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By NASA
5 min read
NASA’s NICER Maps Debris From Recurring Cosmic Crashes
Lee esta nota de prensa en español aquí.
For the first time, astronomers have probed the physical environment of repeating X-ray outbursts near monster black holes thanks to data from NASA’s NICER (Neutron star Interior Composition Explorer) and other missions.
Scientists have only recently encountered this class of X-ray flares, called QPEs, or quasi-periodic eruptions. A system astronomers have nicknamed Ansky is the eighth QPE source discovered, and it produces the most energetic outbursts seen to date. Ansky also sets records in terms of timing and duration, with eruptions every 4.5 days or so that last approximately 1.5 days.
“These QPEs are mysterious and intensely interesting phenomena,” said Joheen Chakraborty, a graduate student at the Massachusetts Institute of Technology in Cambridge. “One of the most intriguing aspects is their quasi-periodic nature. We’re still developing the methodologies and frameworks we need to understand what causes QPEs, and Ansky’s unusual properties are helping us improve those tools.”
Watch how astronomers used data from NASA’s NICER (Neutron star Interior Composition Explorer) to study a mysterious cosmic phenomenon called a quasi-periodic eruption, or QPE.
NASA’s Goddard Space Flight Center Ansky’s name comes from ZTF19acnskyy, the moniker of a visible-light outburst seen in 2019. It was located in a galaxy about 300 million light-years away in the constellation Virgo. This event was the first indication that something unusual might be happening.
A paper about Ansky, led by Chakraborty, was published Tuesday in The Astrophysical Journal.
A leading theory suggests that QPEs occur in systems where a relatively low-mass object passes through the disk of gas surrounding a supermassive black hole that holds hundreds of thousands to billions of times the Sun’s mass.
When the lower-mass object punches through the disk, its passage drives out expanding clouds of hot gas that we observe as QPEs in X-rays.
Scientists think the eruptions’ quasi-periodicity occurs because the smaller object’s orbit is not perfectly circular and spirals toward the black hole over time. Also, the extreme gravity close to the black hole warps the fabric of space-time, altering the object’s orbits so they don’t close on themselves with each cycle. Scientists’ current understanding suggests the eruptions repeat until the disk disappears or the orbiting object disintegrates, which may take up to a few years.
A system astronomers call Ansky, in the galaxy at the center of this image, is home to a recently discovered series of quasi-periodic eruptions. Sloan Digital Sky Survey “Ansky’s extreme properties may be due to the nature of the disk around its supermassive black hole,” said Lorena Hernández-García, an astrophysicist at the Millennium Nucleus on Transversal Research and Technology to Explore Supermassive Black Holes, the Millennium Institute of Astrophysics, and University of Valparaíso in Chile. “In most QPE systems the supermassive black hole likely shreds a passing star, creating a small disk very close to itself. In Ansky’s case, we think the disk is much larger and can involve objects farther away, creating the longer timescales we observe.”
Hernández-García, in addition to being a co-author on Chakraborty’s paper, led the study that discovered Ansky’s QPEs, which was published in April in Nature Astronomy and used data from NICER, NASA’s Neil Gehrels Swift Observatory and Chandra X-ray Observatory, as well as ESA’s (European Space Agency’s) XMM-Newton space telescope.
NICER’s position on the International Space Station allowed it to observe Ansky about 16 times every day from May to July 2024. The frequency of the observations was critical in detecting the X-ray fluctuations that revealed Ansky produces QPEs.
Chakraborty’s team used data from NICER and XMM-Newton to map the rapid evolution of the ejected material driving the observed QPEs in unprecedented detail by studying variations in X-ray intensity during the rise and fall of each eruption.
The researchers found that each impact resulted in about a Jupiter’s worth of mass reaching expansion velocities around 15% of the speed of light.
The NICER (Neutron star Interior Composition Explorer) X-ray telescope is reflected on NASA astronaut and Expedition 72 flight engineer Nick Hague’s spacesuit helmet visor in this high-flying “space-selfie” taken during a spacewalk on Jan. 16, 2025. NASA/Nick Hague The NICER telescope’s ability to frequently observe Ansky from the space station and its unique measurement capabilities also made it possible for the team to measure the size and temperature of the roughly spherical bubble of debris as it expanded.
“All NICER’s Ansky observations used in these papers were collected after the instrument experienced a ‘light leak’ in May 2023,” said Zaven Arzoumanian, the mission’s science lead at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Even though the leak – which was patched in January – affected the telescope’s observing strategy, NICER was still able to make vital contributions to time domain astronomy, or the study of changes in the cosmos on timescales we can see.”
After the repair, NICER continued observing Ansky to explore how the outbursts have evolved over time. A paper about these results, led by Hernández-García and co-authored by Chakraborty, is under review.
Observational studies of QPEs like Chakraborty’s will also play a key role in preparing the science community for a new era of multimessenger astronomy, which combines measurements using light, elementary particles, and space-time ripples called gravitational waves to better understand objects and events in the universe.
One goal of ESA’s future LISA (Laser Interferometer Space Antenna) mission, in which NASA is a partner, is to study extreme mass-ratio inspirals — or systems where a low-mass object orbits a much more massive one, like Ansky. These systems should emit gravitational waves that are not observable with current facilities. Electromagnetic studies of QPEs will help improve models of those systems ahead of LISA’s anticipated launch in the mid-2030s.
“We’re going to keep observing Ansky for as long as we can,” Chakraborty said. “We’re still in the infancy of understanding QPEs. It’s such an exciting time because there’s so much to learn.”
Download images and videos through NASA’s Scientific Visualization Studio.
By Jeanette Kazmierczak
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media Contact:
Claire Andreoli
301-286-1940
claire.andreoli@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated May 06, 2025 Editor Jeanette Kazmierczak Location Goddard Space Flight Center Related Terms
The Universe Astrophysics Black Holes Galaxies, Stars, & Black Holes Galaxies, Stars, & Black Holes Research International Space Station (ISS) ISS Research NICER (Neutron star Interior Composition Explorer) Science & Research Supermassive Black Holes X-ray Astronomy View the full article
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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Located off the coast of Ecuador, Paramount seamount is among the kinds of ocean floor features that certain ocean-observing satellites like SWOT can detect by how their gravitational pull affects the sea surface.NOAA Okeanos Explorer Program More accurate maps based on data from the SWOT mission can improve underwater navigation and result in greater knowledge of how heat and life move around the world’s ocean.
There are better maps of the Moon’s surface than of the bottom of Earth’s ocean. Researchers have been working for decades to change that. As part of the ongoing effort, a NASA-supported team recently published one of the most detailed maps yet of the ocean floor, using data from the SWOT (Surface Water and Ocean Topography) satellite, a collaboration between NASA and the French space agency CNES (Centre National d’Études Spatiales).
Ships outfitted with sonar instruments can make direct, incredibly detailed measurements of the ocean floor. But to date, only about 25% of it has been surveyed in this way. To produce a global picture of the seafloor, researchers have relied on satellite data.
This animation shows seafloor features derived from SWOT data on regions off Mexico, South America, and the Antarctic Peninsula. Purple denotes regions that are lower relative to higher areas like seamounts, depicted in green. Eötvös is the unit of measure for the gravity-based data used to create these maps.
NASA’s Scientific Visualization Studio Why Seafloor Maps Matter
More accurate maps of the ocean floor are crucial for a range of seafaring activities, including navigation and laying underwater communications cables. “Seafloor mapping is key in both established and emerging economic opportunities, including rare-mineral seabed mining, optimizing shipping routes, hazard detection, and seabed warfare operations,” said Nadya Vinogradova Shiffer, head of physical oceanography programs at NASA Headquarters in Washington.
Accurate seafloor maps are also important for an improved understanding of deep-sea currents and tides, which affect life in the abyss, as well as geologic processes like plate tectonics. Underwater mountains called seamounts and other ocean floor features like their smaller cousins, abyssal hills, influence the movement of heat and nutrients in the deep sea and can attract life. The effects of these physical features can even be felt at the surface by the influence they exert on ecosystems that human communities depend on.
This map of seafloor features like abyssal hills in the Indian Ocean is based on sea surface height data from the SWOT satellite. Purple denotes regions that are lower relative to higher areas like abyssal hills, depicted in green. Eötvös is the unit of measure for the gravity-based data used to create these maps.NASA Earth Observatory This global map of seafloor features is based on ocean height data from the SWOT satellite. Purple denotes regions that are lower compared to higher features such as seamounts and abyssal hills, depicted in green. Eötvös is the unit of measure for the gravity-based data used to create these maps.NASA Earth Observatory This map of ocean floor features like seamounts southwest of Acapulco, Mexico, is based on sea surface height data from SWOT. Purple denotes regions that are lower relative to higher areas like seamounts, indicated with green. Eötvös is the unit of measure for the gravity-based data used to create these maps.NASA Earth Observatory Mapping the seafloor isn’t the SWOT mission’s primary purpose. Launched in December 2022, the satellite measures the height of water on nearly all of Earth’s surface, including the ocean, lakes, reservoirs, and rivers. Researchers can use these differences in height to create a kind of topographic map of the surface of fresh- and seawater. This data can then be used for tasks such as assessing changes in sea ice or tracking how floods progress down a river.
“The SWOT satellite was a huge jump in our ability to map the seafloor,” said David Sandwell, a geophysicist at Scripps Institution of Oceanography in La Jolla, California. He’s used satellite data to chart the bottom of the ocean since the 1990s and was one of the researchers responsible for the SWOT-based seafloor map, which was published in the journal Science in December 2024.
How It Works
The study authors relied the fact that because geologic features like seamounts and abyssal hills have more mass than their surroundings, they exert a slightly stronger gravitational pull that creates small, measurable bumps in the sea surface above them. These subtle gravity signatures help researchers predict the kind of seafloor feature that produced them.
Through repeated observations — SWOT covers about 90% of the globe every 21 days — the satellite is sensitive enough to pick up these minute differences, with centimeter-level accuracy, in sea surface height caused by the features below. Sandwell and his colleagues used a year’s worth of SWOT data to focus on seamounts, abyssal hills, and underwater continental margins, where continental crust meets oceanic crust.
Previous ocean-observing satellites have detected massive versions of these bottom features, such as seamounts over roughly 3,300 feet (1 kilometer) tall. The SWOT satellite can pick up seamounts less than half that height, potentially increasing the number of known seamounts from 44,000 to 100,000. These underwater mountains stick up into the water, influencing deep sea currents. This can concentrate nutrients along their slopes, attracting organisms and creating oases on what would otherwise be barren patches of seafloor.
Looking Into the Abyss
The improved view from SWOT also gives researchers more insight into the geologic history of the planet.
“Abyssal hills are the most abundant landform on Earth, covering about 70% of the ocean floor,” said Yao Yu, an oceanographer at Scripps Institution of Oceanography and lead author on the paper. “These hills are only a few kilometers wide, which makes them hard to observe from space. We were surprised that SWOT could see them so well.”
Abyssal hills form in parallel bands, like the ridges on a washboard, where tectonic plates spread apart. The orientation and extent of the bands can reveal how tectonic plates have moved over time. Abyssal hills also interact with tides and deep ocean currents in ways that researchers don’t fully understand yet.
The researchers have extracted nearly all the information on seafloor features they expected to find in the SWOT measurements. Now they’re focusing on refining their picture of the ocean floor by calculating the depth of the features they see. The work complements an effort by the international scientific community to map the entire seafloor using ship-based sonar by 2030. “We won’t get the full ship-based mapping done by then,” said Sandwell. “But SWOT will help us fill it in, getting us close to achieving the 2030 objective.”
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. NASA’s Jet Propulsion Laboratory, managed for the agency by Caltech in Pasadena, California, 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.
818-354-0307 / 626-379-6874
jane.j.lee@jpl.nasa.gov / andrew.wang@jpl.nasa.gov
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Last Updated Mar 19, 2025 Related Terms
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
In-person participants (L-R) – Back row: Jason Lytle, Stuart Lee, Eric Bershad, Ashot Sargsyan, Aaron Everson, Philip Wells, Sergi Vaquer Araujo, Steven Grover, John A. Heit, Mehdi Shishehbor, Laura Bostick; Middle row: Sarah Childress Taoufik, Stephan Moll, Brandon Macias, Kristin Coffey, Ann-Kathrin Vlacil, Dave Francisco; Front row: James Pavela, Doug Ebert, Kathleen McMonigal, Esther Kim, Emma Hwang; Not pictured: Tyson Brunstetter, J. D. Polk
Online participants: Stephen Alamo, Mark Crowther, Steven Nissen, Mark Rosenberg, Jeffrey Weitz, R. Eugene Zierler, Serena Aunon, Tina Bayuse, Laura Beachy, Becky Brocato, Daniel Buckland, Jackie Charvat, Diana Cruz Topete, Quinn Dufurrena, Robert Haddon, Joanne Kaouk, Kim Lowe, Steve Laurie, Karina Marshall-Goebel, Sara Mason, Shannan Moynihan, James Pattarini, Devan Petersen, Ruth Reitzel, Donna Roberts, Lucia Roccaro, Mike Stenger, Terry Taddeo, Gavin Travers, Mary Van Baalen, Liz WarrenNASA In October 2024, NASA’s Office of the Chief Health and Medical Officer (OCHMO) initiated a working group to review the status and progress of research and clinical activities intended to mitigate the risk of venous thromboembolism (VTE) during spaceflight. The working group took place over two days at NASA’s Johnson Space Center; a second meeting on the topic was held in December 2024 at the European Space Agency (ESA) facility in Cologne, Germany.
Read More about the Risk of VTE The working group was assembled from internal NASA subject matter experts (SMEs), the NASA OCHMO Standards Team, NASA and ESA stakeholders, and external SMEs, including physicians and medical professionals from leading universities and medical centers in the United States and Canada.
Background
Spaceflight Venous Thrombosis (SVT)
Spaceflight Venous Thrombosis (SVT) refers to a phenomenon experienced during spaceflight in which a thrombus (blood clot) forms in the internal jugular vein (and/or associated vasculature) that may be symptomatic (thrombus accompanied by, but not limited to, visible internal jugular vein swelling, facial edema beyond “nominal” spaceflight adaptation, eyelid edema, and/or headache) or asymptomatic. Obstructive thrombi have been identified in a very small number of crewmembers, as shown in the figure below.
Note that the figure below is for illustrative purposes only; locations are approximate, and size is not to scale.
Approximate location of identified thrombi in crewmembers.Source: Modified from Cerebral Sinus Venous Thrombosis – University of Colorado Denver With treatment, crewmembers were able to complete their mission, and anticoagulants were discontinued several days prior to landing to minimize the risk of bleeding in the event of a traumatic injury. Some thromboses completely resolved post landing, and some required additional treatment.
Pathophysiology of Venous Thromboembolism (VTE)
The proposed pathogenesis of VTE is referred to as Virchow’s triad and suggests that VTE occurs as the result of:
Alterations in blood flow (i.e., stasis), Vascular endothelial injury/changes, and/or, Alterations in the constituents of the blood leading to hypercoagulability (i.e., hereditary predisposition or acquired hypercoagulability). Note: pathophysiology are the changes that occur during a disease process; hypercoagulability is the increased tendency to develop blood to clots.
The Virchow’s triad of risk factors for venous thrombosis.Bouchnita, 2017 Blood stasis, or venous stasis, refers to a condition in which the blood flow in the veins slows down which leads to pooling in the veins. This slowing of the blood may be due to vein valves becoming damaged or weak, immobility, and/or the absence of muscular contractions. Associated symptoms include swelling, skin changes, varicose veins, and slow-healing sores or ulcers. In terrestrial medicine, venous thrombosis is typically caused by damaged or weakened vein valves, which can be due to many factors, including aging, blood clots, varicose veins, obesity, pregnancy, sedentary lifestyle, estrogen use, and hereditary predisposition.
Spaceflight Considerations
Altered Venous Blood Flow and Spaceflight Associated Neuro-ocular Syndrome
In addition to the terrestrial risk factors of VTE, there are physiological changes associated with spaceflight that are hypothesized to potentially play a role in the development of VTE in weightlessness. Specifically, researchers have explored the effects of the microgravity environment and subsequent observed headward fluid shifts that occur, and the potential impact on blood flow. Crewmembers onboard the International Space Station (ISS) experience weightlessness due to the microgravity environment and thus experience a sustained redistribution of bodily fluids from the legs toward the head. The prolonged headward fluid shifts during weightlessness results in facial puffiness, decreased leg volume, increased cardiac stroke volume, and decreased plasma volume.
Crewmembers have also experienced altered blood flow during spaceflight, including retrograde venous blood flow (RVBF) (the backflow of venous blood towards the brain) or stasis (a stoppage or slowdown in the flow of blood). While the causes of the observed stasis and retrograde blood flow in spaceflight participants is not well understood, the potential clinical significance of the role it may have in the development of thrombus formation warrants further investigation.
Doppler imaging of a retrograde flow in the left internal jugular vein.Yan & Seow, 2009 Other physiological concerns affected by fluid shifts are being studied to consider if any relation to VTE exists. Chronic weightlessness can cause bodily fluids such as blood and cerebrospinal fluid to move toward the head, which can lead to optic nerve swelling, folds in the retina, flattening of the back of the eye, and swelling in the brain. This collection of eye and brain changes is called “spaceflight associated neuro-ocular syndrome,” or SANS. Some astronauts only experience mild changes in space, while others have clinically significant outcomes. The long-term health outcome from these changes is unknown but actively being investigated. The risk of developing SANS is higher during longer-duration missions and remains a top research priority for scientists ahead of a Mars mission.
Conclusions and Further Work
Based on expert opinion and the assessment of the risk factors for thrombosis, an algorithm was developed to provide guidance for in-mission assessment and treatment of thrombus formation in weightlessness. The algorithm is based on early in-flight ultrasound testing to determine the flow characteristic of the left internal jugular vein and associated vasculature.
NASA Working Group Recommendations
The working group recommended several areas for further investigation to assess feasibility and potential to mitigate the risk of thrombosis in spaceflight:
Improved detection capabilities to identify when a thrombus has formed in-flight, Pathophysiology/factors leading to thrombi formation during spaceflight, Countermeasures and treatment
For more information on the working group meeting and a complete list of references, please see the Risk of Venous Thromboembolism (VTE) During Spaceflight Summary Report.
Risk of Venous Thromboembolism (VTE) During Spaceflight Summary Report Share
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Last Updated Mar 14, 2025 EditorKim Lowe Related Terms
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