Year: 2026

Uranus’s moon Oberon, of which we know little

11:38 am

Uranus' five biggest moonsThe historically known moons of Uranus. Click for original NASA press release.

Oberon, as seen by Voyager-2
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

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German rocket startup signs deal to launch from SaxaVord spaceport in Scotland

9:56 am

Proposed or active spaceports in North Europe
Proposed or active spaceports in North Europe

The German rocket startup HyImpulse yesterday signed a contract with the SaxaVord spaceport on the Shetland Islands in Scotland to do a suborbital test launch at SaxaVord later this year.

HyImpulse has agreed a launch deal with the Unst spaceport, with the aim of a suborbital launch in quarter three of 2026. It will be the second launch of the company’s SR75 suborbital launch vehicle following a successful lift-off in Australia in 2024, which used a hybrid propulsion system involving paraffin “candle wax” and liquid oxygen. HyImpulse said that initial launch, from Koonibba, showed the vehicle could demonstrate “stable flight validating system performance under operational conditions”.

Under the agreement, SaxaVord will provide launch infrastructure and operational support for the launch of the SR75.

HyImpulse is the second German rocket startup to sign a deal to launch from SaxaVord. Rocket Factory Augsburg plans its second attempt to do an orbital launch from there later this year. In 2024 it was gearing up to do that launch but an explosion during a full static fire test of the rocket’s first stage killed that plan.

Considering the red tape the United Kingdom has imposed on rocket companies, bankrupting two and delaying all launches for years from both SaxaVord and the other proposed spaceport in Sutherland, Scotland, I am surprised these two rocket companies have signed these deals. Maybe the UK’s Civil Aviation Authority (CAA) has been reformed and eased that red tape.

Or maybe HyImpulse will find its plans blocked by the CAA as that agency once again ponders at glacial pace the issuing of a new launch license. Stay tuned.

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OHB wins $285 million contract to build weather satellite constellation for ESA

9:36 am

ESA logo

Capitalism in space The Swedish subsidiary of the European aerospace company OHB yesterday announced it has won a $285 million contract from the European Space Agency (ESA) to build and maintain a six satellite weather satellite constellation.

The company had already successfully launched and tested a single demo satellite, proving a small satellite could do the job.

The foundation for this is the Arctic Weather Satellite (AWS), which OHB Sweden successfully placed in orbit as a demonstrator more than a year ago. The OHB SE subsidiary developed the small satellite on behalf of the European Space Agency ESA in record time, using a deliberately chosen New Space approach. Only three years passed between contract award and launch.

This new constellation is dubbed EUMETSAT Polar System – Sterna (EPS-Sterna), and will supplement and eventually replace the expensive government-built Eumetsat weather constellation presently in orbit.

OHB Sweden is the prime contractor for the delivery of the satellites for the EPS Sterna constellation. The consortium also includes Omnisys in Sweden as the supplier of the microwave instruments, which constitute the primary meteorological payload. A total of 20 satellites will be delivered under the contract. The industrial team includes approximately 30 companies. Germany is also strongly represented by SMEs that will contribute key hardware for the instrument and the satellite platform. The satellites will be procured by EUMETSAT through ESA. EUMETSAT itself will develop the ground segment, procure and provide the launch services, operate the satellites, manage the constellation and distribute the data through its data distribution mechanisms, which has a planned operational lifetime of 13 years.

This contract is another example of Europe’s fast shift in the past three years from the government model to the capitalism model. It took ESA almost a decade to finally decide to make that shift, but once it did it seems to be moving far faster than NASA did to implement it.

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Update on SpaceX’s preparations for the 12th orbital test flight of Starship/Superheavy

9:22 am

Link here. The testing has apparently verified the fueling system of Superheavy at the new launchpad.

Starship Flight 12 took another step toward launch, with Booster 19 completing an initial test campaign on the newly commissioned Pad 2 at Starbase, Texas. Culminating in a short Static Fire test, the series of tests was a first for Pad 2, the Block 3/V3 Super Heavy Booster, and for the upgraded Raptor 3 outside of single engine testing.

As the inaugural vehicle to undergo operations on this pad, B19’s campaign served as both a booster qualification test and a commissioning milestone for the expanded launch infrastructure, paving the way for a long-awaited static fire test of its Raptor 3 engines.

Lots of details worth reading. Ground testing will now shift to Starship. All in all, it does appear that an early April launch is likely.

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Rocket Lab wins $190 million hypersonic test contract from War Department

9:14 am

War Department logo

Rocket Lab yesterday announced it has won a $190 million contract from War Department to do another twenty suborbital test launches using its HASTE first stage version of its Electron rocket.

Rocket Lab Corporation … today announced the signing of its single largest launch agreement yet: a $190 million contract for a block buy of 20 hypersonic test flights with its HASTE launch vehicle for the Test Resource Management Center (TRMC) Multi-Service Advanced Capability Hypersonic Test Bed (MACH-TB) 2.0 program – a U.S. Department of War effort executed in partnership with Naval Surface Warfare Center Crane Division (NSWC Crane) to rapidly accelerate hypersonic flight tests and advanced aerospace technologies shaping the future of defense missions.

Under MACH-TB 2.0 Task Area 1, led by Kratos Defense & Security Solutions, Inc, Rocket Lab will perform 20 hypersonic test flights with its HASTE launch vehicle over a four-year period. The first of these 20 new missions is expected to take place within months of contract signing, demonstrating Rocket Lab’s operational efficiency and ability to move quickly to meet modern warfare demands.

This is the work that Stratolaunch had hoped to grab with its giant Roc airplane and Talon hypersonic test vehicle. Rocket Lab saw an opportunity and quickly reconfigured the first stage of its Electron rocket for the same work, dubbing this version HASTE. In the past three years both it and Stratolaunch have done hypersonic test flights, but Rocket Lab’s work has been more frequent and extensive, doing seven HASTE hypersonic launches to one test by Stratolaunch. That success apparently convinced the military to give Rocket Lab this larger new contract.

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Scientists: Shadowcam images suggest there is little water in permanently shadowed lunar craters

8:58 am

Shadowcam-LRO mosaic
The floor of Shackleton Crater showing no obvious ice deposits,
as seen by Shadowcam, imposed on a Lunar Reconnaissance Orbiter
image. The black cross marks the south pole. Click for original image.

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.

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March 18, 2026 Quick space links

2:42 pm

Courtesy of BtB’s stringer Jay. This post is also an open thread. I welcome my readers to post any comments or additional links relating to any space issues, even if unrelated to the links below.

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Tantalizing Titania, Uranus’s largest moon

11:45 am

Uranus' five biggest moonsThe historically known moons of Uranus. Click for original NASA press release.

Titania as seen by Voyager-2
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.

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Scientists detect the five chemicals that make up DNA/RNA inside Ryugu samples

11:05 am

Ryugu's northern hemisphere
Ryugu as seen by Hayabusa-2 shortly before it grabbed
samples from the surface. Arrow indicates planned touchdown
site.

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.

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Solar scientists: We finally think we know the location of the Sun’s dynamo

10:42 am

The Sun's interior
NASA graphic used in the press release and
annotated to post here.

The uncertainty of science: Using three decades of data gathered during the last three solar cycles, scientists now think they have finally determined the location of the Sun’s dynamo in its interior, at a transition point about 125,000 miles below the surface called the tachocline. From the abstract of their paper [pdf]:

The exact location of the solar dynamo remains uncertain–whether it operates primarily in the near-surface shear layer, throughout the entire convection zone, or near the tachocline – a region of sharp transition in the solar rotation, located at the base of the convection zone, approximately 200,000 km [125,000 miles] beneath the surface. Various studies have supported each of these possibilities.

…Our analysis reveals that the gradient of rotation displays ‘butterfly’–like behavior near the tachocline, which is similar to the magnetic butterfly diagram at the surface. This result supports the idea that the solar dynamo has a deep-seated origin, likely operating either near the tachocline or throughout the convection zone, thereby disfavoring the recent scenario of a shallow, near-surface dynamo. This finding may also have important implications for understanding how stellar dynamos operate in general. [emphasis mine]

Even though scientists have known for more than a century that the Sun’s eleven-year cycle of flipping the polarity of its magnetic field is the fundamental cause of the sunspot cycle, they actually know very little about the dynamo that causes that magnetic field, as this study implies. They not only don’t have any understanding of the fundamental processes that creates that dynamo or causes it to flip polarity every eleven years, they still aren’t entirely sure where it is located within the Sun.

Thus, the highlighted sentence above is one large understatement. Of course knowing the dynamos location will have “important implications for understanding stellar dynamics.” This study is a first good stab at the problem, but it also shows us how little we actually know.

Remember this when anyone tells you “the science is settled” about climate change. The Sun is the number one influence on the Earth’s climate, and its solar cycle appears to be an important factor in that influence. Until we have a better understanding of the Sun, its magnetic field, and the dynamo that creates it, no climate prediction will be worth anything. Such predictions will be all guesswork, and likely put forth for political reasons.

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