The James Webb Space Telescope plans to explore strange new rocky worlds in unprecedented detail.
The telescope scientific consortium has an ambitious agenda to perform geology on these tiny planets from “50 light-years away,” they said in a statement Thursday (May 26). The works will represent a major effort for the new observatory, which should come out of commissioning in a few weeks.
Rocky planets are harder to spot than gas giants in current telescope technology, due to the relative brightness of smaller planets near a star and their relatively small size. But Webb’s powerful mirror and deep space location should allow him to examine two planets slightly larger than Earth, known as “super-Earths”.
None of these worlds are as habitable as we know them, but studying them could still be a test bed for future in-depth studies on planets like ours. The two planets highlighted by Webb officials include the super-hot 55 Cancri and lava-capped and LHS 3844 b, which lacks a substantial atmosphere.
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55 Cancri and orbits its parent star at a distance of 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 have also speculated that the planet is bound to the star, which means that one side is always facing the scorching sun, although observations from NASA’s Spitzer Space Telescope suggest that the hottest zone may be slightly offset.
Scientists say the compensated heat could be due to a thick atmosphere that can move heat around the planet, or because it rains lava at night in a process that removes heat from the atmosphere. (Nocturnal lava also suggests a day-night cycle, which could be due to a 3: 2 resonance, or three rotations for every two orbits, which we see on Mercury in our solar system.)
Two teams will test these hypotheses: one led by researcher Renyu Hu of NASA’s Jet Propulsion Laboratory will examine the planet’s thermal emission for signs of the atmosphere, while a second team led by Alexis Brandeker, associate professor at Stockholm University, will measure the heat emitted from the illuminated side of 55 Cancri e.
LHS 3844 b is also a close orbiter, moving around its parent star only once every 11 hours. The star, on the other hand, is smaller and cooler than that of 55 Cancri e. So the planet’s surface is likely much cooler, and Spitzer’s observations have shown that there is probably no substantial atmosphere present on the planet.
A team led by astronomer Laura Kreidberg of the Max Planck Institute for Astronomy hopes to capture a surface signal using spectroscopy, in which different wavelengths of light suggest different elements. The thermal emission spectra of the day side of the planet will be compared with known rocks such as basalt and granite to see if they can deduce a surface composition.
The two investigations “will provide us with fantastic new perspectives on Earth-like planets in general, helping us understand what the early Earth might have looked like when it was as hot as these planets are today,” Kreidberg said in the same statement.
Webb is now working with the final stage commissioning procedures, such as detecting targets in the solar system and switching from warmer to cooler attitudes to test the strength of his mirror and instrument alignment. The $ 10 billion observatory is expected to finish commissioning around June and transition to its Cycle 1 of observations shortly thereafter.