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Explore This Section Webb News Latest News Latest Images Webb’s Blog Awards X (offsite – login reqd) Instagram (offsite – login reqd) Facebook (offsite- login reqd) Youtube (offsite) Overview About Who is James Webb? Fact Sheet Impacts+Benefits FAQ Science Overview and Goals Early Universe Galaxies Over Time Star Lifecycle Other Worlds Observatory Overview Launch Deployment Orbit Mirrors Sunshield Instrument: NIRCam Instrument: MIRI Instrument: NIRSpec Instrument: FGS/NIRISS Optical Telescope Element Backplane Spacecraft Bus Instrument Module Multimedia About Webb Images Images Videos What is Webb Observing? 3d Webb in 3d Solar System Podcasts Webb Image Sonifications Team International Team People Of Webb More For the Media For Scientists For Educators For Fun/Learning 6 Min Read NASA’s Webb Lifts Veil on Common but Mysterious Type of Exoplanet
This artist’s concept shows what the hot sub-Neptune exoplanet TOI-421 b could look like. It is based on spectroscopic data gathered by Webb, as well as previous observations from other telescopes on the ground and in space. Credits:
Illustration: NASA, ESA, CSA, Dani Player (STScI) Though they don’t orbit around our Sun, sub-Neptunes are the most common type of exoplanet, or planet outside our solar system, that have been observed in our galaxy. These small, gassy planets are shrouded in mystery…and often, a lot of haze. Now, by observing exoplanet TOI-421 b, NASA’s James Webb Space Telescope is helping scientists understand sub-Neptunes in a way that was not possible prior to the telescope’s launch.
“I had been waiting my entire career for Webb so that we could meaningfully characterize the atmospheres of these smaller planets,” said principal investigator Eliza Kempton of the University of Maryland, College Park. “By studying their atmospheres, we’re getting a better understanding of how sub-Neptunes formed and evolved, and part of that is understanding why they don’t exist in our solar system.”
Image A: Artist’s Concept of TOI-421 b
This artist’s concept shows what the hot sub-Neptune exoplanet TOI-421 b could look like. It is based on spectroscopic data gathered by Webb, as well as previous observations from other telescopes on the ground and in space. Illustration: NASA, ESA, CSA, Dani Player (STScI) Small, Cool, Shrouded in Haze
The existence of sub-Neptunes was unexpected before they were discovered by NASA’s retired Kepler space telescope in the last decade. Now, astronomers are trying to understand where these planets came from and why are they so common.
Before Webb, scientists had very little information on them. While sub-Neptunes are a few times larger than Earth, they are still much smaller than gas-giant planets and typically cooler than hot Jupiters, making them much more challenging to observe than their gas-giant counterparts.
A key finding prior to Webb was that most sub-Neptune atmospheres had flat or featureless transmission spectra. This means that when scientists observed the spectrum of the planet as it passed in front of its host star, instead of seeing spectral features – the chemical fingerprints that would reveal the composition of the atmosphere – they saw only a flat-line spectrum. Astronomers concluded from all of those flat-line spectra that at least certain sub-Neptunes were probably very highly obscured by either clouds or hazes.
Image B: Spectrum of TOI-421 b
A transmission spectrum captured by NASA’s James Webb Space Telescope reveals chemicals in the atmosphere of the hot sub-Neptune exoplanet TOI-421 b. Illustration: NASA, ESA, CSA, Joseph Olmsted (STScI) A Different Kind of Sub-Neptune?
“Why did we observe this planet, TOI-421 b? It’s because we thought that maybe it wouldn’t have hazes,” said Kempton. “And the reason is that there were some previous data that implied that maybe planets over a certain temperature range were less enshrouded by haze or clouds than others.”
That temperature threshold is about 1,070 degrees Fahrenheit. Below that, scientists hypothesized that a complex set of photochemical reactions would occur between sunlight and methane gas, and that would trigger the haze. But hotter planets shouldn’t have methane and therefore perhaps shouldn’t have haze.
The temperature of TOI-421 b is about 1,340 degrees Fahrenheit, well above the presumed threshold. Without haze or clouds, researchers expected to see a clear atmosphere – and they did!
A Surprising Finding
“We saw spectral features that we attribute to various gases, and that allowed us to determine the composition of the atmosphere,” said the University of Maryland’s Brian Davenport, a third-year Ph.D. student who conducted the primary data analysis. “Whereas with many of the other sub-Neptunes that had been previously observed, we know their atmospheres are made of something, but they’re being blocked by haze.”
The team found water vapor in the planet’s atmosphere, as well as tentative signatures of carbon monoxide and sulfur dioxide. Then there are molecules they didn’t detect, such as methane and carbon dioxide. From the data, they can also infer that a large amount of hydrogen is in TOI-421 b’s atmosphere.
The lightweight hydrogen atmosphere was the big surprise to the researchers. “We had recently wrapped our mind around the idea that those first few sub-Neptunes observed by Webb had heavy-molecule atmospheres, so that had become our expectation, and then we found the opposite,” said Kempton. This suggests TOI-421 b may have formed and evolved differently from the cooler sub-Neptunes observed previously.
Is TOI-421 b Unique?
The hydrogen-dominated atmosphere is also interesting because it mimics the composition of TOI-421 b’s host star. “If you just took the same gas that made the host star, plopped it on top of a planet’s atmosphere, and put it at the much cooler temperature of this planet, you would get the same combination of gases. That process is more in line with the giant planets in our solar system, and it is different from other sub-Neptunes that have been observed with Webb so far,” said Kempton.
Aside from being hotter than other sub-Neptunes previously observed with Webb, TOI-421 b orbits a Sun-like star. Most of the other sub-Neptunes that have been observed so far orbit smaller, cooler stars called red dwarfs.
Is TOI-421b emblematic of hot sub-Neptunes orbiting Sun-like stars, or is it just that exoplanets are very diverse? To find out, the researchers would like to observe more hot sub-Neptunes to determine if this is a unique case or a broader trend. They hope to gain insights into the formation and evolution of these common exoplanets.
“We’ve unlocked a new way to look at these sub-Neptunes,” said Davenport. “These high-temperature planets are amenable to characterization. So by looking at sub-Neptunes of this temperature, we’re perhaps more likely to accelerate our ability to learn about these planets.”
The team’s findings appear on May 5 in the Astrophysical Journal Letters.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
To learn more about Webb, visit:
https://science.nasa.gov/webb
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Laura Betz – laura.e.betz@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Ann Jenkins – jenkins@stsci.edu
Space Telescope Science Institute, Baltimore, Md.
Hannah Braun – hbraun@stsci.edu
Space Telescope Science Institute, Baltimore, Md.
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By Space Force
The DoD is offering a path back to service for military personnel who voluntarily separated or left to avoid the COVID-19 vaccination mandate.
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4 Min Read Five Facts About NASA’s Moon Bound Technology
A view of the Moon from Earth, zooming up to IM-2's landing site at Mons Mouton, which is visible in amateur telescopes. Credits: NASA/Scientific Visualization Studio NASA is sending revolutionary technologies to the Moon aboard Intuitive Machines’ second lunar delivery as part of the agency’s CLPS (Commercial Lunar Payload Services) initiative and Artemis campaign to establish a long-term presence on the lunar surface.
As part of this CLPS flight to the Moon, NASA’s Space Technology Mission Directorate will test novel technologies to learn more about what lies beneath the lunar surface, explore its challenging terrain, and improve in-space communication.
The launch window for Intuitive Machines’ second CLPS delivery, IM-2, opens no earlier than Wednesday, Feb. 26 from Launch Complex 39A at NASA’s Kennedy Space Center in Florida. After the Intuitive Machines’ Nova-C class lunar lander reaches Mons Mouton, a lunar plateau near the Moon’s South Pole region, it will deploy several NASA and commercial technologies including a drill and mass spectrometer, a new cellular communication network, and a small drone that will survey difficult terrain before returning valuable data to Earth.
Caption: The Intuitive Machines lunar lander that will deliver NASA science and technology to the Moon as part of the agency’s CLPS (Commercial Lunar Payload Services) initiative and Artemis campaign is encapsulated in the fairing of the SpaceX Falcon 9 rocket. Credit: SpaceX Here are five things to know about this unique mission to the Moon, the technologies we are sending, and the teams making it happen!
1. Lunar South Pole Exploration
IM-2’s landing site is known as one of the flatter regions in the South Pole region, suitable to meet Intuitive Machines’ requirement for a lit landing corridor and acceptable terrain slope. The landing location was selected by Intuitive Machines using data acquired by NASA’s Lunar Reconnaissance Orbiter.
An illustration of Mons Mouton, a mesa-like lunar mountain that towers above the landscape carved by craters near the Moon’s South Pole.Credit: NASA/Scientific Visualization Studio 2. New Technology Demonstrations
NASA’s Polar Resources Ice Mining Experiment, known as PRIME-1, is a suite of two instruments – a drill and mass spectrometer – designed to demonstrate our capability to look for ice and other resources that could be extracted and used to produce propellant and breathable oxygen for future explorers. The PRIME-1 technology will dig up to about three feet below the surface into the lunar soil where it lands, gaining key insight into the soil’s characteristics and temperature while detecting other resources that may lie beneath the surface.
Data from the PRIME-1 technology demonstration will be made available to the public following the mission, enabling partners to accelerate the development of new missions and innovative technologies.
The Polar Resources Ice Mining Experiment-1 (PRIME-1) will help scientists search for water at the lunar South Pole.Credit: NASA/Advanced Concepts Lab 3. Mobile Robots
Upon landing on the lunar surface, two commercial Tipping Point technology demonstrations will be deployed near Intuitive Machines’ lander, Tipping Points are collaborations between NASA’s Space Technology Mission Directorate and industry that foster the development of commercial space capabilities and benefit future NASA missions.
The first is a small hopping drone developed by Intuitive Machines. The hopper, named Grace, will deploy as a secondary payload from the lander and enable high-resolution surveying of the lunar surface, including permanently shadowed craters around the landing site. Grace is designed to bypass obstacles such as steep inclines, boulders, and craters to cover a lot of terrain while moving quickly, which is a valuable capability to support future missions on the Moon and other planets, including Mars.
Artist rendering of the Intuitive Machines Micro Nova Hopper.Credit: Intuitive Machines 4. Lunar Surface Communication
The next Tipping Point technology will test a Lunar Surface Communications System developed by Nokia. This system employs the same cellular technology used here on Earth, reconceptualized by Nokia Bell Labs to meet the unique requirements of a lunar mission. The Lunar Surface Communications System will demonstrate proximity communications between the lander, a Lunar Outpost rover, and the hopper.
Artist rendering of Nokia’s Lunar Surface Communication System (LSCS), which aims to demonstrate cellular-based communications on the lunar surface. Credit: Intuitive Machines 5. Working Together
NASA is working with several U.S. companies to deliver technology and science to the lunar surface through the agency’s CLPS initiative.
NASA’s Space Technology Mission Directorate plays a unique role in the IM-2 mission by strategically combining CLPS with NASA’s Tipping Point mechanism to maximize the potential benefit of this mission to NASA, industry, and the nation.
NASA’s Lunar Surface Innovation Initiative and Game Changing Development program within the agency’s Space Technology Mission Directorate led the maturation, development, and implementation of pivotal in-situ resource utilization, communication, and mobility technologies flying on IM-2.
Join NASA to watch full mission updates, from launch to landing on NASA+, and share your experience on social media. Mission updates will be made available on NASA’s Artemis blog.
A team of engineers from NASA’s Johnson Space Center in Houston and Honeybee Robotics in Altadena, California inspect TRIDENT – short for The Regolith Ice Drill for Exploring New Terrain – shortly after its arrival at the integration and test facility.Credit: NASA/Robert Markowitz Artist’s rendering of Intuitive Machines’ Athena lunar lander on the Moon. Credit: Intuitive Machines
Artist conception: Earth emerges from behind Mons Mouton on the horizon.Credit: NASA/Scientific Visualization Studio Explore More
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Last Updated Feb 24, 2025 EditorStefanie PayneContactAnyah Demblinganyah.dembling@nasa.govLocationNASA Headquarters Related Terms
Space Technology Mission Directorate Artemis Commercial Lunar Payload Services (CLPS) Game Changing Development Program Kennedy Space Center Lunar Surface Innovation Initiative Missions NASA Headquarters Research and Technology at Kennedy Space Center Science Mission Directorate
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