The ongoing story, as far as the media are concerned, is the question of the Boeing Starliner, still docked to the International Space Station weeks after it was due to return (Fig. 1). Stories keep describing the two astronauts as ‘stranded’, while NASA says, ‘They’re not stranded, we just haven’t decided when they’re coming back’, and adds, ‘They’re making themselves useful in whatever ways they can’. Although that last has attracted derision, the fact is that the work load on a space station is so heavy that extra pairs of hands are always useful. New Scientist used to say that no useful science could be done on the Space Station because all the astronauts’ time would be taken up with maintenance; there is a lot of maintenance to be done, and when it’s unscheduled, it cuts heavily into the time allocated to everything else. In his book Endurance (Transworld, 2017 – Fig. 2), about his 12-month mission on the ISS, Scott Kelly strongly made that point about the repeated breakdowns of the air-purification system (see ‘Axiom Attic and Orbital Reef’, ON, 14th February 2024). And although the press mocked Helen Sharman’s flight to the Mir station, in 1991 (Fig. 3), the cosmonauts were delighted to have her because she was a professional lab technician and a big help to them in their heavy scientific workload.
As far as I can make out, the situation is that the Starliner has been subjected to extensive tests while attached to the ISS, and of its 28 thrusters, all are working satisfactorily except one, which has been permanently turned off. There’s no chance of any of them running out of control, as happened to Neil Armstrong and Dave Scott on Gemini 8, and such leaks as there are don’t prevent a return to Earth. It was noteworthy that when all the astronauts returned to their spacecraft in case of evacuation in a space debris scare, when an old Russian weather satellite called Resurs exploded in orbit, Butch Wilmore and Suni Williams took shelter in the Starliner rather than crowding into the Soyuz and Crew Dragon spacecraft currently docked to the ISS, and if the station had been abandoned, they’d have returned to Earth in it. Starliner’s batteries have been recharged from the ISS supply and their 45-day lifetime can be extended to at least double that if necessary. But they will have to bring it back sometime, because it’s docked to the forward port of the Harmony module and that will be needed for other missions before long.
NASA has now decided on a firm date for the de-orbiting of the ISS, commissioning a Cargo Dragon mission from SpaceX to bring the station down in the Pacific, in 2030. As I’ve previously remarked, the six years before that will be the busiest in the Space Station’s history, and the question arises, what will happen to the research modules if they’re still operational? Russia’s Nauka module is comparatively new, launched only in 2021 (though 14 years late), and Russia has already announced that it will withdraw the module in 2028, to instal it on a new station of their own launched by the Angara booster – which is flying, though with a somewhat chequered record so far. Europe’s Columbus module, primarily for biological research, is the most heavily used one on the ISS (see ‘Axiom Attic and Orbital Reef’, above), and Japan’s 2-part Kibo module, much of it devoted to materials research, also has a long record of success. Now that we have a definite end point for the ISS, I wouldn’t be surprised if their space agencies are negotiating to move them to the new generation of US space stations, with the Orbital Reef and Axiom’s station as the leaders in the current race. If Elon Musk’s Starship is operational by then it would be fully capable of moving them, and as modifications to its Texas launch site are under way to catch the Superheavy booster after the next Starship launch, in four weeks’ time, Elon Musk has announced very ambitious plans for future production, up to 100 vehicles per year.
A news story from Space.com on June 29th (Andrew Jones, ‘Perseverance Mars rover team revives life-hunting instrument after 6 months of effort’) explains why there have been no reports on the organic content (or lack of it) in the rock samples taken by the Perseverance rover in the last six months. The key instrument for that is called SHERLOC (Scanning Habitable Environments with Raman & Luminescence for Organics and Chemicals), and it has been out of action for six months because the protective lens cover on its Autofocus and Context Imager (ACI) camera was jammed by dust (Fig. 4). Major efforts to clear it by the Jet Propulsion Laboratory team have included heating the motor, reorienting the robotic arm and even using the rover’s percussive drill in an attempt to free the cover. The problem is not so different to the one facing the controllers on the NASA-JAXA XRISM x-ray telescope (see ‘The Sky Above You’, July 2024, ON, 1st July 2024), but key differences include that the instrument is on the ground, not free-floating in vacuum, and it’s not hyper-cold. By March 2024, the cover had been freed, and the rover’s robotic arm was then used to determine a new focus point for it. A first image of its calibration target, with the silhouette of Sherlock Holmes in the centre, was obtained on May 11th (Fig. 5). On June 17th it was announced that the re-calibration had been completed and the instrument was again fully operational.
We can expect more detail of the Mars rocks being studied as Perseverance continues its exploration of the ‘Bright Angel’ river tributary, and beyond. We can also expect conspiracy theorists to tell us that the rover must have found life six months ago, and it’s all a cover-up; which hardly does justice to the efforts of the engineers who have restored life to SHERLOC itself.
Continuing analysis of the samples brought back from the asteroid Bennu have turned up a major surprise. Analysis of a 1-mm fragment has revealed magnesium-sodium phosphate material which is found on Earth along mid-ocean ridges, where rocks from the Earth’s mantle meet the water (Fig. 6). A similar find had been made in samples returned by Japan’s Hayabusa-2 from the asteroid Ryugu, but not previously announced. The implication is that the samples and even Bennu itself may have originated and broken off from a miniature water-bearing world. (Deborah Byrd, ‘Asteroid Bennu Sample Suggests an Ocean World Origin, EarthSky, online, June 28th 2024.) That idea was first mooted in March, because preliminary analysis found the Bennu samples to be rich in water, clays, carbon, nitrogen, sulphur, phosphorus, calcium, magnesium and phosphates. (Paul Scott Anderson, ‘Pieces of Asteroid Bennu Now on Display for YOU!’, EarthSky, March 17th 2024.) For liquid water to form and generate phosphates, the parent body must have been at least 10 km in diameter to produce the necessary heating by radioactive decay.
Another revelation is that most of the material on Bennu’s surface appears to be varieties of clay. Traces of clay had previously been found in meteorites, although pebbles and larger lumps of clay wouldn’t survive atmosphere entry. Prof. Graham Cairns-Smith of Glasgow University suggested in his book Genetic Takeover (Cambridge University Press, 1982) that the first living creatures on Earth had been highly evolved clays, a very different form of ‘silicon-based life’ from the normal high-temperature science fiction concept; as the late John Macvey pointed out, such creatures would exhale solid quartz and that might be a touch painful (Whispers from Space, Macmillan, 1974). Cairns-Smith suggested instead that his living carpets of clays evolved to a level of complexity at which they began to use our kind of organic molecules for specialised purposes – and then we stole the planet from them. There have been signs of clays in meteorites, suggesting that such life could even have evolved in the comets, and similar materials were detected when NASA’s Deep Impact probe struck Comet Tempel 1 in July 2005 (Alan Longstaff, ‘Liquid Water in Tempel 1’, Astronomy Now, November 2005), while the amino acid glycine was found in samples returned to Earth from Comet Wild 2 by the Stardust probe in 2006 (Nancy Atkinson, ‘Amino Acid Found in Stardust Comet Sample’, Universe Today, August 17th, 2009). We keep being told that samples like Bennu’s and Ryugu’s may tell us about the origin of life, as well as of the planets; perhaps they’re getting closer than they think.
In previous columns, I’ve been following the series of close flybys of Jupiter’s volcanic moon Io (Fig. 7), made possible by the evolving orbit of the Juno spaceprobe on its extended mission, which was originally supposed to end in 2016. Close passes of Io began in March 2023 and the closest was on Juno’s 58th orbit around Jupiter, passing within 930 miles on February 3rd, 2024. A dramatic artist’s impression was released showing Loki Patera, one of the lava-filled volcanic calderas on Io, as a lake of molten sulphur (black), with floating islands of solid sulphur (white) and a red-hot ring of volcanic magma (Fig. 8). More results show that almost all calderas on Io have similar features, occupying about 3% of its surface (Fig. 9).
Two possible explanations are now put forward. One is that outward sub-surface flow is meeting a wall of sulphur several hundred metres high, and continuing to break against it, exposing the lava below. The other is that lava is welling up in the centre of the caldera, so that the crust is constantly expanding like Earth’s mid-ocean ridges, and the hot rims are caused by collision with the surrounding barriers – like a visible version of the Pacific ‘Ring of Fire’ along the rims of the crustal plates. No doubt the argument will accentuate calls for a dedicated mission to study Io’s volcanic activity (Fig. 10).
