbits its parent star at a tight 1.5 million miles (2.4 million km), about four percent of the relative distance between Mercury and the sun.

Circling its star only once every 18 hours, the planet has blast furnace surface temperatures above the melting point of most types of rocks. Scientists also assumed the planet is tidally locked to the star, meaning one side always faces the scorching sun, although observations from NASA’s Spitzer Space Telescope suggest the hottest zone might be slightly offset.

Scientists believe that the offset heat could be caused by a thick atmosphere that can move heat around planets or because it rains lava at nights in a process that removes heat. (The nighttime lava also suggests a day-night cycle, which might be due to a 3:2 resonance, or three rotations for every two orbits, that we see on Mercury in our own solar system. )

Two teams will test these hypotheses: one led by research scientist Renyu Hu of NASA’s Jet Propulsion Laboratory will examine the planet’s thermal emission for signs of an atmosphere, while a second team led by Alexis Brandeker, an associate professor from Stockholm University, will measure heat emittance from the lit side of 55 Cancri e.

LHS 3844 b is also a close orbiter, moving around its parent star just once every 11 hours. The star, however, is smaller and cooler than that of 55 Cancri e. So the planet’s surface is likely much cooler, and Spitzer observations have shown there is likely no substantial atmosphere present on the planet.

A team headed by Laura Kreidberg, an astronomer at the Max Planck Institute for Astronomy, hopes to capture a signal from the surface using spectroscopy. Different wavelengths of light indicate different elements. To determine the composition of the planet’s surface, they will compare its thermal emission spectrums with known rocks like granite and basalt.

The two investigations “will provide us with fantastic new perspectives on Earthlike planets in general,” Kreidberg stated in the same statement.

Webb is now working through latter-stage commissioning procedures like tracking targets in the solar system and moving between hotter and colder attitudes to test the strength of its mirror and instrument alignment. The $10 billion observatory should finish its commissioning around June or so and move into its Cycle 1 of observations shortly afterwards.

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