Swarm satellite constellation detects changes in the Earth’s magnetic field during the past decade

Changes in the magnetic field over the northern hemisphere
Click for original graphic.

The European Space Agency’s three-satellite Swarm constellation, designed to measure the strength of the Earth’s magnetic field at high resolution, has found that the field’s weak and strong regions have shifted and changed in the past eleven years, since the constellation was launched.

The map to the right shows the changes over the northern hemisphere, related to the movement of the north magnetic pole towards Siberia.

[S]ince Swarm has been in orbit the magnetic field over Siberia has strengthened while it has weakened over Canada. The Canadian strong field region has shrunk by 0.65% of Earth’s surface area, which is almost the size of India, while the Siberian region has grown by 0.42% of Earth’s surface area, which is comparable to the size of Greenland.

Similarly, the Swarm data has shown the South Atlantic Anomaly, a major weak area of the field above South America near the equator, has grown significantly eastward towards Africa. That change is important for satellite operations, as spacecraft passing through it experience higher levels of radiation.

All these changes are thought to be because of shifts within the Earth’s molten core from which the dynamo of the magnetic field is generated.

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Another round of layoffs at JPL

The management at the Jet Propulsion Lab (JPL) in California today announced it will be laying off 550 people this week, about 11% of its work force.

As part of this effort, JPL is undergoing a realignment of its workforce, including a reduction in staff. This reduction — part of a reorganization that began in July and not related to the current government shutdown — will affect approximately 550 of our colleagues across technical, business, and support areas. Employees will be notified of their status on Tuesday, Oct. 14.

As the statement makes clear, this reduction is unrelated to the government shutdown, and is also mostly unrelated directly to the 24% budget cut the Trump administration wishes to impose on NASA. JPL has had major management issues in the last few years, including two previous rounds of layoffs of similar amounts. Much of these budget issues stem from the cancellation by NASA of the Mars sample return mission, which JPL was to play a major part. That money is gone, and even if the mission is resurrected, JPL is almost certainly not going to play a major part.

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Faced with loss of the federal gravy train, Lowell Observatory makes major changes

According to a press release last week, the Lowell Observatory in Arizona is now making major changes to it management and operations due to “declines in federal research funding.”

The new framework centers on two defining pursuits: Planetary Defense, safeguarding our world from cosmic hazards, and Exoplanetary Research, seeking to understand distant worlds and the potential for life beyond Earth.

Declines in federal research funding, coupled with uncertainty about future national priorities, have impacted research institutions across the country. At the same time, Lowell’s historic reliance on internal funding to sustain research is no longer a viable long-term model. To ensure stability and growth, the Observatory will focus its efforts on key scientific areas while building new endowments to support the scientists and technology that drive discovery.

Essentially, it can no longer depend on easy federal cash (thank you Donald Trump!), and thus needs to actually do real research work in fields that others consider important. It will also abandon its “traditional academic tenure system.” Scientists who use the facility will now have to earn that right, in a case-by-case basis. And such researchers will have to be funded by “private, endowed support.”

In other words, Lowell is returning to the model that had been used by American researchers for most of the nation’s history, until World War II, getting their funding from private sources rather than the federal teat.

We should expect therefore the work at Lowell to become more effective and focused, something it has not been for decades.

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New research confirms the steady decline of Martian ice with each glacial cycle

The obliquity cycles of Mars

Using orbital data from Mars Reconnaissance Orbiter (MRO) of glaciers inside mid-latitude craters, scientists have concluded that there was a steady decline in the growth of those glaciers with each new glacial cycle.

They focused on craters with indicative signs of glaciation, such as ridges, moraines (piles of debris left behind by glaciers), and brain terrain (a pitted, maze-like surface formed by ice-rich landforms). By comparing the shapes and orientations of these features with climate models, they found that ice consistently clustered in the colder, shadowed southwestern walls of craters. This trend was consistent across various glacial periods, ranging from approximately 640 million to 98 million years ago.

The results show that Mars didn’t just freeze once—it went through a series of ice ages driven by shifts in its axial tilt, also known as obliquity. Unlike Earth, Mars’ tilt can swing dramatically over millions of years, redistributing sunlight and triggering cycles of ice build-up and melting. These changes shaped where water ice could survive on the planet’s surface. Over time, however, each cycle stored less ice, pointing to a gradual planetary drying. [emphasis mine]

You can read the paper here [pdf]. This result is not new. Based on the orbital data scientists have theorized now for almost a decade that as Mars’ rotational tilt (its obliquity) swings from 11 to 60 degrees, it produces extreme climate cycles on the planet. Those swings are shown on the graph to the right, taken from this 1993 paper [pdf]. When the obliquity is low, the mid-latitudes are warm and the glaciers there shrink, with the snow falling at the poles. When obliquity is high, the poles are warmer and its ice sublimates away to fall as snow in the mid-latitudes, thus causing those glaciers to grow instead.

The orbital data has consistently shown that with each new cycle, the glaciers grew less, suggesting that less global water was available on the planet. This new study further confirms these conclusions.

One last point: Though the amount of water ice on Mars has declined, we mustn’t think the red planet now has none. The orbital data shows that there is a lot of near surface ice on Mars, covering the planet from 30 degrees latitude poleward. As I’ve noted numerous times, Mars is a desert like Antarctica.

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Astronomers take first radio image of the supermassive binary system OJ287

First image of OJ287

Using archive data from the now retired Russian orbiting radio telescope RadioAstron, scientists have now obtained the first image of the binary supermassive black hole system OJ287 that was previously detected flaring as predicted when the smaller black hole (150 million solar masses) circled near the larger (18 billion solar masses).

That image is to the right, cropped and annotated to post here. The cartoon in the lower right shows the theorized orientation of the system, taken from figure 2 of the published paper [pdf]. According to the paper the elongation of the three objects is an artifact of the data and is “not real.” From the press release:

In this latest study, the astronomers compared the earlier theoretical calculations with a radio image. The two black holes were there in the image, just where they were expected to be. This gave the researchers an answer to a question that has been open for 40 years: whether black-hole pairs exist in the first place. “For the first time, we managed to get an image of two black holes circling each other. In the image, the black holes are identified by the intense particle jets they emit. The black holes themselves are perfectly black, but they can be detected by these particle jets or by the glowing gas surrounding the hole,” Valtonen says.

The researchers also identified a completely new kind of a jet emanating from a black hole. The jet coming out of the smaller black hole is twisted like a jet of a rotating garden hose. This is because the smaller black hole moves fast around the primary black hole of OJ287, and its jet is diverted depending on its current motion. The researches liken it to “a wagging tail” which should be seen twisting in different directions in the coming years when the smaller black hole changes its speed and direction of motion.

This image is cropped from the full dataset. The jet continues upward and then curves to the right as it “wags” away.

This incredible black hole binary system, estimated to be about 3.5 billion light years away, has been posited since 1982, when one astronomer noticed that it repeatedly flared every twelve years. Since then scientists have successfully predicted several flares, based on the system’s theorized orbit. These images further confirm the system’s shape.

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Saturn as seen by Cassini in 2004, four months before orbital insertion

Saturn as first seen up close by Cassini
Click for original.

Cool image time! As most of the new cool images coming down from space seem mostly limited to Mars and deep space astronomy, I decided today to dig into the archive of the probe Cassini, which orbited Saturn from July 1, 2004 until September 15, 2017, when it was sent plunging into the gas giant’s atmosphere.

The picture to the right heralded the start of that mission, in that it was taken on February 19, 2004, a little over four months before the spacecraft fired its engines and entered orbit. I have rotated the image and cropped it to post here.

When Cassini snapped this picture it was just approaching the gas giant. The image itself is relatively small, with the resolution also relatively poor. You can see one of Saturn’s moons above the planet, but I can’t tell you which one. As noted at the webpage, this is a raw image that has not been “validated or calibrated.”

While not up to the amazing standard exhibited by Cassini’s images during its thirteen year stay at Saturn, it gave us a flavor of the wonders to come. Of all the planets, Saturn might be the most beautiful.

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Congressional budget action appears to just save two of seventeen on-going NASA missions

Though no final budget has yet been approved, based on the language in the budget the House has approved and sent to the Senate, only two of the seventeen on-going missions presently in space are specifically allocated money, thus allowing the Trump administration to zero out funding for the remaining fifteen.

The two missions saved are Osiris-Apex, on its way to the potentially dangerous asteroid Apophis, and the Magnetospheric Multiscale Mission (MMS), four satellites in orbit that observe the Earth’s magnetosphere.

The article at the link is typical of our propaganda press. It clearly opposes any cuts to NASA, and lobbies repeatedly for all funding to be reinstated. This pattern has gotten quite boring and tedious. It would be so refreshing to see a more objective take, at least one in a while.

However, its reporting confirms my own reporting from mid-September, where I noted that the vague language in the House budget bill would allow Trump to cut these missions. Congress wants to preen itself as supporting all funding for NASA, while carefully allowing Trump to go ahead with large cuts.

It is a good thing these two missions have been saved, though it does appear their funding has been trimmed. Of the fifteen missions in limbo, the only two that seem worth keeping is the Chandra X-Ray Observatory and New Horizons, though the second should likely be set up similar to the two Voyager spacecraft, with a very small crew aimed mainly at keeping the spacecraft functioning and able to send back data periodically.

We are in great debt. It is time that the federal government make some real choices. We can no longer afford to buy all the candy in the store.

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

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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Martian winds are faster than expected

According to an analysis of pairs of 300 hundred orbital images taken seconds apart, scientist have found that Martian winds can reach speeds of 100 miles per hour (160 kilometers per hours), much faster than previously expected.

The results show that the dust devils and the winds surrounding them on Mars can reach speeds of up to 44 m/s, i.e. around 160 km/h, across the entire planet, which is much faster than previously assumed (previous measurements on the surface had shown that winds mostly remain below 50 km/h and – in rare cases – can reach a maximum of 100 km/h). The high wind speed in turn influences the dust cycle on the Red Planet: “These strong, straight-line winds are very likely to bring a considerable amount of dust into the Martian atmosphere – much more than previously assumed,” says Bickel. He continues: “Our data show where and when the winds on Mars seem to be strong enough to lift dust from the surface. This is the first time that such findings are available on a global scale for a period of around two decades.”

You can read the paper here. The study also found dust devils favor the spring and summer in both the north and south hemispheres, and tended to be concentrated in the mid-latitudes.

What is most interesting about this data, which because it is somewhat sparse has a lot of uncertainties, is that it suggests the candidate landing zone for SpaceX’s Starship is a region with one of the most intense dust devil seasons every spring and summer. This is not really a threat to settlement, because the atmosphere is so thin even these high winds would hardly be felt, but it does indicate an environmental condition that must be considered for any future settlement there.

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Fresh slope streak on Mars

Fresh slope streak on Mars
For original images go here and here.

Cool image time! One of the geological mysteries on Mars seen no where on Earth is something scientists have dubbed “slope streaks.” Though they at first glance appear to be avalanches, they do nothing to change the topography, have no debris pile at their base, and sometimes even travel up and over rises on their way downhill. They can also appear randomly throughout the year, can be bright or dark, and fade with time.

No theory as to their cause has yet been accepted, though recent research suggests they are dry events, dust avalanches triggered by dust devils, wind, or the accumulation of dust.

To better understand this geology, scientists repeatedly monitor known slope streak locations looking for changes. The two images to the right are an example, downloaded from the high resolution camera on Mars Reconnaissance Orbiter (MRO) on July 2, 2024 and September 1, 2025. In the fourteen months that passed between the first and second images, two distinct and large slope streaks occurred next to each other, near the bottom of the picture. All the other streaks merely faded.
» Read more

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Martian boxwork on the flanks of Mount Sharp

The boxwork on Mars
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on October 5, 2025 by the left navigation camera on the Mars rover Curiosity.

The picture looks north and downhill from the lower flanks of Mount Sharp, inside Gale Crater. In the far distance on the horizon can be seen the crater’s northern rim, about 20 to 30 miles away. As it is now moving into the dusty season on Mars, the haze has increased from only a month ago, making it hard to see many distant details.

In the foreground can be seen clearly the light-colored ridges of the boxwork that the rover has been traversing for the past three months, with one rover track visible on the nearest ridge. Unlike the very rocky and boulder-strewn terrain the rover has seen in most of its travels on Mount Sharp, this boxwork seems smoother.
» Read more

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The Juno mission at Jupiter is almost certainly over

An article yesterday at Space.com speculated that the Juno mission to Jupiter is likely over, but added that we cannot yet be sure because the government shutdown has prevented NASA from making any definitive announcement.

NASA’s management had previously extended the orbiter’s mission several times, with the last extension going until the end of the 2025 fiscal year, that ended on September 30, 2025. No new budget has yet been approved, and the proposed Trump budget had included no money for extending the mission farther.

Due to the government shutdown, NASA is currently unable to say whether Juno is still operating or already powered down. At the time of publication, responses from agency officials state that “NASA is currently closed due to a lapse in government funding … Please reach back out after an appropriation or continuing resolution is approved.”

Under shutdown rules, only missions that fall under “excepted activities” — those required to protect life, property, or national security — can continue operations or communications. NASA’s continuity plans also specify that carryover funding may only be applied to “presidential priorities,” which limits what science programs can proceed during a lapse.

Juno does not fall into those protected categories, and was also zeroed-out on the President’s fiscal year 2026 budget request — making the mission, presumably, not a priority. So, until normal government operations resume, the spacecraft’s future is uncertain.

I think Juno’s future at this point is not uncertain in the least. While other active missions that the Trump proposed shutting down might get revived, Juno is unlikely to be one of them. I suspect the science team has put it in hibernation, and is already beginning to move on to other projects and work. They are being coy about this in the faint hope Congress will save Juno, but this should not be a priority. At this point I think NASA would be wiser to spend its resources elsewhere.

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A galaxy with a starburst ring within its nucleus

A galaxy with a starburst ring
Click for full image.

Cool image time! The picture to the right, cropped, reduced, sharpened, and annotated to post here, was released today by the science team of the Hubble Space Telescope as the picture of the week. This crop focuses on the central regions of this barred spiral galaxy, about 70 million light years away, with an unusual extra feature, a starburst ring encircling its nucleus. From the caption:

NGC 6951’s bar may be responsible for another remarkable feature: a white-blue ring that encloses the very heart of the galaxy. This is called a circumnuclear starburst ring — essentially, a circle of enhanced star formation around the nucleus of a galaxy. The bar funnels gas toward the centre of the galaxy, where it collects in a ring about 3800 light-years across. Two dark dust lanes that run parallel to the bar mark the points where gas from the bar enters the ring.

The dense gas of a circumnuclear starburst ring is the perfect environment to churn out an impressive number of stars. Using data from Hubble, astronomers have identified more than 80 potential star clusters within NGC 6951’s ring. Many of the stars formed less than 100 million years ago, but the ring itself is longer-lived, potentially having existed for 1–1.5 billion years.

This galaxy has also seen about a half dozen supernova, which raises the question: Does intense star formation trigger more supernovae? That is a question that can’t be answered with the data presently available.

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Update on the plans to observe interstellar Comet 3I/Atlas using interplanetary spacecraft

Link here. The key take-away is that nothing is being repurposed to attempt to fly to Comet 3I/Atlas. Instead, as expected the science teams for all the Mars orbiters will turn their instruments to the comet when it is at its closest point to Mars, about 19 million miles away.

Don’t expect any Earth-shattering revelations:

The cameras on these spacecraft were designed to photograph the surface of Mars from Mars orbit, and won’t be able to pick out much detail on such a relatively small comet 30 million km away. But the cameras may be able to capture images of its long tail and also gather data that scientists can use to find out more about what 3I/ATLAS is made of.

Some spectroscopic data will be obtained, but it likely will not be much better than what Webb and other Earth-based telescopes have gotten already.

Similarly, the science team for Europe’s Juice mission, on its way to Jupiter, will take a look, but the distances and orbital positioning will likely limit what it can detect as well.

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Climategate global-warming activist Michael Mann resigns from PennU after celebrating murder of Charlie Kirk

Michael Mann
Climate activist Michael Mann

Though he has claimed to be a climate scientist for decades, Michael Mann at the University of Pennsylvania has been proven time and again to merely be a leftwing global-warming activist, faking data to make it appear the increase of carbon dioxide in the atmosphere is causing global warming, falsely claiming he was a Nobel laureate winner, and acting to destroy the careers of anyone who challenged the veracity of his research.

Sadly, when these facts were discovered almost two decades ago, about the time the climategate emails were released, the climate science community ignored the facts (a very bad thing for scientists to do) and acted to defend Mann. Thus he was able to continue to publish while keeping his job as a professor in academia, first at Pennsylvania State University and then at the University of Pennsylvania.

Mann’s ability to survive fraud and abuse of power however has finally come to an end, and it did so because he decided to go on line after Charlie Kirk was assassinated to joke about that murder and to slander Kirk by reposting comments that called Kirk “head of Trump’s Hitler Youth.”

Though Mann subsequently denied that was what he was doing, deleting some of his worst tweets while claiming to condemn such violence, it appears no one believes him. As a result, he announced yesterday that he resigning his position at Pennsylvania University in order to become a full time political activist. From his resignation statement:
» Read more

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The growing mystery of the little red dots in the early universe

The uncertainty of science: A review of the population of what scientists call “Little Red Dots” (LRDs) — discovered in the early universe by the Webb Space Telescope — has found that 30% do not appear to be compact objects when viewed in ultraviolet wavelengths.

The team studied 99 LRDs, and found that about 30% are not simply compact dots when observed in the ultraviolet.Instead, they reveal disturbed or clumpy structures, in stark contrast to their smooth, point-like appearance at optical wavelengths. Because these galaxies are so far away, their optical light is stretched, or “redshifted,” into the long-wavelength channel of JWST, where the resolution is not sharp enough to see structure, so they look like simple dots.

Rinaldi: ‘But their ultraviolet light is shifted into JWST’s short-wavelength channel, where the telescope has much finer resolution, and there we suddenly see clumps, asymmetries, and signs of interaction. On top of this, in the spectra of some of our LRDs we directly detect the fingerprints of active black holes, with gas moving at thousands of kilometres per second.’ This shows that at least part of this population is powered by growing black holes, while others seem to be dominated by star formation, making LRDs a mixed and diverse family of sources. This is a crucial clue, suggesting that mergers and galaxy interactions may be the trigger for the “LRD phase”.

In other words, astronomers don’t really know what these dots are at present. If some are supermassive black holes, this poses a problem for Big Bang cosmology, as there should not have been enough time since the Big Bang for these black holes to have formed.

That 70% still appear to be compact single objects might mean that’s what they are, but it could also mean that our present observations tools don’t yet have the ability to resolve them.

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Analysis of archived Cassini data finds a new slate of carbon-based molecules in the plumes of Enceladus

Enceladus at 77 miles
The tiger strip vents on Enceladus, seen
from 77 miles during 2015 fly-by. Resolution is
50 feet per pixel.

A new analysis of the archived Cassini data taken when the spacecraft flew through the plumes of the Saturn moon Enceladus in 2008 has revealed a number of new organic molecules (not life but carbon-based) that suggest the chemistry of the moon of Saturn is far more complex that expected.

You can read the paper here. From the abstract:

Here we present a comprehensive chemical analysis of organic-bearing ice grains sampled directly from the plume during a Cassini fly-by of Enceladus (E5) at an encounter speed of nearly 18 km [per second]. We again detect aryl and oxygen moieties in these fresh ice grains, as previously identified in older E-ring grains. Furthermore, the unprecedented high encounter speed revealed previously unobserved molecular fragments in Cosmic Dust Analyzer spectra, allowing the identification of aliphatic, (hetero)cyclic ester/alkenes, ethers/ethyl and, tentatively, N- and O-bearing compounds. These freshly ejected species are derived from the Enceladus subsurface, hinting at a hydrothermal origin and involvement in geochemical pathways towards the synthesis and evolution of organics.

In other words, this data further suggests there exists an underground ocean inside Enceladus, and that ocean has a lot of complex organic chemistry energized by the planet’s internal heat and the tidal forces imposed by Saturn’s gravity.

This is not the first time scientists have reviewed archived Cassini data of these plumes and found new molecules. It is simply a closer look at earlier analyses in 2018 and 2019.

This data has not discovered life, but it suggests that life is certainly possible within that proposed underground ocean. At a minimum, the chemistry there will be very complex and alien.

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Astronomers snap picture of a baby exoplanet

Baby planet
Click for original image.

Cool image time! The picture to the right, cropped to post here, was taken using Magellan Telescope in Chile and the Large Binocular Telescope in Arizona. The exoplanet is the small purple dot to the right of the star and the accretion ring that surrounds it.

This exoplanet is very young, only about five million years old, and is thus still accumulating material. Even so, its mass is presently estimated to be five times that of Jupiter.

Following [the first] observations of the system, researchers looked at WISPIT 2, and spotted the planet WISPIT 2b for the first time, using the University of Arizona’s MagAO-X extreme adaptive optics system, a high-contrast exoplanet imager at the Magellan 2 (Clay) Telescope at Las Campanas Observatory in Chile. This technology adds another unique layer to this discovery. The MagAO-X instrument captures direct images, so it didn’t just detect WISPIT 2b, it essentially captured a photograph of the protoplanet.

…In addition to discovering WISPIT 2b, this team spotted a second dot in one of the other dark ring gaps even closer to the star WISPIT 2. This second dot has been identified as another candidate planet that will likely be investigated in future studies of the system.

You can read the paper here [pdf]. The other candidate exoplanet is the bright spot below the star, inside the ring.

The technology of astronomy continues to advance.

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Study suggests low dose radiation reduces severe knee pain

A new study suggests that exposing patients with advanced osteoarthritis (OA) to low doses of radiation reduced their pain significantly.

The trial included 114 people with primary knee OA, diagnosed by moderate damage visible on X-rays, and significant pain with walking. They were randomly assigned to one of three groups: very low-dose radiation (0.3 Gy total, spread over six sessions of 0.05 Gy), low-dose radiation (3 Gy total, spread over six sessions of 0.5 Gy), or a sham treatment that did not deliver radiation.

…Each treatment in this trial was 500 mGy, which works out to be 5,000 times the radiation dose of a chest X-ray and around 70 times the dose of a chest CT scan. However, while this sounds like a lot, the treatment delivered in the study is still considered to be low-dose. For radiotherapy cancer treatment, for example, total doses are usually 50 to 70 Gy – so a total of 3 Gy is roughly one-twentieth or less of that.

…Trial participants couldn’t take regular pain meds during the first four months, other than occasional “rescue” meds if needed. No second round of radiation was allowed. The main treatment outcome was how many participants showed significant improvement after four months, as measured by assessments of pain and function.

The 3 Gy group did significantly better than the sham group. About 70% improved vs 42% in the sham group. Over half (57%) of people in the 3 Gy group had a clinically meaningful improvement in joint pain and function scores vs about 31% in the sham group. The 0.3 Gy group didn’t show a statistically significant improvement; about 58% improved. No meaningful differences were seen in blood markers of inflammation or in the amount of pain medication people used. The treatment was deemed to be safe, with no side effects or toxicity reported.

If this result is confirmed, it suggests strongly that especially for the older population there is now a viable treatment for knee pain that avoids surgery and could be far more reliable.

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Modeling suggests Uranus’s moon Ariel needed underground oceans to shape its known surface

Ariel as seen by Voyager-2 in 1986
Ariel as seen by Voyager-2 in 1986.
Click for original image.

The uncertainty of science: Using computer modeling based on our scant data of the surface features of the Uranus moon Ariel, scientists now posit that underground oceans, some of gigantic depth as much as 100 miles deep, were required to shape those features.

“First, we mapped out the larger structures that we see on the surface, then we used a computer program to model the tidal stresses on the surface, which result from distortion of Ariel from soccer ball-shaped to slight football-shaped and back as it moves closer and farther from Uranus during its orbit,” Patthoff said. “By combining the model with what we see on the surface, we can make inferences about Ariel’s past eccentricity and how thick the ocean might have been.”

The team found that, in the past, Ariel needed to have an eccentricity of about 0.04 [to create those surface structures]. This is about 40 times larger than its current value. While 0.04 may not sound dramatic, eccentricity can strengthen the effects of tidal stresses, and Ariel’s orbit would have been four times more eccentric than that of Jupiter’s moon Europa, which is wracked by the tidal forces that push and pull it to create its cracked and broken surface. Yet, to the eye, the orbit will still resemble a circle.

“In order to create those fractures, you have to have either a really thin ice on a really big ocean, or a higher eccentricity and a smaller ocean,” Patthoff said. “But either way, we need an ocean to be able to create the fractures that we are seeing on Ariel’s surface.”

This result does not prove an underground ocean now exists, or even if one existed in the past. The data is based on the few fly-by images taken by Voyager-2 when it passed close to Uranus in 1986. Coverage of the entire surface of Ariel was not complete, nor did the images have much resolution. The data is suggestive of this conclusion, but not conclusive by any means.

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