This artist’s concept shows an M dwarf star, also called a red dwarf star, and a planet. Most rocky planets in the Milky Way galaxy orbit red dwarf stars, which are smaller and cooler than the Sun, but can be much more active, bombarding nearby planets with high-energy X-rays and ultraviolet light.
The Rocky Worlds Director’s Discretionary program, a combined effort by NASA’s Webb and Hubble Space Telescopes, is underway to explore whether rocky planets can maintain atmospheres in this environment.
The team recently completed observations of the first target, Earth-sized rocky planet GJ 3929 b and its star GJ 3929. Credits Illustration: STScI, Ralf Crawford (STScI)
The Rocky Worlds Director’s Discretionary program, a combined effort by NASA’s Webb and Hubble Space Telescopes, is underway to explore whether rocky planets can maintain atmospheres in this environment.
The team recently completed observations of the first target, Earth-sized rocky planet GJ 3929 b and its star GJ 3929. Credits Illustration: STScI, Ralf Crawford (STScI)
Scientists leading the astronomy community’s most ambitious effort to study rocky planets outside of our solar system have reached a major milestone.
The team has completed the coordinated observations of the first target, an Earth-sized rocky planet GJ 3929 b and GJ 3929, the red dwarf star it orbits, using NASA’s James Webb and Hubble Space Telescopes.
While the planet itself is scientifically compelling, researchers say the importance of this milestone extends far beyond a single target.
“This was our proving ground,” said Néstor Espinoza, Rocky Worlds Director’s Discretionary Time (DDT) program lead and mission scientist for exoplanet science at the Space Telescope Science Institute (STScI) in Baltimore. “Finishing these first observations shows that the program works technically, scientifically, and collaboratively.”
The Rocky Worlds DDT program was designed to create a foundational, community-driven dataset for studying rocky exoplanets with Webb and Hubble . While Webb measures mid-infrared light coming from each planet to determine whether it has an atmosphere, Hubble is analyzing ultraviolet light from each host star to assess the planet’s radiation environment.
STScI leads the effort to design the observing strategy, manage the program’s technical implementation, and build the collaborative framework connecting scientists across the broader exoplanet community.
“This team’s efforts reflect the best of the institute’s unique ability to bring together expertise in science operations, engineering, scheduling, software development, and large-scale program management to execute some of astronomy’s most technically challenging observations and answer some of the universe’s biggest questions,” said STScI Director Jennifer Lotz.
The GJ 3929 system became the program’s first completed target after emerging early as one of the strongest candidates for initial observations. Scientists selected the star and its planet through a multi-stage community process involving Science Advisory Council discussions, mini-surveys, and feedback from researchers across the exoplanet community.
The team emphasizes that the target was not chosen because it was expected to produce the most dramatic discovery. Instead, it represents an important balance: scientifically valuable, observationally feasible, and ideal for helping the team learn how to execute a complex program involving complementary observations, some of which are captured simultaneously, from multiple flagship observatories.
The observations required researchers to precisely predict when the planet would pass behind its star, an event known as a secondary eclipse. Even for a comparatively favorable target like GJ 3929 b, uncertainties in the planet’s orbit created significant technical challenges.
Completing the observations demonstrated that the team could overcome those challenges and establish a framework for future targets, many of which are expected to be even more difficult.
“This is exactly why the Rocky Worlds program exists,” added Hannah Diamond-Lowe, deputy lead of the program and assistant astronomer at STScI. “These are high-risk, high-reward observations. Completing this first target shows we know how to do it.”
The milestone also highlights the remarkably collaborative nature of the program. Scientists from around the world shared unpublished supporting observations, including radial velocity measurements used to refine the planet’s orbit and improve scheduling predictions, to help develop and refine the observation plans.
At the same time, the Rocky Worlds team is building new systems intended to encourage open collaboration while reducing duplicated effort across the field and grow the scope, impact and scientific return of the program, including the recently launched Rocky Worlds DDT Data Challenge. The new Community Involvement Initiative also provides an open forum for researchers and research to facilitate share information on analysis techniques, complementary and follow-up observations, project ideas, and plans for publications.
The team has completed the coordinated observations of the first target, an Earth-sized rocky planet GJ 3929 b and GJ 3929, the red dwarf star it orbits, using NASA’s James Webb and Hubble Space Telescopes.
While the planet itself is scientifically compelling, researchers say the importance of this milestone extends far beyond a single target.
“This was our proving ground,” said Néstor Espinoza, Rocky Worlds Director’s Discretionary Time (DDT) program lead and mission scientist for exoplanet science at the Space Telescope Science Institute (STScI) in Baltimore. “Finishing these first observations shows that the program works technically, scientifically, and collaboratively.”
The Rocky Worlds DDT program was designed to create a foundational, community-driven dataset for studying rocky exoplanets with Webb and Hubble . While Webb measures mid-infrared light coming from each planet to determine whether it has an atmosphere, Hubble is analyzing ultraviolet light from each host star to assess the planet’s radiation environment.
STScI leads the effort to design the observing strategy, manage the program’s technical implementation, and build the collaborative framework connecting scientists across the broader exoplanet community.
“This team’s efforts reflect the best of the institute’s unique ability to bring together expertise in science operations, engineering, scheduling, software development, and large-scale program management to execute some of astronomy’s most technically challenging observations and answer some of the universe’s biggest questions,” said STScI Director Jennifer Lotz.
The GJ 3929 system became the program’s first completed target after emerging early as one of the strongest candidates for initial observations. Scientists selected the star and its planet through a multi-stage community process involving Science Advisory Council discussions, mini-surveys, and feedback from researchers across the exoplanet community.
The team emphasizes that the target was not chosen because it was expected to produce the most dramatic discovery. Instead, it represents an important balance: scientifically valuable, observationally feasible, and ideal for helping the team learn how to execute a complex program involving complementary observations, some of which are captured simultaneously, from multiple flagship observatories.
The observations required researchers to precisely predict when the planet would pass behind its star, an event known as a secondary eclipse. Even for a comparatively favorable target like GJ 3929 b, uncertainties in the planet’s orbit created significant technical challenges.
Completing the observations demonstrated that the team could overcome those challenges and establish a framework for future targets, many of which are expected to be even more difficult.
“This is exactly why the Rocky Worlds program exists,” added Hannah Diamond-Lowe, deputy lead of the program and assistant astronomer at STScI. “These are high-risk, high-reward observations. Completing this first target shows we know how to do it.”
The milestone also highlights the remarkably collaborative nature of the program. Scientists from around the world shared unpublished supporting observations, including radial velocity measurements used to refine the planet’s orbit and improve scheduling predictions, to help develop and refine the observation plans.
At the same time, the Rocky Worlds team is building new systems intended to encourage open collaboration while reducing duplicated effort across the field and grow the scope, impact and scientific return of the program, including the recently launched Rocky Worlds DDT Data Challenge. The new Community Involvement Initiative also provides an open forum for researchers and research to facilitate share information on analysis techniques, complementary and follow-up observations, project ideas, and plans for publications.
The program’s leaders say this collaborative structure was part of the vision from the beginning.
“We wanted to create something that belonged to the community,” Espinoza said. “The goal is not only to produce groundbreaking science, but also to build a framework where many researchers can contribute, collaborate, and learn together.”
The data, which are immediately available as soon as they’re downloaded from the telescope, have swiftly sparked scientific interest in the community. Some researchers have already started analyzing the data and publishing their conclusions.
The data, which are immediately available as soon as they’re downloaded from the telescope, have swiftly sparked scientific interest in the community. Some researchers have already started analyzing the data and publishing their conclusions.
For the Rocky Worlds team, that response reinforces the significance of the milestone.
The Space Telescope Science Institute is expanding the frontiers of space astronomy by hosting the science operations center of the Hubble Space Telescope, the science and mission operations centers for the James Webb Space Telescope, and the science operations center for the Nancy Grace Roman Space Telescope. STScI also houses the Barbara A. Mikulski Archive for Space Telescopes (MAST) which is a NASA-funded project to support and provide to the astronomical community a variety of astronomical data archives, and is the data repository for the Hubble, Webb, Roman, Kepler, K2, TESS missions and more. STScI is operated by the Association of Universities for Research in Astronomy in Washington, D.C.
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Hannah Braun
Space Telescope Science Institute, Baltimore
Christine Pulliam
Space Telescope Science Institute, Baltimore
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