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By NASA
Hubble Space Telescope Home NASA’s Hubble Sees… Hubble Space Telescope 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 News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts E-books Lithographs Fact Sheets Glossary Posters Hubble on the NASA App More Online Activities 5 Min Read NASA’s Hubble Sees Aftermath of Galaxy’s Scrape with Milky Way
This artist’s concept shows a closeup of the Large Magellanic Cloud, a dwarf galaxy that is one of the Milky Way galaxy’s nearest neighbors. Credits:
NASA, ESA, Ralf Crawford (STScI) A story of survival is unfolding at the outer reaches of our galaxy, and NASA’s Hubble Space Telescope is witnessing the saga.
The Large Magellanic Cloud, also called the LMC, is one of the Milky Way galaxy’s nearest neighbors. This dwarf galaxy looms large on the southern nighttime sky at 20 times the apparent diameter of the full Moon.
Many researchers theorize that the LMC is not in orbit around our galaxy, but is just passing by. These scientists think that the LMC has just completed its closest approach to the much more massive Milky Way. This passage has blown away most of the spherical halo of gas that surrounds the LMC.
Now, for the first time, astronomers been able to measure the size of the LMC’s halo – something they could do only with Hubble. In a new study to be published in The Astrophysical Journal Letters, researchers were surprised to find that it is so extremely small, about 50,000 light-years across. That’s around 10 times smaller than halos of other galaxies that are the LMC’s mass. Its compactness tells the story of its encounter with the Milky Way.
“The LMC is a survivor,” said Andrew Fox of AURA/STScI for the European Space Agency in Baltimore, who was principal investigator on the observations. “Even though it’s lost a lot of its gas, it’s got enough left to keep forming new stars. So new star-forming regions can still be created. A smaller galaxy wouldn’t have lasted – there would be no gas left, just a collection of aging red stars.”
This artist’s concept shows the Large Magellanic Cloud, or LMC, in the foreground as it passes through the gaseous halo of the much more massive Milky Way galaxy. The encounter has blown away most of the spherical halo of gas that surrounds the LMC, as illustrated by the trailing gas stream reminiscent of a comet’s tail. Still, a compact halo remains, and scientists do not expect this residual halo to be lost. The team surveyed the halo by using the background light of 28 quasars, an exceptionally bright type of active galactic nucleus that shines across the universe like a lighthouse beacon. Their light allows scientists to “see” the intervening halo gas indirectly through the absorption of the background light. The lines represent the Hubble Space Telescope’s view from its orbit around Earth to the distant quasars through the LMC’s gas. NASA, ESA, Ralf Crawford (STScI)
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Though quite a bit worse for wear, the LMC still retains a compact, stubby halo of gas – something that it wouldn’t have been able to hold onto gravitationally had it been less massive. The LMC is 10 percent the mass of the Milky Way, making it heftier than most dwarf galaxies.
“Because of the Milky Way’s own giant halo, the LMC’s gas is getting truncated, or quenched,” explained STScI’s Sapna Mishra, the lead author on the paper chronicling this discovery. “But even with this catastrophic interaction with the Milky Way, the LMC is able to retain 10 percent of its halo because of its high mass.”
A Gigantic Hair Dryer
Most of the LMC’s halo was blown away due to a phenomenon called ram-pressure stripping. The dense environment of the Milky Way pushes back against the incoming LMC and creates a wake of gas trailing the dwarf galaxy – like the tail of a comet.
“I like to think of the Milky Way as this giant hairdryer, and it’s blowing gas off the LMC as it comes into us,” said Fox. “The Milky Way is pushing back so forcefully that the ram pressure has stripped off most of the original mass of the LMC’s halo. There’s only a little bit left, and it’s this small, compact leftover that we’re seeing now.”
As the ram pressure pushes away much of the LMC’s halo, the gas slows down and eventually will rain into the Milky Way. But because the LMC has just gotten past its closest approach to the Milky Way and is moving outward into deep space again, scientists do not expect the whole halo will be lost.
Only with Hubble
To conduct this study, the research team analyzed ultraviolet observations from the Mikulski Archive for Space Telescopes at STScI. Most ultraviolet light is blocked by the Earth’s atmosphere, so it cannot be observed with ground-based telescopes. Hubble is the only current space telescope tuned to detect these wavelengths of light, so this study was only possible with Hubble.
The team surveyed the halo by using the background light of 28 bright quasars. The brightest type of active galactic nucleus, quasars are believed to be powered by supermassive black holes. Shining like lighthouse beacons, they allow scientists to “see” the intervening halo gas indirectly through the absorption of the background light. Quasars reside throughout the universe at extreme distances from our galaxy.
This artist’s concept illustrates the Large Magellanic Cloud’s (LMC’s) encounter with the Milky Way galaxy’s gaseous halo. In the top panel, at the middle of the right side, the LMC begins crashing through our galaxy’s much more massive halo. The bright purple bow shock represents the leading edge of the LMC’s halo, which is being compressed as the Milky Way’s halo pushes back against the incoming LMC. In the middle panel, part of the halo is being stripped and blown back into a streaming tail of gas that eventually will rain into the Milky Way. The bottom panel shows the progression of this interaction, as the LMC’s comet-like tail becomes more defined. A compact LMC halo remains. Because the LMC is just past its closest approach to the Milky Way and is moving outward into deep space again, scientists do not expect the residual halo will be lost. NASA, ESA, Ralf Crawford (STScI)
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The scientists used data from Hubble’s Cosmic Origins Spectrograph (COS) to detect the presence of the halo’s gas by the way it absorbs certain colors of light from background quasars. A spectrograph breaks light into its component wavelengths to reveal clues to the object’s state, temperature, speed, quantity, distance, and composition. With COS, they measured the velocity of the gas around the LMC, which allowed them to determine the size of the halo.
Because of its mass and proximity to the Milky Way, the LMC is a unique astrophysics laboratory. Seeing the LMC’s interplay with our galaxy helps scientists understand what happened in the early universe, when galaxies were closer together. It also shows just how messy and complicated the process of galaxy interaction is.
Looking to the Future
The team will next study the front side of the LMC’s halo, an area that has not yet been explored.
“In this new program, we are going to probe five sightlines in the region where the LMC’s halo and the Milky Way’s halo are colliding,” said co-author Scott Lucchini of the Center for Astrophysics | Harvard & Smithsonian. “This is the location where the halos are compressed, like two balloons pushing against each other.”
The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, Colorado, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, Maryland, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Media Contacts:
Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight Center, Greenbelt, MD
Ann Jenkins, Ray Villard
Space Telescope Science Institute, Baltimore, MD
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Last Updated Nov 14, 2024 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
Astrophysics Astrophysics Division Galaxies Hubble Space Telescope Irregular Galaxies Spiral Galaxies The Milky Way Keep Exploring Discover More Topics From NASA
Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
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By NASA
MuSat2 at Vandenberg Air Force Base, prior to launch. MuSat2 leverages a dual-frequency science antenna developed with support from NASA to measure phenomena such as ocean wind speed. Muon Space A science antenna developed with support from NASA’s Earth Science Technology Office (ESTO) is now in low-Earth orbit aboard MuSat2, a commercial remote-sensing satellite flown by the aerospace company Muon Space. The dual-frequency science antenna was originally developed as part of the Next Generation GNSS Bistatic Radar Instrument (NGRx). Aboard MuSat2, it will help measure ocean surface wind speed—an essential data point for scientists trying to forecast how severe a burgeoning hurricane will become.
“We’re very interested in adopting this technology and pushing it forward, both from a technology perspective and a product perspective,” said Jonathan Dyer, CEO of Muon.
Using this antenna, MuSat2 will gather signals transmitted by navigation satellites as they scatter off Earth’s surface and back into space. By recording how those scattered navigation signals change as they interact with Earth’s surface, MuSat2 will provide meteorologists with data points they can use to study severe weather.
“We use the standard GPS signals you know—the navigation signals that work for your car and your cell phone,” explained Chris Ruf, director of the University of Michigan Space Institute and principal investigator for NGRx.
Ruf designed the entire NGRx system to be an updated version of the sensors on NASA’s Cyclone Global Navigation Satellite System (CYGNSS), another technology he developed with support from ESTO. Since 2016, data from CYGNSS has been a critical resource for people dedicated to forecasting hurricanes.
The science antenna aboard MuSat2 enables two key improvements to the original CYGNSS design. First, the antenna allows MuSat2 to gather measurements from satellites outside the U.S.-based GPS system, such as the European Space Agency’s Galileo satellites. This capability enables MuSat2 to collect more data as it orbits Earth, improving its assessments of conditions on the planet’s surface.
Second, whereas CYGNSS only collected cross-polar radar signals, the updated science antenna also collects co-polar radar signals. This additional information could provide improved information about soil moisture, sea ice, and vegetation. “There’s a whole lot of science value in looking at both polarization components scattering from the Earth’s surface. You can separate apart the effects of vegetation from the effects of surface, itself,” explained Ruf.
Hurricane Ida, as seen from the International Space Station. NASA-developed technology onboard MuSat2 will help supply the U.S. Air Force with critical data for producing reliable weather forecasts. NASA For Muon Space, this technology infusion has been helpful to the company’s business and science missions. Dallas Masters, Vice President of Muon’s Signals of Opportunity Program, explains that NASA’s investments in NGRx technology made it much easier to produce a viable commercial remote sensing satellite. According to Masters, “NGRx-derived technology allowed us to start planning a flight mission early in our company’s existence, based around a payload we knew had flight heritage.”
Dyer agrees. “The fact that ESTO proves out these measurement approaches – the technology and the instrument, the science that you can actually derive, the products from that instrument – is a huge enabler for companies like ours, because we can adopt it knowing that much of the physics risk has been retired,” he said.
Ultimately, this advanced antenna technology for measuring ocean surface wind speed will make it easier for researchers to turn raw data into actionable science products and to develop more accurate forecasts.
“Information is absolutely precious. When it comes to forecast models and trying to understand what’s about to happen, you have to have as good an idea as you can of what’s already happening in the real world,” said oceanographer Lew Gramer, an Associate Scientist with the Cooperative Institute For Marine And Atmospheric Studies and NOAA’s Hurricane Research Division.
Project Lead: Chris Ruf, University of Michigan
Sponsoring Organizations: NASA’s Earth Science Technology Office and Muon Space
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Last Updated Nov 12, 2024 Related Terms
CYGNSS (Cyclone Global Navigation Satellite System) Earth Science Earth Science Division Earth Science Technology Office Oceans Science-enabling Technology Technology Highlights Explore More
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ESA is taking a significant step towards creating a more digitally inclusive Europe through a new partnership that will bring internet access to the hardest-to-reach areas. Reliable connectivity has become essential in today's digital age, yet for many Europeans in rural villages, mountainous regions, and small islands, dependable internet access remains out of reach.
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By NASA
ESA/Hubble & NASA, O. Fox, L. Jenkins, S. Van Dyk, A. Filippenko, J. Lee and the PHANGS-HST Team, D. de Martin (ESA/Hubble), M. Zamani (ESA/Hubble) This NASA/ESA Hubble Space Telescope image features NGC 1672, a barred spiral galaxy located 49 million light-years from Earth in the constellation Dorado. This galaxy is a multi-talented light show, showing off an impressive array of different celestial lights. Like any spiral galaxy, shining stars fill its disk, giving the galaxy a beautiful glow. Along its two large arms, bubbles of hydrogen gas shine in a striking red light fueled by radiation from infant stars shrouded within. Near the galaxy’s center are some particularly spectacular stars embedded within a ring of hot gas. These newly formed and extremely hot stars emit powerful X-rays. Closer in, at the galaxy’s very center, sits an even brighter source of X-rays, an active galactic nucleus. This X-ray powerhouse makes NGC 1672 a Seyfert galaxy. It forms as a result of heated matter swirling in the accretion disk around NGC 1672’s supermassive black hole.
See more images of NGC 1672.
Image credit: ESA/Hubble & NASA, O. Fox, L. Jenkins, S. Van Dyk, A. Filippenko, J. Lee and the PHANGS-HST Team, D. de Martin (ESA/Hubble), M. Zamani (ESA/Hubble)
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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The NISAR mission will help researchers get a better understanding of how Earth’s surface changes over time, including in the lead-up to volcanic eruptions like the one pictured, at Mount Redoubt in southern Alaska in April 2009.R.G. McGimsey/AVO/USGS Data from NISAR will improve our understanding of such phenomena as earthquakes, volcanoes, and landslides, as well as damage to infrastructure.
We don’t always notice it, but much of Earth’s surface is in constant motion. Scientists have used satellites and ground-based instruments to track land movement associated with volcanoes, earthquakes, landslides, and other phenomena. But a new satellite from NASA and the Indian Space Research Organisation (ISRO) aims to improve what we know and, potentially, help us prepare for and recover from natural and human-caused disasters.
The NISAR (NASA-ISRO Synthetic Aperture Radar) mission will measure the motion of nearly all of the planet’s land and ice-covered surfaces twice every 12 days. The pace of NISAR’s data collection will give researchers a fuller picture of how Earth’s surface changes over time. “This kind of regular observation allows us to look at how Earth’s surface moves across nearly the entire planet,” said Cathleen Jones, NISAR applications lead at NASA’s Jet Propulsion Laboratory in Southern California.
Together with complementary measurements from other satellites and instruments, NISAR’s data will provide a more complete picture of how Earth’s surface moves horizontally and vertically. The information will be crucial to better understanding everything from the mechanics of Earth’s crust to which parts of the world are prone to earthquakes and volcanic eruptions. It could even help resolve whether sections of a levee are damaged or if a hillside is starting to move in a landslide.
The NISAR mission will measure the motion of Earth’s surface — data that can be used to monitor critical infrastructure such as airport runways, dams, and levees. NASA/JPL-Caltech What Lies Beneath
Targeting an early 2025 launch from India, the mission will be able to detect surface motions down to fractions of an inch. In addition to monitoring changes to Earth’s surface, the satellite will be able to track the motion of ice sheets, glaciers, and sea ice, and map changes to vegetation.
The source of that remarkable detail is a pair of radar instruments that operate at long wavelengths: an L-band system built by JPL and an S-band system built by ISRO. The NISAR satellite is the first to carry both. Each instrument can collect measurements day and night and see through clouds that can obstruct the view of optical instruments. The L-band instrument will also be able to penetrate dense vegetation to measure ground motion. This capability will be especially useful in areas surrounding volcanoes or faults that are obscured by vegetation.
“The NISAR satellite won’t tell us when earthquakes will happen. Instead, it will help us better understand which areas of the world are most susceptible to significant earthquakes,” said Mark Simons, the U.S. solid Earth science lead for the mission at Caltech in Pasadena, California.
Data from the satellite will give researchers insight into which parts of a fault slowly move without producing earthquakes and which sections are locked together and might suddenly slip. In relatively well-monitored areas like California, researchers can use NISAR to focus on specific regions that could produce an earthquake. But in parts of the world that aren’t as well monitored, NISAR measurements could reveal new earthquake-prone areas. And when earthquakes do occur, data from the satellite will help researchers understand what happened on the faults that ruptured.
“From the ISRO perspective, we are particularly interested in the Himalayan plate boundary,” said Sreejith K M, the ISRO solid Earth science lead for NISAR at the Space Applications Center in Ahmedabad, India. “The area has produced great magnitude earthquakes in the past, and NISAR will give us unprecedented information on the seismic hazards of the Himalaya.”
Surface motion is also important for volcano researchers, who need data collected regularly over time to detect land movements that may be precursors to an eruption. As magma shifts below Earth’s surface, the land can bulge or sink. The NISAR satellite will help provide a fuller picture for why a volcano deforms and whether that movement signals an eruption.
Finding Normal
When it comes to infrastructure such as levees, aqueducts, and dams, NISAR’s ability to provide continuous measurements over years will help to establish the usual state of the structures and surrounding land. Then, if something changes, resource managers may be able to pinpoint specific areas to examine. “Instead of going out and surveying an entire aqueduct every five years, you can target your surveys to problem areas,” said Jones.
The data could be equally valuable for showing that a dam hasn’t changed after a disaster like an earthquake. For instance, if a large earthquake struck San Francisco, liquefaction — where loosely packed or waterlogged sediment loses its stability after severe ground shaking — could pose a problem for dams and levees along the Sacramento-San Joaquin River Delta.
“There’s over a thousand miles of levees,” said Jones. “You’d need an army to go out and look at them all.” The NISAR mission would help authorities survey them from space and identify damaged areas. “Then you can save your time and only go out to inspect areas that have changed. That could save a lot of money on repairs after a disaster.”
More About NISAR
The NISAR mission is an equal collaboration between NASA and ISRO and marks the first time the two agencies have cooperated on hardware development for an Earth-observing mission. Managed for the agency by Caltech, JPL leads the U.S. component of the project and is providing the mission’s L-band SAR. NASA is also providing the radar reflector antenna, the deployable boom, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder, and payload data subsystem. The U R Rao Satellite Centre in Bengaluru, India, which leads the ISRO component of the mission, is providing the spacecraft bus, the launch vehicle, and associated launch services and satellite mission operations. The ISRO Space Applications Centre in Ahmedabad is providing the S-band SAR electronics.
To learn more about NISAR, visit:
https://nisar.jpl.nasa.gov
News Media Contacts
Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0307 / 626-379-6874
jane.j.lee@jpl.nasa.gov / andrew.wang@jpl.nasa.gov
2024-155
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Last Updated Nov 08, 2024 Related Terms
NISAR (NASA-ISRO Synthetic Aperture Radar) Earth Science Earthquakes Jet Propulsion Laboratory Natural Disasters Volcanoes Explore More
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