From The NASA/ESA/CSA James Webb Space Telescope: “Geology from 50 Light Years- Webb Gets Ready to Study Rocky Worlds”
National Aeronautics Space Agency/European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganisation](EU)/ Canadian Space Agency [Agence Spatiale Canadienne](CA) James Webb Infrared Space Telescope annotated, finally launched December 25, 2021, ten years late.
From The NASA/ESA/CSA James Webb Space Telescope
May 26, 2022
MEDIA CONTACT:
Margaret W. Carruthers
Space Telescope Science Institute, Baltimore, Maryland
Christine Pulliam
Space Telescope Science Institute, Baltimore, Maryland
Illustration of Exoplanet 55 Cancri e and Its Star.
About This Image
Illustration showing what exoplanet 55 Cancri e could look like, based on current understanding of the planet.
55 Cancri e is a rocky planet with a diameter almost twice that of Earth orbiting just 0.015 astronomical units from its Sun-like star. Because of its tight orbit, the planet is extremely hot, with dayside temperatures reaching 4,400 degrees Fahrenheit (about 2,400 degrees Celsius).
Although previous studies have ruled out a thick hydrogen, carbon dioxide, or water atmosphere, it is possible that the planet has a substantial atmosphere made of oxygen or nitrogen, or a very thin atmosphere of mineral vapor, such as silicon oxide.
Researchers think that if the planet is tidally locked, the lit surface must be permanently molten. If the planet is not locked, it would experience day-night cycles, with the surface heating up and melting during the day, and cooling and solidifying at night. The extreme heat during the day would also cause some of the molten rock to vaporize, forming a very tenuous mineral vapor atmosphere. In the evening, this vapor would condense and fall as a rain of lava back onto the surface, where it would turn solid overnight.
Spectroscopic observations using Webb’s Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) will help determine whether or not the planet has an atmosphere, and if so, what that atmosphere is made of. The observations will also help determine whether or not the planet is tidally locked. Credits: ARTWORK: NASA, ESA, CSA, Dani Player (STScI).
Illustration of Exoplanet LHS 3844 b and Its Star.
About This Image
Illustration showing what exoplanet LHS 3844 b could look like, based on current understanding of the planet.
LHS 3844 b is a rocky planet with a diameter 1.3 times that of Earth orbiting 0.006 astronomical units from its cool red dwarf star. The planet is hot, with dayside temperatures calculated to be greater than 1,000 degrees Fahrenheit (greater than about 525 degrees Celsius).
Previous studies show that the planet is unlikely to have a substantial atmosphere and that the surface may be composed of dark, perhaps basaltic, rock.
Observations of the planet’s thermal emission spectrum using Webb’s Mid-Infrared Instrument (MIRI) will provide more evidence to help determine what the surface is made of. Credits: ARTWORK: NASA, ESA, CSA, Dani Player (STScI).
Simulated Thermal Emission Spectrum of Exoplanet LHS 3844 b.
About This Image
Possible thermal emission spectrum of the hot super-Earth exoplanet LHS 3844 b, as measured by Webb’s Mid-Infrared Instrument. A thermal emission spectrum shows the amount of light of different infrared wavelengths (colors) that are emitted by the planet. Researchers use computer models to predict what a planet’s thermal emission spectrum will look like assuming certain conditions, such as whether or not there is an atmosphere and what the surface of the planet is made of.
This particular simulation assumes that LHS 3844 b has no atmosphere and the day side is covered in the dark volcanic rock basalt. (Basalt is the most common volcanic rock in our solar system, making up volcanic islands like Hawaii and most of Earth’s ocean floor, as well as large portions of the surfaces of the Moon and Mars.)
For comparison, the gray line represents a model spectrum of basaltic rock based on laboratory measurements. The pink line is the spectrum of granite, the most common igneous rock found on Earth’s continents. The two types of rock have very different spectra because they are made of different minerals, which absorb and emit different amounts of different wavelengths of light.
After Webb observes the planet, researchers will compare the actual spectrum to model spectra of various rock types like these to figure out what the surface of the planet is made of. Credits: ILLUSTRATION: NASA, ESA, CSA, Dani Player (STScI)
SCIENCE: Laura Kreidberg (MPI-A), Renyu Hu (NASA-JPL).
Summary
Researchers will train Webb’s high-precision spectrographs on two intriguing rocky exoplanets: 55 Cancri e and LHS 3844 b.
Comparison of Exoplanets 55 Cancri e and LHS 3844 b to Earth and Neptune.
About This Image
Illustration comparing rocky exoplanets LHS 3844 b and 55 Cancri e to Earth and Neptune. Both 55 Cancri e and LHS 3844 b are between Earth and Neptune in terms of size and mass, but they are more similar to Earth in terms of composition.
The planets are arranged from left to right in order of increasing radius.
Image of Earth from the Deep Space Climate Observatory: Earth is a warm, rocky planet with a solid surface, water oceans, and a dynamic atmosphere.
Illustration of LHS 3844 b: LHS 3844 b is a hot, rocky exoplanet with a solid, rocky surface. The planet is too hot for oceans to exist and does not appear to have any significant atmosphere.
Illustration of 55 Cancri e: 55 Cancri e is a rocky exoplanet whose dayside temperature is high enough for the surface to be molten. The planet may or may not have an atmosphere.
Image of Neptune from Voyager 2: Neptune is a cold ice giant with a thick, dense atmosphere.
The illustration shows the planets to scale in terms of radius, but not location in space or distance from their stars. While Earth and Neptune orbit the Sun, LHS 3844 b orbits a small, cool red dwarf star about 49 light-years from Earth, and 55 Cancri e orbits a Sun-like star roughly 41 light-years away. Both are extremely close to their stars, completing one orbit in less than a single Earth day. Credits: ILLUSTRATION: NASA, ESA, CSA, Dani Player (STScI).
Imagine if Earth were much, much closer to the Sun. So close that an entire year lasts only a few hours. So close that gravity has locked one hemisphere in permanent searing daylight and the other in endless darkness. So close that the oceans boil away, rocks begin to melt, and the clouds rain lava.
While nothing of the sort exists in our own solar system, planets like this—rocky, roughly Earth-sized, extremely hot and close to their stars—are not uncommon in the Milky Way galaxy.
What are the surfaces and atmospheres of these planets really like? NASA’s James Webb Space Telescope is about to provide some answers.
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With its mirror segments beautifully aligned and its scientific instruments undergoing calibration, NASA’s James Webb Space Telescope is just weeks away from full operation. Soon after the first observations are revealed this summer, Webb’s in-depth science will begin.
Among the investigations planned for the first year are studies of two hot exoplanets classified as “super-Earths” for their size and rocky composition: the lava-covered 55 Cancri e and the airless LHS 3844 b. Researchers will train Webb’s high-precision spectrographs on these planets with a view to understanding the geologic diversity of planets across the galaxy, and the evolution of rocky planets like Earth.
Super-Hot Super-Earth 55 Cancri e
55 Cancri e orbits less than 1.5 million miles from its Sun-like star (one twenty-fifth of the distance between Mercury and the Sun), completing one circuit in less than 18 hours. With surface temperatures far above the melting point of typical rock-forming minerals, the day side of the planet is thought to be covered in oceans of lava.
Planets that orbit this close to their star are assumed to be tidally locked, with one side facing the star at all times. As a result, the hottest spot on the planet should be the one that faces the star most directly, and the amount of heat coming from the day side should not change much over time.
But this doesn’t seem to be the case. Observations of 55 Cancri e from NASA’s Spitzer Space Telescope suggest that the hottest region is offset from the part that faces the star most directly, while the total amount of heat detected from the day side does vary.
Does 55 Cancri e Have a Thick Atmosphere?
One explanation for these observations is that the planet has a dynamic atmosphere that moves heat around. “55 Cancri e could have a thick atmosphere dominated by oxygen or nitrogen,” explained Renyu Hu of NASA’s Jet Propulsion Laboratory in Southern California, who leads a team that will use Webb’s Near-Infrared Camera (NIRCam) [below] and Mid-Infrared Instrument (MIRI) [below] to capture the thermal emission spectrum of the day side of the planet. “If it has an atmosphere, [Webb] has the sensitivity and wavelength range to detect it and determine what it is made of,” Hu added.
Or Is It Raining Lava in the Evening on 55 Cancri e?
Another intriguing possibility, however, is that 55 Cancri e is not tidally locked. Instead, it may be like Mercury, rotating three times for every two orbits (what’s known as a 3:2 resonance). As a result, the planet would have a day-night cycle.
“That could explain why the hottest part of the planet is shifted,” explained Alexis Brandeker, a researcher from Stockholm University who leads another team studying the planet. “Just like on Earth, it would take time for the surface to heat up. The hottest time of the day would be in the afternoon, not right at noon.”
Brandeker’s team plans to test this hypothesis using NIRCam to measure the heat emitted from the lit side of 55 Cancri e during four different orbits. If the planet has a 3:2 resonance, they will observe each hemisphere twice and should be able to detect any difference between the hemispheres.
In this scenario, the surface would heat up, melt, and even vaporize during the day, forming a very thin atmosphere that Webb could detect. In the evening, the vapor would cool and condense to form droplets of lava that would rain back to the surface, turning solid again as night falls.
Somewhat Cooler Super-Earth LHS 3844 b
While 55 Cancri e will provide insight into the exotic geology of a world covered in lava, LHS 3844 b affords a unique opportunity to analyze the solid rock on an exoplanet surface.
Like 55 Cancri e, LHS 3844 b orbits extremely close to its star, completing one revolution in 11 hours. However, because its star is relatively small and cool, the planet is not hot enough for the surface to be molten. Additionally, Spitzer observations indicate that the planet is very unlikely to have a substantial atmosphere.
What Is the Surface of LHS 3844 b Made of?
While we won’t be able to image the surface of LHS 3844 b directly with Webb, the lack of an obscuring atmosphere makes it possible to study the surface with spectroscopy.
“It turns out that different types of rock have different spectra,” explained Laura Kreidberg at the Max Planck Institute for Astronomy. “You can see with your eyes that granite is lighter in color than basalt. There are similar differences in the infrared light that rocks give off.”
Kreidberg’s team will use MIRI to capture the thermal emission spectrum of the day side of LHS 3844 b, and then compare it to spectra of known rocks, like basalt and granite, to determine its composition. If the planet is volcanically active, the spectrum could also reveal the presence of trace amounts of volcanic gases.
The importance of these observations goes far beyond just two of the more than 5,000 confirmed exoplanets in the galaxy. “They will give us fantastic new perspectives on Earth-like planets in general, helping us learn what the early Earth might have been like when it was hot like these planets are today,” said Kreidberg.
These observations of 55 Cancri e and LHS 3844 b will be conducted as part of Webb’s Cycle 1 General Observers program. General Observers programs were competitively selected using a dual-anonymous review system, the same system used to allocate time on Hubble.
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The NASA/ESA/CSA James Webb Space Telescope is a large infrared telescope with a 6.5-meter primary mirror. Webb was finally launched December 25, 2021, ten years late. The James Webb Space Telescope will be the premier observatory of the next decade, serving thousands of astronomers worldwide. It will study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System.
The James Webb Space Telescope is the world’s largest, most powerful, and most complex space science telescope ever built. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it.
Webb telescope will be the premier observatory of the next decade, serving thousands of astronomers worldwide. It will study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System.
Webb telescope was formerly known as the “Next Generation Space Telescope” (NGST); it was renamed in Sept. 2002 after a former NASA administrator, James Webb.
Webb is an international collaboration between National Aeronautics and Space Administration, the European Space Agency (ESA), and the Canadian Space Agency (CSA). The NASA Goddard Space Flight Center managed the development effort. The main industrial partner is Northrop Grumman; the Space Telescope Science Institute will operate Webb after launch.
Several innovative technologies have been developed for Webb. These include a folding, segmented primary mirror, adjusted to shape after launch; ultra-lightweight beryllium optics; detectors able to record extremely weak signals, microshutters that enable programmable object selection for the spectrograph; and a cryocooler for cooling the mid-IR detectors to 7K.
There are four science instruments on Webb: The Near InfraRed Camera (NIRCam), The Near InfraRed Spectrograph (NIRspec), The Mid-InfraRed Instrument (MIRI), and The Fine Guidance Sensor/ Near InfraRed Imager and Slitless Spectrograph (FGS-NIRISS). Webb’s instruments are designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range. It will be sensitive to light from 0.6 to 28 micrometers in wavelength.
National Aeronautics Space Agency Webb NIRCam.
The European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganisation](EU) Webb NIRspec.
The European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganisation](EU) Webb MIRI schematic.
Webb Fine Guidance Sensor-Near InfraRed Imager and Slitless Spectrograph FGS/NIRISS.
Webb has four main science themes: The End of the Dark Ages: First Light and Reionization, The Assembly of Galaxies, The Birth of Stars and Protoplanetary Systems, and Planetary Systems and the Origins of Life.
Launch was December 25, 2021 on an Ariane 5 rocket. The launch was from Arianespace’s ELA-3 launch complex at European Spaceport located near Kourou, French Guiana. Webb is located at the second Lagrange point, about a million miles from the Earth.
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