SPACE
BY: COLIN STUART
MARCH 7, 2024 
Faint, small galaxies ionized the opaque fog that obscured the early universe.
Faint, small galaxies ionized the opaque fog that obscured the early universe.
Behind Pandora's Cluster (Abell 2744), imaged here by the James Webb Space Telescope, are eight background galaxies hailing from the early universe.
NASA / ESA / CSA
An international team of astronomers has used the James Webb Space Telescope to make the first spectroscopic observations of the faintest galaxies present during the universe’s first billion years. The results offer vital clues toward solving a mystery in the early years of the universe.
For the first few hundred million years after the Big Bang, the universe was a thick soup of hydrogen fog with no stars to illuminate it. This period is known as the cosmic dark ages. The fog is thought to have eventually cleared when radiation ripped hydrogen atoms apart, a process known as reionization. But debate remained as to whether this reionizing radiation came solely from the first stars that lit up the earliest galaxies or whether material falling onto supermassive black holes also played a significant role.
A team of astronomers led by Hakim Atek (Paris Institute of Astrophysics) used the James Webb Space Telescope to peer at extremely faint dwarf galaxies in the early universe. These distant galaxies wouldn’t normally be visible — even to Webb’s powerful capabilities — but astronomers received a helping hand from the gravity of Pandora’s Cluster, a car crash of galaxies 4 billion light-years away. The cluster’s immense mass magnified the more distant galaxies’ light. The team's findings are published in Nature.
Atek’s team was able to study eight early galaxies in total, taking both images and spectroscopic data with Webb's Near-InfraRed Spectrograph (NIRSpec). The stand-out finding is that the galaxies produced four times more ultraviolet radiation than astronomers had derived from previous scenarios.
“Despite their tiny size, these low-mass galaxies are prolific producers of energetic radiation, and their abundance during this period is so substantial that their collective influence can transform the entire state of the Universe,” Atek says.
“They produce ionizing photons that transform neutral hydrogen into ionized plasma during cosmic reionisation,” adds team member Iryna Chemerynska (also at the Paris Institute of Astrophysics).
“It’s fantastic to see the pieces fitting together, and pointing squarely at tiny galaxies as the culprits,” says Sean McGee (University of Birmingham, UK), who was not involved in the research. Astronomers have long suspected that such galaxies helped light up the early universe, but McGee adds that “this was becoming more debatable recently as JWST has been finding more AGN than previously expected.” Now, the new JWST data on these tiny galaxies puts them back in the limelight.
“It had been an assumption that . . . these small galaxies would play an important role, but it’s very satisfying to see it directly,” McGee says. “It wouldn't have been possible without JWST.”
The next step is an upcoming Webb observing program named GLIMPSE. Astronomers will target another massive galaxy cluster — Abell S1063 — in order to see even fainter galaxies behind it in the early universe. This will allow them to verify whether the dwarf galaxies in the current study are typical of the large-scale distribution of galaxies.
McGee also notes the importance of the upcoming Square Kilometer Array (SKA). “We will be able to map out exactly where the universe hasn’t been reionized,” he says. If the findings of Atek's teams are right, we should only find neutral hydrogen — which gives out a distinctive radio signal at 21 centimetres — far from dwarf galaxies. “The lack of a radio signal around the tiny galaxies will be like the dog who didn’t bark in the night.”
NASA / ESA / CSA
An international team of astronomers has used the James Webb Space Telescope to make the first spectroscopic observations of the faintest galaxies present during the universe’s first billion years. The results offer vital clues toward solving a mystery in the early years of the universe.
For the first few hundred million years after the Big Bang, the universe was a thick soup of hydrogen fog with no stars to illuminate it. This period is known as the cosmic dark ages. The fog is thought to have eventually cleared when radiation ripped hydrogen atoms apart, a process known as reionization. But debate remained as to whether this reionizing radiation came solely from the first stars that lit up the earliest galaxies or whether material falling onto supermassive black holes also played a significant role.
A team of astronomers led by Hakim Atek (Paris Institute of Astrophysics) used the James Webb Space Telescope to peer at extremely faint dwarf galaxies in the early universe. These distant galaxies wouldn’t normally be visible — even to Webb’s powerful capabilities — but astronomers received a helping hand from the gravity of Pandora’s Cluster, a car crash of galaxies 4 billion light-years away. The cluster’s immense mass magnified the more distant galaxies’ light. The team's findings are published in Nature.
Atek’s team was able to study eight early galaxies in total, taking both images and spectroscopic data with Webb's Near-InfraRed Spectrograph (NIRSpec). The stand-out finding is that the galaxies produced four times more ultraviolet radiation than astronomers had derived from previous scenarios.
“Despite their tiny size, these low-mass galaxies are prolific producers of energetic radiation, and their abundance during this period is so substantial that their collective influence can transform the entire state of the Universe,” Atek says.
“They produce ionizing photons that transform neutral hydrogen into ionized plasma during cosmic reionisation,” adds team member Iryna Chemerynska (also at the Paris Institute of Astrophysics).
“It’s fantastic to see the pieces fitting together, and pointing squarely at tiny galaxies as the culprits,” says Sean McGee (University of Birmingham, UK), who was not involved in the research. Astronomers have long suspected that such galaxies helped light up the early universe, but McGee adds that “this was becoming more debatable recently as JWST has been finding more AGN than previously expected.” Now, the new JWST data on these tiny galaxies puts them back in the limelight.
“It had been an assumption that . . . these small galaxies would play an important role, but it’s very satisfying to see it directly,” McGee says. “It wouldn't have been possible without JWST.”
The next step is an upcoming Webb observing program named GLIMPSE. Astronomers will target another massive galaxy cluster — Abell S1063 — in order to see even fainter galaxies behind it in the early universe. This will allow them to verify whether the dwarf galaxies in the current study are typical of the large-scale distribution of galaxies.
McGee also notes the importance of the upcoming Square Kilometer Array (SKA). “We will be able to map out exactly where the universe hasn’t been reionized,” he says. If the findings of Atek's teams are right, we should only find neutral hydrogen — which gives out a distinctive radio signal at 21 centimetres — far from dwarf galaxies. “The lack of a radio signal around the tiny galaxies will be like the dog who didn’t bark in the night.”
Perseverance Sees Phobos, Deimos and Mercury Passing in Front of the Sun
NASA's Perseverance Mars rover used its Mastcam-Z camera to capture the silhouette of Phobos, the larger of Mars' pair of moons, as it passed in front of the Sun on Feb. 8, 2024, the 1,056th Martian day, or sol, of the mission.
The animation below shows Deimos transiting the Sun. This video is sped up because Deimos takes more than two minutes to transit.
NASA’s Mars rovers have captured many of Phobos and Deimos’ transits over the years. There’s more to the effort than just their novelty. Repeatedly capturing these transits informs scientists about their orbits over time.
Mars and Deimos are odd and mysterious. Monitoring them as they transit could help slowly dispel some of the mystery. What we really need are samples.
Russia sent a sample mission to Phobos with the unfortunate name of Phobos-Grunt. They launched it in 2011, but rocket burns needed to send it to the moon failed, and the craft eventually plunged to its destruction in the Pacific Ocean. (For some reason, Roscosmos tried to blame foreign saboteurs, by which everyone assumed he meant the USA.)
Japan is planning to launch a mission to Mars’ moon in 2026. It’s called the Martian Moons eXploration mission, or MMX, and it’ll obtain a sample of Phobos and return it to Earth in 2031
NASA's Perseverance Mars rover used its Mastcam-Z camera to capture the silhouette of Phobos, the larger of Mars' pair of moons, as it passed in front of the Sun on Feb. 8, 2024, the 1,056th Martian day, or sol, of the mission.
Image Credit: NASA/JPL-Caltech/ASU/MSSS/SSI
POSTED ON MARCH 7, 2024 BY EVAN GOUGH
NASA’s Perseverance rover is busy exploring the Martian surface and collecting samples for eventual return to Earth. But the rover recently took some time to gaze upward and observe the heavens. Using Mastcam-Z, the rover’s primary science camera, Perseverance captured Phobos, Deimos, and Mercury as they transited in front of the Sun.
Phobos and Deimos are unusual. They’re lumpy and are often referred to as ‘potato-shaped.’ They’re quite close to their planet as moons go, and they’re most likely captured objects, either asteroids or chunks of debris from the Solar System’s early days. They’re also small for primary moons, and both are tidally locked to Mars.
They share the same composition as carbonaceous chondrite asteroids and also have low albedoes. Both those traits bolster the captured asteroid argument. Phobos has the more unstable orbit of the two, and that reflects a more recent capture. Some think that Phobos and Deimos may have been a single object that only broke into two when it was captured.
But, some aspects of Phobos go against the capture theory. It contains some of the same phyllosilicate minerals that Mars does. This points to an alternate formation. A powerful impact could’ve lofted Martian debris into orbit, and the debris could’ve coagulated together to form the small moon. That may have been how Earth’s Moon formed.
On the other hand, both moons have circular orbits near the Martian equator. That hints at a more complex past, including an impact or the involvement of a third body.
POSTED ON MARCH 7, 2024 BY EVAN GOUGH
NASA’s Perseverance rover is busy exploring the Martian surface and collecting samples for eventual return to Earth. But the rover recently took some time to gaze upward and observe the heavens. Using Mastcam-Z, the rover’s primary science camera, Perseverance captured Phobos, Deimos, and Mercury as they transited in front of the Sun.
Phobos and Deimos are unusual. They’re lumpy and are often referred to as ‘potato-shaped.’ They’re quite close to their planet as moons go, and they’re most likely captured objects, either asteroids or chunks of debris from the Solar System’s early days. They’re also small for primary moons, and both are tidally locked to Mars.
They share the same composition as carbonaceous chondrite asteroids and also have low albedoes. Both those traits bolster the captured asteroid argument. Phobos has the more unstable orbit of the two, and that reflects a more recent capture. Some think that Phobos and Deimos may have been a single object that only broke into two when it was captured.
But, some aspects of Phobos go against the capture theory. It contains some of the same phyllosilicate minerals that Mars does. This points to an alternate formation. A powerful impact could’ve lofted Martian debris into orbit, and the debris could’ve coagulated together to form the small moon. That may have been how Earth’s Moon formed.
On the other hand, both moons have circular orbits near the Martian equator. That hints at a more complex past, including an impact or the involvement of a third body.
The animation below shows Phobos transiting in front of the Sun.
Phobos, in particular, may be in trouble. It’s already the closest moon to any planet in the Solar System, and its orbit is lowering, slowly bringing it closer to Mars. At some point, around 50 million years from now, it’ll breach the Roche limit. Then it’ll either crash directly into Mars or it’ll break apart and form a dust ring around the planet. Either way, it’s game over.
Deimos’ future is different. While Phobos orbits at an altitude of about 6000 km (3700 miles), Deimos is much further away. It orbits at an altitude of about 23,500 km (14,600 miles). So, while Phobos is drawing closer to Mars and to its own eventual destruction, Deimos is slowly drifting away. In the distant future, Mars will lose Deimos.
Phobos, in particular, may be in trouble. It’s already the closest moon to any planet in the Solar System, and its orbit is lowering, slowly bringing it closer to Mars. At some point, around 50 million years from now, it’ll breach the Roche limit. Then it’ll either crash directly into Mars or it’ll break apart and form a dust ring around the planet. Either way, it’s game over.
Deimos’ future is different. While Phobos orbits at an altitude of about 6000 km (3700 miles), Deimos is much further away. It orbits at an altitude of about 23,500 km (14,600 miles). So, while Phobos is drawing closer to Mars and to its own eventual destruction, Deimos is slowly drifting away. In the distant future, Mars will lose Deimos.
The animation below shows Deimos transiting the Sun. This video is sped up because Deimos takes more than two minutes to transit.
NASA’s Mars rovers have captured many of Phobos and Deimos’ transits over the years. There’s more to the effort than just their novelty. Repeatedly capturing these transits informs scientists about their orbits over time.
Mars and Deimos are odd and mysterious. Monitoring them as they transit could help slowly dispel some of the mystery. What we really need are samples.
Russia sent a sample mission to Phobos with the unfortunate name of Phobos-Grunt. They launched it in 2011, but rocket burns needed to send it to the moon failed, and the craft eventually plunged to its destruction in the Pacific Ocean. (For some reason, Roscosmos tried to blame foreign saboteurs, by which everyone assumed he meant the USA.)
Japan is planning to launch a mission to Mars’ moon in 2026. It’s called the Martian Moons eXploration mission, or MMX, and it’ll obtain a sample of Phobos and return it to Earth in 2031
.
This illustration shows JAXA’s MMX spacecraft with Mars and Phobos. If all goes well, the mission will return samples from Phobos to Earth in 2031. Image Credit: JAXA
Those samples could help us finally determine where the moons came from.
Perseverance also watched as Mercury transited the Sun. The images are here.
Those samples could help us finally determine where the moons came from.
Perseverance also watched as Mercury transited the Sun. The images are here.
Jeff Foust
March 7, 2024
WASHINGTON — The Commerce Department office that licenses commercial remote sensing systems is studying whether it should close a potential loophole in how companies comply with orbital debris mitigation rules.
The Commercial Remote Sensing Regulatory Affairs (CRSRA) division of the Office of Space Commerce will formally publish a request for information (RFI) in the Federal Register March 8 on the issue of debris mitigation regulations for systems it licenses. The RFI was released for public inspection March 7.
The RFI notes that while CRSRA had for two decades required companies seeking remote sensing licenses to provide a post-mission disposal plan for their satellites, the office dropped the requirement in 2020 as part of a broader revision of commercial remote sensing regulations. The rationale at the time was that nearly all systems seeking remote sensing licenses also had licenses from the Federal Communications Commission, which requires licensees to have orbital debris mitigation plans.
“To avoid duplicative regulation, Commerce opted to defer to FCC license requirements regarding orbital debris and spacecraft disposal, and therefore removed license conditions requiring specific orbital debris or spacecraft disposal practices in final rule,” CRSRA stated in the RFI.
However, the office noted that, since then, it has seen “an increasing number” of multinational systems that seek commercial remote sensing licenses but have communications licenses in other countries, and thus do not have FCC licenses.
“CRSRA is also sensitive to emerging communications methods not currently licensed by FCC, meaning a satellite using such methods would not be subject to FCC disposal and orbital debris mitigation requirement,” the RFI states. That is an apparent reference to optical communications systems that do not use radio-frequency spectrum managed by the FCC.
The office is seeking input from the remote sensing industry on whether it should restore some degrees of orbital debris regulations on all licensees or only those who do not have FCC licenses. It will also consider “narrow guidance not rising to the level of a rulemaking” for how those without FCC licenses can demonstrate “acceptable means of compliance.”
An Office of Space Commerce official previewed the RFI at a Feb. 29 event by the FCC’s Space Bureau marking two decades of FCC orbital debris regulations. “We’re realizing, though, increasingly there are situations where actors don’t get an FCC license,” said Gabriel Swiney, director of the office’s policy, advocacy and international division. “So we have U.S. companies that may only get a remote sensing license in terms of what U.S. government licensing that they get.”
The goal of the effort, he said, is to avoid companies being able to “jurisdiction shop and avoid any sustainability requirements.”
The RFI comes as the White House and Congress consider proposals for authorization and continuing supervision of “novel space activities” that are not currently licensed by any government agencies, from satellite servicing to commercial lunar landers. Those proposals would give the Office of Space Commerce the authority to oversee some or all of those activities.
That would likely include some regulations on orbital debris mitigation and related space sustainability topics. If that happens, “then it’s going to be really important to work in the interagency to implement that,” Swiney said, to ensure that “if there’s multiple regulators, which should be avoided to the extent possible, there’s not duplicative requirements or even overlapping requirements.”
WASHINGTON — The Commerce Department office that licenses commercial remote sensing systems is studying whether it should close a potential loophole in how companies comply with orbital debris mitigation rules.
The Commercial Remote Sensing Regulatory Affairs (CRSRA) division of the Office of Space Commerce will formally publish a request for information (RFI) in the Federal Register March 8 on the issue of debris mitigation regulations for systems it licenses. The RFI was released for public inspection March 7.
The RFI notes that while CRSRA had for two decades required companies seeking remote sensing licenses to provide a post-mission disposal plan for their satellites, the office dropped the requirement in 2020 as part of a broader revision of commercial remote sensing regulations. The rationale at the time was that nearly all systems seeking remote sensing licenses also had licenses from the Federal Communications Commission, which requires licensees to have orbital debris mitigation plans.
“To avoid duplicative regulation, Commerce opted to defer to FCC license requirements regarding orbital debris and spacecraft disposal, and therefore removed license conditions requiring specific orbital debris or spacecraft disposal practices in final rule,” CRSRA stated in the RFI.
However, the office noted that, since then, it has seen “an increasing number” of multinational systems that seek commercial remote sensing licenses but have communications licenses in other countries, and thus do not have FCC licenses.
“CRSRA is also sensitive to emerging communications methods not currently licensed by FCC, meaning a satellite using such methods would not be subject to FCC disposal and orbital debris mitigation requirement,” the RFI states. That is an apparent reference to optical communications systems that do not use radio-frequency spectrum managed by the FCC.
The office is seeking input from the remote sensing industry on whether it should restore some degrees of orbital debris regulations on all licensees or only those who do not have FCC licenses. It will also consider “narrow guidance not rising to the level of a rulemaking” for how those without FCC licenses can demonstrate “acceptable means of compliance.”
An Office of Space Commerce official previewed the RFI at a Feb. 29 event by the FCC’s Space Bureau marking two decades of FCC orbital debris regulations. “We’re realizing, though, increasingly there are situations where actors don’t get an FCC license,” said Gabriel Swiney, director of the office’s policy, advocacy and international division. “So we have U.S. companies that may only get a remote sensing license in terms of what U.S. government licensing that they get.”
The goal of the effort, he said, is to avoid companies being able to “jurisdiction shop and avoid any sustainability requirements.”
The RFI comes as the White House and Congress consider proposals for authorization and continuing supervision of “novel space activities” that are not currently licensed by any government agencies, from satellite servicing to commercial lunar landers. Those proposals would give the Office of Space Commerce the authority to oversee some or all of those activities.
That would likely include some regulations on orbital debris mitigation and related space sustainability topics. If that happens, “then it’s going to be really important to work in the interagency to implement that,” Swiney said, to ensure that “if there’s multiple regulators, which should be avoided to the extent possible, there’s not duplicative requirements or even overlapping requirements.”
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