The Artemis 2 astronauts remained vigilant while zipping around the far side of the moon last month, on the ready to record meteoroid impact flashes on the lunar landscape.

Their diligence was rewarded. The four crewmembers reported seeing several impact flashes — flickers of light created when a meteoroid hits the lunar surface and vaporizes.

"These observations were made with the unaided eye. It's extremely difficult to capture impact flashes with a camera, which is one of the benefits of sending trained crew to observe the moon," Kelsey Young, NASA Artemis 2 lunar science lead, told Space.com. "Early data indicates that the impact flashes were observed on the far side of the moon."

Citizen scientists help out

Artemis 2, the first crewed moon flight since Apollo 17 in 1972, launched from Florida's Space Coast on April 1 and flew around the far side of the moon on April 6.

As the astronauts scrutinized the moon that day, so did citizen scientists here on Earth. They were also looking for impact hits, although they would likely not have spotted the same ones as the crew.

Those observations were gathered as part of the newly launched Impact Flash citizen science project under the auspices of the Geophysical Exploration of the Dynamics and Evolution of the Solar System (GEODES), a unit within the NASA Solar System Exploration Research Virtual Institute.

The Impact Flash effort is geared to gather more data on the location and brightness of flashes throughout recent and upcoming Artemis moon missions.

"These flashes are vital to scientists who study the moon," notes the Impact Flash website. "By tracking when and where they happen, scientists can learn how often impacts of different sizes occur, what kinds of craters they create, and how the shock waves travel through the moon's interior."

When combined with data from NASA's moon-circuiting Lunar Reconnaissance Orbiter (LRO), future lunar surface instruments, and crew observations, the citizen science observations "can provide valuable constraints on the origin and characteristics of impactors, as well as craters that form from the impacts," Young said.

Observation window

The Artemis 2 astronauts' impact-flash observation window extended out onto the lunar near side in darkness, Benjamin Fernando, of the Department of Earth and Planetary Sciences at Johns Hopkins University in Baltimore, told Space.com.

In a paper posted earlier this year on the preprint server EarthArXiv, Fernando and colleagues reported that coordinated impact flash observations seen both from Earth and from lunar flyby/orbit will allow more detailed information to be gathered about the timing, location and dynamics of flashes than is possible from either method alone.

Joint observation campaigns enable researchers to better constrain the impact flux on the moon and also the associated impact hazard on the lunar surface, Fernando and his colleagues concluded.

Moon base implications

Updated knowledge about the meteoroid impact flux also plays into planning for Artemis Base Camp, the outpost NASA plans to build near the moon's south pole.

"To design for longevity, one must account for the myriad environmental hazards that a long-duration outpost will face — among them radiation, extreme thermal cycling, regolith dynamics, seismic shaking, dust, and, of particular importance to this work, impacts," notes a 2025 study led by Daniel Yahalomi, now a Torres Postdoctoral Fellow at MIT.

The lunar south pole offers a natural reduction in impact risk relative to equatorial sites, according to the study, "supporting its selection for sustained human presence."

Furthermore, currently available shielding technology "is sufficient to suppress micrometeoroid hazards by nearly five orders of magnitude, reducing the effective risk to a manageable level for current habitat designs," Yahalomi and his research colleagues concluded.

Big science haul

Hunting for impact flashes was one of many science tasks for the astronauts during their historic April 6 flyby. The Artemis 2 Lunar Science Team remains busy analyzing the mission's science haul — gathered with the aid of 31 cameras aboard the Orion capsule "Integrity" — and archiving it all on NASA's Planetary Data System.

"Within six months, all imagery of the Earth and moon taken by crew and vehicle cameras, audio recordings of the crew's science observations, and accompanying transcripts will be publicly available for the broader science community to analyze," Wasserman said.

In 2020, Japan's Hayabusa2 spacecraft brought samples of an asteroid named Ryugu to Earth — and now, scientists examining those samples found that the object bears the scars of a recent encounter with tiny space rocks.

The reason the research team believes Ryugu was bombarded by micrometeorites is due to a fine layer of sodium, just 10 nanometers thick, on the surface of the asteroid's fragments. This kind of build-up is unusual because volatile elements like sodium, which can get exposed after an object is blasted with micrometeorites, are usually later depleted by solar winds blowing from the sun and the general influence of space.

Based on the volume of sodium observed by the researchers, they estimate that Ryugu's passage through a dense cloud of micrometeorites must have occurred around 1,000 years ago. That's an extremely recent event considering the asteroid formed 4.6 billion years ago, while planets like Earth were still taking shape around our infant sun.

"Over the past thousand years, the asteroid has passed through a particularly intense swarm that has profoundly altered the chemical properties of its surface. We were able to detect these changes by analyzing two millimeter-thin fragments of Ryugu, using techniques capable of studying the morphology and chemistry of layers just a few billionths of a meter thick," lead researcher Ernesto Palomba of the Italian National Institute for Astrophysics (INAF) said in a statement translated from Italian. "In this context, finding an accumulation of sodium on particles collected on the surface and exposed to external agents is a puzzle we needed to solve."

"Experiments show sodium depletion of up to 50% over very rapid timescales, on the order of a few hundred years," Palomba added. "Based on these data, we considered a maximum time window of a thousand years, beyond which the sodium should have been completely released, making it impossible to observe any accumulation."

The team also discovered evidence of micrometorite impacts in the form of glassy formations, or tiny impact craters, and lattice-like microstructures created by interactions with the solar wind.

"The iron enrichment found in the particle collected on the surface can be traced back to interaction with the solar wind and continuous microimpacts," Palomba said. "This trend, already observed in previous studies, confirms once again that the exposed particle has undergone a more marked alteration than the one that remained protected underground."

The team's findings demonstrate how near-Earth asteroids close to our planet encounter swarms of meteoroids that are capable of altering their surface properties.

"This, in a sense, is what happens to our planet: in the case of Earth, the atmosphere protects us and allows encounters with these swarms to become a beautiful spectacle that periodically lights up our sky, as in the case of the Perseids or the Geminids," Palomba said. "For bodies without an atmosphere like the asteroid Ryugu, however, the outcome is different."

The INAF researcher said the team's next goal will be to conduct specific experiments on chemicals present on the asteroid Ryugu, to reproduce observations of the asteroid's surface chemistry.

The team's research was published on April 16 in the journal The Astrophysical Journal Letters.

HOUSTON — NASA scientists, and the rest of the world, are beaming about the incredible images from the Artemis 2 flyby around the far side of the moon.

On Monday (April 6), astronauts aboard NASA's Orion spacecraft completed their closest approach of the moon. During that historic flyby, the crew snapped stunning photos and made a variety of lunar observations, some of which were met with cheers inside the Science Evaluation Room here at Johnson Space Center.

There were "audible screams of delight," said Kelsey Young, Artemis 2's lunar science lead, during a press conference on Tuesday (April 7). Those excited screams were caused by the astronauts' observations of micrometeor impacts on the moon, which NASA scientists weren't expecting.

Monday's flyby was the centerpiece of the Artemis 2 mission. It was the scientific focus of the crew's 10-day journey out to the moon and back, so researchers were eager to learn what the astronauts saw. And the results have not disappointed so far.

"Spirits are very high," Young said. "We did what we set out to do. The Lunar Science Team and the crew prepared extensively," she said — but they weren't prepared to see so many impacts.

Near the end of Orion's closest lunar approach on Monday evening, the sun dipped behind the moon, creating a solar eclipse for the astronauts that lasted almost an hour. During that time, the crewmates say they witnessed no less than five micrometeor impacts on the lunar far side.

Artemis 2 marks the first time that humans have traveled to lunar space since Apollo 17 in 1972, so the mission science team prepped the astronauts extensively.

During their flight, the crew members were tasked with identifying multiple geographic features, photographing the lunar surface and recording their findings for scientists back on Earth. And, with the brightest part of the sun blocked by the disk of the moon, the Artemis 2 astronauts were able to make out flashes from each impact with just their eyes.

Impact flashes are caused by micrometeors hitting the moon, and can help scientists learn about the dynamics of the lunar environment.

"This is absolutely everything we hoped for by integrating science into flight operations," Young said. "Science enables exploration, and exploration enables science."

This article is republished from Eos, read the original article.

Micrometeorites, unlike their larger brethren, rarely get a spotlight at museums. But there's plenty to learn from these extraterrestrial particles, despite the largest of them measuring just millimeters across.

Nearly 50 tons of extraterrestrial material fall on Earth every day, and the majority of that cosmic detritus is minuscule. Micrometeorites are, by definition, smaller than 2 millimeters in diameter, and they’re ubiquitous, said Fabian Zahnow, an isotope geochemist at Ruhr-Universität Bochum in Germany. "You can basically find them everywhere."

Researchers recently analyzed fossilized micrometeorites that fell to Earth millions of years ago. They extracted whiffs of atmospheric oxygen incorporated into the particles and showed that carbon dioxide (CO₂) levels during the Miocene and Cretaceous did not differ wildly from modern-day values. The results were published in Communications Earth and Environment.

Extraterrestrial needles in rocky haystacks

Newly fallen micrometeorites can be swept from rooftops and dredged from the bottoms of lakes.

Zahnow and his collaborators, however, opted to turn back the clock: The team analyzed a cadre of micrometeorites that fell to Earth millions of years ago and have since been fossilized. The team sifted through more than a hundred kilograms of sedimentary rocks, mostly unearthed in Europe, to discover 92 micrometeorites rich in iron. They added eight other iron-dominated micrometeorites from personal collections to bring their sample to 100 specimens.

Metal-rich micrometeorites such as these are special, said Zahnow, because they function like atmospheric time capsules. As they hurtle through the upper atmosphere on their way to Earth, they melt and oxidize, meaning that atmospheric oxygen gets incorporated into their otherwise oxygen-free makeup.

"When we extract them from the rock record, we have our oxygen, in the best case, purely from the Earth’s atmosphere," said Zahnow.

Ancient carbon dioxide levels

And that oxygen holds secrets about the past. It turns out that atmospheric oxygen isotope ratios—that is, the relative concentrations of the three isotopes of oxygen, ¹⁶O, ¹⁷O, and ¹⁸O—correlate with the amount of photosynthesis occurring and how much CO₂ is present at the time. That fact, paired with model simulations of ancient photosynthesis, allowed Zahnow and his colleagues to infer long-ago atmospheric CO₂ concentrations.

Reconstructing Earth’s atmosphere as it was millions of years ago is important because atmospheric gases affect our planet so fundamentally, said Matt Genge, a planetary scientist at Imperial College London not involved in the work. "The story of the atmosphere is the story of life on Earth."

But Zahnow and his collaborators first had to make sure the oxygen in their micrometeorites hadn't been contaminated. Terrestrial water, with its own unique oxygen isotope ratios, can seep into micrometeorites that would otherwise reflect atmospheric oxygen isotope ratios from long ago. That’s a common problem, said Zahnow, given the ubiquity of water on Earth. "There's always some water present."

The team found that the presence of manganese in their micrometeorites was a tip-off that contamination had occurred. "Extraterrestrial metal has basically no manganese," said Zahnow. "Manganese is really a tracer for alteration."

Unfortunately, the vast majority of the researchers' micrometeorites contained measurable quantities of manganese. In the end, Zahnow and his collaborators deemed that only four of their micrometeorites were uncontaminated.

Those micrometeorites, which fell to Earth during the Miocene (9 million years ago) and the Late Cretaceous (87 million years ago), suggested that CO₂ levels during those time periods were, on average, roughly 250–300 parts per million. That's a bit lower than modern-day levels, which hover around 420 parts per million.

The team's findings are consistent with values suggested previously, said Genge, but unfortunately, the team's numbers just aren’t precise enough to conclude anything meaningful. "You have a really huge uncertainty," he said.

The team's methods are solid, however, said Genge, and the researchers made a valiant effort to measure what are truly faint whiffs of ancient oxygen. "It's a brave attempt."

In the future, it would be valuable to collect a larger number of pristine micrometeorites dating to time periods when model reconstructions suggest anomalously high CO₂ levels, said Zahnow. "What we really hoped for was to get pristine micrometeorites from periods where the reconstructions say really high concentrations."

Confirming, with data, whether such time periods, such as the Triassic, truly had off-the-charts CO₂ levels would be valuable for understanding how life on Earth responded to such an abundance of CO₂.

Two tiny meteorites discovered in a 55-year-old snowpack in Antarctica could reveal secrets about the formation of the solar system, scientists say.

Researchers unearthed these fragments by melting and filtering snow that fell in the mid-20th century near the French-Italian CONCORDIA station in the central part of Antarctica. They found a surprisingly un-contaminated sample of objects, many of which have been roaming the solar system for millions of years before ending up on Earth. Their discovery is detailed in the May 7 issue of the journal Science.

"When we melted this snow and we looked at the particles within this very pure snow, we realized that more than one out of two were extraterrestrial," said study leader Jean Duprat of the Universit? Paris-Sud in Orsay, France, who was working with the French Polar Institute Paul ?mile Victor in Antarctica. "It was the first time we had such an intrinsically clean collection."

Weird little rocks from space

The find turned out to be special in other ways, too.? For one thing, two of the meteorite fragments were packed with carbon, which is unusual in rocks like this.

"More than half of their volume is made of a carbon-rich material," Duprat told SPACE.com. "This is exceptional because normally if you take a primitive meteorite, the carbon accounts for about a few percent in mass of the whole rock."

Another strange aspect of the meteorite fragments was their large amount of a particle called deuterium, which is a rare form of hydrogen (while the normal nucleus of hydrogen is made of one lone proton, deuterium contains one proton and one neutron).

Both these clues ? the abundance of carbon and deuterium ? tell the researchers that the tiny meteorites probably came from comets. Comets are known to deposit material on Earth when they swing in close to the sun and release material that can be captured by Earth's gravity.

"What we know is that these particles are most probably from a parent body that did not evolve since very early in the solar system's history, because the composition of these particles is very primitive," Duprat said.

Older than the planets

The researchers think the fragments they found likely first originated in the solar system before the planets were even formed, when the sun had only a "protoplanetary disk" of material that would later clump into planets.

As such, they offer great clues to how our solar system was built, and could even point toward how life got started on Earth, scientists say. Some experts think that comets and meteorites deposited the organic compounds that would form the seeds of life on our planet.

"The very high carbon contents of [the fragments] may well have profound implications for the original delivery of organic molecules to the early Earth, with possible consequences for the earliest prebiotic chemistry," Carnegie Institution of Washington researcher Larry R. Nittler, who was not involved in the new study, wrote in an accompanying essay in the same issue of Science.

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HOUSTON - Astronauts aboard NASA's space shuttle Discovery will begin afinal inspection of their spacecraft's wings today in a first-ever hunt for any signs ofimpact from miniscule space rocks.

Discovery'sSTS-121 mission specialists LisaNowak and StephanieWilson will scan the shuttle's port wing with its sensor-laden inspectionboom to determine whether micrometeorites or other orbital debris have struckthe spacecraft during its stay at International Space Station(ISS).

"Anyspacecraft in orbit has a fundamental risk of being hit by something,"Discovery's pilot Mark Kelly told CNN Friday during a series of space-to-groundinterviews on NASA TV. "By doing a late inspection, it will slightly reduce therisk of damage to our thermal protection system, or at least, if there isdamage we'll know about it."

Friday'slate inspection is slated to begin at 1:18 p.m. EDT (1718 GMT) after Discovery'sastronauts unberth the Italian-builtLeonardo cargo module from the ISS and stow it in the shuttle's payloadbay. Once Discovery and its six-astronaut crew undock from the ISS on Saturday,Nowak and Wilson - which flight controllers dubbed the "ROBO chicks" in today'sexecute package - will also inspect the shuttle's nose cap and starboard wing.

"It is moreremote than ascent debris," Wilson told CBS News today of the micrometeoritethreat.

Nowak addedthat the initial FlightDay 2 inspections of Discovery's heat shield coupled with focusedlooks after the shuttle docked at the ISS should help make this weekend'sfinal checks of the orbiter's nose and wing leading edges go smoother. Discovery'sheat shield has already been clearedof any launch debris concerns.

Steve Poulos,NASA's orbiter project manager, told the Associated Press Thursday that thelate inspections could reduce the odds of losing a spacecraft due tomicrometeorite damage from the average 1 in 210 to about 1 in 282.

Discovery'sSTS-121 mission is NASA's the second shuttle to visit theISS since the 2003 Columbiaaccident and the last of two test flights before major constructionresumes on the orbital laboratory. Launchedon July 4, the 13-daymission has returned the station to its three-person capacity,delivered vital supplies to the outpost and tested shuttle heat shield repairtools and methods.

Engineerson the ground continue to study a pair ofissues with two of three Auxiliary Power Units (APUs) that power Discovery'shydraulics during reentry and landing.

Aworkaround has been developed for an errant heater in one of the units, andcalls for the STS-121 crew to switch to a backup or orient the Discoverytowards the Sun to keep the APU warm. The second problem, a potential fuelleak, is still under study, according to today's flight execute package.

Back towork

Discovery'sSTS-121crew and the three-astronaut Expedition13 team aboard the ISS are getting back to work today after a lightday of rest and nominal duties on Thursday.

In additionto having a joint meal aboard the ISS and speaking with their families fromorbit, the STS-121 astronauts fielded several questions from reporters on Earthand - in the case of one spacewalker - Texas governor Rick Perry.

A graduateof Texas A & M University, Perry called STS-121 mission specialist andfellow Aggie Michael Fossum to congratulate him on completing the thirdand last of the spacewalks planned for his mission.

"I justwanted to call to tell you how proud we are of you Mike, the entire state of Texas," Perry told Fossum. "Of course, the Aggies are up in great arms and in celebrationtoday to have the first Aggie in space, you're making history Mike."

Fossum thankedPerry for his support for NASA's Johnson Space Center (JSC) here in Houston and graciously accepted an offer for 50-yard-line tickets for the big football gamebetween the Texas A & M Aggies and the University of Texas Longhorns laterthis year.

Fossum'screwmate Wilson, a Longhorn, was also offered the tickets, Perry said.

Fossum,Wilson and Nowak are making their first spaceflight for Discovery's STS-121mission. While all three of them have waited long - at least 10 years forWilson and Nowak and 25 for Fossum, the patience has paid off.

"It wasdefinitely a long wait and it was definitely worth it," Nowak said Thursday. "Thisis a trip of a lifetime...it's thrilling to be up here."

TheAssociated Press contributed to this report.

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