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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
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A thick torus of gas and dust surrounding a supermassive black hole is shown in this artist’s concept. The torus can obscure light that’s generated by material falling into the black hole. Observations by NASA telescopes have helped scientists identify more of these hidden black holes.NASA/JPL-Caltech An effort to find some of the biggest, most active black holes in the universe provides a better estimate for the ratio of hidden to unhidden behemoths.
Multiple NASA telescopes recently helped scientists search the sky for supermassive black holes — those up to billions of times heavier than the Sun. The new survey is unique because it was as likely to find massive black holes that are hidden behind thick clouds of gas and dust as those that are not.
Astronomers think that every large galaxy in the universe has a supermassive black hole at its center. But testing this hypothesis is difficult because researchers can’t hope to count the billions or even trillions of supermassive black holes thought to exist in the universe. Instead they have to extrapolate from smaller samples to learn about the larger population. So accurately measuring the ratio of hidden supermassive black holes in a given sample helps scientists better estimate the total number of supermassive black holes in the universe.
The new study published in the Astrophysical Journal found that about 35% of supermassive black holes are heavily obscured, meaning the surrounding clouds of gas and dust are so thick they block even low-energy X-ray light. Comparable searches have previously found less than 15% of supermassive black holes are so obscured. Scientists think the true split should be closer to 50/50 based on models of how galaxies grow. If observations continue to indicate significantly less than half of supermassive black holes are hidden, scientists will need to adjust some key ideas they have about these objects and the role they play in shaping galaxies.
Hidden Treasure
Although black holes are inherently dark — not even light can escape their gravity — they can also be some of the brightest objects in the universe: When gas gets pulled into orbit around a supermassive black hole, like water circling a drain, the extreme gravity creates such intense friction and heat that the gas reaches hundreds of thousands of degrees and radiates so brightly it can outshine all the stars in the surrounding galaxy.
The clouds of gas and dust that surround and replenish the bright central disk may roughly take the shape of a torus, or doughnut. If the doughnut hole is facing toward Earth, the bright central disk within it is visible; if the doughnut is seen edge-on, the disk is obscured.
A supermassive black hole surrounded by a torus of gas and dust is depicted in four different wavelengths of light in this artist’s concept. Visible light (top right) and low-energy X-rays (bottom left) are blocked by the torus; infrared (top left) is scattered and reemitted; and some high energy X-rays (bottom right) can penetrate the torus. NASA/JPL-Caltech Most telescopes can rather easily identify face-on supermassive black holes, though not edge-on ones. But there’s an exception to this that the authors of the new paper took advantage of: The torus absorbs light from the central source and reemits lower-energy light in the infrared range (wavelengths slightly longer than what human eyes can detect). Essentially, the doughnuts glow in infrared.
These wavelengths of light were detected by NASA’s Infrared Astronomical Satellite, or IRAS, which operated for 10 months in 1983 and was managed by NASA’s Jet Propulsion Laboratory in Southern California. A survey telescope that imaged the entire sky, IRAS was able to see the infrared emissions from the clouds surrounding supermassive black holes. Most importantly, it could spot edge-on and face-on black holes equally well.
IRAS caught hundreds of initial targets. Some of them turned out to be not heavily obscured black holes but galaxies with high rates of star formation that emit a similar infrared glow. So the authors of the new study used ground-based, visible-light telescopes to identify those galaxies and separate them from the hidden black holes.
To confirm edge-on, heavily obscured black holes, the researchers relied on NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array), an X-ray observatory also managed by JPL. X-rays are radiated by some of the hottest material around the black hole. Lower-energy X-rays are absorbed by the surrounding clouds of gas and dust, while the higher-energy X-rays observed by NuSTAR can penetrate and scatter off the clouds. Detecting these X-rays can take hours of observation, so scientists working with NuSTAR first need a telescope like IRAS to tell them where to look.
NASA’s NuSTAR X-ray telescope, depicted in this artist’s concept, has helped astronomers get a better sense of how many supermassive black holes are hidden from view by thick clouds of gas and dust that surround them.NASA/JPL-Caltech “It amazes me how useful IRAS and NuSTAR were for this project, especially despite IRAS being operational over 40 years ago,” said study lead Peter Boorman, an astrophysicist at Caltech in Pasadena, California. “I think it shows the legacy value of telescope archives and the benefit of using multiple instruments and wavelengths of light together.”
Numerical Advantage
Determining the number of hidden black holes compared to nonhidden ones can help scientists understand how these black holes get so big. If they grow by consuming material, then a significant number of black holes should be surrounded by thick clouds and potentially obscured. Boorman and his coauthors say their study supports this hypothesis.
In addition, black holes influence the galaxies they live in, mostly by impacting how galaxies grow. This happens because black holes surrounded by massive clouds of gas and dust can consume vast — but not infinite — amounts of material. If too much falls toward a black hole at once, the black hole starts coughing up the excess and firing it back out into the galaxy. That can disperse gas clouds within the galaxy where stars are forming, slowing the rate of star formation there.
“If we didn’t have black holes, galaxies would be much larger,” said Poshak Gandhi, a professor of astrophysics at the University of Southampton in the United Kingdom and a coauthor on the new study. “So if we didn’t have a supermassive black hole in our Milky Way galaxy, there might be many more stars in the sky. That’s just one example of how black holes can influence a galaxy’s evolution.”
More About NuSTAR
A Small Explorer mission led by Caltech and managed by NASA’s Jet Propulsion Laboratory in Southern California for the agency’s Science Mission Directorate in Washington, NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp. in Dulles, Virginia. NuSTAR’s mission operations center is at the University of California, Berkeley, and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center at NASA’s Goddard Space Flight Center. ASI provides the mission’s ground station and a mirror data archive. Caltech manages JPL for NASA.
For more information on NuSTAR, visit:
www.nustar.caltech.edu
News Media Contact
Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.
626-808-2469
calla.e.cofield@jpl.nasa.gov
2025-002
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Last Updated Jan 13, 2025 Related Terms
NuSTAR (Nuclear Spectroscopic Telescope Array) Astrophysics Black Holes Galaxies, Stars, & Black Holes Jet Propulsion Laboratory The Universe Explore More
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By NASA
NASA/Don Pettit On Jan. 10, 2025, NASA astronaut Don Pettit posted two images of the Los Angeles fires from the International Space Station. Multiple destructive fires broke out in the hills of Los Angeles County in early January 2025, fueled by a dry landscape and winds that gusted up to 100 miles per hour.
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Image credit: NASA/Don Pettit
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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
LMS instrument aboard the Blue Ghost Lander heading to Mare Crisium in mid-January
As part of its Artemis campaign, NASA is developing a series of increasingly complex lunar deliveries and missions to ultimately build a sustained human presence at the Moon for decades to come. Through the agency’s CLPS (Commercial Lunar Payload Services) initiative, commercial provider Firefly’s Blue Ghost lander will head to the Moon’s Mare Crisium for a 14-day lunar lander mission, carrying NASA science and technology that will help understand the lunar subsurface in a previously unexplored location.
From within the Mare Crisium impact basin, the SwRI-led Lunar Magnetotelluric Sounder (LMS) may provide the first geophysical measurements representative of the bulk of the Moon. Most of the Apollo missions landed in the region of linked maria to the west (left image), whose crust was later shown to be compositionally distinct (right image) as exemplified by the concentration of the element thorium. Mare Crisium provides a smooth landing site on the near side of the Moon outside of this anomalous region. NASA Developed by the Southwest Research Institute (SwRI), NASA’s Lunar Magnetotelluric Sounder (LMS) will probe the interior of the Moon to depths of up to 700 miles, two-thirds of the way to the lunar center. The measurements will shed light on the differentiation and thermal history of our Moon, a cornerstone to understanding the evolution of solid worlds.
Magnetotellurics uses natural variations in surface electric and magnetic fields to calculate how easily electricity flows in subsurface materials, which can reveal their composition and structure.
“For more than 50 years, scientists have used magnetotellurics on Earth for a wide variety of purposes, including to find oil, water, and geothermal and mineral resources, as well as to understand geologic processes such as the growth of continents,” said SwRI’s Dr. Robert Grimm, principal investigator of LMS. “The LMS instrument will be the first extraterrestrial application of magnetotellurics.”
Mare Crisium is an ancient, 350-mile-diameter impact basin that subsequently filled with lava, creating a dark spot visible on the Moon from Earth. Early astronomers who dubbed dark spots on the moon “maria,” Latin for seas, mistook them for actual seas.
Mare Crisium stands apart from the large, connected areas of dark lava to the west where most of the Apollo missions landed. These vast, linked lava plains are now thought to be compositionally and structurally different from the rest of the Moon. From this separate vantage point, LMS may provide the first geophysical measurements representative of most of the Moon.
The Lunar Magnetotelluric Sounder (LMS) will probe the interior of the Moon to depths of up to 700 miles or two-thirds of the lunar radius. The measurements will shed light on the differentiation and thermal history of our Moon, a cornerstone to understanding the evolution of solid worlds.
NASA’s Goddard Space Flight Center The LMS instrument ejects cables with electrodes at 90-degree angles to each other and distances up to 60 feet. The instrument measures voltages across opposite pairs of electrodes, much like the probes of a conventional voltmeter. The magnetometer is deployed via an extendable mast to reduce interference from the lander. The magnetotelluric method reveals a vertical profile of the electrical conductivity, providing insight into the temperature and composition of the penetrated materials in the lunar interior.
“The five individual subsystems of LMS, together with connecting cables, weigh about 14 pounds and consume about 11 Watts of power,” Grimm said. “While stowed, each electrode is surrounded by a ‘yarn ball’ of cable, so the assembly is roughly spherical and the size of a softball.”
The LMS payload was funded and will be delivered to the lunar surface through NASA’s CLPS initiative. Southwest Research Institute based in San Antonio built the central electronics and leads the science investigation. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provided the LMS magnetometer to measure the magnetic fields, and Heliospace Corp. provided the electrodes used to measure the electrical fields.
Under the CLPS model, NASA is investing in commercial delivery services to the Moon to enable industry growth and support long-term lunar exploration. As a primary customer for CLPS deliveries, NASA aims to be one of many customers on future flights. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the development of seven of the 10 CLPS payloads carried on Firefly’s Blue Ghost lunar lander.
Media Contact: Rani Gran
NASA’s Goddard Space Flight Center, Greenbelt, Maryland
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Last Updated Jan 10, 2025 EditorRob GarnerContactRani GranLocationGoddard Space Flight Center Related Terms
Commercial Lunar Payload Services (CLPS) Earth's Moon Goddard Space Flight Center View the full article
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By European Space Agency
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By European Space Agency
Image: Fanned by very strong winds, a wildfire is ripping through the Pacific Palisades in Los Angeles, California. This image captured by the Copernicus Sentinel-2 mission vividly depicts the smoke billowing from the fire near Santa Monica on 7 January 2025, not long after the fire broke out. View the full article
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