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Detailed Dark Matter Map Yields Clues to Galaxy Cluster Growth
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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 Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations 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 Studies Small but Mighty Galaxy
This NASA/ESA Hubble Space Telescope features the nearby galaxy NGC 4449. ESA/Hubble & NASA, E. Sabbi, D. Calzetti, A. Aloisi This portrait from the NASA/ESA Hubble Space Telescope puts the nearby galaxy NGC 4449 in the spotlight. The galaxy is situated just 12.5 million light-years away in the constellation Canes Venatici (the Hunting Dogs). It is a member of the M94 galaxy group, which is near the Local Group of galaxies that the Milky Way is part of.
NGC 4449 is a dwarf galaxy, which means that it is far smaller and contains fewer stars than the Milky Way. But don’t let its small size fool you — NGC 4449 packs a punch when it comes to making stars! This galaxy is currently forming new stars at a much faster rate than expected for its size, which makes it a starburst galaxy. Most starburst galaxies churn out stars mainly in their centers, but NGC 4449 is alight with brilliant young stars throughout. Researchers believe that this global burst of star formation came about because of NGC 4449’s interactions with its galactic neighbors. Because NGC 4449 is so close, it provides an excellent opportunity for Hubble to study how interactions between galaxies can influence the formation of new stars.
Hubble released an image of NGC 4449 in 2007. This new version incorporates several additional wavelengths of light that Hubble collected for multiple observing programs. These programs encompass an incredible range of science, from a deep dive into NGC 4449’s star-formation history to the mapping of the brightest, hottest, and most massive stars in more than two dozen nearby galaxies.
The NASA/ESA/CSA James Webb Space Telescope has also observed NGC 4449, revealing in intricate detail the galaxy’s tendrils of dusty gas, glowing from the intense starlight radiated by the flourishing young stars.
Text Credit: ESA/Hubble
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Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight Center, Greenbelt, MD
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Last Updated Jun 20, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
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By European Space Agency
Astronomers have discovered a huge filament of hot gas bridging four galaxy clusters. At 10 times as massive as our galaxy, the thread could contain some of the Universe’s ‘missing’ matter, addressing a decades-long mystery.
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By NASA
A funky effect Einstein predicted, known as gravitational lensing — when a foreground galaxy magnifies more distant galaxies behind it — will soon become common when NASA’s Nancy Grace Roman Space Telescope begins science operations in 2027 and produces vast surveys of the cosmos.
This image shows a simulated observation from NASA’s Nancy Grace Roman Space Telescope with an overlay of its Wide Field Instrument’s field of view. More than 20 gravitational lenses, with examples shown at left and right, are expected to pop out in every one of Roman’s vast observations. A journal paper led by Bryce Wedig, a graduate student at Washington University in St. Louis, Missouri, estimates that of those Roman detects, about 500 from the telescope’s High-Latitude Wide-Area Survey will be suitable for dark matter studies. By examining such a large population of gravitational lenses, the researchers hope to learn a lot more about the mysterious nature of dark matter.Credit: NASA, Bryce Wedig (Washington University), Tansu Daylan (Washington University), Joseph DePasquale (STScI) A particular subset of gravitational lenses, known as strong lenses, is the focus of a new paper published in the Astrophysical Journal led by Bryce Wedig, a graduate student at Washington University in St. Louis. The research team has calculated that over 160,000 gravitational lenses, including hundreds suitable for this study, are expected to pop up in Roman’s vast images. Each Roman image will be 200 times larger than infrared snapshots from NASA’s Hubble Space Telescope, and its upcoming “wealth” of lenses will vastly outpace the hundreds studied by Hubble to date.
Roman will conduct three core surveys, providing expansive views of the universe. This science team’s work is based on a previous version of Roman’s now fully defined High-Latitude Wide-Area Survey. The researchers are working on a follow-up paper that will align with the final survey’s specifications to fully support the research community.
“The current sample size of these objects from other telescopes is fairly small because we’re relying on two galaxies to be lined up nearly perfectly along our line of sight,” Wedig said. “Other telescopes are either limited to a smaller field of view or less precise observations, making gravitational lenses harder to detect.”
Gravitational lenses are made up of at least two cosmic objects. In some cases, a single foreground galaxy has enough mass to act like a lens, magnifying a galaxy that is almost perfectly behind it. Light from the background galaxy curves around the foreground galaxy along more than one path, appearing in observations as warped arcs and crescents. Of the 160,000 lensed galaxies Roman may identify, the team expects to narrow that down to about 500 that are suitable for studying the structure of dark matter at scales smaller than those galaxies.
“Roman will not only significantly increase our sample size — its sharp, high-resolution images will also allow us to discover gravitational lenses that appear smaller on the sky,” said Tansu Daylan, the principal investigator of the science team conducting this research program. Daylan is an assistant professor and a faculty fellow at the McDonnell Center for the Space Sciences at Washington University in St. Louis. “Ultimately, both the alignment and the brightness of the background galaxies need to meet a certain threshold so we can characterize the dark matter within the foreground galaxies.”
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This video shows how a background galaxy’s light is lensed or magnified by a massive foreground galaxy, seen at center, before reaching NASA’s Roman Space Telescope. Light from the background galaxy is distorted, curving around the foreground galaxy and appearing more than once as warped arcs and crescents. Researchers studying these objects, known as gravitational lenses, can better characterize the mass of the foreground galaxy, which offers clues about the particle nature of dark matter.Credit: NASA, Joseph Olmsted (STScI) What Is Dark Matter?
Not all mass in galaxies is made up of objects we can see, like star clusters. A significant fraction of a galaxy’s mass is made up of dark matter, so called because it doesn’t emit, reflect, or absorb light. Dark matter does, however, possess mass, and like anything else with mass, it can cause gravitational lensing.
When the gravity of a foreground galaxy bends the path of a background galaxy’s light, its light is routed onto multiple paths. “This effect produces multiple images of the background galaxy that are magnified and distorted differently,” Daylan said. These “duplicates” are a huge advantage for researchers — they allow multiple measurements of the lensing galaxy’s mass distribution, ensuring that the resulting measurement is far more precise.
Roman’s 300-megapixel camera, known as its Wide Field Instrument, will allow researchers to accurately determine the bending of the background galaxies’ light by as little as 50 milliarcseconds, which is like measuring the diameter of a human hair from the distance of more than two and a half American football fields or soccer pitches.
The amount of gravitational lensing that the background light experiences depends on the intervening mass. Less massive clumps of dark matter cause smaller distortions. As a result, if researchers are able to measure tinier amounts of bending, they can detect and characterize smaller, less massive dark matter structures — the types of structures that gradually merged over time to build up the galaxies we see today.
With Roman, the team will accumulate overwhelming statistics about the size and structures of early galaxies. “Finding gravitational lenses and being able to detect clumps of dark matter in them is a game of tiny odds. With Roman, we can cast a wide net and expect to get lucky often,” Wedig said. “We won’t see dark matter in the images — it’s invisible — but we can measure its effects.”
“Ultimately, the question we’re trying to address is: What particle or particles constitute dark matter?” Daylan added. “While some properties of dark matter are known, we essentially have no idea what makes up dark matter. Roman will help us to distinguish how dark matter is distributed on small scales and, hence, its particle nature.”
Preparations Continue
Before Roman launches, the team will also search for more candidates in observations from ESA’s (the European Space Agency’s) Euclid mission and the upcoming ground-based Vera C. Rubin Observatory in Chile, which will begin its full-scale operations in a few weeks. Once Roman’s infrared images are in hand, the researchers will combine them with complementary visible light images from Euclid, Rubin, and Hubble to maximize what’s known about these galaxies.
“We will push the limits of what we can observe, and use every gravitational lens we detect with Roman to pin down the particle nature of dark matter,” Daylan said.
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 in Southern California; Caltech/IPAC in Pasadena, 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 Melbourne, Florida; and Teledyne Scientific & Imaging in Thousand Oaks, California.
By Claire Blome
Space Telescope Science Institute, Baltimore, Md.
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Last Updated Jun 12, 2025 EditorAshley BalzerContactAshley Balzerashley.m.balzer@nasa.govLocationNASA Goddard Space Flight Center Related Terms
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By NASA
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 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 Webb’s First Images Team International Team People Of Webb More For the Media For Scientists For Educators For Fun/Learning 5 Min Read NASA’s Webb ‘UNCOVERs’ Galaxy Population Driving Cosmic Renovation
White diamonds show the locations of 20 of the 83 young, low-mass, starburst galaxies found in infrared images of the giant galaxy cluster Abell 2744. Full image and description shown below. Credits:
NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025 Astronomers using data from NASA’s James Webb Space Telescope have identified dozens of small galaxies that played a starring role in a cosmic makeover that transformed the early universe into the one we know today.
“When it comes to producing ultraviolet light, these small galaxies punch well above their weight,” said Isak Wold, an assistant research scientist at Catholic University of America in Washington and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Our analysis of these tiny but mighty galaxies is 10 times more sensitive than previous studies, and shows they existed in sufficient numbers and packed enough ultraviolet power to drive this cosmic renovation.”
Wold discussed his findings Wednesday at the 246th meeting of the American Astronomical Society in Anchorage, Alaska. The study took advantage of existing imaging collected by Webb’s NIRCam (Near-Infrared Camera) instrument, as well as new observations made with its NIRSpec (Near-Infrared Spectrograph) instrument.
Image A: Webb search finds dozens of tiny, young star-forming galaxies
Symbols mark the locations of young, low-mass galaxies bursting with new stars when the universe was about 800 million years old. Using a filter sensitive to such galaxies, NASA’s James Webb Space Telescope imaged them with the help of a natural gravitational lens created by the massive galaxy cluster Abell 2744. In all, 83 young galaxies were found, but only the 20 shown here (white diamonds) were selected for deeper study. The inset zooms into one of the galaxies.
Download high-resolution images from NASA’s Scientific Visualization Studio NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025 The tiny galaxies were discovered by Wold and his Goddard colleagues, Sangeeta Malhotra and James Rhoads, by sifting through Webb images captured as part of the UNCOVER (Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization) observing program, led by Rachel Bezanson at the University of Pittsburgh in Pennsylvania.
The project mapped a giant galaxy cluster known as Abell 2744, nicknamed Pandora’s cluster, located about 4 billion light-years away in the southern constellation Sculptor. The cluster’s mass forms a gravitational lens that magnifies distant sources, adding to Webb’s already considerable reach.
Image B: Galaxy cluster helps reveal young, low-mass galaxies bursting with stars
White diamonds show the locations of 20 of the 83 young, low-mass, starburst galaxies found in infrared images of the giant galaxy cluster Abell 2744. This composite incorporates images taken through three NIRCam filters (F200W as blue, F410M as green, and F444W as red). The F410M filter is highly sensitive to light emitted by doubly ionized oxygen — oxygen atoms that have been stripped of two electrons — at a time when reionization was well underway. Emitted as green light, the glow was stretched into the infrared as it traversed the expanding universe over billions of years. The cluster’s mass acts as a natural magnifying glass, allowing astronomers to see these tiny galaxies as they were when the universe was about 800 million years old. NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025 For much of its first billion years, the universe was immersed in a fog of neutral hydrogen gas. Today, this gas is ionized — stripped of its electrons. Astronomers, who refer to this transformation as reionization, have long wondered which types of objects were most responsible: big galaxies, small galaxies, or supermassive black holes in active galaxies. As one of its main goals, NASA’s Webb was specifically designed to address key questions about this major transition in the history of the universe.
Recent studies have shown that small galaxies undergoing vigorous star formation could have played an outsized role. Such galaxies are rare today, making up only about 1% of those around us. But they were abundant when the universe was about 800 million years old, an epoch astronomers refer to as redshift 7, when reionization was well underway.
The team searched for small galaxies of the right cosmic age that showed signs of extreme star formation, called starbursts, in NIRCam images of the cluster.
“Low-mass galaxies gather less neutral hydrogen gas around them, which makes it easier for ionizing ultraviolet light to escape,” Rhoads said. “Likewise, starburst episodes not only produce plentiful ultraviolet light — they also carve channels into a galaxy’s interstellar matter that helps this light break out.”
Image C: A deeper look into small, young, star-forming galaxies during reionization
At left is an enlarged infrared view of galaxy cluster Abell 2744 with three young, star-forming galaxies highlighted by green diamonds. The center column shows close-ups of each galaxy, along with their designations, the amount of magnification provided by the cluster’s gravitational lens, their redshifts (shown as z — all correspond to a cosmic age of about 790 million years), and their estimated mass of stars. At right, measurements from NASA’s James Webb Space Telescope’s NIRSpec instrument confirm that the galaxies produce strong emission in the light of doubly ionized oxygen (green bars), indicating vigorous star formation is taking place. NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025 The astronomers looked for strong sources of a specific wavelength of light that signifies the presence of high-energy processes: a green line emitted by oxygen atoms that have lost two electrons. Originally emitted as visible light in the early cosmos, the green glow from doubly ionized oxygen was stretched into the infrared as it traversed the expanding universe and eventually reached Webb’s instruments.
This technique revealed 83 small starburst galaxies as they appear when the universe was 800 million years old, or about 6% of its current age of 13.8 billion years. The team selected 20 of these for deeper inspection using NIRSpec.
“These galaxies are so small that, to build the equivalent stellar mass of our own Milky Way galaxy, you’d need from 2,000 to 200,000 of them,” Malhotra said. “But we are able to detect them because of our novel sample selection technique combined with gravitational lensing.”
Image D: Tiny but mighty galaxy helped clear cosmic fog
One of the most interesting galaxies of the study, dubbed 41028 (the green oval at center), has an estimated stellar mass of just 2 million Suns — comparable to the masses of the largest star clusters in our own Milky Way galaxy. NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025 Similar types of galaxies in the present-day universe, such as green peas, release about 25% of their ionizing ultraviolet light into surrounding space. If the low-mass starburst galaxies explored by Wold and his team release a similar amount, they can account for all of the ultraviolet light needed to convert the universe’s neutral hydrogen to its ionized form.
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
By Francis Reddy
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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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 9 min read
NASA’s TROPICS Mission: Offering Detailed Images and Analysis of Tropical Cyclones
Introduction
Tropical cyclones represent a danger to life, property, and the economies of communities. Researchers who study tropical cyclones have focused on remote observations using space-based platforms to image these storms, inform forecasts, better predict landfall, and improve understanding of storm dynamics and precipitation evolution – see Figure 1.
Figure 1. TROPICS imagery of Typhoon Kong-rey observed on October 29, 2024 near 205 GHz revealing a large and well-defined eye. Figure credit: U.S. Naval Research Laboratory The tropical cyclone community has leveraged data from Earth observing platforms for more than 30 years. These data have been retrieved from numerous instruments including: the Advanced Baseline Imager (ABI) on the National Oceanic and Atmospheric Administration’s (NOAA) Geostationary Operational Environmental Satellite (GOES)–Series R satellites; the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI); the Global Precipitation Measurement (GPM) Microwave Imager (GMI); the Special Sensor Microwave Imager/Sounder (SSMIS) on the Defense Meteorological Satellite (DSMP) satellites; the Advanced Microwave Scanning Radiometer (AMSR-E) on Aqua; AMSR2 on the Japan Aerospace Exploration Agency’s (JAXA) Global Change Observation Mission–Water (GCOM-W) mission; the Advanced Microwave Sounding Unit (AMSU) on Aqua and the Advanced Technology Microwave Sounder (ATMS) on the NASA–NOAA Suomi National Polar-Orbiting Partnership (Suomi NPP), NOAA-20, and NOAA-21; the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra and Aqua Platform; and the Visible Infrared Imaging Radiometer Suite (VIIRS) on Suomi NPP, as well as on the first two Joint Polar Satellite System (JPSS) missions (i.e., NOAA-20 and NOAA-21).
Despite having decades of data at their disposal, scientists lack data from instruments placed in low-inclination orbits that provide more frequent views within tropical regions. This limitation is especially pronounced in the tropical and subtropical latitudes, which is where tropical storms develop and intensify.
The NASA Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) grew from the Precipitation and All-weather Temperature and Humidity (PATH) to address a need for obtaining three-dimensional (3D) temperature and humidity measurements as well as precipitation with a temporal revisit rate of one hour or better – see Figure 2. TROPICS uses multiple small satellites flying in a carefully engineered formation to obtain rapid revisits of measurements of precipitation structure within the storms, as well as temperature and humidity profiles, both within and outside of the storms, including the intensity of the upper-level warm core. In addition, the instruments provide a median revisit time of about one hour. The data gathered also informs changes in storm track and intensity and provides data to improve weather prediction models.
The imagery is focused on inner storm structure (near 91 and 205 GHz), temperature soundings (near 118 GHz), and moisture soundings (near 183 GHz). Spatial resolution at nadir is approximately 24 km (16.8 mi) for temperature and 17 km (10.6 mi) for moisture and precipitation, covering a swath of approximately 2000 km (1243 mi) in width. Researchers can use TROPICS data to create hundreds of high-resolution images of tropical cyclones throughout their lifecycle.
Figure 2. TROPICS space vehicle showing the CubeSat bus, radiometer payload, and deployed articulated solar array. Figure credit: Blue Canyon Technologies and MIT Lincoln Laboratory This article provides an overview of the two years of successful science operations of TROPICS, with a focus on the suite of geophysical Level-2 (L2) products (e.g., atmospheric vertical temperature and moisture profiles, instantaneous surface rain rate, and tropical cyclone intensity) and the science investigations resulting from these measurements. The complete article, available in the Proceedings Of The IEEE: Special Issue On Satellite Remote Sensing Of The Earth, provides more comprehensive details of the results.
From Pathfinder to Constellation
A single TROPICS satellite was launched as a Pathfinder vehicle on June 30, 2021, aboard a SpaceX Falcon 9 rideshare into a Sun-synchronous polar orbit. TROPICS was originally conceived as a six-satellite constellation, with two satellites launched into each of three low-inclination orbits. Regrettably, the first launch, on June 22, 2022 aboard an Astra Rocket 3.3, failed to reach orbit. While unfortunate, the mission could still proceed with four satellites and meet its baseline revisit rate requirement (with no margin), with the silver lining of an extra year of data gathered from TROPICS Pathfinder that allowed the tropical cyclone research community to prepare and test communications systems and data processing algorithms before the launch of the four remaining constellation satellites. These satellites were deployed on two separate launches – May 8, 2023 and May 26, 2023 aboard a Rocket Lab launch vehicle. The early testing accelerated calibration and validation for the constellation.
Collecting Data Critical to Understanding Tropical Cyclones
Tropical cyclone investigations require rapid quantitative observations to create 2D storm structure information. The four radiance data products in the TROPICS constellation [i.e., antenna temperature (L1a), brightness temperature (L1b), unified brightness temperature, and regularized scan pattern and limb-adjusted brightness temperature (L1c)] penetrate below the cloud top to gather data at greater frequency for a lower cost than current operational systems. The constellation data has been used to evaluate the development of the warm core and evolution of the ice water path within storms – two indicators of storm formation and subsequent changes in intensity.
The upper-level warm core is key to tropical cyclone development and intensification. Precipitation may instigate rapid intensification through convective bursts that are characterized by expanding cold cloud tops, increasing ice scattering, lightning, and towers of intense rain and ice water that are indicative of strong updrafts. TROPICS frequencies provide a wealth of information on scattering by precipitation-sized ice particles in the eyewall and rainbands that will allow for researchers to track the macrostructure of convective bursts in tropical cyclones across the globe. In addition, TROPICS data helps clarify how variations in environmental humidity around tropical cyclones affect storm structure and intensification.
Upper-level Warm Core
Analysis of the upper-level warm core of a tropical cyclone reveals valuable information about the storm’s development. The tropical cyclone community is using data from TROPICS to understand the processes that lead to precipitating ice structure and the role it plays in intensification – see Figure 3. While the warm core has been studied for decades, TROPICS provides a new opportunity to get high-revisit rate estimates of the atmospheric vertical temperature profile. By pairing the temperature profile with the atmospheric vertical moisture profile, researchers can define the relative humidity in the lower-to-middle troposphere, which is critical to understanding the impact of dry environmental air on storm evolution and structure.
Figure 3. TROPICS-3 imagery of Typhoon Kong-rey observed on October 29, 2024, a Category-5 storm that formed in the Pacific Ocean basin. Data gathered near 118 GHz was used to characterize temperature while data gathered near 205 GHz [right] revealed more about the inner structure of the storm. These data are used to define the warm core of the well-defined eye, located at 18.5° N. Figure Credit: U.S. Naval Research Laboratory Ice Water Path and Precipitation
Another variable that helps to provide insight into the development of tropical cyclones is the ice water path, which details the total mass of ice present in a vertical column of the atmosphere and is therefore useful for characterizing the structure and intensity of these storms. Increasing ice water path can reflect strengthening convection within a storm and thereby be an indicator of likely intensification – see Figure 4. TROPICS is the first spaceborne sensor equipped with a 205-GHz channel that, along with the traditional 89, 118, and 183 GHz channels, is more sensitive to detecting precipitation-sized ice particles. In addition, the TROPICS Precipitation Retrieval and Profiling Scheme (PRPS) provides an estimate of precipitation. This scheme is based solely on the satellite radiances linked to precipitation rates, which can be used to generate products across time scales, from near-real-time to climatological scales.
Figure 4. Global precipitation ice water path (PIWP) retrievals derived from TROPICS [top] compared to those derived using data from the GPM Dual-frequency Precipitation Radar (GPM DPR) [bottom] The strong agreement between the two datasets is further validated through case studies over hurricanes, where TROPICS observations correspond well with known storm characteristics. Figure Credit: Blackwell, W. J. et al. (2025) Collaborations and TROPICS Data in Action
To evaluate and enhance the data gathered by TROPICS, the TROPICS application team enlisted the assistance of operational weather forecasters that formed the TROPICS Early Adopters program. In 2018, the program connected the application team to stakeholders interested in using TROPICS data for research, forecasting, and decision making. This collaboration improved approaches to diagnose and predict tropical cyclones. For example, the National Hurricane Center (NHC) found that the new TROPICS channel at 204.8 GHz offered the best approach to capture convective storm structure, followed by the more traditionally used 91-GHz channel. In addition, the U.S. Joint Typhoon Warning Center (JTWC) has been using TROPICS data to center-fix tropical cyclones and identify cloud formations. In particular, the JTWC team found that the 91-GHz channel was most useful for identifying cloud structure. Both NHC and JTWC found the TROPICS high revisit rate to be beneficial.
In 2024, the TROPICS applications team developed the TROPICS Satellite Validation Module as part of the NOAA Hurricane Research Division’s annual Advancing the Prediction of Hurricanes Experiment (APHEX). The module coordinated data collection from NOAA’s Hurricane Hunter aircraft beneath TROPICS satellite overpasses to provide data to calibrate and validate TROPICS temperature, moisture, and precipitation measurements. Using this approach, the Hurricane Hunter team tracked Hurricane Ernesto over the central North Atlantic on August 15 and 16, 2024 and used the data to characterize the environment of Ernesto’s rain bands – see Figure 5.
Figure 5. Brightness temperature (K) measured at 205 GHz from TROPICS-5 [right] and TROPICS-6 [left and center] from Hurricane Ernesto on August 15 and 16, 2024. The shaded circles denote 850–700 hPa relative humidity (%). Wind barbs are 850–700 hPa layer averaged winds (kt). Dropsonde data within 30 minutes of the TROPICS overpass times are plotted. Figure Credit: Blackwell, W. J. et al. (2025) In addition, the team used TROPICS observations in combination with GPM constellation precipitation estimates to characterize the lifecycle of Hurricane Franklin, which formed on August 19, 2023 and underwent a period of rapid intensification about eight days later. Intensification of the storm, in particular the period of rapid intensification (45 knot increase in maximum winds in 24 hours), occurred in association with a decrease in environmental vertical wind shear, a contraction of the radius of maximum precipitation, and an increase in the precipitation rate. Intensification ended with the formation of secondary rainbands and an outward shift in the radius of maximum precipitation.
Conclusion
TROPICS data offer the potential for improving forecasts from numerical weather prediction models and operational forecasts using its high spatial resolution and high revisit rates that enable enhanced characterization of tropical cyclones globally. To date, the TROPICS mission has produced a high-quality aggregate data record spanning 10 billion observations and 10 satellite years, using relatively low-cost microwave sounder constellations. All L1 (i.e., radiances) and L2 (i.e., geophysical products) data products and Algorithm Theoretical Basis Documents are available to the general public through the Goddard Earth Sciences Data and Information Services Center (GES DISC). The GES DISC data discussed in this article include L1 and L2 products for TROPICS-1, TROPICS-3, TROPICS-5, and TROPICS-6.
TROPICS data has aided hurricane track forecasting for multiple storms as forecasters have used the data at multiple operational tropical cyclone forecast centers. Data gathered by TROPICS will soon be complemented by multiple commercial constellations that are coming online to improve the revisit rate and performance.
William Blackwell
MIT Lincoln Laboratory
wjb@ll.mit.edu
Scott Braun
NASA GSFC, TROPICS Project Scientist
scott.a.braun@nasa.gov
Stacy Kish
Earth Observer Staff
Earthspin.science@gmail.com
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Last Updated Jun 09, 2025 Related Terms
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