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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
Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Media Contact:
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
Hubble Space Telescope Astrophysics Astrophysics Division Galaxies Goddard Space Flight Center Irregular Galaxies The Universe Keep Exploring Discover More Topics From Hubble
Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
Hubble’s Galaxies
Galaxy Details and Mergers
Hubble’s Night Sky Challenge
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By NASA
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of the Mapping Sub-cm Orbital Debris in LEO concept.NASA/Christine Hartzell Christine Hartzell
University of Maryland, College Park
The proposed investigation will address key technological challenges associated with a previously funded NIAC Phase I award titled “On-Orbit, Collision-Free Mapping of Small Orbital Debris”. Sub-cm orbital debris in LEO is not detectable or trackable using conventional technologies and poses a major hazard to crewed and un-crewed spacecraft. Orbital debris is a concern to NASA, as well as commercial and DoD satellite providers. In recent years, beginning with our NIAC Phase I award, we have been developing the idea that the sub-cm orbital debris environment may be monitored by detecting the plasma signature of the debris, rather than optical or radar observations of the debris itself. Our prior work has shown that sub-cm orbital debris may produce plasma solitons, which are a type of wave in the ionosphere plasma that do not disperse as readily as traditional waves. Debris may produce solitons that are co-located with the debris (called pinned solitons) or that travel ahead of the debris (called precursor solitons). We have developed computational models to predict the characteristics of the plasma solitons generated by a given piece of debris. These solitons may be detectable by 12U smallsats outfitted with multi-needle Langmuir probes.
In this Phase II NIAC award, we will address two key technical challenges that significantly effect the value of soliton-based debris detection: 1. Develop an algorithm to constrain debris size and speed based on observed soliton characteristics. Our prior investigations have produced predictions of soliton characteristics as a function of debris characteristics. However, the inverse problem is not analytically solvable. We will develop machine learning algorithms to address this challenge. 2. Evaluate the feasibility and value of detecting soliton velocity. Multiple observations of the same soliton may allow us to constrain the distance that the soliton has traveled from the debris. When combined with the other characteristics of the soliton and knowledge of the local plasma environment, back propagation of the soliton in plasma simulations may allow us to extract the position and velocity vectors of the debris. If it is possible to determine debris size, position and velocity from soliton observations, this would provide a breakthrough in space situational awareness for debris that is currently undetectable using conventional technology. However, even if only debris size and speed can be inferred from soliton detections, this technology is still a revolutionary improvement on existing methods of characterizing the debris flux, which provide data only on a multi-year cadence. This proposed investigation will answer key technological questions about how much information can be extracted from observed soliton signals and trade mission architectures for complexity and returned data value. Additionally, we will develop a roadmap to continue to advance this technology.
2025 Selections
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Last Updated May 27, 2025 EditorLoura Hall Related Terms
NIAC Studies NASA Innovative Advanced Concepts (NIAC) Program Keep Exploring Discover More NIAC Topics
Space Technology Mission Directorate
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By NASA
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of Gravity Poppers: Hopping Probes for the Interior Mapping of Small Solar System Bodies concept.NASA/Benjamin Hockman Benjamin Hockman
NASA Jet Propulsion Laboratory
The goal of this effort is to develop a robust and affordable mission architecture that enables the gravimetric density reconstruction of small body interiors to unprecedented precision. Our architecture relies on the novel concept of “Gravity Poppers,” which are small, minimalistic probes that are deployed to the surface of a small body and periodically “pop” so as to perpetuate a random hopping motion around the body. By tracking a large swarm of poppers from orbit, a mother spacecraft can precisely estimate their trajectories and continuously refine a high-resolution map of the body’s gravity field, and thus, its internal mass distribution. Hopping probes are also equipped with minimalistic in-situ sensors to measure the surface temperature (when landed) and strength (when bouncing) in order to complement the gravity field and build a more accurate picture of the interior. The Phase I study focused on feasibility assessment of three core technologies that enable such a mission: (1) the mechanical design of hopping probes to be small, simple, robust, and “visible” to a distant spacecraft, (2) the tracking strategy for detecting and estimating the trajectories of a large number of ballistic probes, and (3) the algorithmic framework by which such measurements can be used to iteratively refine a gravity model of the body. The key finding was that the concept is feasible, and demonstrated to have the potential to resolve extremely accurate gravity models, allowing scientists to localize density anomalies such as “weighing” large boulders on the surface. This Phase II Proposal aims to further develop these three core technologies through continued mission trade studies and sensitivity analysis, case studies for simulated missions, and hardware prototypes demonstrating both hopping behavior and tracking performance.
2025 Selections
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Last Updated May 27, 2025 EditorLoura Hall Related Terms
NIAC Studies NASA Innovative Advanced Concepts (NIAC) Program Keep Exploring Discover More NIAC Topics
Space Technology Mission Directorate
NASA Innovative Advanced Concepts
NIAC Funded Studies
About NIAC
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By Space Force
Secretary of the Air Force Troy Meink, alongside Air Force Chief of Staff Gen. David Allvin and Chief of Space Operations Gen. B. Chance Saltzman, testified before the Senate Armed Services Committee
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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Sunlight reflects off the ocean surface near Norfolk, Virginia, in this 1991 space shuttle image, highlighting swirling patterns created by features such as internal waves, which are produced when the tide moves over underwater features. Data from the international SWOT mission is revealing the role of smaller-scale waves and eddies.NASA The international mission collects two-dimensional views of smaller waves and currents that are bringing into focus the ocean’s role in supporting life on Earth.
Small things matter, at least when it comes to ocean features like waves and eddies. A recent NASA-led analysis using data from the SWOT (Surface Water and Ocean Topography) satellite found that ocean features as small as a mile across potentially have a larger impact on the movement of nutrients and heat in marine ecosystems than previously thought.
Too small to see well with previous satellites but too large to see in their entirety with ship-based instruments, these relatively small ocean features fall into a category known as the submesoscale. The SWOT satellite, a joint effort between NASA and the French space agency CNES (Centre National d’Études Spatiales), can observe these features and is demonstrating just how important they are, driving much of the vertical transport of things like nutrients, carbon, energy, and heat within the ocean. They also influence the exchange of gases and energy between the ocean and atmosphere.
“The role that submesoscale features play in ocean dynamics is what makes them important,” said Matthew Archer, an oceanographer at NASA’s Jet Propulsion Laboratory in Southern California. Some of these features are called out in the animation below, which was created using SWOT sea surface height data.
This animation shows small ocean features — including internal waves and eddies — derived from SWOT observations in the Indian, Atlantic, and Pacific oceans, as well as the Mediterranean Sea. White and lighter blue represent higher ocean surface heights compared to darker blue areas. The purple colors shown in one location represent ocean current speeds.
NASA’s Scientific Visualization Studio “Vertical currents move heat between the atmosphere and ocean, and in submesoscale eddies, can actually bring up heat from the deep ocean to the surface, warming the atmosphere,” added Archer, who is a coauthor on the submesoscale analysis published in April in the journal Nature. Vertical circulation can also bring up nutrients from the deep sea, supplying marine food webs in surface waters like a steady stream of food trucks supplying festivalgoers.
“Not only can we see the surface of the ocean at 10 times the resolution of before, we can also infer how water and materials are moving at depth,” said Nadya Vinogradova Shiffer, SWOT program scientist at NASA Headquarters in Washington.
Fundamental Force
Researchers have known about these smaller eddies, or circular currents, and waves for decades. From space, Apollo astronauts first spotted sunlight glinting off small-scale eddies about 50 years ago. And through the years, satellites have captured images of submesoscale ocean features, providing limited information such as their presence and size. Ship-based sensors or instruments dropped into the ocean have yielded a more detailed view of submesoscale features, but only for relatively small areas of the ocean and for short periods of time.
The SWOT satellite measures the height of water on nearly all of Earth’s surface, including the ocean and freshwater bodies, at least once every 21 days. The satellite gives researchers a multidimensional view of water levels, which they can use to calculate, for instance, the slope of a wave or eddy. This in turn yields information on the amount of pressure, or force, being applied to the water in the feature. From there, researchers can figure out how fast a current is moving, what’s driving it and —combined with other types of information — how much energy, heat, or nutrients those currents are transporting.
“Force is the fundamental quantity driving fluid motion,” said study coauthor Jinbo Wang, an oceanographer at Texas A&M University in College Station. Once that quantity is known, a researcher can better understand how the ocean interacts with the atmosphere, as well as how changes in one affect the other.
Prime Numbers
Not only was SWOT able to spot a submesoscale eddy in an offshoot of the Kuroshio Current — a major current in the western Pacific Ocean that flows past the southeast coast of Japan — but researchers were also able to estimate the speed of the vertical circulation within that eddy. When SWOT observed the feature, the vertical circulation was likely 20 to 45 feet (6 to 14 meters) per day.
This is a comparatively small amount for vertical transport. However, the ability to make those calculations for eddies around the world, made possible by SWOT, will improve researchers’ understanding of how much energy, heat, and nutrients move between surface waters and the deep sea.
Researchers can do similar calculations for such submesoscale features as an internal solitary wave — a wave driven by forces like the tide sloshing over an underwater plateau. The SWOT satellite spotted an internal wave in the Andaman Sea, located in the northeastern part of the Indian Ocean off Myanmar. Archer and colleagues calculated that the energy contained in that solitary wave was at least twice the amount of energy in a typical internal tide in that region.
This kind of information from SWOT helps researchers refine their models of ocean circulation. A lot of ocean models were trained to show large features, like eddies hundreds of miles across, said Lee Fu, SWOT project scientist at JPL and a study coauthor. “Now they have to learn to model these smaller scale features. That’s what SWOT data is helping with.”
Researchers have already started to incorporate SWOT ocean data into some models, including NASA’s ECCO (Estimating the Circulation and Climate of the Ocean). It may take some time until SWOT data is fully a part of models like ECCO. But once it is, the information will help researchers better understand how the ocean ecosystem will react to a changing world.
More About SWOT
The SWOT satellite was jointly developed by NASA and CNES, with contributions from the Canadian Space Agency (CSA) and the UK Space Agency. Managed for NASA by Caltech in Pasadena, California, JPL leads the U.S. component of the project. For the flight system payload, NASA provided the Ka-band radar interferometer (KaRIn) instrument, a GPS science receiver, a laser retroreflector, a two-beam microwave radiometer, and NASA instrument operations. The Doppler Orbitography and Radioposition Integrated by Satellite system, the dual frequency Poseidon altimeter (developed by Thales Alenia Space), the KaRIn radio-frequency subsystem (together with Thales Alenia Space and with support from the UK Space Agency), the satellite platform, and ground operations were provided by CNES. The KaRIn high-power transmitter assembly was provided by CSA.
To learn more about SWOT, visit:
https://swot.jpl.nasa.gov
News Media Contacts
Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
626-491-1943 / 626-379-6874
jane.j.lee@jpl.nasa.gov / andrew.wang@jpl.nasa.gov
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Last Updated May 15, 2025 Related Terms
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