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By NASA
NASA’s Nancy Grace Roman Space Telescope will help scientists better understand our Milky Way galaxy’s less sparkly components — gas and dust strewn between stars, known as the interstellar medium.
One of Roman’s major observing programs, called the Galactic Plane Survey, will peer through our galaxy to its most distant edge, mapping roughly 20 billion stars—about four times more than have currently been mapped. Scientists will use data from these stars to study and map the dust their light travels through, contributing to the most complete picture yet of the Milky Way’s structure, star formation, and the origins of our solar system.
Our Milky Way galaxy is home to more than 100 billion stars that are often separated by trillions of miles. The spaces in between, called the interstellar medium, aren’t empty — they’re sprinkled with gas and dust that are both the seeds of new stars and the leftover crumbs from stars long dead. Studying the interstellar medium with observatories like NASA’s upcoming Nancy Grace Roman Space Telescope will reveal new insight into the galactic dust recycling system.
Credit: NASA/Laine Havens; Music credit: Building Heroes by Enrico Cacace [BMI], Universal Production Music “With Roman, we’ll be able to turn existing artist’s conceptions of the Milky Way into more data-driven models using new constraints on the 3D distribution of interstellar dust,” said Catherine Zucker, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts.
Solving Milky Way mystery
Scientists know how our galaxy likely looks by combining observations of the Milky Way and other spiral galaxies. But dust clouds make it hard to work out the details on the opposite side of our galaxy. Imagine trying to map a neighborhood while looking through the windows of a house surrounded by a dense fog.
Roman will see through the “fog” of dust using a specialized camera and filters that observe infrared light — light with longer wavelengths than our eyes can detect. Infrared light is more likely to pass through dust clouds without scattering.
This artist’s concept visualizes different types of light moving through a cloud of particles. Since infrared light has a longer wavelength, it can pass more easily through the dust. That means astronomers observing in infrared light can peer deeper into dusty regions.Credit: NASA’s Goddard Space Flight Center Light with shorter wavelengths, including blue light produced by stars, more easily scatters. That means stars shining through dust appear dimmer and redder than they actually are.
By comparing the observations with information on the source star’s characteristics, astronomers can disentangle the star’s distance from how much its colors have been reddened. Studying those effects reveals clues about the dust’s properties.
“I can ask, ‘how much redder and dimmer is the starlight that Roman detects at different wavelengths?’ Then, I can take that information and relate it back to the properties of the dust grains themselves, and in particular their size,” said Brandon Hensley, a scientist who studies interstellar dust at NASA’s Jet Propulsion Laboratory in Southern California.
Scientists will also learn about the dust’s composition and probe clouds to investigate the physical processes behind changing dust properties.
Clues in dust-influenced starlight hint at the amount of dust between us and a star. Piecing together results from many stars allows astronomers to construct detailed 3D dust maps. That would enable scientists like Zucker to create a model of the Milky Way, which will show us how it looks from the outside. Then scientists can better compare the Milky Way with other galaxies that we only observe from the outside, slotting it into a cosmological perspective of galaxy evolution.
“Roman will add a whole new dimension to our understanding of the galaxy because we’ll see billions and billions more stars,” Zucker said. “Once we observe the stars, we’ll have the dust data as well because its effects are encoded in every star Roman detects.”
Galactic life cycles
The interstellar medium does more than mill about the Milky Way — it fuels star and planet formation. Dense blobs of interstellar medium form molecular clouds, which can gravitationally collapse and kick off the first stages of star development. Young stars eject hot winds that can cause surrounding dust to clump into planetary building blocks.
“Dust carries a lot of information about our origins and how everything came to be,” said Josh Peek, an associate astronomer and head of the data science mission office at the Space Telescope Science Institute in Baltimore, Maryland. “Right now, we’re basically standing on a really large dust grain — Earth was built out of lots and lots of really tiny grains that grew together into a giant ball.”
Roman will identify young clusters of stars in new, distant star-forming regions as well as contribute data on “star factories” previously identified by missions like NASA’s retired Spitzer Space Telescope.
“If you want to understand star formation in different environments, you have to understand the interstellar landscape that seeds it,” Zucker said. “Roman will allow us to link the 3D structure of the interstellar medium with the 3D distribution of young stars across the galaxy’s disk.”
Roman’s new 3D dust maps will refine our understanding of the Milky Way’s spiral structure, the pinwheel-like pattern where stars, gas, and dust bunch up like galactic traffic jams. By combining velocity data with dust maps, scientists will compare observations with predictions from models to help identify the cause of spiral structure—currently unclear.
The role that this spiral pattern plays in star formation remains similarly uncertain. Some theories suggest that galactic congestion triggers star formation, while others contend that these traffic jams gather material but do not stimulate star birth.
Roman will help to solve mysteries like these by providing more data on dusty regions across the entire Milky Way. That will enable scientists to compare many galactic environments and study star birth in specific structures, like the galaxy’s winding spiral arms or its central stellar bar.
NASA’s Nancy Grace Roman Space Telescope will conduct a Galactic Plane Survey to explore our home galaxy, the Milky Way. The survey will map around 20 billion stars, each encoding information about intervening dust and gas called the interstellar medium. Studying the interstellar medium could offer clues about our galaxy’s spiral arms, galactic recycling, and much more.
Credit: NASA, STScI, Caltech/IPAC The astronomy community is currently in the final stages of planning for Roman’s Galactic Plane Survey.
“With Roman’s massive survey of the galactic plane, we’ll be able to have this deep technical understanding of our galaxy,” Peek said.
After processing, Roman’s data will be available to the public online via the Roman Research Nexus and the Barbara A. Mikulski Archive for Space Telescopes, which will each provide open access to the data for years to come.
“People who aren’t born yet are going to be able to do really cool analyses of this data,” Peek said. “We have a really beautiful piece of our heritage to hand down to future generations and to celebrate.”
Roman is slated to launch no later than May 2027, with the team working toward a potential early launch as soon as fall 2026.
The Nancy Grace Roman Space Telescope is managed at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, with participation by NASA’s Jet Propulsion Laboratory and Caltech/IPAC in Southern California, the Space Telescope Science Institute in Baltimore, and a science team comprising scientists from various research institutions. The primary industrial partners are BAE Systems Inc. in Boulder, Colorado; L3Harris Technologies in Rochester, New York; and Teledyne Scientific & Imaging in Thousand Oaks, California.
Download additional images and video from NASA’s Scientific Visualization Studio.
For more information about the Roman Space Telescope, visit:
https://www.nasa.gov/roman
By Laine Havens
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Sep 16, 2025 EditorAshley BalzerContactAshley Balzerashley.m.balzer@nasa.govLocationGoddard Space Flight Center Related Terms
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By European Space Agency
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By Space Force
The Department of the Air Force is aligning with a new federal initiative to overhaul how government services are designed and delivered, a move leaders say will sharpen warfighting readiness, increase lethality and save taxpayer dollars.
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By NASA
Explore This Section Earth Earth Observer Editor’s Corner Feature Articles Meeting Summaries News Science in the News Calendars In Memoriam Announcements More Archives Conference Schedules Style Guide 13 min read
The Earth Observer Editor’s Corner: July–September 2025
NOTE TO READERS: After more than three decades associated with or directly employed by NASA, Steve Platnick [GSFC—Deputy Director for Atmospheres, Earth Sciences Division] stepped down effective August 8, 2025. Steve began his civil servant career at GSFC in 2002, but his GSFC association went back to 1993, first as a contractor and then as one of the earliest employees of the Joint Center for Earth Systems Technology (JCET). During his time at NASA, Steve played an integral role in the sustainability and advancement of NASA’s Earth Observing System platforms and data. He was actively involved in the Moderate Resolution Imaging Spectroradiometer (MODIS) Science Team, where he helped advance several key components of the MODIS instrument. He was also the NASA Lead/co-Lead for the Suomi National Polar-orbiting Partnership (Suomi NPP), Atmosphere Discipline from 2012–2020 where he focused on operational cloud optical and microphysical products.
In 2008, Steve became the Earth Observing System (EOS) Senior Project Scientist. In this role, he led the EOS Project Science Office that supported airborne sensors, ground networks, and calibration labs. The Kudos article titled “Steve Platnick Steps Down from NASA After 34 Years of Service” includes a more detailed account of Steve’s career and includes a list of awards he has received.
Steve’s departure leaves a vacancy in the author’s chair for “The Editor’s Corner” – another role Steve filled as EOS Senior Project Scientist. Barry Lefer [NASA Headquarters—Associate Director of Research, Earth Science Division] graciously agreed to serve as guest author of the editorial in the current compilation. I want to thank Steve for all his support for The Earth Observer over the years and thank Barry for stepping in as the author of “The Editor’s Corner” for the time being.
–Alan Ward, Executive Editor, The Earth Observer
I begin this editorial with news of a successful Earth science launch. At 5:40 PM Indian Standard Time (IST), or 8:10 AM Eastern Daylight Time (EDT), on July 30, 2025, the joint NASA–Indian Space Research Organization (ISRO) Synthetic Aperture Radar, or NISAR, mission launched from the Satish Dhawan Space Centre on India’s southeastern coast aboard an ISRO Geosynchronous Satellite Launch Vehicle (GSLV) rocket 5. The ISRO ground controllers began communicating with NISAR about 20 minutes after launch, at just after 8:29 AM EDT, and confirmed it is operating as expected.
NISAR will use two different radar frequencies (L-band SAR and S-band SAR) to penetrate clouds and forest canopies. Including L-band and S-band radars on one satellite is an evolution in SAR airborne and space-based missions that, for NASA, started in 1978 with the launch of Seasat. In 2012, ISRO began launching SAR missions starting with Radar Imaging Satellite (RISAT-1), followed by RISAT-1A in 2022, to support a wide range of applications in India.
Combining the data from these two radars will allow researchers to systematically and globally map Earth – measuring changes of our planet’s surface down to a centimeter (~0.4 inches). With this detailed view, researchers will have an unprecedented ability to observe and measure complex processes from ecosystem disturbances to natural hazards to groundwater issues. All NISAR science data will be freely available and open to the public.
Following the successful launch, NISAR entered an approximately 90-day commissioning phase to test out systems before science operations begin. A key milestone of that phase was the completion of the deployment of the 39-ft (12-m) radar antenna reflector on August 15 – see Video. The process began on August 9, when the satellite’s boom, which had been tucked close to its main body, started unfolding one joint at a time until it was fully extended about four days later. The reflector assembly is mounted at the end of the boom. On August 15, small explosive bolts that held the reflector assembly in place were fired, enabling the antenna to begin a process called the bloom – its unfurling by the release of tension stored in its flexible frame while stowed like an umbrella. Subsequent activation of motors and cables pulled the antenna into its final, locked position.
Video: NISAR mission team members at NASA JPL, working with colleagues in India, executed the deployment of the satellite’s radar antenna reflector on Aug. 15, 2025. About 39 feet (12 meters) in diameter, the reflector directs microwave pulses from NISAR’s two radars toward Earth and receives the return signals. Credit: NASA/JPL-Caltech The radar reflector will be used to direct and receive microwave signals from the two radars. By interpreting the differences between the L-band and S-band measurements, researchers will be able to discern characteristics about the surface below. As NISAR passes over the same locations twice every 12 days, scientists can evaluate how those characteristics have changed over time to reveal new insights about Earth’s dynamic surfaces.
With the radar reflector now in full bloom, scientists have turned their attention to tuning and testing the radar and preparing NISAR for Science Operations, which are anticipated to start around the beginning of November. Congratulations to the NISAR team on a successful launch and deployment of the radar reflector. Along with the science community, I am excited to see what new discoveries will result from the data collected by the first Earth System Observatory mission.
Turning now to news from active missions, the Soil Moisture Active Passive (SMAP) mission has collected over 10 years of global L-band radiometry observations that have resulted in surface soil moisture, vegetation optical depth (VOD), and freeze/thaw state estimates that outperform past and current products. A decade of SMAP soil moisture observations has led to scientific achievements, including quantifying the linkages of the three main metabolic cycles (e.g., carbon, water, and energy) on land. The data have been widely used by the Earth system science community to improve drought assessments and flood prediction as well as the accuracy of numerical weather prediction models.
SMAP’s Early Adopter program has helped connect SMAP data with people and organizations that need it. The program has increased the awareness of SMAP mission products, broadened the user community, increased collaboration with potential users, improved knowledge of SMAP data product capabilities, and expedited the distribution and uses of mission products for a suite of 16 products available. For example, the L-band VOD, which is related to water content in vegetation, is being used to better understand water exchanges in the soil–vegetation–atmosphere continuum.
The SMAP Active–Passive (AP) algorithm – based on data from SMAP and the European Copernicus Program Sentinel-1 C-band synthetic aperture radar (SAR) – will be adapted to work with L-band data from the newly launched NISAR mission. The result will be estimates of global soil moisture at a spatial resolution of 1 km (0.62 mi) or better approximately once per week.
In addition, the data collected during the SMAP mission would be continued and further enhanced by the European Union’s Copernicus Imaging Microwave Radiometer (CIMR) mission if it launches. This proposed multichannel microwave radiometry observatory includes L-band and four other microwave channels sharing a large mesh reflector – like the one used with SMAP. The plan calls for CIMR to follow a similar approach as SMAP for RFI detection and meet the instrument thermal noise and data latency of SMAP for next-mission desired characteristics.
To learn more about what SMAP has accomplished see “A Decade of Global Water Cycle Monitoring: NASA Soil Moisture Active Passive Mission.”
NASA’s Orbiting Carbon Observatory-2 (OCO-2) has been the “gold standard” for atmospheric carbon dioxide (CO2) observations from space for over a decade. The data returned from OCO-2 provide insights into plant health, forest management, forecasting crop yields, fire-risk models, and anticipating droughts.
OCO-3, constructed from spare parts left after OCO-2, was launched to the International Space Station (ISS) in 2019, where it has operated for over five years. OCO-3 extends the global CO2 measurement record while adding new capabilities made possible by being on ISS (e.g., detailed views of urban and tropical regions).
The overarching OCO mission hasn’t just about been about data and hardware. Although both those elements are parts of the story, the human stories woven through the mission’s successes and setbacks are really what holds the mission together. The feature, “A Tapestry of Tales: 10th Anniversary Reflections from NASA’s OCO-2 Mission,” sheds light on some of these personal stories from the OCO-2 and OCO-3 missions.
The individual tales contained in this article reveal the grit and determination behind the scenes of the success of OCO-2 and OCO-3, from the anxiety and excitement surrounding the launch of OCO-2, to moments of fieldwork in the Nevada desert, to internships where wildfire responders turned to OCO-2 data to improve fire-risk models. Taken together, these stories form a “tapestry” that reveals how the OCO-2 and OCO-3 missions continue to illuminate the dynamics of Earth’s atmosphere – one breath at a time.
These personal perspectives underscore that science is not just numbers; it’s people pushing boundaries, navigating failure, and inspiring ways to make our planet safer and healthier. In a time such as this, this is an important reminder.
The joint NASA–U.S. Geological Survey (USGS) Landsat program has been a cornerstone of Earth observation for over 50 years. On July 13, Landsat 9 collected its millionth image: a stunning shot of the Arctic National Wildlife Refuge in Alaska – see Figure. Landsat 9, the most recent satellite in the Landsat series, orbits Earth alongside Landsat 8. Together, these satellites collect invaluable data about Earth’s changing land surface every eight days.
Figure: This Landsat 9 image showing the Beaufort Sea shoreline off Alaska and Canada is just one of the scenes captured and processed on July 13, 2025— the same day the USGS EROS archive reached a milestone of one million Landsat 9 Level-1 products. This false color image was made with bands 6, 5, and 4 from the Operational Land Imager. This remote area allows the pristine wilderness environment to support a diverse wildlife and unique ecosystem that includes various species of mammals, birds, and fish. Landsat Level-1 products from Landsat 1 through Landsat 9 can be downloaded at no charge from a number of systems – visit the Landsat Data Access webpage to learn more. Credit: Public Domain After collecting more than 3.3 million images over the course of more than 26 years in orbit, Landsat 7 was decommissioned on June 4, 2025. A YouTube video released at the time of decommissioning provides a concise visual summary of the Landsat 7 mission’s achievements – and the technical challenges overcome. In addition, The Earth Observer did a feature for the 20th anniversary of Landsat 7 in the July–August 2019 issue, called “The Living Legacy of Landsat 7: Still Going Strong After 20 Years in Orbit” [Volume 31, Issue 4, pp. 4–14] that is a useful resource to learn more about the history and achievements (through 20 years) of the mission.
One of the strengths of the Landsat program is its potential for data integration with other satellites. The Harmonized Landsat and Sentinel-2 (HLS) product exemplifies this collaborative approach by combining data from Landsat 8 and 9 with data from the European Space Agency’s Copernicus Sentinel-2 A, B, and C missions. Whereas Landsat alone has a repeat time of eight days (i.e., combining Landsat 8 and 9 data); the combined HLS dataset provides imagery for the same location on Earth every 1.6 days – enabling researchers to monitor short-term changes in Earth’s land surface much more effectively than using Landsat or Sentinel-2 data alone.
HLS became one of the most-downloaded NASA data products in fiscal year 2024, with continued growth on the horizon. In February 2025, the program expanded with nine new vegetation indices based on HLS data, with historical processing back to 2013 scheduled for completion by early 2026. Low-latency HLS products will also be available in late 2026. For the full story of how HLS came to be – see the feature: “Harmonized Landsat and Sentinel-2: Collaboration Drives Innovation.”
Following a 13-month hibernation, the Global Ecosystem Dynamics Investigation (GEDI) mission was reinstalled to its original location aboard the ISS and resumed operations on April 22, 2024. Since this storage period, GEDI’s lasers have been operating nominally and the mission has continued to produce high-quality observations of the Earth’s three-dimensional structure, amassing 33 billion land surface returns as of November 27, 2024.
The mission team has been actively processing and releasing post-storage data to the public, with Version 2.1 – GEDI L1B, L2A, L2B, and L4A data products, which include data through November 2024, all available for download. The new L4C footprint-level Waveform Structural Complexity Index (WSCI) product using pre-storage data has also been released. Looking ahead, the team is preparing Version 3.0 (V3) of all data products, which will incorporate post-storage data while improving quality filtering, geolocation accuracy, and algorithm performance.
The 2025 GEDI Science Team Meeting (STM) brought together the mission science team, competed science team, representatives from the distributed active archive centers (DAACs), collaborators, stakeholders, and data users. Notably, it marked the first in-person gathering of the second competed science team, who shared updates on their research projects. The STM held an important space for brainstorming, knowledge-sharing, and discussion as the GEDI mission continues to flourish in its second epoch. To learn more, see “Summary of the 2025 GEDI Science Team Meeting.”
Shifting focus to the boreal forests of North America, the NASA Arctic–Boreal Vulnerability Experiment (ABoVE) is now in its final year, marking the end of a decade-long scientific endeavor that has transformed our understanding of environmental change in Alaska and western Canada. This ambitious campaign, funded primarily by NASA’s Terrestrial Ecology Program, has successfully progressed through three distinct phases: ecosystem dynamics (2015–2018), ecosystem services (2017–2022), and the current analysis and synthesis phase (2023–present).
As ABoVE approaches its conclusion, the program has grown to encompass 67 NASA-funded projects with over 1000 participating researchers – a testament to the collaborative scale required to address complex Arctic–boreal ecosystem questions. The program’s integrated approach, combining field research, airborne campaigns, and satellite remote sensing, has generated unprecedented insights into how environmental changes in these northern regions affect both vulnerable ecosystems and society.
The recent 11th – and final – ABoVE Science Team Meeting was an opportunity to showcase the program’s evolution from data collection to synthesis, highlighting successful community engagement initiatives, cutting-edge research on carbon dynamics and ecosystem responses, and innovative science communication strategies that have made this complex research accessible to diverse audiences. With synthesis activities now underway, ABoVE is positioned to deliver comprehensive insights that will inform Arctic and boreal research for years to come. To learn more, see “Summary of the 11th and Final ABoVE Science Team Meeting.”
Last but certainly not least, I want to both recognize and congratulate Compton J. Tucker [GSFC—Senior Researcher]. Compton retired from NASA in March 2025 after 48 years of public service, and then in April, was among 149 newly elected members to the National Academy of Sciences (NAS) – which is one of the highest honors in American science. This recognition from NAS brings Compton’s career full circle. He came to GSFC as a NAS postdoc before joining NASA as a civil servant. Compton is a pioneer in the field of satellite-based environmental analysis, using data from various Landsat missions and from the National Oceanographic and Atmospheric Administration’s (NOAA) Advanced Very High Resolution Radiometer (AVHRR) instrument. His research has focused on global photosynthesis on land, determining land cover, monitoring droughts and food security, and evaluating ecologically coupled disease outbreaks. The Kudos, “Compton J. Tucker Retires from NASA and is Named NAS Fellow,” provides more details about Compton’s research achievements and all of the other scientific awards and honors received throughout his career.
Barry Lefer
Associate Director of Research, Earth Science Division
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Last Updated Sep 10, 2025 Related Terms
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By Space Force
The United States Space Force announced when Guardians will have the opportunity to be sized for and order the new service dress uniform.
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