Mars’ moons could be the remains of an ill-starred asteroid that got too close to the Red Planet.

A shredded asteroid origin could help explain mysterious features of the small, odd-shaped moons, scientists suggest in the January issue of Icarus.

Where most moons are big round orbs, Mars’ Phobos and Deimos are small lumpy potatoes.

There are two main ideas for how the moons formed. One is that the moons actually were asteroids that were caught by Mars’s gravity. But that idea doesn’t explain the moons’ circular, stable orbits around Mars’ equator. More

Within the dusty cloud left behind by supernova 1987A, the most famous stellar explosion in modern history, astronomers have found compelling evidence for a long-sought neutron star.

NASA’s James Webb Space Telescope has spied indirect hints of a powerful source of X-rays — likely some type of neutron star — coming from the core of the supernova remnant, researchers report February 22 in Science. The findings are part of a 37-year-old quest to determine what happened in the aftermath of the closest supernova in nearly 400 years and could provide insights into how a neutron star behaves mere decades after its birth.

“Supernova 1987A is truly a unique laboratory to study supernovas,” astronomer Patrick Kavanagh said February 17 in a news conference at the American Association for the Advancement of Science meeting in Denver. It’s “the gift that keeps on giving, with new observations continually yielding new discoveries,” said Kavanagh, of Maynooth University in Ireland.

It’s rare for scientists to have observations of a giant star before it explodes in a supernova — but they got lucky with supernova 1987A. On the left is the blue supergiant before the explosion. On the right is the explosion itself.David Malin, AAT

On February 23, 1987, telescopes around the world got a front-row seat to a spectacular supernova in the Large Magellanic Cloud, a companion galaxy to the Milky Way (SN: 2/8/17). Such explosions occur when a star at least eight times the mass of the sun dies. Located at the astronomically close distance of 160,000 light-years, supernova 1987A, as it came to be known, was visible with the naked eye in the night sky for months afterward. The energetic explosion generated tremendous amounts of neutrinos, a handful of which ended up in detectors on Earth. It was the first time such ghostly particles had been seen coming from beyond the solar system.

Since then, scientists have wondered whether the iron core of the blue supergiant star that led to 1987A collapsed into an ultradense neutron star or shrank all the way down to a black hole. The fact that neutrinos escaped the event favors the neutron star possibility, but whatever was left behind has yet to be spotted. That’s partly because the original star’s outer layers, now traveling away from the explosion at 10,000 kilometers per second, create a thick haze of dust that obscures the area. More

Uracil, a building block of life, has been found on the asteroid Ryugu.

Yasuhiro Oba and colleagues discovered the precursor to life in samples collected from the asteroid and returned to Earth by Japan’s Hayabusa2 spacecraft, the team reports March 21 in Nature Communications.

“The detection of uracil in the Ryugu sample is very important to clearly demonstrate that it is really present in extraterrestrial environments,” says Oba, an astrochemist at Hokkaido University in Sapporo, Japan.

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Uracil had been previously detected in samples from meteorites, including a rare class called CI-chondrites, which are abundant in organic compounds. But those meteorites landed on Earth, leaving open the possibility they had been contaminated by humans or Earth’s atmosphere. Because the Ryugu samples were collected in space, they are the purest bits of the solar system scientists have studied to date (SN: 6/9/22). That means the team could rule out the influence of terrestrial biology.

Oba’s team was given only about 10 milligrams of the Ryugu sample for its analysis. As a result, the researchers were not confident they would be able to detect any building blocks, even though they’d been able to previously detect uracil and other nucleobases inmeteorites (SN: 4/26/22).

Nucleobases are biological building blocks that form the structure of RNA, which is essential to protein creation in all living cells. One origin-of-life theory suggests RNA predated DNA and proteins and that ancient organisms relied on RNA for the chemical reactions associated with life (SN: 4/4/04).

The Japanese spacecraft Hayabusa2 collected these samples of Ryugu on two separate touchdowns on the asteroid. The sample on the left contains 38.4 milligrams of material and the one on the right, 37.5 milligrams. Analysis of about 10 milligrams of the sample revealed the presence of uracil, a key building block of life.Y. Oba et al/Nature Communications 2023, JAXA

The team used hot water to extract organic material from the Ryugu samples, followed by acid to further break chemical bonds and separate out uracil and other smaller molecules.

Laura Rodriguez, a prebiotic chemist at the Lunar and Planetary Institute in Houston, Texas, who was not involved in the study, says this method leaves the possibility that the uracil was separated from a longer chain of molecules in the process. “I think it’d be interesting in future work to look at more complex molecules rather than just the nucleobases,” Rodriguez says.

She says she’s seen in her research that the nucleobases can form bonds to create more complex structures, such as a possible precursor to the nucleic acid which may lead to RNA formation. “My question is, are those more complex structures also forming in the asteroids?”

Oba says his team plans to analyze samples from NASA’s OSIRIS-REX mission, which grabbed a bit of asteroid Bennu in 2020 and will return it to Earth this fall (SN: 10/21/20). More

Sand on Earth is continuously being created by the slow erosion of rocks. But on Mars, violent asteroid impacts may play an important role in making new sand.

As much as a quarter of Martian sand is composed of spherical bits of glass forged in the intense heat of impacts, a new study shows. Since windblown sand sculpts the Martian landscape, this discovery reveals how asteroid impacts contribute to shaping Mars, even long after the collisions occur, Purdue University planetary scientist Briony Horgan and colleagues suggest. The team will present their results August 18 at the 85th Annual Meeting of the Meteoritical Society in Glasgow, Scotland.

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Using data collected by spacecraft orbiting Mars, Horgan and collaborators looked at different wavelengths of visible and infrared light reflected from the planet’s surface to determine the minerals present in Martian sand. The team found signatures of glass all over the planet, particularly at higher latitudes.

One explanation for all that glass is volcanic eruptions, which are known to produce glass when magma mixes with water. But the most glass-rich swath of Mars — the planet’s northern plains — is conspicuously bereft of volcanoes, the researchers note. That rules out volcanic eruptions as the culprit in that location and instead suggests that far more cataclysmic events — asteroid impacts — might be involved.

That’s a plausible argument, says Steven Goderis, a geochemist at the Vrije Universiteit Brussel in Belgium who was not involved in the research. “Often Mars is seen as a volcanic planet. But there’s also a very strong impact component, and this is often overlooked.”

When an asteroid moving at several kilometers per second slams into a rocky planet like Mars, the energy of the event melts nearby rocks and launches them skywards. That molten shrapnel fragments and produces sand grain–sized pieces that are roughly spherical. Those bits of glass — called impact spherules — eventually rain back onto the planet (SN: 3/31/21).

Martian sand, imaged by NASA’s Phoenix Mars Lander, contains dark, spherical grains that were most likely created by asteroid impacts.Briony Horgan/ICL/UA/JPL/NASA

Over the last 3 billion years, asteroid impacts could have plausibly blanketed the surface of Mars in a layer of impact spherules roughly half a meter thick, Horgan and her colleagues calculate. All that material added to the sand on Mars that formed through normal erosion. “Impacts helped supply sand to the surface continuously over time,” Horgan says.

Scientists might have the opportunity to analyze Martian impact spherules in the future. NASA’s Perseverance rover is currently storing samples of Martian sand and rocks for eventual return to Earth (SN: 9/10/21). That’s exciting, Horgan says. “The record of all this is in the sand.” More

Arecibo’s days are done. After two support cables failed in recent months, the radio observatory’s 305-meter-wide dish is damaged beyond repair, the National Science Foundation announced on November 19. It will be decommissioned and dismantled.
“It’s a death in the family,” says astronomer Martha Haynes of Cornell University, who has used the telescope in Puerto Rico to study hydrogen in the universe since she was fresh out of college in 1973. “For those of us who use Arecibo and had hoped to use it in the future, it’s a disaster.”
The telescope, famous for appearances in movies like GoldenEye and Contact, consists of a wide dish to collect radio waves from space and focus them into detectors housed in a dome suspended above the dish. In August, one of the cables that holds up the dome slipped out of a socket and punched a hole in the dish.
The NSF and the University of Central Florida, which manages the telescope, had plans to repair the cable, Haynes said. But then a second cable unexpectedly broke on November 6. If a third cable were to break, it could send the platform holding up the dome swinging, or the whole structure could collapse.

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The NSF determined that there was no safe way to repair the telescope, the agency announced on November 19.
“Until these assessments came in, our question was not if the observatory should be repaired but how,” said Ralph Gaume, director of NSF’s Division of Astronomical Sciences, in a statement. “But in the end, a preponderance of data showed that we simply could not do this safely. And that is a line we cannot cross.”
The closure is the last in a series of near disasters for Arecibo. A different cable was damaged in an earthquake in 2014. Repairs on that cable were delayed by Hurricane Maria in 2017, which temporarily shut down the observatory as Puerto Rico weathered widespread power outages and humanitarian crises (SN: 9/29/17). And the observatory has been the victim of threatened or actual budget cuts for years (SN: 11/17/17).
But its loss is a major blow for astronomy. Built in 1963, Arecibo was one of the best facilities in the world for observations ranging from mysterious blasts of radio waves from deep space (SN: 2/7/20) to tracking near-Earth asteroids that could potentially crash into our planet (SN: 1/20/20). It also was used in the early days of the search for extraterrestrial intelligence, or SETI (SN: 5/29/12).
The Arecibo Observatory starred in major films, scanned the sky for hazardous asteroids and spotted mysterious radio bursts from space, among other things.University of Central Florida
“Astronomers don’t have a lot of facilities,” Haynes says. Each new one is designed to have unique advantages over existing telescopes. “So when you lose one, it’s gone.”
The observatory’s end is also a symbolic and practical loss for Puerto Rico, says radio astronomy researcher Kevin Ortiz Ceballos, a senior at the University of Puerto Rico at Arecibo who used the observatory to study the first known interstellar comet and stars that host exoplanets (SN: 10/14/19).
“Arecibo is like an icon of Puerto Rican science,” he says. “This is absolutely devastating.”
Ortiz Ceballos grew up watching Puerto Rican cartoons in which the characters went to Arecibo to use the telescope. His parents drove him an hour and a half to visit the telescope. He credits it with sparking his interest in astronomy, and he had hoped to come back to Puerto Rico to work at Arecibo after completing his Ph.D.
“Puerto Rico has a huge mass emigration problem,” he says. “It’s a lot of people, and they’re all my age. It’s a huge brain drain. Being able to do what I love without having to leave, it was a huge dream for me.”
And not just him, he notes: Dozens of students at the university and the observatory, plus more than 200 Puerto Rican students who went through the observatory’s high school program, have a similar story.
“Losing this, especially after all that we’ve lost over the past half decade, makes me feel like we’re condemned to have our country just be ruins,” he says. “It becomes a signifier of a broader collapse. That’s just really tragic.” More