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Gaia: Milky Way’s last major collision was surprisingly recent
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By NASA
A black hole has blasted out a surprisingly powerful jet in the distant universe, according to a study from NASA’s Chandra X-ray Observatory.X-ray: NASA/CXC/CfA/J. Maithil et al.; Illustration: NASA/CXC/SAO/M. Weiss; Image Processing: NASA/CXC/SAO/N. Wolk A black hole has blasted out a surprisingly powerful jet in the distant universe, according to a new study from NASA’s Chandra X-ray Observatory and discussed in our latest press release. This jet exists early enough in the cosmos that it is being illuminated by the leftover glow from the big bang itself.
Astronomers used Chandra and the Karl G. Jansky Very Large Array (VLA) to study this black hole and its jet at a period they call “cosmic noon,” which occurred about three billion years after the universe began. During this time most galaxies and supermassive black holes were growing faster than at any other time during the history of the universe.
The main graphic is an artist’s illustration showing material in a disk that is falling towards a supermassive black hole. A jet is blasting away from the black hole towards the upper right, as Chandra detected in the new study. The black hole is located 11.6 billion light-years from Earth when the cosmic microwave background (CMB), the leftover glow from the big bang, was much denser than it is now. As the electrons in the jets fly away from the black hole, they move through the sea of CMB radiation and collide with microwave photons. These collisions boost the energy of the photons up into the X-ray band (purple and white), allowing them to be detected by Chandra even at this great distance, which is shown in the inset.
Researchers, in fact, identified and then confirmed the existence of two different black holes with jets over 300,000 light-years long. The two black holes are 11.6 billion and 11.7 billion light-years away from Earth, respectively. Particles in one jet are moving at between 95% and 99% of the speed of light (called J1405+0415) and in the other at between 92% and 98% of the speed of light (J1610+1811). The jet from J1610+1811 is remarkably powerful, carrying roughly half as much energy as the intense light from hot gas orbiting the black hole.
The team was able to detect these jets despite their great distances and small separation from the bright, growing supermassive black holes — known as “quasars” — because of Chandra’s sharp X-ray vision, and because the CMB was much denser then than it is now, enhancing the energy boost described above.
When quasar jets approach the speed of light, Einstein’s theory of special relativity creates a dramatic brightening effect. Jets aimed toward Earth appear much brighter than those pointed away. The same brightness astronomers observe can come from vastly different combinations of speed and viewing angle. A jet racing at near-light speed but angled away from us can appear just as bright as a slower jet pointed directly at Earth.
The researchers developed a novel statistical method that finally cracked this challenge of separating effects of speed and of viewing angle. Their approach recognizes a fundamental bias: astronomers are more likely to discover jets pointed toward Earth simply because relativistic effects make them appear brightest. They incorporated this bias using a modified probability distribution, which accounts for how jets oriented at different angles are detected in surveys.
Their method works by first using the physics of how jet particles scatter the CMB to determine the relationship between jet speed and viewing angle. Then, instead of assuming all angles are equally likely, they apply the relativistic selection effect: jets beamed toward us (smaller angles) are overrepresented in our catalogs. By running ten thousand simulations that match this biased distribution to their physical model, they could finally determine the most probable viewing angles: about 9 degrees for J1405+0415 and 11 degrees for J1610+1811.
These results were presented by Jaya Maithil (Center for Astrophysics | Harvard & Smithsonian) at the 246th meeting of the American Astronomical Society in Anchorage, AK, and are also being published in The Astrophysical Journal. A preprint is available here. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
Read more from NASA’s Chandra X-ray Observatory Learn more about the Chandra X-ray Observatory and its mission here:
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https://chandra.si.edu
Visual Description
This release is supported by an artist’s illustration of a jet blasting away from a supermassive black hole.
The black hole sits near the center of the illustration. It resembles a black marble with a fine yellow outline. Surrounding the black hole is a swirling disk, resembling a dinner plate tilted to face our upper right. This disk comprises concentric rings of fiery swirls, dark orange near the outer edge, and bright yellow near the core.
Shooting out of the black hole are two streaky beams of silver and pale violet. One bright beam shoots up toward our upper right, and a second somewhat dimmer beam shoots in the opposite direction, down toward our lower left. These beams are encircled by long, fine, corkscrewing lines that resemble stretched springs.
This black hole is located 11.6 billion light-years from Earth, much earlier in the history of the universe. Near this black hole, the leftover glow from the big bang, known as the cosmic microwave background or CMB, is much denser than it is now. As the electrons in the jets blast away from the black hole, they move through the sea of CMB radiation. The electrons boost the energies of the CMB light into the X-ray band, allowing the jets to be detected by Chandra, even at this great distance.
Inset at our upper righthand corner is an X-ray image depicting this interaction. Here, a bright white circle is ringed with a band of glowing purple energy. The jet is the faint purple line shooting off that ring, aimed toward our upper right, with a blob of purple energy at its tip.
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Megan Watzke
Chandra X-ray Center
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Lane Figueroa
Marshall Space Flight Center, Huntsville, Alabama
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By NASA
The core portion of NASA’s Nancy Grace Roman Space Telescope has successfully completed vibration testing, ensuring it will withstand the extreme shaking experienced during launch. Passing this key milestone brings Roman one step closer to helping answer essential questions about the role of dark energy and other cosmic mysteries.
“The test could be considered as powerful as a pretty severe earthquake, but there are key differences,” said Cory Powell, the Roman lead structural analyst at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Unlike an earthquake, we sweep through our frequencies one at a time, starting with very low-level amplitudes and gradually increasing them while we check everything along the way. It’s a very complicated process that takes extraordinary effort to do safely and efficiently.”
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This video shows the core components of NASA’s Nancy Grace Roman Space Telescope undergoing a vibration test at the agency’s Goddard Space Flight Center. The test ensures this segment of the observatory will withstand the extreme shaking associated with launch. Credit: NASA’s Goddard Space Flight Center The team simulated launch conditions as closely as possible. “We performed the test in a flight-powered configuration and filled the propulsion tanks with approximately 295 gallons of deionized water to simulate the propellent loading on the spacecraft during launch,” said Joel Proebstle, who led this test, at NASA Goddard. This is part of a series of tests that ratchet up to 125 percent of the forces the observatory will experience.
This milestone is the latest in a period of intensive testing for the nearly complete Roman Space Telescope, with many major parts coming together and running through assessments in rapid succession. Roman currently consists of two major assemblies: the inner, core portion (telescope, instrument carrier, two instruments, and spacecraft) and the outer portion (outer barrel assembly, solar array sun shield, and deployable aperture cover).
Now, having completed vibration testing, the core portion will return to the large clean room at Goddard for post-test inspections. They’ll confirm that everything remains properly aligned and the high-gain antenna can deploy. The next major assessment for the core portion will involve additional tests of the electronics, followed by a thermal vacuum test to ensure the system will operate as planned in the harsh space environment.
This video highlights some of the important hardware milestones as NASA’s Nancy Grace Roman Space Telescope moves closer to completion. The observatory is almost fully assembled, currently built up into two large pieces: the inner portion (telescope, instrument carrier, two instruments, and spacecraft) and outer portion (outer barrel assembly, solar array sun shield, and deployable aperture cover). This video shows the testing these segments have undergone between February and May 2025. Credit: NASA’s Goddard Space Flight Center In the meantime, Goddard technicians are also working on Roman’s outer portion. They installed the test solar array sun shield, and this segment then underwent its own thermal vacuum test, verifying it will control temperatures properly in the vacuum of space. Now, technicians are installing the flight solar panels to this outer part of the observatory.
The team is on track to connect Roman’s two major assemblies in November, resulting in a whole observatory by the end of the year that will then undergo final tests. Roman remains on schedule for launch by May 2027, with the team aiming for as early as fall 2026.
Click here to virtually tour an interactive version of the telescope 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 Rochester, New York; and Teledyne Scientific & Imaging in Thousand Oaks, California.
By Ashley Balzer
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Jun 04, 2025 Related Terms
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By NASA
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 5 Min Read Apocalypse When? Hubble Casts Doubt on Certainty of Galactic Collision
This NASA Hubble Space Telescope image of NGC 520 offers one example of possible encounter scenarios between our Milky Way and the Andromeda galaxy. NGC 520 is the product of a collision between two disk galaxies that started 300 million years ago. Credits:
NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and B. Whitmore (STScI) As far back as 1912, astronomers realized that the Andromeda galaxy — then thought to be only a nebula — was headed our way. A century later, astronomers using NASA’s Hubble Space Telescope were able to measure the sideways motion of Andromeda and found it was so negligible that an eventual head-on collision with the Milky Way seemed almost certain.
A smashup between our own galaxy and Andromeda would trigger a firestorm of star birth, supernovae, and maybe toss our Sun into a different orbit. Simulations had suggested it was as inevitable as, in the words of Benjamin Franklin, “death and taxes.”
But now a new study using data from Hubble and the European Space Agency’s (ESA) Gaia space telescope says “not so fast.” Researchers combining observations from the two space observatories re-examined the long-held prediction of a Milky Way – Andromeda collision, and found it is far less inevitable than astronomers had previously suspected.
“We have the most comprehensive study of this problem today that actually folds in all the observational uncertainties,” said Till Sawala, astronomer at the University of Helsinki in Finland and lead author of the study, which appears today in the journal Nature Astronomy.
His team includes researchers at Durham University, United Kingdom; the University of Toulouse, France; and the University of Western Australia. They found that there is approximately a 50-50 chance of the two galaxies colliding within the next 10 billion years. They based this conclusion on computer simulations using the latest observational data.
These galaxy images illustrate three possible encounter scenarios between our Milky Way and the neighboring Andromeda galaxy. Top left: Galaxies M81 and M82. Top right: NGC 6786, a pair of interacting galaxies. Bottom: NGC 520, two merging galaxies. Science: NASA, ESA, STScI, DSS, Till Sawala (University of Helsinki); Image Processing: Joseph DePasquale (STScI) Sawala emphasized that predicting the long-term future of galaxy interactions is highly uncertain, but the new findings challenge the previous consensus and suggest the fate of the Milky Way remains an open question.
“Even using the latest and most precise observational data available, the future of the Local Group of several dozen galaxies is uncertain. Intriguingly, we find an almost equal probability for the widely publicized merger scenario, or, conversely, an alternative one where the Milky Way and Andromeda survive unscathed,” said Sawala.
The collision of the two galaxies had seemed much more likely in 2012, when astronomers Roeland van der Marel and Tony Sohn of the Space Telescope Science Institute in Baltimore, Maryland published a detailed analysis of Hubble observations over a five-to-seven-year period, indicating a direct impact in no more than 5 billion years.
“It’s somewhat ironic that, despite the addition of more precise Hubble data taken in recent years, we are now less certain about the outcome of a potential collision. That’s because of the more complex analysis and because we consider a more complete system. But the only way to get to a new prediction about the eventual fate of the Milky Way will be with even better data,” said Sawala.
100,000 Crash-Dummy Simulations
Astronomers considered 22 different variables that could affect the potential collision between our galaxy and our neighbor, and ran 100,000 simulations called Monte Carlo simulations stretching to 10 billion years into the future.
“Because there are so many variables that each have their errors, that accumulates to rather large uncertainty about the outcome, leading to the conclusion that the chance of a direct collision is only 50% within the next 10 billion years,” said Sawala.
“The Milky Way and Andromeda alone would remain in the same plane as they orbit each other, but this doesn’t mean they need to crash. They could still go past each other,” said Sawala.
Researchers also considered the effects of the orbits of Andromeda’s large satellite galaxy, M33, and a satellite galaxy of the Milky Way called the Large Magellanic Cloud (LMC).
“The extra mass of Andromeda’s satellite galaxy M33 pulls the Milky Way a little bit more towards it. However, we also show that the LMC pulls the Milky Way off the orbital plane and away from Andromeda. It doesn’t mean that the LMC will save us from that merger, but it makes it a bit less likely,” said Sawala.
In about half of the simulations, the two main galaxies fly past each other separated by around half a million light-years or less (five times the Milky Way’s diameter). They move outward but then come back and eventually merge in the far future. The gradual decay of the orbit is caused by a process called dynamical friction between the vast dark-matter halos that surround each galaxy at the beginning.
In most of the other cases, the galaxies don’t even come close enough for dynamical friction to work effectively. In this case, the two galaxies can continue their orbital waltz for a very long time.
The new result also still leaves a small chance of around 2% for a head-on collision between the galaxies in only 4 to 5 billion years. Considering that the warming Sun makes Earth uninhabitable in roughly 1 billion years, and the Sun itself will likely burn out in 5 billion years, a collision with Andromeda is the least of our cosmic worries.
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, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
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Milky Way and Andromeda Encounters
This selection of images of external galaxies illustrates three encounter scenarios between our Milky Way and the neighboring Andromeda galaxy. Top left: Galaxies M81 and M82. Top right: NGC 6786, a pair of interacting galaxies. Bottom: NGC 520, two merging galaxies.
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Last Updated Jun 02, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center
Contact Media Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov
Ray Villard
Space Telescope Science Institute
Baltimore, Maryland
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By European Space Agency
Over a decade’s worth of NASA/ESA Hubble Space Telescope data was used to re-examine the long-held prediction that the Milky Way galaxy will collide with the Andromeda galaxy in about 4.5 billion years. The astronomers found that, based on the latest observational data from Hubble and Gaia, there is only a 50-50 chance of the two galaxies colliding within the next 10 billion years.
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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Advancing new hazard detection and precision landing technologies to help future space missions successfully achieve safe and soft landings is a critical area of space research and development, particularly for future crewed missions. To support this, NASA’s Space Technology Mission Directorate (STMD) is pursuing a regular cadence of flight testing on a variety of vehicles, helping researchers rapidly advance these critical systems for missions to the Moon, Mars, and beyond.
“These flight tests directly address some of NASA’s highest-ranked technology needs, or shortfalls, ranging from advanced guidance algorithms and terrain-relative navigation to lidar-and optical-based hazard detection and mapping,” said Dr. John M. Carson III, STMD technical integration manager for precision landing and based at NASA’s Johnson Space Center in Houston.
Since the beginning of this year, STMD has supported flight testing of four precision landing and hazard detection technologies from many sectors, including NASA, universities, and commercial industry. These cutting-edge solutions have flown aboard a suborbital rocket system, a high-speed jet, a helicopter, and a rocket-powered lander testbed. That’s four precision landing technologies tested on four different flight vehicles in four months.
“By flight testing these technologies on Earth in spaceflight-relevant trajectories and velocities, we’re demonstrating their capabilities and validating them with real data for transitioning technologies from the lab into mission applications,” said Dr. Carson. “This work also signals to industry and other partners that these capabilities are ready to push beyond NASA and academia and into the next generation of Moon and Mars landers.”
The following NASA-supported flight tests took place between February and May:
Suborbital Rocket Test of Vision-Based Navigation System
Identifying landmarks to calculate accurate navigation solutions is a key function of Draper’s Multi-Environment Navigator (DMEN), a vision-based navigation and hazard detection technology designed to improve safety and precision of lunar landings.
Aboard Blue Origin’s New Shepard reusable suborbital rocket system, DMEN collected real-world data and validated its algorithms to advance it for use during the delivery of three NASA payloads as part of NASA’s Commercial Lunar Payload Services (CLPS) initiative. On Feb. 4, DMEN performed the latest in a series of tests supported by NASA’s Flight Opportunities program, which is managed at NASA’s Armstrong Flight Research Center in Edwards, California.
During the February flight, which enabled testing at rocket speeds on ascent and descent, DMEN scanned the Earth below, identifying landmarks to calculate an accurate navigation solution. The technology achieved accuracy levels that helped Draper advance it for use in terrain-relative navigation, which is a key element of landing on other planets.
New Shepard booster lands during the flight test on February 4, 2025.Blue Origin High-Speed Jet Tests of Lidar-Based Navigation
Several highly dynamic maneuvers and flight paths put Psionic’s Space Navigation Doppler Lidar (PSNDL) to the test while it collected navigation data at various altitudes, velocities, and orientations.
Psionic licensed NASA’s Navigation Doppler Lidar technology developed at Langley Research Center in Hampton, Virginia, and created its own miniaturized system with improved functionality and component redundancies, making it more rugged for spaceflight. In February, PSNDL along with a full navigation sensor suite was mounted aboard an F/A-18 Hornet aircraft and underwent flight testing at NASA Armstrong.
The aircraft followed a variety of flight paths over several days, including a large figure-eight loop and several highly dynamic maneuvers over Death Valley, California. During these flights, PSNDL collected navigation data relevant for lunar and Mars entry and descent.
The high-speed flight tests demonstrated the sensor’s accuracy and navigation precision in challenging conditions, helping prepare the technology to land robots and astronauts on the Moon and Mars. These recent tests complemented previous Flight Opportunities-supported testing aboard a lander testbed to advance earlier versions of their PSNDL prototypes.
The Psionic Space Navigation Doppler Lidar (PSNDL) system is installed in a pod located under the right wing of a NASA F/A-18 research aircraft for flight testing above Death Valley near NASA’s Armstrong Flight Research Center in Edwards, California, in February 2025.NASA Helicopter Tests of Real-Time Mapping Lidar
Researchers at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, developed a state-of-the-art Hazard Detection Lidar (HDL) sensor system to quickly map the surface from a vehicle descending at high speed to find safe landing sites in challenging locations, such as Europa (one of Jupiter’s moons), our own Moon, Mars, and other planetary bodies throughout the solar system. The HDL-scanning lidar generates three-dimensional digital elevation maps in real time, processing approximately 15 million laser measurements and mapping two football fields’ worth of terrain in only two seconds.
In mid-March, researchers tested the HDL from a helicopter at NASA’s Kennedy Space Center in Florida, with flights over a lunar-like test field with rocks and craters. The HDL collected numerous scans from several different altitudes and view angles to simulate a range of landing scenarios, generating real-time maps. Preliminary reviews of the data show excellent performance of the HDL system.
The HDL is a component of NASA’s Safe and Precise Landing – Integrated Capabilities Evolution (SPLICE) technology suite. The SPLICE descent and landing system integrates multiple component technologies, such as avionics, sensors, and algorithms, to enable landing in hard-to-reach areas of high scientific interest. The HDL team is also continuing to test and further improve the sensor for future flight opportunities and commercial applications.
NASA’s Hazard Detection Lidar field test team at Kennedy Space Center’s Shuttle Landing Facility in Florida in March 2025. Lander Tests of Powered-Descent Guidance Software
Providing pinpoint landing guidance capability with minimum propellant usage, the San Diego State University (SDSU) powered-descent guidance algorithms seek to improve autonomous spacecraft precision landing and hazard avoidance. During a series of flight tests in April and May, supported by NASA’s Flight Opportunities program, the university’s software was integrated into Astrobotic’s Xodiac suborbital rocket-powered lander via hardware developed by Falcon ExoDynamics as part of NASA TechLeap Prize’s Nighttime Precision Landing Challenge.
The SDSU algorithms aim to improve landing capabilities by expanding the flexibility and trajectory-shaping ability and enhancing the propellant efficiency of powered-descent guidance systems. They have the potential for infusion into human and robotic missions to the Moon as well as high-mass Mars missions.
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As part of a series of tethered and free-flight tests in April and May 2025, algorithms developed by San Diego State University guided the descent of the Xodiac lander testbed vehicle.Astrobotic By advancing these and other important navigation, precision landing, and hazard detection technologies with frequent flight tests, NASA’s Space Technology Mission Directorate is prioritizing safe and successful touchdowns in challenging planetary environments for future space missions.
Learn more: https://www.nasa.gov/space-technology-mission-directorate/
By: Lee Ann Obringer
NASA’s Flight Opportunities program
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These two printable STL files demonstrate the differences between the near and far side of Earth’s Moon. The near side…
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