Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was taken on February 23, 2026 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team calls “layers exposed around [a] streamlined feature”.

The elevation difference between the mesa top on the left and the canyon floor on the right is about 1,000 feet. The layers are the terraces stepping downward along that drop.

What makes these layers interesting is how they have been exposed. The material that makes up the layers appears very sandy and delicate, so it breaks away it very small pieces, just like sand on a beach. The result is this feathery look. If you look close you can see that some small craters have been partly obliterated by that erosion, with their existence only marked by their remaining rim, on the high side.

The white dot on the overview map to the right marks the location, about 89 miles to the northeast from where Mars Pathfinder landed in 1997, depositing the small Sojourner rover. This is the outlet point for the canyon dubbed Ares Vallis. It is also part of the major drainage outlet coming from Mars’ biggest canyon, Valles Marineris. The streamlined features noted by the science team are those tear-dropped shaped mesas shown in the inset, suggesting a strong flow of liquid moving from the south to the north.

The most popular present hypothesis to explain these features is that one or several catastrophic floods poured out from Valles Marineris several billion years ago, flooding and reshaping these mesas and producing for a short time that inland sea and northern ocean. The layers are evidence that there were multiple floods, each depositing a layer of silt and sand. Wind erosion in the eons that followed has now exposed those multiple layers.

At least, that’s one theory. We are working with largely superficial data from orbit, so no theory can be taken very seriously at this point.

For today’s cool image we return to Mars. The picture to the right, cropped and brightened to post here, was taken on December 3, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The focus of the picture was a strange crater in the floor of Mawrth Vallis, a channel that drains northward from Mars’ cratered southern highlands to its northern lowland plains. You can see the crater in the full image if you click on the picture. It is intriguing because its rim is strangely abrupt and flat on all sides, something that is not seen with impact craters, which have a raised rim of material plowed out by the impact.

In the picture to the right I have however focused on the two small 50-70-foot-high mesas and cracked ground that surrounds them. What struck me was the dry appearance of this landscape. Located at 23 degrees north latitude, it is in the dry tropics of Mars, where little near surface ice is found. The cracks emphasize this conclusion, as they so well resemble the cracks you see in dried mud on Earth.

The white dot on the overview map to the right marks the location, inside the Mawrth Vallis, a 400-mile channel that was once considered a candidate landing zone for Europe’s Franklin rover, now targeting a location several hundred miles to the southwest.

The location of Mawrth strongly suggests that it was once a drainage route down from the cratered highlands into that theorized northern ocean. Whether the material draining was glacial ice or liquid water remains unknown, but in either case that’s what is implied by the surface geology, and has resulted in a great deal of research studying this canyon.

Now however that water is long gone, and as a result the surface has instead this dry and cracked appearance. The dark patch on the image’s left edge is a low point, and is likely filled with dust trapped there over eons.

The black line cutting across the image is an artifact of MRO’s camera, which is aging and loses some data in certain wavelengths along its vertical scans.

Today we conclude our tour of the Voyager-2 fly-bys of Uranus in 1986 and Neptune in 1989 with what is the most detailed look at the alien surface of Neptune’s moon Triton, taken on August 25, 1989 and shown to the right, cropped, rotated, reduced, and sharpened to post here.

Taken from a distance of only 25,000 miles, the frame is about 140 miles across and shows details as small as [a half mile in width]. Most of the area is covered by a peculiar landscape of roughly circular depressions separated by rugged ridges. This type of terrain, which covers large tracts of Triton’s northern hemisphere, is unlike anything seen elsewhere in the solar system. The depressions are probably not impact craters: They are too similar in size and too regularly spaced. Their origin is still unknown, but may involve local melting and collapse of the icy surface.

A conspicuous set of grooves and ridges cuts across the landscape, indicating fracturing and deformation of Triton’s surface. The rarity of impact craters suggests a young surface by solar system standards, probably less than a few billion years old.

What this photograph as well as the handful of other Voyager-2 images of Triton tell us is that we only have gotten a tiny taste of what’s there, only enough to tell us we don’t understand what we are seeing in the slightest. This is a truly alien world, cold, dark, and composed of materials far different then that found in the inner solar system. Its formation is a mystery, and its subsequent geological history a cypher. Scientists have made some guesses, but to get a real understanding we need to go back, and be there for a long time.

In fact, this is the final conclusion of all of the Voyager-2 images from both Uranus and Neptune. That probe gave humanity its first good close look at these distant worlds, but the look was still a quick and very superficial one. The images and data left us with far more questions than answers.

Unfortunately, there is at present no mission approved and under development to go to either Uranus or Neptune, though several have been proposed. Thus, it will likely be at least two decades before any mission gets there, if that soon.

Cool image time! The picture to the right, cropped, reduced slightly, and sharpened to post here, was taken by Voyager-2 on August 26, 1989 shortly after it had completed its close fly-by of Neptune, looking back at the planet from a distance of about 175,000 miles.

The two main rings are clearly visible and appear complete over the region imaged. … Also visible in this image is the inner faint ring at about 25,000 miles from the center of Neptune, and the faint band which extends smoothly from the 33,000 miles ring to roughly halfway between the two bright rings. Both of these newly discovered rings are broad and much fainter than the two narrow rings.

These long exposure images were taken while the rings were back-lighted by the sun at a phase angle of 135 degrees. This viewing geometry enhances the visibility of dust and allows fainter, dusty parts of the ring to be seen. The bright glare in the center is due to over-exposure of the crescent of Neptune. The two gaps in the upper part of the outer ring in the image on the left are due to blemish removal in the computer processing. Numerous bright stars are evident in the background. Both bright rings have material throughout their entire orbit, and are therefore continuous.

While Voyager-2 took other pictures of these rings (here, here, here, here, and here), I think this picture shows the rings best, if not terrible well. Images using the Hubble and Webb space telescopes as well as others have not been better.

The rings were first confirmed to exist in the mid-1980s, shortly before Voyager-2’s fly-by. We now think there are five rings total, all made of dark material, likely a mix of carbon-based molecules, much of it the equivalent of dust and soot.

The new Rubin Observatory, a ground-based telescope in Chile, has discovered over 11,000 new asteroids in its first preliminary observations, with most in the main asteroid belt but a large number in the Kuiper Belt beyond Neptune and 33 previously unknown near-Earth asteroids.

The graphic to the right, annotated by me to post here, shows all of Rubin’s asteroid detections in light blue.

The submission to MPC [Minor Planet Center] comprises approximately one million observations, taken over the span of a month and a half, of over 11,000 new asteroids and more than 80,000 already known asteroids, including some that had previously been observed but were later “lost” because their orbits were too uncertain to predict their future locations. You can interact with all of Rubin’s asteroid discoveries in the Rubin Orbitviewer, which uses real data to provide an intuitive way to explore the structure of our cosmic backyard in three dimensions and in real time. Also, visit the Rubin Asteroid Discoveries Dashboard to learn about the new objects Rubin has uncovered.

…Among the newly identified objects are 33 previously unknown near-Earth objects (NEOs), which are small asteroids and comets whose closest approach to the Sun is less than 1.3 times the distance between Earth and the Sun. None of the newly discovered NEOs pose a threat to Earth, and the largest is about 500 meters wide.

Astronomers predict that Rubin will eventually find 90,000 new near-Earth objects, with some expected to pose a risk of hitting the Earth. It does this by repeatedly surveying the southern sky with its large mirror, then identifying new objects with its sophisticated software.

Cool image time! When Voyager-2 flew past Uranus in 1986, the data showed the gas giant’s weather to be relatively sedate and quiet, with little changing during the fly-by. Scientists expected this: Uranus’s distance from the Sun meant it got little energy to fuel an active climate, with any activity produced by internal heating due to the gravitational pressure of its mass. And Uranus did not produce that much heat internally.

When Voyager-2 passed Neptune three year later, the scientists expected something similar, or even less, due to Neptune’s greater distance from the Sun. Instead, Voyager-2’s data showed Neptune’s weather patterns to be changing constantly and quickly, as illustrated by the three images of the Great Dark Spot to the right, the biggest storm on Neptune at that time and located in the planet’s southern mid-latitudes.

The bright cirrus-like clouds of Neptune change rapidly, often forming and dissipating over periods of several to tens of hours. In this sequence spanning two rotations of Neptune (about 36 hours) Voyager 2 observed cloud evolution in the region around the Great Dark Spot at an effective resolution of about 60 miles per pixel. The surprisingly rapid changes which occur over the 18 hours separating each panel shows that in this region Neptune’s weather is perhaps as dynamic and variable as that of the Earth. However, the scale is immense by our standards — the Earth and the [Great Dark Spot] are of similar size.

In Neptune’s frigid atmosphere, where temperatures are as low as 55 degrees Kelvin (-360 F), the cirrus clouds are composed of frozen methane rather than Earth’s crystals of water ice.

Subsequent observations by the Hubble Space Telescope in 1994 found this Great Dark Spot was gone, replaced by a comparable storm in the northern hemisphere. Further Hubble observations found Neptune’s storms tend to last about two years, fading as they drifted towards the equator. Those observations however also detected storms drifting away from the equator. Other research suggested the storms might be influenced by the Sun’s sunspot cycle.

All of the data post-Voyager-2 remains very coarse and uncertain, as we are looking at Neptune at a great distance. Thus, no theory about what is happening carries much weight, especially because we do not know why Neptune produces so much more internal heat than Uranus, fueling this fast-changing weather. For example, Neptune gets 1/20th of the energy received by Jupiter, yet its atmosphere appears even more active and variable.

Time to continue our cool image tour this week of the Voyager-2 archive of Neptune, taken during the spacecraft’s August 25, 1989 close fly-by of the gas giant, zipping only 2,700 miles above the cloud-tops. This remains the only mission to visit Neptune so far.

The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken two hours before Voyager-2’s closest approach. From the caption:

These clouds were observed at a latitude of 29 degrees north near Neptune’s east terminator. The linear cloud forms are stretched approximately along lines of constant latitude and the sun is toward the lower [right]. The bright sides of the clouds which face the sun are brighter than the surrounding cloud deck because they are more directly exposed to the sun. Shadows can be seen on the side opposite the sun.

These shadows are less distinct at short wavelengths (violet filter) and more distinct at long wavelengths (orange filter). This can be understood if the underlying cloud deck on which the shadow is cast is at a relatively great depth, in which case scattering by molecules in the overlying atmosphere will diffuse light into the shadow. Because molecules scatter blue light much more efficiently than red light, the shadows will be darkest at the longest (reddest) wavelengths, and will appear blue under white light illumination.

The resolution of this image is 6.8 miles per pixel and the range is only 98,000 miles. The width of the cloud streaks range from 30 to 125 miles, and their shadow widths range from 18 to 30 miles. Cloud heights appear to be of the order of 31 miles.

Of all the high resolution images taken of Neptune by Voyager-2, this is the only one that clearly shows some dimensionality. Later photographs taken by Hubble and other ground- and space-based telescopes can only show global views that are far less sharp than the global views produced by Voyager-2.

This picture hints at Neptune’s very complex weather patterns, which has no well-defined surface and is made up mostly of gas and liquid. Though scientists have used Hubble to roughly track those weather patterns, they can only glean the most basic facts. For example, its fast-changing weather appears to be driven by high winds, thought to move as fast as 1,300 miles per hour. This fact however is woefully incomplete and very uncertain, as we have no way to track detailed weather patterns at multiple depths.

Our tour will continue tomorrow.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope as part of two different surveys aimed at studying galaxies with what scientists call active galactic nuclei.

IC 486 lies right on the edge of the constellation Gemini (the Twins), around 380 million light-years from Earth. Classified as a barred spiral galaxy, it features a bright central bar-shaped structure from which its spiral arms unfurl, wrapping around the core in a smooth, almost ring-like pattern.

…At the galaxy’s center a noticeable white glow outshines the starlight around it. This is light given off by IC 486’s active galactic nucleus (AGN), powered by a supermassive black hole more than 100 million times the mass of the Sun. Every sufficiently large galaxy hosts a supermassive black hole at its center, but some of these black holes are particularly ravenous, marshaling vast amounts of gas and dust into swirling accretion discs from which they feed. The intense heat generated by the orbiting disc of material generates intense radiation up to and including X-rays, which can outshine the entire rest of the galaxy. In these cases, the galaxy is known as an active galaxy, with an AGN at its center.

For comparison, the relatively inactive supermassive black hole at the center of the Milky Way has a mass of about four million Suns, considerably smaller than IC 486’s. Why one is active and the other not however is not yet truly understood, though their different masses might provide part of the explanation.

Cool image time! In two earlier posts I highlighted the pictures taken by Voyager-2 of Neptune’s two largest moons, Triton and Proteus, when it made its close fly-by of Neptune in 1989. Other than a very distant low resolution picture of 105-mile-wide Nereid, Voyager-2 took no other good images of Neptune’s other known moons.

So today, let’s begin a tour of some of Voyager-2’s imagery of Neptune itself. The picture to the right, reduced slightly to post here, was taken on August 20, 1989 as the spacecraft was beginning its approach to Neptune. It shows the full daylight hemisphere of the gas giant. From the caption:

The images were taken at a range of 4.4 million miles from the planet, 4 days and 20 hours before closest approach. The picture shows the Great Dark Spot and its companion bright smudge; on the west limb the fast moving bright feature called Scooter and the little dark spot are visible. These clouds were seen to persist for as long as Voyager’s cameras could resolve them. North of these, a bright cloud band similar to the south polar streak may be seen.

Next week I will post some of the other good shots taken of Neptune, as well as one or two close-ups of Triton that need highlighting. Sadly, at that point we will have more or less reviewed most of the best data now available of this distant world. Astronomers have used the Hubble Space Telescope in subsequent years to attempt to track its weather patterns, but even Hubble really can’t provide enough resolution to really make that research substantive.

But stay tuned. The Voyager-2 images to come are worth viewing.

The Japanese lunar lander startup Ispace has been forced to institute a major shake-up of its upgraded lunar lander design because a subcontractor’s engine did not meet the required specifications.

The engine, called Voidrunner and built by Agile Space Industries, was about to be installed in the lander for a 2027 launch of NASA lunar lander mission when a review found its performance to be unsatisfactory.

After closely monitoring the engine’s status and conducting careful review, Ispace has determined that a change in the development plan to incorporate a new alternative engine is necessary to ensure the successful execution of the lunar landing mission. The new engine, which will replace VoidRunner, has already been developed by the alternative supplier and has a proven track record of operation in past lunar missions.

The company has also decided to standardize its two lunar lander designs, one developed in Japan and the second in parallel by its American division. The new lander, dubbed Ultra, will use this new engine and fly all of Ispace’s subsequent missions. The image above shows the company’s original lander Hakuto-R on the left, compared to its new Ultra lander on the right.

This change will delay its planned NASA mission by three years, to 2030, though the company hopes it will not impact the schedule of two other lunar lander missions for Japan. Its new updated schedule, all using Ultra:

• 2028: a Japanese mission funded by Japan’s Ministry of Economy, Trade and Industry
• 2029: a Japanese mission funded by Japan’s Space Strategy Fund (designed at encouraging the private space sector
• 2030: NASA’s mission, being built in partnership with the American company Draper

Ispace has also created a new lunar satellite program, to provide communications, location data, and satellite tracking from lunar orbit, with a goal of launching its first lunar orbiter by next year, and five by 2030.

As a lunar lander company Ispace has had a very mixed record. It has successfully flown two landers to lunar orbit and then down to the surface. Each however crashed, failing just prior to landing due to software issues. This new delay of its NASA mission is not going to please NASA administrator Jared Isaacman, who instead wants to speed up the agency’s lunar lander program, flying almost monthly beginning in 2030. It likely means Ispace is going to have problems winning any new NASA lander contracts, until it proves its new Ultra lander design.

Our tour continues of the only close visit to Neptune on August 25, 1989 by Voyager-2. The two pictures to the right were taken by the spacecraft during that fly-by of Neptune’s second largest moon, dubbed Proteus. Both pictures are shown as Voyager-2 took them.

The top picture was taken from a distance of about 540,000 miles, and has a resolution of about five miles per pixel.

The satellite has an average radius of about 120 miles and is uniformly dark with an albedo of about 6 percent. The irregular shape suggests that 1989N1 has been cold and rigid throughout its history and subject to significant impact cratering.

The bottom picture was taken from a distance of about 91,000 miles, and can resolve objects as small as 1.7 miles in size.

Hints of crater-like forms and groove-like lineations can be discerned. The apparent graininess of the image is caused by the short exposure necessary to avoid significant smear.

Proteus was not known prior to Voyager-2’s fly-by, because it orbits so close to Neptune (about 73,000 miles) that the ground-based telescopes of the time could not see it in the glare of the gas giant. It was discovered in early global pictures of Neptune as Voyager-2 approached.

While planetary scientists have made some educated guesses about the moon’s origin and geology based on these two images, they are simply guesses. These are the only detailed images we have of Proteus, and neither is particularly good.

Astronomers using both the Hubble Space Telescope and the Webb Space Telescope have produced new complementary views of the ringed planet Saturn.

Those photographs are shown above, with Webb’s false-color infrared image to the left and Hubble’s optical image to the right. From the press release:

In the Webb image, a long-lived jet stream known as the “ribbon wave” meanders across the northern mid-latitudes, influenced by otherwise undetectable atmospheric waves. Just below that, a small spot represents a lingering remnant from the “Great Springtime Storm” of 2010 to 2012. Several other storms dotting the southern hemisphere of Saturn are visible in Webb’s image, as well. All these features are shaped by powerful winds and waves beneath the visible cloud deck, making Saturn a natural laboratory for studying fluid dynamics under extreme conditions.

…In Webb’s infrared image, the rings are extremely bright because they are made of highly reflective water ice. In both images, we’re seeing the sunlit face of the rings, a little less so in the Hubble image, hence the shadows visible underneath on the planet.

There are also subtle ring features such as spokes and structure in the B ring (the thick central region of the rings) that appear differently between the two observatories. The F ring, the outermost ring, looks thin and crisp in the Webb image, while it only slightly glows in the Hubble image.

The press release says little about the Hubble image, mostly because it shows little new by itself. It however is part of an on-going decade-long survey using Hubble to track Saturn’s changing weather patterns.

While both images are valuable, they also highlight our present limits in observing Saturn. Views from Earth can only see so much. It is like trying to watch a football game from ten miles away, with binoculars. And sadly, no mission is presently planned to return to Saturn.

Today’s cool image begins a new tour I plan on doing over the next week or so of the few close-up photographs we have of Neptune and its moons, sent back by Voyager-2 when it did its close fly-by of this distant planet on August 25, 1989. That fly-by was almost 37 years ago, and it remains our only close look. While at the time it shined a quick flashlight of new knowledge on Neptune, its moons, and its ring system, we remain generally in the dark about what’s there, despite some good imagery produced in subsequent years by Hubble and some ground-based telescopes.

The image above, cropped and enhanced to post here, shows a portion of the southern mid-latitudes of Triton, Neptune’s largest moon, as Voyager-2 made its closest pass at a distance of about 25,000 miles. The photo to the right, cropped and reduced, shows a more global view to provide some context, with the box indicating the approximate area covered by the upper image. It was taken when Voyager-2 was on approach, at a distance of about 330,000 miles. The top picture captures several dozen black plumes that appear to vent material from below. From the caption:

The plumes originate at very dark spots generally a few miles in diameter and some are more than 100 miles long. The spots which clearly mark the source of the dark material may be vents where gas has erupted from beneath the surface and carried dark particles into Triton’s nitrogen atmosphere. Southwesterly winds then transported the erupted particles, which formed gradually thinning deposits to the northeast of most vents.

It is possible that the eruptions have been driven by seasonal heating of very shallow subsurface deposits of volatiles, and the winds transporting particles similarly may be seasonal winds. The polar terrain, upon which the dark streaks have been deposited, is a region of bright materials mottled with irregular, somewhat dark patches. The pattern of irregular patches suggests that they may correspond to lag deposits of moderately dark material that cap the bright ice over the polar terrain.

As we only have a few images of this planet, and those provided views of only about 40% of its surface, any theory that tries to explain the weird geology here is certain to be wrong to some degree.

More to come in the next few days. As much as we think we know, these pictures are going instead highlight how sparse that knowledge really is.

The lunar lander startup Intuitive Machines announced yesterday that it has won its fifth contract from NASA, a $180.4 million deal to place its larger upgraded Nova-D lander near the Moon’s south pole.

The IM-5 mission will target Mons Malapert, a ridge near the Lunar South Pole that offers continuous Earth visibility, stable illumination conditions, and access to permanently shadowed regions. These characteristics make the site a compelling location for future communications, navigation, and surface infrastructure.

The artist’s rendering to the right shows this Nova-D lander. What stands out immediately is its low-slung appearance. Intuitive Machines’ smaller Nova-C lander was tall (see this image), with a high center of gravity. In its only two landing attempts on the Moon it tipped over both times after touchdown. It appears the company has finally recognized the issue and reworked this new lander to make it more stable after touchdown.

This contract award appears to be part of the accelerated program by NASA administrator Jared Isaacman to land 30 unmanned rovers on the moon in three years, beginning in 2027. Mons Malapert is a plateau that Intuitive Machines second lander tipped over on. It is also the landing site for Astrobotics’ Griffin lander, as well as a candidate landing site for the first Artemis manned missions.

Note the small rover on the right in the graphic. While the mission will carry seven NASA science instrument payloads, it will also carry this commercial rover, built by Honeybee Robotics, a subsidiary of Blue Origin. As the company states above, the lander on this mission also has additional available payload capacity for more commercial customers.

Juno made 12 passes over isolated storms during that period, and was close enough on four of them to measure microwave static from lightning. The flashes averaged three per second during these passes; on one flyover, Juno detected 206 separate pulses of microwave radiation. Of a total of 613 pulses measured, Wong calculated that the power ranged from about that of a lightning bolt on Earth to 100 or more times the power of an Earth bolt. Because he compared Earth lightning emissions at one radio wavelength to Jupiter lightning emissions at a different wavelength, there’s some uncertainty in the comparison, Wong cautioned. Based on one study of lightning radio emissions on Earth, Jupiter’s bolts could have been a million times more powerful than those on Earth.

Lots of uncertainty and assumptions in these conclusions, but they are not only not surprising, they fit earlier data collected before Juno.

Using the Hubble Space Telescope, astronomers have obtained a new high resolution image of the Crab Nebula, and by comparing it with earlier Hubble images taken in 1999/2000 have been able to track the continuing expansion and evolution of this supernova remnant over a period now covering almost a quarter century.

The supernova itself became visible on Earth in 1054, though it actually erupted about 6,500 years earlier, as the Crab Nebula is 6,500 light years away. In the 25 years Hubble has been tracking the remnant’s expansion astronomers estimate it is expanding at about 3.4 million miles per hour.

[William Blair of Johns Hopkins University] noted that filaments around the periphery of the nebula appear to have moved more compared to those in the center, and that rather than stretching out over time, they appear to have simply moved outward. This is due to the nature of the Crab as a pulsar wind nebula powered by synchrotron radiation, which is created by the interaction between the pulsar’s magnetic field and the nebula’s material. In other well-known supernova remnants, the expansion is instead driven by shockwaves from the initial explosion, eroding surrounding shells of gas that the dying star previously cast off.

The new, higher-resolution Hubble observations are also providing additional insights into the 3D structure of the Crab Nebula, which can be difficult to determine from a 2D image, Blair said. Shadows of some of the filaments can be seen cast onto the haze of synchrotron radiation in the nebula’s interior. Counterintuitively, some of the brighter filaments in the latest Hubble images show no shadows, indicating they must be located on the far side of the nebula.

A movie showing the changes between these two images can be seen here. It is worth your while to take a look. These optical images will be further enhanced as the Webb Space Telescope gathers infrared data.

Every few months or so the Curiosity science team uses one of the rover’s cameras to do a survey of the rover’s wheels to track their condition. Since early in the mission they had found the wheels were not holding up as well as expected as they rolled over the rough terrain in Gale Crater and on Mount Sharp, and so they take great care in how they move the rover as well as review the wheels regularly.

A year ago it had appeared that the damage to one particular wheel had increased, to a point where its outer section might even break off.

Yesterday the science team did another survey, as shown in the picture to the right.

The two photos above (found here and here) focus on one particular wheel of that survey, which I suspect is the same wheel that was the focus of last year’s post. After taking the first image on the left the team moved Curiosity so that the other side of the wheel could be photographed. As you can see, the damage is extensive, so much so that it is possible the wheel could collapse entirely in the not-to-distant future.

It also looks like another wheel is beginning to see similar damage (see here and here), though not yet as extreme.

The good news is that Curiosity has six wheels, and that it can continue to travel even with the loss of one or maybe two wheels. It also appears that future terrain might not be so rocky.

The bad news is that this wheel damage is likely the one problem that will likely end the mission, possibly sooner than anyone would like. And from these photographs, that end might be sooner rather than later.

The orbital tug startup Exlabs has signed up a second payload customer to fly on its private ApophisExL mission to rendezvous with the potentially dangerous asteroid Apophis when it makes its April 13, 2029 close fly-by of the Earth.

ExLabs has announced its partnership with Japan’s Chiba Institute of Technology (ChibaTech) and its Planetary Exploration Research Center (PERC) to send university-led payloads to the surface of asteroid Apophis during its rare near-Earth flyby in 2029. ApophisExL is the world’s first commercial deep-space rideshare and is supported by mission design and operations collaboration with NASA’s Jet Propulsion Laboratory (JPL) operated by Caltech.

Under the leadership of planetary scientist and PERC Director, Dr. Tomoko Arai, ChibaTech students and researchers are developing two landing payloads to be deployed on the asteroid’s surface.

An Australian satellite startup, Fleet Space Technologies, had already signed on to fly a mapping instrument on ApophisExL.

Though the press release at the link calls this private mission “a new model,” using private enterprise rather than relying on the government for doing planetary missions, it actually harks back to the way things were done in the U.S. before World War II, when the private sector did most of this pure research. In fact, as late as the 1960s there was at least one company, American Science and Engineering, doing the first X-ray astronomical observations flying suborbital rockets. It later won contracts from NASA and other agencies to help build several later orbiting X-ray telescopes.

Over time the government space agencies became dominant, so that most of this design work was either done by them or by universities, with private companies relegated to the roles of minor subcontractors.

This new model is simply an extension of the capitalism model that is taking over the entire space industry, shifting power and ownership from big, expensive, and inefficient government programs to small, cheap, and economical private missions. Those space agencies can still do missions, but they do it by buying payload space on these private missions.

Below is a list of the missions going to Apophis in 2029:

• Osiris-Apex, already on its way to Apophis after completing its asteroid mission to Bennu.
• Ramses, a European mission scheduled to launch in 2028, which will also deploy these additional probes:
  • Farinella, built by a partnership of the Italian Space Agency and Terran Orbital
  • Destiny+, built by Japan’s space agency JAXA. It will first fly past Apophis, then head to its prime target, the asteroid Phaethon
  • A radar cubesat being built Tyvak
  • A cubesat lander being built by Emxys
• AphophisExL, a private mission being built by the startup Exlabs, which will also deploy two smaller landers built as part of a Japanese university student project.

China might also send two cubesats, but it is not clear that mission has been approved. Blue Origin has also said it is contemplating a mission, but no one should take this very seriously, considering this company proposes a lot and accomplishes relatively litte.

I close today our week-long tour of Voyager-2’s fly-by of Uranus in January 1986 with three cool images, the two images of the planet itself above and a close-up of its rings. All three illustrate that though Voyager-2 gave us our first very good first close-up view of this distant world, it also gave us only a tiny glimpse, very superficial and lacking in any larger context.

The two images above were taken on January 17, 1986 when Voyager 2 was till 5.7 million miles away, on approach.

The picture at left has been processed to show Uranus as human eyes would see it from the vantage point of the spacecraft. The picture is a composite of images taken through blue, green and orange filters. The darker shadings at the upper right of the disk correspond to the day-night boundary on the planet. Beyond this boundary lies the hidden northern hemisphere of Uranus, which currently remains in total darkness as the planet rotates. The blue-green color results from the absorption of red light by methane gas in Uranus’ deep, cold and remarkably clear atmosphere.

The picture at right uses false color and extreme contrast enhancement to bring out subtle details in the polar region of Uranus. Images obtained through ultraviolet, violet and orange filters were respectively converted to the same blue, green and red colors used to produce the picture at left. The very slight contrasts visible in true color are greatly exaggerated here. In this false-color picture, Uranus reveals a dark polar hood surrounded by a series of progressively lighter concentric bands. One possible explanation is that a brownish haze or smog, concentrated over the pole, is arranged into bands by zonal motions of the upper atmosphere. The bright orange and yellow strip at the lower edge of the planet’s limb is an artifact of the image enhancement. In fact, the limb is dark and uniform in color around the planet.

The third cool image below of Uranus’s rings was taken just after the closest approach, when Voyager-2 was in Uranus’s shadow and looking back at its rings from a distance of 142,000 miles.

Click for original image.

From the caption:

All the previously known rings are visible here; However, some of the brightest features in the image are bright dust lanes not previously seen. The combination of this unique geometry and a long, 96 second exposure allowed this spectacular observation, acquired through the clear filter of Voyager’s wide-angle camera. The long exposure produced a noticeable, non-uniform smear as well as streaks due to trailed stars.

The total number of observations of these rings, by both Voyager-2 and other ground- and space-based telescopes, is quite few. Similarly, in the forty years since Voyager-2 scientists have used the Hubble Space Telescope and more recently the Webb Space Telescope to get more data of the planet, its moons, and its rings, but generally that data is poor or very limited. We are simply too far away to see what’s happening on Uranus with any clarity or understanding.

As for the planet’s moons, this later research has so far found 29, but other than the five largest that I have highlighted in the past week (see here, here, here, here, and here), we know little else about them. They are mere dots on images.

Yet, for us to really understand the formation of our solar system, and how the Earth got to be the life-filled planet it is, we need to map in close detail our entire solar system. Right now, however, our map is comparable to that of the New World in the half century after Columbus, filled with blank spots and guesses.

We simply don’t know very much. Worse, it appears to me we often think we know more than we do.

NASA engineers today began the long and slow 12-hour trip of the SLS rocket from the Vehicle Assembly Building (VAB) to the launchpad in preparation for a targeted April 1, 2026 launch date of this Artemis-2 mission around the Moon.

NASA’s Artemis II SLS (Space Launch System) rocket and Orion spacecraft slated to send four astronauts around the Moon began rolling to Launch Pad 39B at 12:20 a.m. EDT on Friday, March 20. Rollout operations at the agency’s Kennedy Space Center in Florida were delayed earlier in the day due to high winds in the area.

The trek to the pad is expected to take up to 12 hours, as NASA’s crawler-transporter 2 carefully carries the rocket on top of the mobile launcher approximately 4 miles along the crawlerway.

The launch will send four astronauts on a ten-day mission swinging around the Moon and back to Earth, using a questionable heat shield and a life support system not yet been tested in space. On the first unmanned Artemis-1 mission around the Moon in 2022, the shield experienced far more damage than predicted, with large chunks breaking off. NASA engineers think they understand why this happened, and have decided that they can mitigate the problem by using a less stressful flight path upon return into Earth’s atmosphere.

They don’t really know if this is so, but they hope so. As for the life support system, the plan is to remain in a high Earth orbit for the mission’s first day to test it. If it has problems then, the crew will be able to return to Earth somewhat quickly. If it has problems after heading to the Moon, however, that won’t be possible.

If a private company tried to convince NASA to do this mission with these issues, the agency would say “Hell no!” It is proceeding because, like the Challenger and Columbia failures, it is a NASA-built project and politics and schedule have superseded safety and good engineering procedures

Scientists reviewing the more than 6,000 exoplanets so far discovered have now compiled a detailed catalog describing the 69 known rocky exoplanets that are also in the habitable zone.

The graph to the right, cropped and reduced to post here, shows the 45 exoplanets most likely to be habitable, with the amount of energy they get from their star measured relative to that of Earth and the Sun (shown center top). You can read their paper here. From the press release:

The researchers pinpointed 45 rocky worlds that may support life in the habitable zone, and another 24 in a narrower 3D habitable zone that makes a more conservative assumption of how much heat a planet can take before it loses its habitability.

They include some famous exoplanets, including Proxima Centauri b, TRAPPIST-1f and Kepler 186f, as well as others that are not as well known, such as TOI-715 b. The most interesting planets of those listed, according to the authors, are TRAPPIST-1 d, e, f and g, which are 40 light-years from Earth, as well as LHS 1140 b, which is 48 light-years away. Whether these planets could have liquid water depends in part if they can hold an atmosphere.

The worlds that get light from their stars most similar to what modern Earth receives from the Sun are the transiting planets TRAPPIST-1 e, TOI-715 b, Kepler-1652 b, Kepler-442 b, Kepler-1544 b and the planets Proxima Centauri b, GJ 1061 d, GJ 1002 b, and Wolf 1069 b, which make their stars wobble.

The paper includes tables listing the best exoplanets that do transits of their stars, the best with the oldest estimated ages, and the best for testing the limits of the habitable zone itself. As the researchers say in their abstract:

The resulting list of rocky exoplanet targets in the HZ will allow observers to shape and optimize search strategies with space- and ground-based telescopes – such as the James Webb Space Telescope (JWST), Extremely Large Telescope (ELT), Habitable Worlds Observatory (HWO), and Large Interferometer For Exoplanets (LIFE) – and design new observing strategies and instruments to explore these worlds, addressing the question of the limits of exoplanet surface habitability.

In other words, the focus of exoplanet research is now shifting from simply finding these planets to studying them directly, with the potentially habitable worlds listed above the most interesting of all. Astronomers might not find alien life or civilizations on these worlds, but at a minimum they will be doing the first preliminary scouting for humanity’s the first interstellar missions, with the Trappist-1 solar system appearing to head the list.

Click for original image.

Today we finish our week-long tour of the five largest moons of Uranus, all discovered by astronomers before the start of the space age, and imaged successfully if not very completely by Voyager-2 when it did its fly-by of the planet on January 24, 1986. The gallery of these moons above was taken by the spacecraft when it was on approach, still about three million miles from Uranus, and shows them in order from the innermost on the left to the outermost on the right. They are also scaled to show their relative sizes. To see Voyager-2’s close-up images of the four inner moons, posted earlier this week, go here, here, here, and here.

The picture to the right, cropped slightly to post here, is Voyager-2’s only high resolution image of Oberon, the outermost moon of this group. From NASA’s press release:

This Voyager 2 picture of Oberon is the best the spacecraft acquired of Uranus’ outermost moon. The picture was taken shortly after 3:30 a.m. PST on Jan. 24, 1986, from a distance of 410,000 miles. The color was reconstructed from images taken through the narrow-angle camera’s violet, clear and green filters.

The picture shows features as small as 7 miles on the moon’s surface. Clearly visible are several large impact craters in Oberon’s icy surface surrounded by bright rays similar to those seen on Jupiter’s moon Callisto. Quite prominent near the center of Oberon’s disk is a large crater with a bright central peak and a floor partially covered with very dark material. This may be icy, carbon-rich material erupted onto the crater floor sometime after the crater formed. Another striking topographic feature is a large mountain, about 6 km (4 mi) high, peeking out on the lower left limb.

Oberon is about 946 miles in diameter, making it the tenth-largest moon in the solar system. Because of the quickness of Voyager-2’s fly-by, it could get no closer images, and none of the planet’s nightside. Thus, only 40% of the surface has been photographed, and at not very high resolution.

Later spectroscopy from Hubble and other telescopes suggests there is water ice on the surface. Other data suggests Oberon may have a liquid underground ocean, but that conclusion is highly uncertain. Other than these vague facts and the image to the right, we essentially know almost nothing about this moon. Like Titiania, Uranus’s largest moon, Voyager-2’s data merely gave us a tantalizing glimpse, and that glimpse is now forty years old. No other mission has been there since, and none is planned in the near future.

Tomorrow, to summarize this tour, I will outline further what little we know of Uranus and its moons

In a new paper published yesterday, the science team for the low-light Shadowcam instrument on South Korea’s lunar orbiter Danuri confirmed their earlier conclusion from 2024, that there appears to be far less water ice than expected in the permanently shadowed lunar craters near the Moon’s south pole. From their abstract:

We used the high-reflectance and forward-scattering optical properties to search for water ice in lunar PSRs [permanently shaded regions]. We found no evidence of widespread water ice in PSRs at abundances above the detection limit of 20 to 30 wt % but could not rule out widespread low-content water ice. A few small locations with both high reflectance and forward-scattering behavior were observed, which could be consistent with >10 wt % ice.

And from their conclusion:

Our manual examination of ShadowCam radiance images that cover all lunar PSRs suggests either that most of the lunar PSRs lack surface ice exposures or that their ice concentration is below the detection limit, approximately 20 to 30 wt % on the basis of the visible reflectance enhancement, which aligns well with previous ShadowCam findings. Only a few candidate high-reflectance anomalies were seen, which, if they are water ice, is consistent with previous sparse detections of lunar surface water ice.

There is still a chance there is water ice in these permanently shadowed craters, but it appears once again that if it exists, it will likely require processing to extract it from the soil, and there won’t be that much available regardless.

These results are not conclusive, but they do suggest that the south pole of the Moon will not be as ideal a location for a lunar base as previously imagined.

Click for original image.

This week’s tour of the five largest moons of Uranus continues today with a look at the highest resolution picture taken Uranus’s largest moon, Titania, when Voyager-2 did its fly-by of the solar system’s seventh planet on January 24, 1986. The image to the right, cropped and reduced to post here, was taken from about 229,000 miles, and can only resolve objects bigger than eight miles across. From the press release:

Titania is the largest satellite of Uranus, with a diameter of a little more than 1,000 miles. Abundant impact craters of many sizes pockmark the ancient surface. The most prominent features are fault valleys that stretch across Titania. They are up to 1,000 miles long and as much as 45 miles wide. In valleys seen at right-center, the sunward-facing walls are very bright. While this is due partly to the lighting angle, the brightness also indicates the presence of a lighter material, possibly young frost deposits. An impact crater more than 125 miles in diameter distinguishes the very bottom of the disk; the crater is cut by a younger fault valley more than 60 miles wide. An even larger impact crater, perhaps 180 miles across, is visible at top.

Two or three other images were taken by Voyager-2, but they don’t provide any significant additional information. All told the spacecraft was only able to see about 40% of Titania’s surface.

Subsequent research using a variety of orbiting telescopes have suggested there is water ice and carbon dioxide on the surface. This data also hints of the presence of a very very thin atmosphere. These results however are quite uncertain.

As with Uranus’s other moons Miranda, Ariel, and Umbriel that I highlighted earlier this week, the Voyager-2 data merely gives us a taste of what’s there. Forty years later we have learned almost nothing more about these distant worlds.

Tomorrow we look at Oberon. I will then follow-up the next day with a look at what we don’t know about Uranus and its moons.

Scientists studying the samples brought back from the asteroid Ryugu by Japan’s probe Hayabusa-2 have found therein a full set of the five fundamental chemicals that make up either DNA or RNA: adenine, guanine, cytosine, thymine and uracil. From the paper’s [pdf] abstract:

Organic molecules delivered from extraterrestrial materials may have played a key role in supplying building blocks for life on Earth. Here we report all five canonical nucleobases—purines (adenine and guanine) and pyrimidines (cytosine, thymine and uracil)—in samples returned from the C-type asteroid (162173) Ryugu by JAXA’s Hayabusa2 mission and compare the results with data from similar extraterrestrial material.

Ryugu samples contain nearly equal amounts of purines and pyrimidines, whereas Murchison is enriched in purines and Bennu and Orgueil in pyrimidines. Samples from Ryugu, Bennu and Orgueil, which have a similar mineralogy and elemental composition, show purine-to-pyrimidine ratios negatively correlating with ammonia.

These observations indicate that the nucleobases in these samples may have formed via a shared pathway depending on the physicochemical environment of the respective parent bodies. The detection of diverse nucleobases in asteroid and meteorite materials demonstrates their widespread presence throughout the Solar System and reinforces the hypothesis that carbonaceous asteroids contributed to the prebiotic chemical inventory of early Earth.

In other words, the data from these samples suggests that the formation of life on Earth was greatly aided by the deposition of these carbon molecules from asteroids onto the Earth.

At the same time, some caution must be exercised. At present we only have samples from three asteroids, one of which (Orgueil) was obtained shortly after it crashed on Earth. It will take a much larger census of many in-space asteroids to confirm this hypothesis.

Click for source.

Today’s cool image continues our tour of the five largest moons of Uranus, as seen by Voyager-2 in 1986 during its close-up visit. The family portrait above, taken from more than three million miles away during Voyager-2’s approach, shows the relative sizes of those five moons as well as their location relative to Uranus, with Miranda in the closest orbit and Oberon the farthest. I have already posted close-ups from Miranda and Ariel. Today’s image moves us outward to Umbriel.

The image to the right is Voyager-2’s best picture. In fact, it is really Voyager-2’s only close-up image, and as you can see, it is not that close or sharp. I have not reduced it at all. This is how NASA released it. From the NASA press release:

The southern hemisphere of Umbriel displays heavy cratering in this Voyager 2 image, taken Jan. 24, 1986, from a distance of 346,000 miles. This frame, taken through the clear-filter of Voyager’s narrow-angle camera, is the most detailed image of Umbriel, with a resolution of about 6 miles.

Umbriel is the darkest of Uranus’ larger moons and the one that appears to have experienced the lowest level of geological activity. It has a diameter of about 750 miles and reflects only 16 percent of the light striking its surface; in the latter respect, Umbriel is similar to lunar highland areas. Umbriel is heavily cratered but lacks the numerous bright-ray craters seen on the other large Uranian satellites; this results in a relatively uniform surface albedo (reflectivity). The prominent crater on the terminator (upper right) is about 70 miles across and has a bright central peak.

The strangest feature in this image (at top) is a curious bright ring, the most reflective area seen on Umbriel. The ring is about 90 miles in diameter and lies near the satellite’s equator. The nature of the ring is not known, although it might be a frost deposit, perhaps associated with an impact crater. Spots against the black background are due to ‘noise’ in the data.

This lone picture of Umbriel by Voyager-2 illustrates even more starkly the very sparse data we have of Uranus and its moons. Voyager-2 is the only spacecraft to ever visit this planet, and it only did a quick fly-by, just long enough to give us this one dim snapshot view. It is forty years later, and no other missions have flown there, nor is any planned in the near future. There are proposals, but none are yet approved.

According to new computer modeling, some astronomers now believe that a collision between the Small Magellanic Cloud (SMC) and the Large Magellanic Cloud (LMC) 200 million years ago best explains the chaotic movement of the stars in the former.

The SMC contains more mass in gas than in stars. Gas cools, contracts under gravity and settles into a rotating disk, the same process that shaped the spinning plane of our solar system. But when researchers, including those at University of Arizona, previously measured the motion of the SMC’s stars using the Hubble Space Telescope and the Gaia satellite of the European Space Agency, the SMC’s stars were not orbiting around the galaxy’s center the way stars in most galaxies do.

The possible reason, Rathore said, is a collision. A few hundred million years ago, the SMC crashed directly through the LMC’s disk. The LMC’s gravity disrupted the SMC’s internal structure and sent its stars into random, disordered motion. Also, the LMC’s gas applied a tremendous amount of pressure to the SMC’s gas and destroyed its gas rotation.

The graphic to the right illustrates that collision, based on the computer modeling. It appears the Small Magellanic Cloud’s passage through the Large Magellanic Cloud acted to shake the smaller cloud apart, spreading its stars and gas across a wider space.

You can read the paper here [pdf]. There is of course a great deal of uncertainty in these results, but they add weight to the general theory that galaxy formation is strongly impacted by such collisions. As the scientists note in the conclusion of their paper, “The SMC gives a front row view of group processes driving dramatic morphological and kinematic transformations.”

Amit Kshatriya, NASA Associate Administrator was very vague in his statement, but nonetheless this was what it appears he was saying:

We have opened up the, I would say, the performance specification for the early landing missions in as many ways as we can, in terms of different lunar orbits we want to take, or different other constraints … to make it as agile as possible, to recognize performance limitations in some of the machines we have and let our providers tell us, hey, if you took these constraints out of the way, how could we go faster? So we’re going to do that.

The agency’s administrator, Jared Isaacman, is also pushing to quickly begin sending a lot of unmanned landers to the south pole by next year. Thus, under this plan, we might actually find out first whether there really is water in those permanently shadowed craters, before committing our manned lunar base to this location.

This new approach makes a great deal of sense, especially since the data that has looked into those craters has been very inconclusive, some positive and some negative.

You see, when these images were first released in 1986 they were exciting because they gave us that first look. Suddenly, a light was shined on something that had always been shrouded in darkness. It was a flood of data that needed processing.

It is now forty years later. No spacecraft has been there since, and thus we have gotten no more close-up information about Uranus or its moons. Data from Hubble and Webb has helped increase our knowledge of the planet itself, but of the moons nothing really new has been gleaned from this distance.

And so, to highlight how little we know, for the rest of this week I am going give my readers a tour of the few images Voyager-2 gave us of Uranus’ five biggest moons, the five that early astronomers had discovered prior to the space age and shown in the five pictures above, taken by Voyager-2 as it was approaching Uranus from a distance of about three million miles. They are, in order going from closest to farthest from Uranus, Miranda, Ariel, Umbriel, Titania and Oberon, with the images above designed to show their approximate relative sizes.

I already highlighted the strange, patchwork surface of Miranda last week, the smallest of these moons. Below is a mosaic made from the four highest resolution images of 720-mile-wide Ariel, the next out from Uranus, taken from a distance of about 80,000 miles.

Click for original image.

The image to the right has been cropped, reduced, and sharpened to post here. From NASA’s the May 5, 1999 press release:

Much of Ariel’s surface is densely pitted with craters 5 to 10 km (3 to 6 mi) across. These craters are close to the threshold of detection in this picture. Numerous valleys and fault scarps crisscross the highly pitted terrain. Voyager scientists believe the valleys have formed over down-dropped fault blocks (graben); apparently, extensive faulting has occurred as a result of expansion and stretching of Ariel’s crust. The largest fault valleys, near the terminator at right, as well as a smooth region near the center of this image, have been partly filled with deposits that are younger and less heavily cratered than the pitted terrain. Narrow, somewhat sinuous scarps and valleys have been formed, in turn, in these young deposits. It is not yet clear whether these sinuous features have been formed by faulting or by the flow of fluids.

Voyager-2 took a few other pictures, but none enhance significantly what this mosaic shows. The image is tantalizing, suggesting a complex geology that we can only guess at.

Like Miranda, however, Voyager-2 was only able to image one hemisphere of this moon, because the other side was in darkness during the spacecraft’s short fly-by. Though scientists have culled a lot of information from this sparse data, the truth is we will never really understand the geology of Ariel until we can get a global map of the entire planet.

Tomorrow, we move outward to Umbriel.

Their results reveal that the mantle of L98-59d is likely molten silicate (similar to lava on Earth), with a global magma ocean extending thousands of kilometres beneath. This vast molten reservoir allows the planet to store extremely large amounts of sulphur deep inside its interior, over geologic timescales. The magma ocean also helps L98-59d to retain a thick hydrogen-rich atmosphere containing sulphur-bearing gases such as hydrogen sulphide (H2S). Normally, this would be lost to space over time, due to X-ray radiation produced by the host star.

You can read the peer-reviewed paper here [pdf]. This planet is part of a three-planet solar system, all of which transit the face of the star, allowing for excellent observations of their make-up. L98-59d is the outermost of the three.

This is the first molten exoplanet yet detected, though it is likely not the last. As new better telescopes come on-line both on Earth and especially in space, the ability to make more detailed observations of the thousands of exoplanets so far identified is certain to reveal many more strange objects, some of which will be probably far stranger than we can yet imagine.