Tag: asteroids

The second known asteroid discovered orbiting closer to the Sun than Venus

8:56 am

Using ground-based telescopes scanning the morning and evening sky, an astronomer has discovered only the second known asteroid circling the Sun within the orbit of Venus.

The manner of the discovery itself, by Scott Sheppard of the Carnegie Institution, also illustrated our modern world.

He first observed it using the Cerro Tololo Dark Energy Camera the night before leaving on a hiking trip. Because the object was moving fast, he knew it must be very close to the Sun, so he’d need to image it again and soon to confirm its orbit before it became lost in the Sun’s glare.

“I had to schedule new observations to re-observe the object while deep in the forest of Pennsylvania,” he says. “It is just amazing that even camp sites today have good Wi-Fi access — that allowed me to download the new second observations of this asteroid and determine its unique orbit that is interior to Venus.”

Astronomers have found so few asteroids close to the Sun because the Sun’s glare makes observations difficult. Some scientists like to speculate to the press that there could be a large unknown population, with some posing a threat to Earth. The computer predictions however say the population is small, because the push of the Sun’s light and radiation should easily shift their orbits outward or make them unstable.

The two asteroids so far found confirm these models in a counter-intuitive way. The new asteroid is estimated to be a little less than a half mile across, while the previously discovered asteroid is thought to have a diameter of more than a mile. Their larger size makes it harder for the Sun’s light and radiation to shift their orbit.

In other words, this inner population of asteroids is likely to be low in number, but made up of larger objects.

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New study claims the giant impact that created the Moon’s South Pole-Aitken Basin was oblique, from the south

9:14 am

South Pole-Aitken Basin
Click for original. Blue indicates the basin, red
the “thorium-rich and iron-rich ejecta deposit”

While previous work had suggested the giant bolide that had created the Moon’s South Pole-Aitken Basin came in from the north, a new study now proposes that the impact was instead oblique from the south. From the paper’s abstract:

The ancient South Pole–Aitken impact basin provides a key data point for our understanding of the evolution of the Moon, as it formed during the earliest pre-Nectarian epoch of lunar history, excavated more deeply than any other known impact basin, and is found on the lunar far side, about which less is known than the well-explored near side. Here we show that the tapering of the basin outline and the more gradual topographic and crustal thickness transition towards the south support a southward impact trajectory, opposite of that commonly assumed. A broad thorium-rich and iron-rich ejecta deposit southwest of the basin is consistent with partial excavation of late-stage magma ocean liquids.

These observations indicate that thorium-rich magma ocean liquids persisted only beneath the southwestern half of the basin at the time of impact, matching predictions for the transition from a global magma ocean to a local enrichment of potassium, rare-earth elements and phosphorus (KREEP) in the near-side Procellarum KREEP Terrane.

In other words, when this impact occurred, part of the impact site in the south was still a magma ocean.

This result, if confirmed, has research implications for the missions targeting the Moon’s south pole. It suggests the geology will have that KREEP materials readily available, which will provide important information about the Moon’s early geological history.

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Australian satellite startup to fly an instrument on private mission to Apophis

8:59 am

In March 2024 the orbital tug startup Exlab’s announced that it will use its orbital tug to deliver three cubesats to the asteroid Apophis when that object makes its next close fly-by of the Earth on April 13, 2029.

The California-based Exlab has now signed its first customer for that mission. An Australian satellite startup, Fleet Space Technologies, has agreed to fly an instrument on this private commercial mission.

Under the ApophisExL mission, Fleet will provide geophysical sensing technologies for ExLabs’ mothership to collect targeted data and characterize the asteroid. The datasets should enable new avenues for data sharing and commercial use, set criteria for prioritizing asteroids for prospecting and feed critical intelligence into planetary‑defence planning.

Fleet already has a contract to fly another instrument, a seismometer, on Firefly’s second Blue Ghost lander mission to the Moon. It has also developed and flown satellite instruments used to detect minerals on Earth.

Both companies are clearly aiming to enhance their brand name with this mission, set to launch in 2028.

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Astronomers refine the spin and size of Hayabusa-2’s next target asteroid

10:15 am

Using a number of ground-based telescopes, astronomers have determined that asteroid 1998 KY26, which Japan’s Hayabusa-2 probe will visit in 2031, spins much faster and is much smaller than previously estimated.

The new observations, combined with previous radar data, have revealed that the asteroid, 1998 KY26, is just 11 meters wide. It is also spinning about twice as fast as previously thought: “One day on this asteroid lasts only five minutes!” he says. Previous data indicated that the asteroid was around 30 meters in diameter and completed a rotation in approximately 10 minutes. The smaller size and faster rotation will make the spacecraft’s touchdown maneuver more difficult to perform than anticipated.

The observations also found that 1998 KY26 is bright, suggesting it is a solid object, not a rubble pile. Its fast rotation adds weight to this conclusion.

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Lucy scientists name the features on asteroid Donaldjohanson

10:16 am

The named features on Donaldjohanson
Click for original.

The science team for the asteroid probe Lucy have now released their names for the features they discovered on the main belt asteroid Donaldjohanson when the spacecraft flew past in April 2025.

The smaller lobe is called Afar Lobus, after the Ethiopian region where Lucy and other hominin fossils were found. The larger lobe is named Olduvai Lobus, after the Tanzanian river gorge that has also yielded many important hominin discoveries.

The asteroid’s neck, Windover Collum, which joins those two lobes, is named after the Windover Archeological Site near Cape Canaveral Space Force Station in Florida — where NASA’s Lucy mission launched in 2021. Human remains and artifacts recovered from that site revolutionized our understanding of the people who lived in Florida around 7,300 years ago.

Two smooth areas on the asteroid’s neck are named Hadar Regio, marking the specific site of Johanson’s discovery of the Lucy fossil, and Minatogawa Regio, after the location where the oldest known hominins in Japan were found. Select boulders and craters on Donaldjohanson are named after notable fossils ranging from pre-Homo sapiens hominins to ancient modern humans.

These names were “approved” by the International Astronautical Union (IAU), which claims the authority over the naming of every rock, boulder, pebble in space. The truth is, however, that future spacefarers are going to accept these names no matter what the IAU had said, simply because these scientists did the first exploration of this asteroid. They get to choose, not the IAU.

The spacecraft is now on its long coast out of the main belt and on to the orbit of Jupiter, where it will make fly-bys of ten different asteroids.

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Radar images reveal near Earth asteroid to be a contact binary

12:06 pm

Peanut shaped asteroid
Click for original image.

Just after asteroid 1997 QK1 made its first really close pass of the Earth on August 20, 2025, scientists used the Goldstone radio antenna take 28 high resolution images and discovered that the asteriod is peanut shaped, meaning that it is a contact binary of two objects that have fused together.

Those images, cropped, reduced, and sharpened to post here, are shown to the right.

The asteroid is about 660 feet (200 meters) long and completes one rotation every 4.8 hours. It passed closest to our planet on the day before these observations were made at a distance of about 1.9 million miles (3 million kilometers), or within eight times the distance between Earth and the Moon. The 2025 flyby is the closest that 1997 QK1 has approached to Earth in more than 350 years. Prior to the recent Goldstone observations, very little was known about the asteroid.

These observations resolve surface features down to a resolution of about 25 feet (7.5 meters) and reveal that the object has two rounded lobes that are connected, with one lobe twice the size of the other. Both lobes appear to have concavities that are tens of meters deep.

Though this asteroid is classified as potentially dangerous, calculations of its orbit show it poses no threat for the “foreseeable future.”

That it is a contact binary reinforces the present theory that about 15% of all larger asteroids belong to this class.

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Meteorite that crashed through roof of home in Georgia dated to beginning of solar system

11:40 am

A meteorite that crashed through the roof of a home in Georgia in June 2025 has now been dated to have formed 4.56 billion years ago, to a time when the solar system was just beginning to form.

[The University of Georgia] received 23 grams of the 50 recovered from the piece that penetrated the house. Using optical and electron microscopy to analyze the fragments, Harris says he believes the meteorite to be a Low Metal (L) ordinary Chondrite. That classification means he expects the meteorite to have formed 4.56 billion years ago in the presence of oxygen — older than the Earth itself.

“It belongs to a group of asteroids in the main asteroid belt between Mars and Jupiter that we now think we can tie to a breakup of a much larger asteroid about 470 million years ago,” Harris said. “But in that breakup, some pieces get into Earth-crossing orbits, and if given long enough, their orbit around the sun and Earth’s orbit around the sun end up being at the same place, at the same moment in time.”

There has been a lot of unjustified hype in the mainstream press about this story, mostly about the age of the meteorite. The fact is that this age for a meteorite is simply not a surprise, that almost all chondrite meteorites found are of comparable age, coming from the beginnings of the solar system.

The most unusual part of the story is that the impact occurred through a person’s house. Such events are exceedingly rare. That it happened however was actually fortuitous, in that, first, no one was hurt, and second, it allowed the meteorite to be quickly recovered and analyzed.

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Psyche snaps picture of Earth-Moon system

9:42 am

Earth and Moon, as seen by Psyche
Click for original image.

In a successful test of its cameras and pointing capabilities, the science team operating the probe Psyche — on its way to the asteroid Psyche — were able to snap a picture of Earth-Moon system from about 180 million miles away.

On July 20 and July 23, the spacecraft’s twin cameras captured multiple long-exposure (up to 10-second) pictures of the two bodies, which appear as dots sparkling with reflected sunlight amid a starfield in the constellation Aries.

One of those pictures is shown to the right. The scientists had previously taken similar calibration images of Jupiter and Mars.

To determine whether the imager’s performance is changing, scientists also compare data from the different tests. That way, when the spacecraft slips into orbit around Psyche, scientists can be sure that the instrument behaves as expected. “After this, we may look at Saturn or Vesta to help us continue to test the imagers,” said Jim Bell, the Psyche imager instrument lead at Arizona State University in Tempe. “We’re sort of collecting solar system ‘trading cards’ from these different bodies and running them through our calibration pipeline to make sure we’re getting the right answers.”

The spacecraft is scheduled to arrive at the metal asteroid Psyche in 2029, and will then spend at least two years flying in formation with it.

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Scientists link near Earth asteroids Bennu and Ryugu to much larger main belt asteroid

9:29 am

Ryugu and Bennu

Scientists comparing the spectroscopy of samples returned from the near Earth asteroids Bennu and Ryugu have found they closely resemble the much larger main belt asteroid Polana, suggesting all three formed at the same time and place.

You can read the paper here [pdf] From the press release:

The study compared spectroscopy data from Polana with spacecraft and laboratory data from Bennu and Ryugu samples, discovering similarities in their near-infrared spectrum sufficient to support the theory that they originate from the same parent asteroid. “Very early in the formation of the solar system, we believe large asteroids collided and broke into pieces to form an ‘asteroid family’ with Polana as the largest remaining body,” said SwRI’s Dr. Anicia Arredondo, lead author of the study. “Theories suggest that remnants of that collision not only created Polana, but also Bennu and Ryugu as well.”

While the similarities are great, the paper notes there are differences, possibly from “space weathering, particle size, surface texture, or different compositions.” The scientists believe the differences were caused by the asteroids’ different environments, with the 33-mile-wide and much older Polana in the asteroid belt beyond Mars, and Ryugu and Bennu, both less than a mile wide, orbiting the Sun inside Mars.

It is also possible the asteroids have little to do with each other, and the similar spectroscopy only informs us of some of the more common components of the early solar system.

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Radar images of near Earth asteroid as it zipped past the Earth

9:11 am

Radar images of near Earth asteroid
Click for original. Go here for movie made from these images.

Using the Goldstone radar antenna in California, astronomers have produced a series of 41 radar images of the near Earth asteroid 2025 OW as it made a close pass of the Earth on July 28, 2025.

Those images, cropped, reduced, and sharpened to post here, are to the right.

The asteroid safely passed at about 400,000 miles (640,000 kilometers), or 1.6 times the distance from Earth to the Moon.

The asteroid was discovered on July 4, 2025, by the NASA-funded Pan-STARRS2 survey telescope on Haleakala in Maui, Hawaii. These Goldstone observations suggest that 2025 OW is about 200 feet (60 meters) wide and has an irregular shape. The observations also indicate that it is rapidly spinning, completing one rotation every 1½ to 3 minutes, making it one of the fastest-spinning near-Earth asteroids that the powerful radar system has observed. The observations resolve surface features down to 12 feet (3.75 meters) wide.

The asteroid’s fast rotation suggests it is a solid object, structurally strong, rather than a rubble pile held together loosely by gravity. It would thus be very damaging if it should ever hit the Earth.

No worries however. The refined orbital data says this asteroid will not come this close again in the foreseeable future.

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Hera photographs two main belt asteroids on its way to Didymos/Dimorphos

10:12 am

Asteroid Otero as seen by Hera
Click for original image.

The science team for the European Space Agency’s Hera asteroid probe, on its way to the binary asteroid Didymos/Dimorphos in late 2026, has successfully taken images of two different main belt asteroids, demonstrating once again that its camera and pointing capabilities are operating as expected.

The image to the right, cropped, reduced, and enhanced, shows all the observations of Otero, the first asteroid observed, as it moved upward in the field of view. The result was that vertical line of dots.

On 11 May 2025, as Hera cruised through the main asteroid belt beyond the orbit of Mars, the spacecraft turned its attention toward Otero, a rare A-type asteroid discovered almost 100 years ago.

From a distance of approximately three million kilometres, Otero appeared as a moving point of light – easily mistaken for a star if not for its subtle motion across the background sky. Hera captured images of Otero using its Asteroid Framing Camera – a navigational and scientific instrument that will be used to guide the spacecraft during its approach to Didymos next year.

The second observation of asteroid Kellyday was even less spectacular visually, but because that asteroid was forty times fainter than Otero, the observation was more challenging, and thus its success more significant.

Hera will arrive at the Didymos/Dimorphos binary asteroid in 2026, where it will make close-up observations of the changes the asteroids have undergone following Dart’s impact of Dimorphos in 2022. Subsequent ground- and space-based observations have been extensive and on-going, but the close-up view will be ground-breaking.

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First Hubble images of interstellar comet 3I/Atlas released

5:03 pm

Comet 3I/Atlas, taken by Hubble
Click for original.

An undergraduate student has just released the first pictures taken by the Hubble Space Telescope of the interstellar object 3I/Atlas, confirming that it is a comet as indicated by the earlier image taken by the Gemini North telescope.

One of those images, taken only hours ago, is the inset on the map showing the comet’s route through the solar system to the right. The streaks on the image are either stars or cosmic rays. Though this image is of significantly lower quality than the Gemini North picture, it once again shows both the comet’s nucleus and developing coma.

A preprint [pdf] of a new research paper based on data from both telescopes further confirms this conclusion:

[T]hese results suggest that 3I/ATLAS hosts a coma containing large water ice grains, and that its dust continuum is stable over at least week-long timescales. The spectral characteristics further distinguish 3I from known ultrared trans-Neptunian objects and align it more closely with active Jupiter-family comets.

The last conclusion is very significant. Though the path and speed of this interstellar object says it must come from beyond the solar system, its cometary make-up more resembles comets that reside in the inner solar system. These facts strongly imply that there is at least one other solar systems not very different from our own.

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A Martian meteorite discovered in Africa is up for auction

9:10 am

A Martian rock that fell as a meteorite in Africa and was discovered by a professional meteorite hunter and is the largest such Mars rock found so far is about to go up for sale by auction.

NWA16788 is the largest known piece of Mars on Earth, and its internal composition suggests it was disgorged from the surface of the Red Planet by an asteroid impact so extreme that it turned some of the meteorite’s minerals into glass.

Looking certain to blow past its lower estimate of US$2.0 million, this monumental 54-lb (24.67-kg) lump of Mars has already been bid to $1,920,000 (inc Buyer’s Premium) 12 days before the on-line hammer falls, and even its $4-milllion upper estimate doesn’t look safe with this much interest so early in an online auction.

The expected high price is partly because of the meteorite’s size, and partly because almost such meteorites are found by scientists working for NASA, and are thus never made available for sale. To have one available for purchase is rare indeed.

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Another interstellar object identified entering the solar system

11:44 am

A11pl3Z's path through the solar system

Astronomers think they have identified another interstellar object that is now entering the solar system.

The dim space rock is currently at about magnitude 18.8. Our new visitor, A11pl3Z, will get its closest to the sun – at about 2 astronomical units (AU), or twice as far as Earth is from the sun – in October. As it reaches perihelion – its closest point to the sun – it should be moving at about 68 km/s relative to the sun, or at about 152,000 miles per hour.

The object’s calculated path through the solar system, shown by the blue line in the graphic to the right, as well as the object’s high speed, are why the astronomers think it is interstellar in origin. Both facts suggest it is coming from beyond the Oort cloud.

This is the third such object discovered, after Oumuamua (whose nature remains somewhat unknown), followed by Comet 21/Borisov.

UPDATE: The object has now been renamed 3I/Atlas. The “3I” indicates it is the third interstellar object discovered, and “Atlas” refers to the discovering telescope survey.

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China releases images of Earth and Moon, taken by its Tianwen-2 asteroid probe

9:40 am

Tianwen-2 images of the Earth and the Moon
For original images go here and here.

According to a report today in China’s state-run press, its Tianwen-2 asteroid sample return spacecraft is operating normally, and has successfully taken pictures of both the Earth and the Moon to test its instrumentation.

Those images are to the right, cropped, reduced, and sharpened to post here.

The CNSA [China National Space Administration] said that the narrow-field-of-view navigation sensor equipped on the probe recently captured the images of Earth and the moon, demonstrating good functional performance.

The images released include a photograph of Earth obtained by Tianwen-2 when it was approximately 590,000 kilometers away from the planet, as well as a new photograph of the moon captured when it was about the same distance from the moon. After the images were transmitted back to the ground, they were processed and produced by scientific researchers.

The Tianwen-2 probe has currently been in orbit for over 33 days, at a distance from Earth exceeding 12 million kilometers, and it is in good working condition, the CNSA said.

The probe will take about a year to reach asteroid Kamo’oalewa, where it will fly in formation studying it for another year, during which time it will attempt to grab samples by two methods. One method is a copy of the touch-and-go technique used by OSIRIS-REx on Bennu. The second method, dubbed “anchor and attach,” is untried, and involves using four robot arms, each with their own drill.

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Scientists discover unexpected mineral in Ryugu asteroid sample

1:21 pm

Scientists analyzing the samples brought back from the rubble pile asteroid Ryugu by Japan’s Hayabusa-2 spacecraft have now discovered an unexpected mineral, dubbed djerfisherite, that the formation theories of the asteroid say should not be there.

“Djerfisherite is a mineral that typically forms in very reduced environments, like those found in enstatite chondrites, and has never been reported in CI chondrites or other Ryugu grains,” says first and corresponding author Masaaki Miyahara, associate professor at the Graduate School of Advanced Science and Engineering, Hiroshima University. “Its occurrence is like finding a tropical seed in Arctic ice—indicating either an unexpected local environment or long-distance transport in the early solar system.”

At present the scientists propose two hypotheses for explaining the mineral. Either it came from another asteroid as Ryugu was congealing, or it formed in Ryugu when conditions raised its temperature above 350 degrees Celsius. The researchers now favor the latter theory, even though the generally accepted histories of Ryugu’s formation never included such conditions.

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Scientists increase the odds asteroid 2024 YR4 will impact the Moon in 2032

9:10 am

Asteroid 2024 YR4 in 2032
Click for original image.

Using additional data obtained by the Webb Space Telescope, scientists have now refined the orbit of potentially dangerous asteroid 2024 YR4 and confirmed that while it will almost certainly not hit the Earth in 2032, the odds of it impacting the Moon have increased.

With the additional data, experts from NASA’s Center for Near-Earth Object Studies at the agency’s Jet Propulsion Laboratory in Southern California further refined the asteroid’s orbit. The Webb data improved our knowledge of where the asteroid will be on Dec. 22, 2032, by nearly 20%. As a result, the asteroid’s probability of impacting the Moon has slightly increased from 3.8% to 4.3%. In the small chance that the asteroid were to impact, it would not alter the Moon’s orbit.

The yellow line in the image to the right shows the present range of positions the asteroid could be in as it passes the Moon on that date. It is expected this range will be narrowed further when the asteroid flies past the Earth harmlessly in 2028.

If the asteroid should hit the Moon, the impact will provide scientists a great opportunity to learn more about asteroids and the Moon. If it should miss, it will then be essential to recalculate its orbit to see what will happen on later near approaches, whether the fly-by increased or decreased the chances of a later Earth impact.

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China launches its first asteroid sample return mission

12:28 pm

China today successfully launched Tianwen-2, its first mission attempting to return a sample from a near Earth asteroid, its Long March 3B rocket lifting off from its Xichang spaceport in southwest China.

Video of the launch can be found here. The probe will take about a year to reach asteroid Kamo’oalewa, where it will fly in formation studying it for another year, during which time it will attempt to grab samples by two methods. One method is a copy of the touch-and-go technique used by OSIRIS-REx on Bennu. The second method, dubbed “anchor and attach,” is untried, and involves using four robot arms, each with their own drill.

Some data suggests Kamo’oalewa is possibly a fragment from the Moon, but that is not confirmed.

After a year studying Kamo-oalewa, Tienwen-2 will then return past the Earth where it will release its sample capsule. The spacecraft will then travel to Comet 311P/PANSTARRS, reaching it in 2034. This comet is puzzling because it has an asteroid-like orbit but exhibits activity similar to a comet.

As for the launch, there is no word where the Long March 3B’s lower stages and four strap-on boosters, all using very toxic hypergolic fuels, crashed inside China. It should be noted that the video I link to above was taken by an ordinary citizen watching from a hill nearby, bringing with him a group of children as well. Considering the nature of the rocket’s fuel (which can dissolve your skin if it touches you), China’s attitude is remarkably sanguine to not only drop these stages on its people, but to allow tourists to get so close to launches.

The leaders in the 2025 launch race:

65 SpaceX
31 China (with one more launch scheduled later today)
6 Rocket Lab (with one launch scheduled for today SCRUBBED)
6 Russia

SpaceX now leads the rest of the world in successful launches, 65 to 50.

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Engineers pinpoint and bypass fuel line problem on Psyche

9:00 am

Psyche's flight path to the asteroid Psyche
Psyche’s flight path to the asteroid Psyche.
Click for original image.

In troubleshooting a significant drop in pressure in the xenon gas fuel lines to the ion engines of the Psyche asteroid probe, engineers have now pinpointed the problem to a failed valve and have switched to a back-up fuel line.

Powered by two large solar arrays, Psyche’s thrusters ionize and expel xenon gas to gently propel the spacecraft, which gradually picks up speed during its journey. The team paused the four electric thrusters in early April to investigate an unexpected drop in pressure. They determined that a mechanical issue in one of the valves, which open and close to manage the flow of propellant, caused the decrease. Through extensive testing and diagnostic work, the team concluded that a part inside one of the valves is no longer functioning as expected and is obstructing the flow of xenon to the thrusters.

Now that the swap to the backup fuel line is completed, engineers will command the spacecraft’s thrusters to resume firing by mid-June.

This issue had to be resolved before that scheduled firing in June or else Psyche would have fallen off its course to reach the metal asteroid Psyche by August 2029.

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Astronomers discover another object in an orbit so extreme it reaches the outskirts of the theorized Oort Cloud

12:45 pm

Orbits of known Trans-Neptunian Objects

Astronomers analyzing a dark energy survey by a ground-based telescope have discovered what might be another dwarf planet orbiting the Sun, but doing so in an orbit so extreme that it reaches the outskirts of the theorized Oort Cloud more than 151 billion miles out.

This object, dubbed, 2017 OF201, was found in 19 different observations from 2011 to 2018, allowing the scientists to determine its orbit. The map to the right is figure 2 from their paper [pdf], with the calculated orbit of 2017 OF201 indicated in red. As you can see, this new object — presently estimated to be about 450 miles in diameter — is not the first such object found in the outer solar system with such a wide eccentric orbit. However, the object also travels in a very different region than all those other similar discoveries, suggesting strongly that there are a lot more such objects in the distant outer solar system.

Its existence also contradicts a model that proposed the existence of a larger Planet X. That theory posited that this as-yet undetected Planet X was clustering the orbits of those other distant Trans-Neptunian objects shown on the map.

As shown in Figure 2, the longitude of perihelion of 2017 OF201 lies outside the clustering region near π ≈ 60◦ observed among other extreme TNOs [Trans-Nepturnian Objects]. This distinction raises the question of whether 2017 OF201 is dynamically consistent with the Planet X hypothesis, which suggests that a distant massive planet shepherds TNOs into clustered orbital configurations. Siraj et al. (2025) computed the most probable orbit for a hypothetical Planet X by requiring that it both reproduces the observed clustering in the orbits of extreme TNOs.

…These results suggest that the existence of 2017 OF201 may be difficult to reconcile with this particular instantiation of the Planet X hypothesis. While not definitive, 2017 OF201 provides an additional constraint that complements other challenges to the Planet X scenario, such as observational selection effects and the statistical robustness of the observed clustering.

Planet X might exist, but if so it is likely simple one of many such objects in the outer solar system. It is also likely to be comparable in size to these other objects, which range from Pluto-sized and smaller, making it less unique and less distinct.

In other words, our solar system has almost certainly far more planets than nine (including Pluto).

Hat tip to BtB’s stringer Jay.

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More missions to Apophis when it flies past Earth in 2029?

11:45 am

Apophis' path past the Earth in 2029
A cartoon (not to scale) showing Apophis’s
path in 2029

There were two stories today that heralded the addition of one real and two potential new spacecraft to rendezvous with the potentially dangerous asteroid Apophis when it flies past the Earth on April 13, 2029.

First, the European Space Agency (ESA) awarded a 1.5 million euro contract to the Spanish company Emxys to build a small cubesat that will fly on ESA’s Ramses mission to Apophis. This is the second cubesat now to fly attached to Ramses, with the first designed to use radar to study Apophis’ interior.

The second CubeSat, led by Emxys, will be deployed from the main spacecraft just a few kilometres from Apophis. It will study the asteroid’s shape and geological properties and will carry out an autonomous approach manoeuvre before attempting to land on the surface. If the landing is successful, it will also measure the asteroid’s seismic activity.

Second, American planetary scientists have been lobbying NASA to repurpose the two small Janus spacecraft for a mission to Apophis. These probes were originally built to go to an asteroid as a secondary payload when the Pysche asteroid mission was launched, but when Pysche was delayed they could no longer go that that asteroid on the new launch date. Since then both Janus spacecraft have been in storage, with no place to go.

The scientists say they could easily be repurposed to go to Apophis, but NASA will have to commit to spending the cost for launch, approximately $100 million. NASA officials were not hostile to this idea, but they were also non-committal. I suspect no decision can be made until the new administrator, Jared Isaacman, is confirmed by the Senate and takes office.

Time however is a factor. The longer it takes to make a decision the fewer options there will be to get it to Apophis on time.

At the moment there is only one spacecraft in space and on its way to Apophis, and that is the repurposed Osiris-Rex mission, now called Osiris-Apex. Japan might also send a craft past Apophis as part of its mission to another asteroid.

Learning as much as we can about Apophis is critical, as there is a chance it will impact the Earth sometime in the next two hundred years.

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Psyche asteroid probe experiences an unexplained engine problem

12:36 pm

Psyche's flight path to the asteroid Psyche
Psyche’s flight path to the asteroid Psyche.
Click for original image.

The probe Psyche, presently on its way to the asteroid of the same name, has experienced a thruster issue with its electric ion-type main engine that has forced engineers to postpone further engine use as they troubleshoot the problem.

Psyche began firing its thrusters in May 2024. On April 1, the spacecraft detected a pressure drop in the line that feeds the xenon gas to the thrusters, going from 36 pounds per square inch (psi) to about 26 psi. As designed, the orbiter powered off the thrusters in response to the decrease.

The mission team has chosen to defer thrusting while engineers work to understand the pressure decrease. The mission design supports a pause in thrusting until at least mid-June before the spacecraft would see an effect on its trajectory. The electric propulsion system has two identical fuel lines, and the team may decide to switch to the backup fuel line to resume thrusting.

This mission has been plagued with problems. First its software was completed late, forcing a year delay in its launch. Next it was discovered — too late to fix — that transistors on the spacecraft had not been properly hardened for the hostile environment of space. Engineers hope these transistors “will heal themselves” once in that environment, but there are no guarantees. [My memory is becoming fuzzy. As many of my readers pointed out, this transistor problem was with Europa Clipper, not Psyche.]

Now its electric ion engine, essential to getting it to Psyche, is not working properly.

If this problem is fixed and Pysche resumes engine firing, it is targeting an arrival at the asteroid Psyche in 2029.

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First images from Lucy’s fly-by of asteroid Donaldjohanson

8:57 am

Asteroid Donaldjohanson
Closest view of asteroid DonaldJohanson.
Click for movie.

The science team for the asteroid probe Lucy today released the pictures taken by the spacecraft as it approached the asteroid Donaldjohanson on April 20, 2025, compiled into a short movie.

The asteroid was previously observed to have large brightness variations over a 10-day period, so some of Lucy team members’ expectations were confirmed when the first images showed what appeared to be an elongated contact binary (an object formed when two smaller bodies collide). However, the team was surprised by the odd shape of the narrow neck connecting the two lobes, which looks like two nested ice cream cones.

…From a preliminary analysis of the first available images collected by the spacecraft’s L’LORRI imager, the asteroid appears to be larger than originally estimated, about 5 miles (8 km) long and 2 miles (3.5 km) wide at the widest point. In this first set of high-resolution images returned from the spacecraft, the full asteroid is not visible as the asteroid is larger than the imager’s field of view. It will take up to a week for the team to downlink the remainder of the encounter data from the spacecraft; this dataset will give a more complete picture of the asteroid’s overall shape.

Lucy is now on its way to the orbit of Jupiter, where it will get close-up views of five different Trojan asteroids in 2027, followed by a later visit to another group of Trojans in 2033.

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Japan’s Hayabusa-2 asteroid probe in safe mode

9:29 am

Japan’s Hayabusa-2 asteroid probe, which had successfully dropped off samples from the rubble-pile asteroid Ryugu in 2020 and then was sent on a long journey to visit two more asteroids, has suffered an unknown anomaly and shifted into safe mode to protect its instruments.

Communications between Earth and the spacecraft were stable, however, and teams were investigating the situation and its impact on the extended mission, a machine translation of the post read. JAXA has yet to provide a new update since posting about the anomaly.

If engineers can identify the problem and bring the spacecraft back into full operations, the hope is that it will fly past another asteroid in 2026 on its way to a third in 2031, where it will remain for a period of time doing more detailed observations.

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Lucy’s next asteroid fly-by on April 20, 2025

9:28 am

Lucy's future route through the solar system
Lucy’s route to the asteroids, with its first picture
of Donaldjohanson in lower right, taken in February.
Click for original blink animation.

The science team operating the probe Lucy are now preparing for the spacecraft’s second asteroid fly-by, set of April 20, 2025, and passing within 600 miles of the surface of asteroid Donaldjohanson.

Lucy’s closest approach to Donaldjohanson will occur at 1:51pm EDT on April 20, at a distance of 596 miles (960 km). About 30 minutes before closest approach, Lucy will orient itself to track the asteroid, during which its high-gain antenna will turn away from Earth, suspending communication. Guided by its terminal tracking system, Lucy will autonomously rotate to keep Donaldjohanson in view. As it does this, Lucy will carry out a more complicated observing sequence than was used at Dinkinesh [the first asteroid that Lucy saw up close in 2023]. All three science instruments – the high-resolution greyscale imager called L’LORRI, the color imager and infrared spectrometer called L’Ralph, and the far infrared spectrometer called L’TES – will carry out observation sequences very similar to the ones that will occur at the Trojan asteroids.

However, unlike with Dinkinesh, Lucy will stop tracking Donaldjohanson 40 seconds before the closest approach to protect its sensitive instruments from intense sunlight.

“If you were sitting on the asteroid watching the Lucy spacecraft approaching, you would have to shield your eyes staring at the Sun while waiting for Lucy to emerge from the glare. After Lucy passes the asteroid, the positions will be reversed, so we have to shield the instruments in the same way,” said encounter phase lead Michael Vincent of Southwest Research Institute (SwRI) in Boulder, Colorado. “These instruments are designed to photograph objects illuminated by sunlight 25 times dimmer than at Earth, so looking toward the Sun could damage our cameras.”

Unlike most of the Trojan asteroids Lucy will study, Donaldjohanson is a main belt asteroid. It is thought to be only 150 million years old, but its history would be expected to be very different than those Trojan asteroids.

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Astronomers: Potentially dangerous asteroid 2024 YR4 originally came from main asteroid belt

12:26 pm

Using new data from ground-based telescopes, astronomers now believe that the potentially dangerous asteroid 2024 YR4 originally came from main asteroid belt and is a stony solid body, not a rubble pile.

The study reveals YR4 is a solid, stony type that likely originated from an asteroid family in the central Main Belt between Mars and Jupiter, a region not previously known to produce Earth-crossing asteroids. “YR4 spins once every 20 minutes, rotates in a retrograde direction, has a flattened, irregular shape, and is the density of solid rock,” said Bryce Bolin, research scientist with Eureka Scientific and lead author of the study.

You can read the paper here [pdf].

At present calculations suggest it has an almost zero chance of hitting the Earth in 2032, though during that close approach the chances of it hitting the Moon range from 2% to 4%, depending on which scientist you ask.

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Europe’s Hera asteroid probe sends back data from Mars fly-by

1:00 pm

Deimos and Mars as seen by Hera
Click to see full movie.

The European Space Agency (ESA) Hera probe, on its way to study the Didymos/Dimorphos asteroid binary, has successfully sent back images and data obtained during its close-by of Mars yesterday.

The infrared image to the right, a screen capture from a short movie assembled from Hera’s first images, shows the Martian moon Deimos with Mars in the background. The mission scientists have compiled all of these first images taken by Hera to create a short movie, that I have embedded below. From the movie’s caption:

The car-sized Hera spacecraft was about 1000 km away from Deimos as these images were acquired. Deimos orbits approximately 23 500 km from the surface of Mars and is tidally locked, so that this side of the moon is rarely seen. Hera’s TIRI – supplied to the mission by the Japan Aerospace Exploration Agency, JAXA – sees in mid-infrared spectral bands to chart surface temperature. Because Deimos lacks an atmosphere, the side of the moon being illuminated by the Sun is considerably warmer than the planet beneath it.

Although it appears as if Deimos is passing in front of Mars from south to north, the image was actually taken as Hera passed very close to Deimos from north to south at high speed.

Deimos appears brighter than Mars. This means that the surface of airless Deimos is hotter than the surface of Mars. The material covering the surface of Deimos has low reflectivity and is pitch black. This allows it to absorb sunlight well and become hotter. In contrast, the surface of Mars is highly reflective, and its atmosphere transports heat from the warm daytime side to the cooler nighttime side. This is why there is a large temperature difference between Mars and Deimos.

These infrared images also tell us the excellent quality of the camera. Note how detailed the features are on the Martian surface. When Hera gets to Didymos/Dimorphos in December 2026 it is going to be able to document those two asteroids in remarkable detail, including the results of the Dart impact on Dimorphos in September 2022.
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Europe’s Hera probe to fly past Mars tomorrow

10:22 am

As part of its journey to the binary asteroid Didymos/Dimorphos, the European Space Agency’s (ESA) Hera probe will slingshot past Mars tomorrow, obtaining images and data of both the red planet and its moon Deimos.

Three instruments will gather data, a navigational camera, and infrared camera, and a spectral camera, with the goal mostly to calibrate the instruments and make sure they are working as designed. The data won’t be available until the next day, when the ESA will hold a webcast unveiling the images.

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Psyche captures Jupiter and Mars on its way to asteroid Psyche

11:02 am

Jupiter and Mars as seen by Psyche
Click for original image.

As part of routine maintenance and calibration, engineers on January 30, 2025 used the cameras on the Psyche asteroid probe to photograph Jupiter, Mars, and several stars, proving all is well with the spacecraft.

Scientists on the imaging team, led by Arizona State University, also took images of the bright stars Vega and Canopus, which have served as standard calibration sources for astronomers for decades. The team is also using the data to assess the effects of minor wiggles or “jitter” in the spacecraft’s pointing system as it points the cameras to different places in the sky. The observations of Jupiter and Mars also help the team determine how the cameras respond to solar system objects that shine by reflected sunlight, just like the Psyche asteroid.

The starfield pictures shown here are long-exposure (five-second) images captured by each camera. By over-exposing Jupiter to bring out some of the background stars in the Taurus constellation, the imagers were able to capture Jupiter’s fainter Galilean moons as well.

The picture to the right, cropped and reduced to post here, might not be much to look at, but it clearly demonstrates the cameras work and the spacecraft can point accurately, and will work as planned when it arrives at the metal asteroid Psyche in August 2029.

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Astroforge’s Odin spacecraft tumbling and probably be lost

9:09 am

According to a video update by the company’s founder, Matt Gialich, Astroforge’s Odin spacecraft is slowly tumbling, and is likely going to be lost.

Gialich noted that they still have one more possibility to save the spacecraft, but “hope is fading.”

The goal had been to make the first fly-by of an asteroid by a private company, getting data on the M-type asteroid 2022 OB5, thought to be made up largely of nickel-iron which would make it extremely valuable.

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