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Explore Webb 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 Webb Timeline Science Overview and Goals Early Universe Galaxies Over Time Star Lifecycle Other Worlds Science Explainers 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 Webb’s First Images Team International Team People Of Webb More For the Media For Scientists For Educators For Fun/Learning 5 Min Read Glittering Glimpse of Star Birth From NASA’s Webb Telescope
Webb captured this sparkling scene of star birth in Pismis 24. Full image and caption below. Credits:
Image: NASA, ESA, CSA, STScI; Image Processing: A. Pagan (STScI) This is a sparkling scene of star birth captured by NASA’s James Webb Space Telescope. What appears to be a craggy, starlit mountaintop kissed by wispy clouds is actually a cosmic dust-scape being eaten away by the blistering winds and radiation of nearby, massive, infant stars.
Called Pismis 24, this young star cluster resides in the core of the nearby Lobster Nebula, approximately 5,500 light-years from Earth in the constellation Scorpius. Home to a vibrant stellar nursery and one of the closest sites of massive star birth, Pismis 24 provides rare insight into large and massive stars. Its proximity makes this region one of the best places to explore the properties of hot young stars and how they evolve.
At the heart of this glittering cluster is the brilliant Pismis 24-1. It is at the center of a clump of stars above the jagged orange peaks, and the tallest spire is pointing directly toward it. Pismis 24-1 appears as a gigantic single star, and it was once thought to be the most massive known star. Scientists have since learned that it is composed of at least two stars, though they cannot be resolved in this image. At 74 and 66 solar masses, respectively, the two known stars are still among the most massive and luminous stars ever seen.
Image A: Pismis 24 (NIRCam Image)
Webb captured this sparkling scene of star birth in Pismis 24, a young star cluster about 5,500 light-years from Earth in the constellation Scorpius. This region is one of the best places to explore the properties of hot young stars and how they evolve. Image: NASA, ESA, CSA, STScI; Image Processing: A. Pagan (STScI) Captured in infrared light by Webb’s NIRCam (Near-Infrared Camera), this image reveals thousands of jewel-like stars of varying sizes and colors. The largest and most brilliant ones with the six-point diffraction spikes are the most massive stars in the cluster. Hundreds to thousands of smaller members of the cluster appear as white, yellow, and red, depending on their stellar type and the amount of dust enshrouding them. Webb also shows us tens of thousands of stars behind the cluster that are part of the Milky Way galaxy.
Super-hot, infant stars –some almost 8 times the temperature of the Sun – blast out scorching radiation and punishing winds that are sculpting a cavity into the wall of the star-forming nebula. That nebula extends far beyond NIRCam’s field of view. Only small portions of it are visible at the bottom and top right of the image. Streamers of hot, ionized gas flow off the ridges of the nebula, and wispy veils of gas and dust, illuminated by starlight, float around its towering peaks.
Dramatic spires jut from the glowing wall of gas, resisting the relentless radiation and winds. They are like fingers pointing toward the hot, young stars that have sculpted them. The fierce forces shaping and compressing these spires cause new stars to form within them. The tallest spire spans about 5.4 light-years from its tip to the bottom of the image. More than 200 of our solar systems out to Neptune’s orbit could fit into the width its tip, which is 0.14 lightyears.
In this image, the color cyan indicates hot or ionized hydrogen gas being heated up by the massive young stars. Dust molecules similar to smoke here on Earth are represented in orange. Red signifies cooler, denser molecular hydrogen. The darker the red, the denser the gas. Black denotes the densest gas, which is not emitting light. The wispy white features are dust and gas that are scattering starlight.
Video A: Expedition to Star Cluster Pismis 24
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This scientific visualization takes viewers on a journey to a glittering young star cluster called Pismis 24. NASA’s James Webb Space Telescope captured this fantastical scene in the heart of the Lobster Nebula, approximately 5,500 light-years from Earth. Video: NASA, ESA, CSA, STScI, Leah Hustak (STScI), Christian Nieves (STScI); Image Processing: Alyssa Pagan (STScI); Script Writer: Frank Summers (STScI); Narration: Frank Summers (STScI); Music: Christian Nieves (STScI); Audio: Danielle Kirshenblat (STScI); Producer: Greg Bacon (STScI); Acknowledgment: VISTA Video B: Zoom to Pismis 24
This zoom-in video shows the location of the young star cluster Pismis 24 on the sky. It begins with a ground-based photo of the constellation Scorpius by the late astrophotographer Akira Fujii. The sequence closes in on the Lobster Nebula, using views from the Digitized Sky Survey. As the video homes in on a select portion, it fades to a VISTA image in infrared light. The zoom continues in to the region around Pismis 24, where it transitions to the stunning image captured by NASA’s James Webb Space Telescope in near-infrared light.
Video: NASA, ESA, CSA, STScI, Alyssa Pagan (STScI); Narration: Frank Summers (STScI); Script Writer: Frank Summers (STScI); Music: Christian Nieves (STScI); Audio: Danielle Kirshenblat (STScI); Producer: Greg Bacon (STScI); Acknowledgment: VISTA, Akira Fujii, DSS 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:
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NASA/Nichole Ayers On July 26, 2025, NASA astronaut Nichole Ayers took this long-exposure photograph – taken over 31 minutes from a window inside the International Space Station’s Kibo laboratory module – capturing the circular arcs of star trails.
In its third decade of continuous human presence, the space station has a far-reaching impact as a microgravity lab hosting technology, demonstrations, and scientific investigations from a range of fields. The research done on the orbiting laboratory will inform long-duration missions like Artemis and future human expeditions to Mars.
Image credit: NASA/Nichole Ayers
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Explore Hubble Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Universe Uncovered Hubble’s Partners in Science AI and Hubble Science Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Astronaut Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts Multimedia Images Videos Sonifications Podcasts e-Books Online Activities 3D Hubble Models Lithographs Fact Sheets Posters Hubble on the NASA App Glossary News Hubble News Social Media Media Resources More 35th Anniversary Online Activities 2 min read
Hubble Homes in on Galaxy’s Star Formation
This NASA/ESA Hubble Space Telescope image features the asymmetric spiral galaxy Messier 96. ESA/Hubble & NASA, F. Belfiore, D. Calzetti This NASA/ESA Hubble Space Telescope image features a galaxy whose asymmetric appearance may be the result of a galactic tug of war. Located 35 million light-years away in the constellation Leo, the spiral galaxy Messier 96 is the brightest of the galaxies in its group. The gravitational pull of its galactic neighbors may be responsible for Messier 96’s uneven distribution of gas and dust, asymmetric spiral arms, and off-center galactic core.
This asymmetric appearance is on full display in the new Hubble image that incorporates data from observations made in ultraviolet, near infrared, and visible/optical light. Earlier Hubble images of Messier 96 were released in 2015 and 2018. Each successive image added new data, building up a beautiful and scientifically valuable view of the galaxy.
The 2015 image combined two wavelengths of optical light with one near infrared wavelength. The optical light revealed the galaxy’s uneven form of dust and gas spread asymmetrically throughout its weak spiral arms and its off-center core, while the infrared light revealed the heat of stars forming in clouds shaded pink in the image.
The 2018 image added two more optical wavelengths of light along with one wavelength of ultraviolet light that pinpointed areas where high-energy, young stars are forming.
This latest version offers us a new perspective on Messier 96’s star formation. It includes the addition of light that reveals regions of ionized hydrogen (H-alpha) and nitrogen (NII). This data helps astronomers determine the environment within the galaxy and the conditions in which stars are forming. The ionized hydrogen traces ongoing star formation, revealing regions where hot, young stars are ionizing the gas. The ionized nitrogen helps astronomers determine the rate of star formation and the properties of gas between stars, while the combination of the two ionized gasses helps researchers determine if the galaxy is a starburst galaxy or one with an active galactic nucleus.
The bubbles of pink gas in this image surround hot, young, massive stars, illuminating a ring of star formation in the galaxy’s outskirts. These young stars are still embedded within the clouds of gas from which they were born. Astronomers will use the new data in this image to study how stars are form within giant dusty gas clouds, how dust filters starlight, and how stars affect their environments.
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This graphic features data from NASA’s Chandra X-ray Observatory of the Cassiopeia A (Cas A) supernova remnant that reveals that the star’s interior violently rearranged itself mere hours before it exploded. The main panel of this graphic is Chandra data that shows the location of different elements in the remains of the explosion: silicon (represented in red), sulfur (yellow), calcium (green) and iron (purple). The blue color reveals the highest-energy X-ray emission detected by Chandra in Cas A and an expanding blast wave. The inset reveals regions with wide ranges of relative abundances of silicon and neon. This data, plus computer modeling, reveal new insight into how massive stars like Cas A end their lives.X-ray: NASA/CXC/Meiji Univ./T. Sato et al.; Image Processing: NASA/CXC/SAO/N. Wolk The inside of a star turned on itself before it spectacularly exploded, according to a new study from NASA’s Chandra X-ray Observatory. Today, this shattered star, known as the Cassiopeia A supernova remnant, is one of the best-known, well-studied objects in the sky.
Over three hundred years ago, however, it was a giant star on the brink of self-destruction. The new Chandra study reveals that just hours before it exploded, the star’s interior violently rearranged itself. This last-minute shuffling of its stellar belly has profound implications for understanding how massive stars explode and how their remains behave afterwards.
Cassiopeia A (Cas A for short) was one of the first objects the telescope looked at after its launch in 1999, and astronomers have repeatedly returned to observe it.
“It seems like each time we closely look at Chandra data of Cas A, we learn something new and exciting,” said Toshiki Sato of Meiji University in Japan who led the study. “Now we’ve taken that invaluable X-ray data, combined it with powerful computer models, and found something extraordinary.”
As massive stars age, increasingly heavy elements form in their interiors by nuclear reactions, creating onion-like layers of different elements. Their outer layer is mostly made of hydrogen, followed by layers of helium, carbon and progressively heavier elements – extending all the way down to the center of the star.
Once iron starts forming in the core of the star, the game changes. As soon as the iron core grows beyond a certain mass (about 1.4 times the mass of the Sun), it can no longer support its own weight and collapses. The outer part of the star falls onto the collapsing core, and rebounds as a core-collapse supernova.
The new research with Chandra data reveals a change that happened deep within the star at the very last moments of its life. After more than a million years, Cas A underwent major changes in its final hours before exploding.
“Our research shows that just before the star in Cas A collapsed, part of an inner layer with large amounts of silicon traveled outwards and broke into a neighboring layer with lots of neon,” said co-author Kai Matsunaga of Kyoto University in Japan. “This is a violent event where the barrier between these two layers disappears.”
This upheaval not only caused material rich in silicon to travel outwards; it also forced material rich in neon to travel inwards. The team found clear traces of these outward silicon flows and inward neon flows in the remains of Cas A’s supernova remnant. Small regions rich in silicon but poor in neon are located near regions rich in neon and poor in silicon.
The survival of these regions not only provides critical evidence for the star’s upheaval, but also shows that complete mixing of the silicon and neon with other elements did not occur immediately before or after the explosion. This lack of mixing is predicted by detailed computer models of massive stars near the ends of their lives.
There are several significant implications for this inner turmoil inside of the doomed star. First, it may directly explain the lopsided rather than symmetrical shape of the Cas A remnant in three dimensions. Second, a lopsided explosion and debris field may have given a powerful kick to the remaining core of the star, now a neutron star, explaining the high observed speed of this object.
Finally, the strong turbulent flows created by the star’s internal changes may have promoted the development of the supernova blast wave, facilitating the star’s explosion.
“Perhaps the most important effect of this change in the star’s structure is that it may have helped trigger the explosion itself,” said co-author Hiroyuki Uchida, also of Kyoto University. “Such final internal activity of a star may change its fate—whether it will shine as a supernova or not.”
These results have been published in the latest issue of The Astrophysical Journal and are available online.
To learn more about Chandra, visit:
https://science.nasa.gov/chandra
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Visual Description
This release features a composite image of Cassiopeia A, a donut-shaped supernova remnant located about 11,000 light-years from Earth. Included in the image is an inset closeup, which highlights a region with relative abundances of silicon and neon.
Over three hundred years ago, Cassiopeia A, or Cas A, was a star on the brink of self-destruction. In composition it resembled an onion with layers rich in different elements such as hydrogen, helium, carbon, silicon, sulfur, calcium, and neon, wrapped around an iron core. When that iron core grew beyond a certain mass, the star could no longer support its own weight. The outer layers fell into the collapsing core, then rebounded as a supernova. This explosion created the donut-like shape shown in the composite image. The shape is somewhat irregular, with the thinner quadrant of the donut to the upper left of the off-center hole.
In the body of the donut, the remains of the star’s elements create a mottled cloud of colors, marbled with red and blue veins. Here, sulfur is represented by yellow, calcium by green, and iron by purple. The red veins are silicon, and the blue veins, which also line the outer edge of the donut-shape, are the highest energy X-rays detected by Chandra and show the explosion’s blast wave.
The inset uses a different color code and highlights a colorful, mottled region at the thinner, upper left quadrant of Cas A. Here, rich pockets of silicon and neon are identified in the red and blue veins, respectively. New evidence from Chandra indicates that in the hours before the star’s collapse, part of a silicon-rich layer traveled outwards, and broke into a neighboring neon-rich layer. This violent breakdown of layers created strong turbulent flows and may have promoted the development of the supernova’s blast wave, facilitating the star’s explosion. Additionally, upheaval in the interior of the star may have produced a lopsided explosion, resulting in the irregular shape, with an off-center hole (and a thinner bite of donut!) at our upper left.
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Last Updated Aug 28, 2025 EditorLee MohonContactCorinne M. Beckingercorinne.m.beckinger@nasa.govLocationMarshall Space Flight Center Related Terms
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Harmonized Landsat and Sentinel-2: Collaboration Drives Innovation
Introduction
Landsat, a joint program of NASA and the U.S. Geological Survey (USGS), has been an invaluable tool for monitoring changes in Earth’s land surface for over 50 years. Researchers use instruments on Landsat satellites to monitor decades-long trends, including urbanization and agricultural expansion, as well as short-term dynamics, including water use and disaster recovery. However, scientists and land managers often encounter one critical limitation of this program: Landsat has a revisit time of eight days (with Landsat 8 and 9 operating), which is too long to capture events and disasters that occur on short timescales. Floods, for example, can quickly inundate a region, and cloud cover from storms can delay Landsat’s ability to get a clear observation on damage.
In 2015, the European Space Agency’s (ESA) Copernicus Sentinel-2A mission joined Landsat 7 and 8 in orbit. It was designed to collect comparable optical land data with the intention of leveraging Landsat’s archive. Two years later, ESA launched Sentinel-2B, a satellite identical to Sentinel-2A.
Led by a science team at NASA’s Goddard Space Flight Center (GSFC), the USGS, NASA, and ESA began to work on combining the capabilities of Sentinel-2 and Landsat satellites. This idea was the impetus behind Harmonized Landsat and Sentinel-2 (HLS) project, a NASA initiative that created a seamless product from the Operational Land Imager (OLI) and Multi-Spectral Instrument (MSI) aboard Landsat and Sentinel-2 satellites, respectively. HLS Version 2.0 (V2.0) is the most recent version of these data and had a global median repeat frequency of 1.6 days in 2022 by combining observations from Landsat 8 and 9 and Sentinel-2A and B. The recent addition of Sentinel-2C data will provide even more frequent observations. With near-global coverage and improved harmonization algorithms, HLS V2.0 paves the way for new applications and improved land monitoring systems – see Animation 1. HLS data are available for download on NASA Earthdata: HLSL30v2.0 and HLSS30v2.0. These data can also be accessed through Google Earth Engine: HLSL30v2.0 and HLSS30v2.0.
Animation 1. This visualization shows the change in vegetation in Maryland from January 1 to December 30, 2016, using Normalized Difference Vegetation Index (NDVI) data from Harmonized Landsat Sentinel-2 (HLS). The visualization shows land on both sides of the Chesapeake Bay, where red represents bare soil and green indicates healthy, growing vegetation. Animation credit: Michael Taylor [Science Systems and Applications Inc. (SSAI)], Matthew Radcliff [USRA], and Jeffrey Masek [GSFC]. Caption adapted from Laura Rocchio [SSAI] The Dawn of HLS
The story of HLS begins before the launch of Sentinel-2A in 2015. Jeffrey Masek [GSFC], who was at that time project scientist for Landsat 8, led a group of researchers who wanted to find a way to harmonize Landsat data with other satellite data. Their aim was to create a “virtual constellation” similar to how weather satellites operate.
“HLS meets a need that people have been asking for for a long time,” said Masek.
What began as a research question with an experimental product evolved into an operational project with the involvement of the Satellite Needs Working Group (SNWG). SNWG is an interagency effort to develop solutions that address Earth observation needs of civilian federal agencies. Every two years, SNWG conducts a survey of federal agencies to see how their work could benefit from satellite data. The answers span the gamut of application areas, from water quality monitoring to disaster recovery to planning how best to protect and use natural resources. SNWG brings these ideas to NASA, USGS, and the National Oceanic and Atmospheric Administration (NOAA) – the three main U.S. government providers of satellite data. These agencies work together to create and implement solutions that serve those needs. NASA plays a critical role in every step of the SNWG process, including leading the assessment of survey responses from over 30 federal agencies, managing and supporting the implementation of identified solutions, and encouraging solution co-design with federal partners to maximize impact.
The HLS surface reflectance product was an outcome of the very first SNWG solution cycle in 2016. This product was expanded, following additional SNWG requests in 2020 and 2022. The 2020 cycle saw the creation of nine HLS-derived vegetation indices, and the 2022 cycle aimed for a six-hour latency product.
The U.S. Department of Agriculture (USDA) now uses HLS to map crop emergence at the field scale in the corn belt, allowing farmers to better plan their growing seasons. Ranchers in Colorado use the dataset to decide where to graze their cattle during periods of drought. HLS also informs the use and termination of cover crops in the Chesapeake Bay area. In 2024, the Federal Emergency Management Agency (FEMA) employed HLS to identify where to focus aid in the aftermath of Hurricane Helene.
A New and Improved HLS
In the July 2025 issue of Remote Sensing of Environment, a team of researchers outlined the HLS V2.0 surface reflectance dataset and algorithms. The team included seven NASA co-authors, members of the 2018–2023 Landsat Science Team, and ESA. The lead author, Junchang Ju [GSFC—Remote Sensing Scientist], has been the technical lead on HLS since its inception. Co-author Christopher Neigh [GSFC—Landsat 8/9 Project Scientist] is the principal investigator on the HLS project. V2.0, which was completed in Summer 2023, incorporates several major improvements over HLS V1.4, the most recent publicly available HLS product. HLS V1.4 covered about 30% of the global land area, providing data on North America and other select locations. HLS V2.0 provides data at a spatial resolution of 30 m (98 ft) with near-global coverage from 2013 onward. The dataset includes all land masses except Antarctica. HLS V2.0 also has key algorithmic improvements in atmospheric correction, cloud masking, and bidirectional reflectance distribution function (BRDF) correction. Together, these algorithms “harmonize” the data, or ensure that the distinct Landsat and Sentinel-2 datasets can effectively be used interchangeably – see Animation 2.
Animation 2: The visualization provides the Normalized Difference Vegetation Index (NDVI) data from Harmonized Landsat Sentinel-2 (HLS) for farm fields south of Columbus, NE. The red represents bare soil and green represents healthy, growing vegetation. The animation runs from January 1 to December 30, 2016. Animation credit: Michael Taylor [SSAI], Matthew Radcliff [USRA], and Jeffrey Masek [GSFC]. Caption adapted from Laura Rocchio [SSAI] HLS V2.0 in Action
The increased frequency of observations improved the ability of the scientific community to track disaster recovery, changes in phenology, agricultural intensification, rapid urban growth, logging, and deforestation. Researchers are already putting these advances to use.
The land disturbance product (DIST-ALERT) is a global land change monitoring system that uses HLS V2.0 data to track vegetation anomalies in near real-time – see Figure 1. DIST-ALERT captures agricultural expansion, urban growth, fire, flooding, logging, drought, landslides, and other forces of change to vegetation. Amy Pickens [University of Maryland, Department of Geographical Sciences—Assistant Research Professor] said that HLS is the perfect dataset for tracking disturbances because of the frequency of observations.
DIST-ALERT was created through Observational Products for End-Users from Remote Sensing Analysis (OPERA), a project at NASA/Jet Propulsion Laboratory (JPL). OPERA products respond to agency needs identified by the SNWG. In 2018, SNWG identified tracking surface disturbance as a key need. OPERA partnered with the Global Land Analysis and Discovery (GLAD) lab at University of Maryland to develop the change detection algorithm.
To track changes in vegetation, the DIST-ALERT system establishes a rolling baseline – meaning that for any given pixel, the vegetation cover is compared against vegetation cover from the same 31-day window in the previous three years. The primary algorithm detects any vegetation loss relative to the established baseline. A secondary algorithm flags any spectral anomaly (i.e., any change in reflectance) compared to that same baseline. This approach ensures that the algorithm catches non-vegetation change (e.g., new building or road projects in unvegetated areas). Used together, these algorithms can identify long-term changes in agricultural expansion, deforestation, and urbanization alongside short-term changes in crop harvest, drought, selective logging, and the impacts of disasters. On average, DIST-ALERT is made available on LP DAAC within six hours of when new HLS data is available. Currently, the dataset does not provide attribution to disturbances.
Figure 1. In March 2025, wildfires burned through South Korea, resulting in heavy vegetation loss. [left] Output of the DIST-ALERT product on NASA Worldview from May 8, 2025, with vegetation loss in percent flagged with varying levels of confidence. Yellow and red represent areas with confirmed vegetation cover losses of right] Natural-color image captured by the Multi-Spectral Instrument (MSI) aboard Sentinel-2C on May 8, 2025. The large brown burn scar in the center of the image corresponds to vegetation loss detected by DIST-ALERT. It stands in contrast to the surrounding green vegetation. Figure credit: NASA Earthdata Disturbance alerts already exist in some ecosystems. Brazil’s National Institute for Space Research [Instituto Nacional de Pesquisas Espaciais (INPE)] runs two projects that detect deforestation in the Amazon: Programa de Cálculo do Desflorestamento da Amazônia (PRODES) and Sistema de Detecção de Desmatamento em Tempo Real (DETER). The GLAD lab created its own forest loss alerts – GLAD-L and GLAD-S2 – using Landsat and Sentinel-2 data respectively. Global Forest Watch integrates GLAD-L and GLAD-S2 data with Radar for Detecting Deforestation (RADD) observations – derived from synthetic aperture radar data from Copernicus Sentinel-1 – into an integrated deforestation alert.
The implementation of these alert systems, some of which have been around for decades, have been shown to impact deforestation rates in the tropics. For example, a 2021 study in Nature Climate Change found that deforestation alerts decreased the probability of deforestation in Central Africa by 18% relative to the average 2011–2016 levels.
DIST-ALERT is distinct from other alert systems in a few ways. First, it has global coverage. Second, the rolling baseline allows for tracking changes in seasonality and disturbances to dynamic ecosystems. When HLS V2.0 data are input to DIST-ALERT, the system is also better at identifying disturbances in cloudy ecosystems than other individual alert systems – because it is more likely to obtain clear observations. This also enables it to identify the start and end of the disturbance more precisely.
Pickens said that the DIST-ALERT team is already working with end-users who are implementing their data product. She has spoken to some who use the system to help logging companies prove that they are complying with regulations. The U.S. Census Bureau is also using DIST-ALERT to monitor fast-growing communities so that they can do targeted assessments in the interim between the larger decennial census.
Alongside DIST-ALERT, OPERA has also been developing the Dynamic Surface Water eXtent (DSWx) product suite, which employs HLS to track surface water (e.g., lakes, reservoirs, rivers, and floods) around the globe – see Figure 2. These new products represent the new applications made possible by the HLS interagency and international collaboration.
Figure 2. The map shows flood extent and estimates of flood depth in areas west of Porto Alegre, Brazil on May 6, 2024. The flood extent is from the Observational Products for End-Users from Remote Sensing Analysis (OPERA) Dynamic Surface Water eXtent product, which uses Harmonized Landsat Sentinel-2 data. The flood depth estimate is from the Floodwater Depth Estimation Tool (FwD ET). The darkest blue areas represent floodwater at least 5 m (20 ft) deep. Much of the inundated floodplain is light blue, which equates to depths of between 0.1–1 m (4–40 in). Figure credit: Lauren Dauphin [NASA’s Earth Observatory], Dinuke Munasinghe [JPL], Sagy Cohen [University of Alabama], and Alexander Handwerger [JPL] Conclusion
HLS is set to continue improving land monitoring efforts across the globe. Meanwhile, the HLS science team is working to improve the algorithms for a more seamless harmonization of Landsat 8 and 9 and Sentinel-2 data. They are also working to improve the cloud-masking algorithm, have recently released vegetation indices, and are working on developing a low-latency (six-hour) HLS surface reflectance product, all while incorporating user feedback.
Looking ahead, the launch of future Sentinel and Landsat satellites will further the development of HLS. The additional data and unique capabilities will continue to meet researchers’ need for more frequent, high-quality satellite observations of Earth’s land surface.
Madeleine Gregory
NASA’s Goddard Space Flight Center/Science Systems and Applications Inc.
madeleine.s.gregory@nasa.gov
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Last Updated Aug 25, 2025 Related Terms
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