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By NASA
This graphic features data from NASA’s Chandra X-ray Observatory of the Cassiopeia A (Cas A) supernova remnant that reveals that the star’s interior violently rearranged itself mere hours before it exploded. The main panel of this graphic is Chandra data that shows the location of different elements in the remains of the explosion: silicon (represented in red), sulfur (yellow), calcium (green) and iron (purple). The blue color reveals the highest-energy X-ray emission detected by Chandra in Cas A and an expanding blast wave. The inset reveals regions with wide ranges of relative abundances of silicon and neon. This data, plus computer modeling, reveal new insight into how massive stars like Cas A end their lives.X-ray: NASA/CXC/Meiji Univ./T. Sato et al.; Image Processing: NASA/CXC/SAO/N. Wolk The inside of a star turned on itself before it spectacularly exploded, according to a new study from NASA’s Chandra X-ray Observatory. Today, this shattered star, known as the Cassiopeia A supernova remnant, is one of the best-known, well-studied objects in the sky.
Over three hundred years ago, however, it was a giant star on the brink of self-destruction. The new Chandra study reveals that just hours before it exploded, the star’s interior violently rearranged itself. This last-minute shuffling of its stellar belly has profound implications for understanding how massive stars explode and how their remains behave afterwards.
Cassiopeia A (Cas A for short) was one of the first objects the telescope looked at after its launch in 1999, and astronomers have repeatedly returned to observe it.
“It seems like each time we closely look at Chandra data of Cas A, we learn something new and exciting,” said Toshiki Sato of Meiji University in Japan who led the study. “Now we’ve taken that invaluable X-ray data, combined it with powerful computer models, and found something extraordinary.”
As massive stars age, increasingly heavy elements form in their interiors by nuclear reactions, creating onion-like layers of different elements. Their outer layer is mostly made of hydrogen, followed by layers of helium, carbon and progressively heavier elements – extending all the way down to the center of the star.
Once iron starts forming in the core of the star, the game changes. As soon as the iron core grows beyond a certain mass (about 1.4 times the mass of the Sun), it can no longer support its own weight and collapses. The outer part of the star falls onto the collapsing core, and rebounds as a core-collapse supernova.
The new research with Chandra data reveals a change that happened deep within the star at the very last moments of its life. After more than a million years, Cas A underwent major changes in its final hours before exploding.
“Our research shows that just before the star in Cas A collapsed, part of an inner layer with large amounts of silicon traveled outwards and broke into a neighboring layer with lots of neon,” said co-author Kai Matsunaga of Kyoto University in Japan. “This is a violent event where the barrier between these two layers disappears.”
This upheaval not only caused material rich in silicon to travel outwards; it also forced material rich in neon to travel inwards. The team found clear traces of these outward silicon flows and inward neon flows in the remains of Cas A’s supernova remnant. Small regions rich in silicon but poor in neon are located near regions rich in neon and poor in silicon.
The survival of these regions not only provides critical evidence for the star’s upheaval, but also shows that complete mixing of the silicon and neon with other elements did not occur immediately before or after the explosion. This lack of mixing is predicted by detailed computer models of massive stars near the ends of their lives.
There are several significant implications for this inner turmoil inside of the doomed star. First, it may directly explain the lopsided rather than symmetrical shape of the Cas A remnant in three dimensions. Second, a lopsided explosion and debris field may have given a powerful kick to the remaining core of the star, now a neutron star, explaining the high observed speed of this object.
Finally, the strong turbulent flows created by the star’s internal changes may have promoted the development of the supernova blast wave, facilitating the star’s explosion.
“Perhaps the most important effect of this change in the star’s structure is that it may have helped trigger the explosion itself,” said co-author Hiroyuki Uchida, also of Kyoto University. “Such final internal activity of a star may change its fate—whether it will shine as a supernova or not.”
These results have been published in the latest issue of The Astrophysical Journal and are available online.
To learn more about Chandra, visit:
https://science.nasa.gov/chandra
Read more from NASA’s Chandra X-ray Observatory Learn more about the Chandra X-ray Observatory and its mission here:
https://www.nasa.gov/chandra
https://chandra.si.edu
Visual Description
This release features a composite image of Cassiopeia A, a donut-shaped supernova remnant located about 11,000 light-years from Earth. Included in the image is an inset closeup, which highlights a region with relative abundances of silicon and neon.
Over three hundred years ago, Cassiopeia A, or Cas A, was a star on the brink of self-destruction. In composition it resembled an onion with layers rich in different elements such as hydrogen, helium, carbon, silicon, sulfur, calcium, and neon, wrapped around an iron core. When that iron core grew beyond a certain mass, the star could no longer support its own weight. The outer layers fell into the collapsing core, then rebounded as a supernova. This explosion created the donut-like shape shown in the composite image. The shape is somewhat irregular, with the thinner quadrant of the donut to the upper left of the off-center hole.
In the body of the donut, the remains of the star’s elements create a mottled cloud of colors, marbled with red and blue veins. Here, sulfur is represented by yellow, calcium by green, and iron by purple. The red veins are silicon, and the blue veins, which also line the outer edge of the donut-shape, are the highest energy X-rays detected by Chandra and show the explosion’s blast wave.
The inset uses a different color code and highlights a colorful, mottled region at the thinner, upper left quadrant of Cas A. Here, rich pockets of silicon and neon are identified in the red and blue veins, respectively. New evidence from Chandra indicates that in the hours before the star’s collapse, part of a silicon-rich layer traveled outwards, and broke into a neighboring neon-rich layer. This violent breakdown of layers created strong turbulent flows and may have promoted the development of the supernova’s blast wave, facilitating the star’s explosion. Additionally, upheaval in the interior of the star may have produced a lopsided explosion, resulting in the irregular shape, with an off-center hole (and a thinner bite of donut!) at our upper left.
News Media Contact
Megan Watzke
Chandra X-ray Center
Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu
Corinne Beckinger
Marshall Space Flight Center, Huntsville, Alabama
256-544-0034
corinne.m.beckinger@nasa.gov
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Last Updated Aug 28, 2025 EditorLee MohonContactCorinne M. Beckingercorinne.m.beckinger@nasa.govLocationMarshall Space Flight Center Related Terms
Chandra X-Ray Observatory General Marshall Astrophysics Marshall Space Flight Center Supernova Remnants Supernovae The Universe Explore More
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By European Space Agency
Video: 00:09:30 In Tenerife, Spain, stands a unique duo: ESA’s Izaña-1 and Izaña-2 laser-ranging stations. Together, they form an optical technology testbed of the European Space Agency that takes the monitoring of space debris and satellites to a new level while maturing new technologies for commercialisation.
Space debris is a threat to satellites and is rapidly becoming a daily concern for satellite operators. The Space Safety Programme, part of ESA Operations, managed from ESOC in Germany, helps develop new technologies to detect and track debris, and to prevent collisions in orbit in new and innovative ways.
One of these efforts takes place at the Izaña station in Tenerife. There, ESA and partner companies are testing how to deliver precise orbit data on demand with laser-based technologies. The Izaña-2 station was recently finalised by the German company DiGOS and is now in use.
To perform space debris laser ranging, Izaña-2 operates as a laser transmitter, emitting high-power laser pulses towards objects in space. Izaña-1 then acts as the receiver of the few photons that are reflected back. The precision of the laser technology enables highly accurate data for precise orbit determination, which in turn is crucial for actionable collision avoidance systems and sustainable space traffic management.
With the OMLET (Orbital Maintenance via Laser momEntum Transfer) project, ESA combines different development streams and possibilities for automation to support European industry with getting two innovative services market-ready: on-demand ephemeris provision and laser-based collision avoidance services for end users such as satellite operators.
A future goal is to achieve collision avoidance by laser momentum transfer, where instead of the operational satellite, the piece of debris will be moved out of the way. This involves altering the orbit of a piece of space debris slightly by applying a small force to the object through laser illumination.
The European Space Agency actively supports European industry in capitalising on the business opportunities that not only safeguard our satellites but also pave the way for the sustainable use of space.
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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Written by Michael Allen
An international team of astronomers using NASA’s IXPE (Imaging X-ray Polarimetry Explorer), has challenged our understanding of what happens to matter in the direct vicinity of a black hole.
With IXPE, astronomers can study incoming X-rays and measure the polarization, a property of light that describes the direction of its electric field.
The polarization degree is a measurement of how aligned those vibrations are to each other. Scientists can use a black hole’s polarization degree to determine the location of the corona – a region of extremely hot, magnetized plasma that surrounds a black hole – and how it generates X-rays.
This illustration of material swirling around a black hole highlights a particular feature, called the “corona,” that shines brightly in X-ray light. In this depiction, the corona can be seen as a purple haze floating above the underlying accretion disk, and extending slightly inside of its inner edge. The material within the inner accretion disk is incredibly hot and would glow with a blinding blue-white light, but here has been reduced in brightness to make the corona stand out with better contrast. Its purple color is purely illustrative, standing in for the X-ray glow that would not be obvious in visible light. The warp in the disk is a realistic representation of how the black hole’s immense gravity acts like an optical lens, distorting our view of the flat disk that encircles it. NASA/Caltech-IPAC/Robert Hurt In April, astronomers used IXPE to measure a 9.1% polarization degree for black hole IGR J17091-3624, much higher than they expected based on theoretical models.
“The black hole IGR J17091-3624 is an extraordinary source which dims and brightens with the likeness of a heartbeat, and NASA’s IXPE allowed us to measure this unique source in a brand-new way.” said Melissa Ewing, the lead of the study based at Newcastle University in Newcastle upon Tyne, England.
In X-ray binary systems, an extremely dense object, like a black hole, pulls matter from a nearby source, most often a neighboring star. This matter can begin to swirl around, flattening into a rotating structure known as an accretion disc.
The corona, which lies in the inner region of this accretion disc, can reach extreme temperatures up to 1.8 billion degrees Fahrenheit and radiate very luminous X-rays. These ultra-hot coronas are responsible for some of the brightest X-ray sources in the sky.
Despite how bright the corona is in IGRJ17091-364, at some 28,000 light-years from Earth, it remains far too small and distant for astronomers to capture an image of it.
“Typically, a high polarization degree corresponds with a very edge-on view of the corona. The corona would have to be perfectly shaped and viewed at just the right angle to achieve such a measurement,” said Giorgio Matt, professor at the University of Roma Tre in Italy and a co-author on this paper. “The dimming pattern has yet to be explained by scientists and could hold the keys to understanding this category of black holes.”
The stellar companion of this black hole isn’t bright enough for astronomers to directly estimate the system’s viewing angle, but the unusual changes in brightness observed by IXPE suggest that the edge of the accretion disk was directly facing Earth.
The researchers explored different avenues to explain the high polarization degree.
In one model, astronomers included a “wind” of matter lifted from the accretion disc and launched away from the system, a rarely seen phenomenon. If X-rays from the corona were to meet this matter on their way to IXPE, Compton scattering would occur, leading to these measurements.
Fast Facts
Polarization measurements from IXPE carry information about the orientation and alignment of emitted X-ray light waves. The high the degree of polarization, the more the X-ray waves are traveling in sync. Most polarization in the corona come from a process known as Compton scattering, where light from the accretion disc bounces off the hot plasma of the corona, gaining energy and aligning to vibrate in the same direction. “These winds are one of the most critical missing pieces to understand the growth of all types of black holes,” said Maxime Parra, who led the observation and works on this topic at Ehime University in Matsuyama, Japan. “Astronomers could expect future observations to yield even more surprising polarization degree measurements.”
Another model assumed the plasma in the corona could exhibit a very fast outflow. If the plasma were to be streaming outwards at speeds as high as 20% the speed of light, or roughly 124 million miles per hour, relativistic effects could boost the observed polarization.
In both cases, the simulations could recreate the observed polarization without a very specific edge-on view. Researchers will continue to model and test their predictions to better understand the high polarization degree for future research efforts.
More about IXPE
IXPE, which continues to provide unprecedented data enabling groundbreaking discoveries about celestial objects across the universe, is a joint NASA and Italian Space Agency mission with partners and science collaborators in 12 countries. IXPE is led by NASA’s Marshall Space Flight Center in Huntsville, Alabama. BAE Systems, Inc., headquartered in Falls Church, Virginia, manages spacecraft operations together with the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder.
Learn more about IXPE’s ongoing mission here:
https://www.nasa.gov/ixpe
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Last Updated Aug 12, 2025 EditorBeth RidgewayContactCorinne Edmistoncorinne.m.edmiston@nasa.govLocationMarshall Space Flight Center Related Terms
IXPE (Imaging X-ray Polarimetry Explorer) Marshall Astrophysics Marshall Science Research & Projects Marshall Space Flight Center Explore More
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Explore This Section Science Uncategorized NASA eClips STEM Student… Overview Learning Resources Science Activation Teams SME Map Opportunities More Science Activation Stories Citizen Science 3 min read
NASA eClips STEM Student Ambassadors Light Up CNU’s 2025 STEM Community Day
More than 2,000 curious visitors from Newport News and the surrounding Hampton Roads region of Virginia flocked to Christopher Newport University (CNU) on May 31, 2025 for their annual STEM (Science, Technology, Engineering, & Mathematics) Community Day, and the NASA eClips team from the National Institute of Aerospace’s Center for Integrative STEM Education (NIA-CISE) made sure every one of them left with their eyes—and imaginations—fixed on the Sun.
At the heart of the NASA eClips exhibit were NIA’s STEM Student Ambassadors—a team of carefully selected high school students from the Tidewater region of Virginia who underwent extensive training with NASA eClips educators during the summer of 2024. These bright, enthusiastic young leaders are passionate about communicating about and advocating for STEM. The STEM Student Ambassador program is made possible through a Coastal Virginia STEM Hub grant from the Virginia General Assembly and is already having an impact.
Throughout the day, the Ambassadors engaged learners of all ages with two creative, hands-on experiences that connected STEM and the arts:
Chalk Corona – Using black construction paper and vibrant chalk, participants recreated the Sun’s corona—the super-hot, gaseous “crown” that’s visible during a total solar eclipse. While they shaded and smudged, the Ambassadors explained why the corona is so important to solar research and handed out certified solar viewers for safe Sun-watching back home. Pastel Auroras – Visitors also discovered how solar wind, storms, and coronal mass ejections (aka Sun “sneezes”) spark Earth’s dazzling auroras. Guided by the Ambassadors, budding artists layered pastels to capture swirling curtains of light, tying recent mid-Atlantic aurora sightings to real-time space weather. Throughout the day, the Ambassadors’ energy was contagious, turning complex heliophysics into hands-on fun and opening eyes to the opportunities and careers that await in STEM. Judging by the smiles—and the dusting of chalk and pastels—NASA eClips’ presence was, quite literally, the “crowning” touch on an unforgettable community celebration of STEM.
The NASA eClips project provides educators with standards-based videos, activities, and lessons to increase STEM literacy through the lens of NASA. It is supported by NASA under cooperative agreement award number NNX16AB91A and is part of NASA’s Science Activation Portfolio. Learn more about how Science Activation connects NASA science experts, real content, and experiences with community leaders to do science in ways that activate minds and promote deeper understanding of our world and beyond: https://science.nasa.gov/learn
Two STEM Student Ambassadors engage a young girl while she creates her own Pastel Aurora artwork. Share
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By NASA
An artist’s concept of NASA’s Orion spacecraft orbiting the Moon while using laser communications technology through the Orion Artemis II Optical Communications System.Credit: NASA/Dave Ryan As NASA prepares for its Artemis II mission, researchers at the agency’s Glenn Research Center in Cleveland are collaborating with The Australian National University (ANU) to prove inventive, cost-saving laser communications technologies in the lunar environment.
Communicating in space usually relies on radio waves, but NASA is exploring laser, or optical, communications, which can send data 10 to 100 times faster to the ground. Instead of radio signals, these systems use infrared light to transmit high-definition video, picture, voice, and science data across vast distances in less time. NASA has proven laser communications during previous technology demonstrations, but Artemis II will be the first crewed mission to attempt using lasers to transmit data from deep space.
To support this effort, researchers working on the agency’s Real Time Optical Receiver (RealTOR) project have developed a cost-effective laser transceiver using commercial-off-the-shelf parts. Earlier this year, NASA Glenn engineers built and tested a replica of the system at the center’s Aerospace Communications Facility, and they are now working with ANU to build a system with the same hardware models to prepare for the university’s Artemis II laser communications demo.
“Australia’s upcoming lunar experiment could showcase the capability, affordability, and reproducibility of the deep space receiver engineered by Glenn,” said Jennifer Downey, co-principal investigator for the RealTOR project at NASA Glenn. “It’s an important step in proving the feasibility of using commercial parts to develop accessible technologies for sustainable exploration beyond Earth.”
During Artemis II, which is scheduled for early 2026, NASA will fly an optical communications system aboard the Orion spacecraft, which will test using lasers to send data across the cosmos. During the mission, NASA will attempt to transmit recorded 4K ultra-high-definition video, flight procedures, pictures, science data, and voice communications from the Moon to Earth.
An artist’s concept of the optical communications ground station at Mount Stromlo Observatory in Canberra, Australia, using laser communications technology.Credit: The Australian National University Nearly 10,000 miles from Cleveland, ANU researchers working at the Mount Stromlo Observatory ground station hope to receive data during Orion’s journey around the Moon using the Glenn-developed transceiver model. This ground station will serve as a test location for the new transceiver design and will not be one of the mission’s primary ground stations. If the test is successful, it will prove that commercial parts can be used to build affordable, scalable space communication systems for future missions to the Moon, Mars, and beyond.
“Engaging with The Australian National University to expand commercial laser communications offerings across the world will further demonstrate how this advanced satellite communications capability is ready to support the agency’s networks and missions as we set our sights on deep space exploration,” said Marie Piasecki, technology portfolio manager for NASA’s Space Communications and Navigation (SCaN) Program.
As NASA continues to investigate the feasibility of using commercial parts to engineer ground stations, Glenn researchers will continue to provide critical support in preparation for Australia’s demonstration.
Strong global partnerships advance technology breakthroughs and are instrumental as NASA expands humanity’s reach from the Moon to Mars, while fueling innovations that improve life on Earth. Through Artemis, NASA will send astronauts to explore the Moon for scientific discovery, economic benefits, and build the foundation for the first crewed missions to Mars.
The Real Time Optical Receiver (RealTOR) team poses for a group photo in the Aerospace Communications Facility at NASA’s Glenn Research Center in Cleveland on Friday, Dec. 13, 2024. From left to right: Peter Simon, Sarah Tedder, John Clapham, Elisa Jager, Yousef Chahine, Michael Marsden, Brian Vyhnalek, and Nathan Wilson.Credit: NASA The RealTOR project is one aspect of the optical communications portfolio within NASA’s SCaN Program, which includes demonstrations and in-space experiment platforms to test the viability of infrared light for sending data to and from space. These include the LCOT (Low-Cost Optical Terminal) project, the Laser Communications Relay Demonstration, and more. NASA Glenn manages the project under the direction of agency’s SCaN Program at NASA Headquarters in Washington.
The Australian National University’s demonstration is supported by the Australian Space Agency Moon to Mars Demonstrator Mission Grant program, which has facilitated operational capability for the Australian Deep Space Optical Ground Station Network.
To learn how space communications and navigation capabilities support every agency mission, visit:
https://www.nasa.gov/communicating-with-missions
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