The James Webb Space Telescope is about to start looking into deep space in one of the most anticipated missions of recent years.
Five months after launch, and after a million-mile journey to a location that put it into orbit around our sun, the most powerful space telescope ever built is currently undergoing final calibrations of its onboard science instruments. Then, in just a few weeks, the exciting work of trying to unlock the mysteries of our universe will begin.
This week, NASA revealed that the James Webb Space Telescope team has already identified two celestial bodies it wants to explore with the space observatory: the 55 Cancri e covered in lava and the LHS 3844b without air.
Both exoplanets (a planet outside our solar system) are classified as “super-Earths” because of their size and rocky composition. Webb’s team will train the telescope’s high-precision spectrographs on both in hopes of discovering more about the “geological diversity of planets throughout the galaxy and the evolution of rocky planets like Earth.” NASA said.
55 Cancri e is only 1.5 million miles from its sun (we are 93 million miles from our own), and thus has surface temperatures well above the melting point of typical rock-forming minerals. It means that parts of its surface are likely to be covered in oceans of lava.
Webb’s team is eager to find out if 55 Cancri e is tidally locked, resulting in one side always facing its star. Such a state would be typical for planets orbiting so close to a star, but previous observations by NASA’s Spitzer Space Telescope suggest that the hottest part of the planet is far from the area directly facing the star and that the heat on the day side it varies.
This has left scientists wondering if 55 Cancri e has a dynamic atmosphere that changes heat around it. It’s a question Webb’s Near Infrared Camera (NIRCam) and Mid Infrared Instrument (MIRI) should be able to answer by capturing the thermal emission spectrum of the planet’s day side.
Alternatively, it is also possible that the planet is not tidally locked and is actually rotating. In this case, the surface would “heat, melt, and even vaporize during the day, forming a very thin atmosphere that Webb could detect,” NASA said, adding that, at night, the vapor would cool and condense to form “lava droplets that would rain back to the surface, becoming solid again as night falls.” Once again, the team plans to use Webb’s NIRCam to determine if this is the case.
The much smaller and cooler LHS 3844 b offers Webb scientists the opportunity to take a closer look at the solid rock on the surface of an exoplanet. Different types of rock have different spectra, so Webb’s team plans to use MIRI to learn more about the planet’s composition.
MIRI will capture the thermal emission spectrum from the dayside of LHS 3844 and compare it to spectra of known rocks, such as basalt and granite, to determine their composition, NASA said.
Webb’s observations of the two exoplanets are expected to help scientists in much broader ways. “They will give us fantastic new insights into Earth-like planets in general, helping us learn what early Earth might have looked like when it was hot like these planets are today,” said Laura Kreidberg of the Max Planck Institute for Astronomy.
The James Webb Space Telescope mission also aims to track the first galaxies formed after the Big Bang, discover how galaxies evolved from formation to now, and measure the physical and chemical properties of planetary systems, among other goals.