Category: Space Sunday

On Tuesday, March, 18th, 2025, A SpaceX Crew Dragon – mission Crew-9 – made a safe splashdown off the Florida coast prior to being successfully brought aboard the waiting recovery vehicle. This brought to an end what has been perhaps the most mis-reported human space mission thus far.

This is because the vehicle which carried NASA astronauts Barry “Butch” Wilmore and Sunita “Suni” Williams into space back in June 2024 was the much-troubled Boeing CST-100 Starliner. Whilst the vehicle reached orbit successfully, it suffered further problems with it primary propulsion system – located on the vehicle’s expendable service module. As a result, and exercising an understandable over-abundance of caution, NASA opted to leave Wilmore and Williams on the ISS until an alternate means of bringing them home could be scheduled.

However, at no time did this ever mean Williams and Wilmore were “stranded” on the ISS: just because NASA did not want to bring the astronauts back to Earth in an emergency did not ever equate to the agency being unable to do so. This was proven in July 2024 when, following the disintegration of a Russian satellite led to a short-term threat of possible debris impact with the ISS. As a result the station’s crew were ordered by NASA and Roscosmos to “shelter in place” aboard their respective space vehicles – including Wilmore and Williams aboard the CST-100 – in case an emergency departure and return to Earth was required if the debris could showed signs of intersecting the ISS in orbit.

In fact, one of the reasons Starliner remained at the ISS even after the decision had been made to return Williams and Wilmore to Earth via other means was as much about providing them with a “lifeboat” return to Earth for as long as possible, as it was about carrying out further tests on the vehicle.

As it was, Starliner did eventually undock from the ISS in September 2024 ahead of the launch of the Crew 9 mission, with the crew capsule Calypso successfully landing on Earth at the end of a fully automated flight and despite two further system hiccups.  Meanwhile, the Crew-9 mission also arrived at the ISS in September 2024 to become NASA Expedition 72, with Williams and Wilmore slotting into the two Expedition 72 crew slots vacated for them, in order to see out the mission’s 170-day rotation on the station.

The rotation came to an end on Tuesday, March 18th, 2025 when Crew 9 – Williams and Wilmore together with mission commander Nick Hague and cosmonaut Aleksandr Gorbunov undocked from the ISS at 0505 UTC, their places having been taken by the Crew 10 / Expedition 73 crew, who arrived at the ISS two days previously.

And while much has been made of Williams and Wilmore’s extended stay on the ISS, overall, the 286 days they spent on the station is not exactly record-breaking or that unusual. Among NASA’s astronauts, five others have spent longer periods of time on a single ISS crew rotation (even if their time was planned from the outset to be so), whilst four cosmonauts have spent in excess of 330 days each (437 in the case of Valeri Polyakov) on either the Soviet / Russian Mir station or the ISS. That said, Williams has now accumulated the second highest number of continuous days in space by a US astronaut – 608 days – slotting in behind Peggy Whitson who accumulated 675 days in space with NASA and a further 9 days as a private citizen astronaut on the Axiom Ax-2 mission.

What of Starliner?

Whilst Wilmore and Williams may not have been stranded in space, the Starliner programme does have issues, notably with the design of the four propulsion pods – dubbed “doghouses” because of their appearance – mounted on the Starliner’s service module, and which have yet to be fully resolved.

The pods, each of which mounts five “large” orbital manoeuvring and control (OMAC) thrusters as a “primary” means of propulsion and seven smaller reaction control system (RCS) thrusters used for very precise manoeuvring and control, have been something of a bane to Starliner for the last several years. During preparations for the second uncrewed flight of the CST-100 system (itself the result of an embarrassing cock-up in integrating the timing systems between the launch vehicle and the Starliner craft in the first orbital test flight), it was found that a large number of the values within the thrusters had jammed, delaying the launch by several months, only for a number of the thrusters to have issues during the flight.

During the first Crew Test Flight with Williams and Wilmore, no fewer than five of the RCS thrusters failed during initial docking attempts at the ISS, although four were brought back on-line and the docking completed. This failure, coupled with the discovery that the issue was related to overheating within the “doghouse” units which had not been picked up during the development and testing of the units, then led to something of an embarrassing public spat between Boeing, as the main vehicle contractor, and Aerojet Rocketdyne, makers of the propulsion units, prior to NASA banging some heads together.

Since then, work on rectifying the propulsion unit issues has continued in near-silence. However, the return of the two astronauts to Earth inevitably caused some of the spotlight to swing back towards Boeing and Starliner and if / when / whether it night fly again. There is little doubt that NASA does want Starliner to continue: having all of their eggs in the Crew Dragon / Falcon 9 basket is far from ideal despite that successes of those systems thus far. This was something noted by Steve Stich, NASA’s Commercial Crew Programme Manager, following the Crew 9 splashdown.

We really need to get Boeing into a crewed rotation. Butch and Suni’s return on Dragon, to me, shows how important it is to have two different crew transportation systems, the importance of Starliner and the redundancy that we’re building into human spaceflight for our low Earth orbit economy.

– Steve Stich, NASA Commercial Crew Programme Manager

While progress has been made on mitigating the overheating issue by means of changing the operating parameters of the thrusters software system so as to avoid the need for any excessive redesign of the “doghouse” systems, these changes will need to be tested at some point through an actual flight test – and the same is true of the more minor, but still required, alterations to the helium purge systems within the propulsion systems.  This raises another issue: should such a test be carried out via a crewed or uncrewed mission.

The final decision on this lies with NASA, although in their rare comments on the work, Boeing has been somewhat bullish, pushing for the flight to be crewed. For its part, the space agency will not be drawn on what form any additional test flight should take – only that the vehicle used should be “mission ready”, with Boeing in a position to rapidly pivot from completion of a test flight to flying a full crew rotation afterwards.

Even if we were to fly the vehicle without a crew in the return, we want that to be crew-capable. So, we want it to have all the systems in place that that we could fly a crew with. What we’d like to do is that one flight and then get into a crew rotation flight. So, the next flight up would really test all the changes we’re making to the vehicle, and then the next fight beyond that, we really need to get Boeing into a crew rotation. So, that’s the strategy.

– Steve Stich, NASA Commercial Crew Programme Manager

As to when any such flight might take place remains an open-ended question. NASA continues to signal it would like at least the test flight to occur in 2025, but the overall mission schedule for the ISS this year – crew rotation flights, resupply missions (including the demonstration flight of the Dream Chaser resupply vehicle) – mean that docking opportunities for any Starliner test flight are not that numerous in the near-to-medium term.

Blue Ghost says “Night-night” with Stunning Images

In my previous Space Sunday update, I wrote about the private Blue Ghost lander by Firefly Aerospace, which successfully touched-down on the Moon on March 2nd, 2025, marking the company as the first to carry out a “fully successful” (e.g. without rolling or toppling over) commercial lunar landing.

Over the next lunar daylight period (14 terrestrial days), the vehicle carried out its assigned surface science work, with only the drill system – called LISTER (for Lunar Instrumentation for Subsurface Thermal Exploration with Rapidity rather than having any reference to a character from Red Dwarf) failing to operate as hoped, only reaching a depth of around 1 metre than the hoped-for 3 metres.

However, on Sunday, March 16th, the lander went quiet as the lunar night took hold, denying it the sunlight it needed to convert into electrical power and heat, and temperatures plummeted.

While there is a chance residual energy stored in the lander’s batteries might be sufficient to keep its essential electronics functioning, the Firefly team are not expecting to be able to re-establish contact when daylight returns on the vehicle in April.

Rather than simply bid farewell to their plucky little lander, however, on March 18th, Firefly Aerospace, via NASA – the mission being part of NASA’s Commercial Lunar Payload Services (CLPS) programme – released some images captured during the mission to highlight its success. Taken in high definition, they are regarded as some of the best ever taken from the surface of the Moon, and I’ve reproduced some of them here for your appreciation.

Discovering Biosigns on Other Worlds Just Go Easier. Sort-of

So far, we’ve discovered in excess of 4,000 planets orbiting stars beyond our own, and while many are unlikely to support life of any kind, much less life as we know it, there are equally many that just might. The trick is actually recognising the fact they do across the vast interstellar distances involved.

Thus far, the common technique used to try to determine whether or not an exoplanet might harbour life is to look for biosignatures – the by-products of life processes – when analysing the composition of its atmosphere. However, there are a number of problems with this approach, including the fact that many biological interactions can be similarly produced through purely abiotic means such as inorganic chemical reactions, and determining one from the other over interstellar distances in next to impossible.

To combat this, researchers from University of California, Riverside, have suggested that astronomers looking for potential signs of life examine the atmospheres of potentially habitable worlds for concentrations of methyl halides. These are gases combining a methyl group with a halogen atom – and they are only produced via organic means by anything from bacteria through to plants. Ergo, if they can be detected in the atmosphere of a planet, they would potentially point to some form of organic process at work on that world.

Clever, right? Well, yes, but there is a hitch. Even here on Earth, atmospheric concentrations of methyl halide are low and prone to being broken-up and “lost” within the general atmospheric “noise”, thus making them hard to detect – and this would likely be true for many potentially life-bearing worlds orbiting other stars. Fortunately, the researchers have an answered for that: look for methyl halides in the atmospheres of hycean worlds.

These are planets which have been shown to have hydrogen-rich atmospheres and are believed to have liquid water surfaces (“hycean” being a portmanteau of “hydrogen” and “ocean”). Generally, speaking, these worlds exist within the “Goldilocks zone” around their parent star: the region wherein all the “right” conditions come together to potentially give life the “kick start” it needs. Further, such are their general atmospheric composition and character, they could support far higher – and more detectable – concentrations of methyl halides.

In this, the researchers are supported by the fact that one biosignature appears to have been detected within the atmosphere of an exoplanet – dimethyl sulphide. This was reported as being discovered within the atmosphere of K2-18b, a hycean world, in 2023. And even while the overall number of hycean worlds thus far discovered is small, finding traces of methyl halides in the atmosphere of just one would be ground-breaking news.

Another potential area where the detection of methyl halides might work is in the study of the water vapours expelled from the likes of Europa and Enceladus in our own solar system. Both of these moons give off plumes of water vapour through geysers, which in the case of Enceladus, is sufficient to actually help renew the otherwise unstable E- ring around Saturn. Were methyl halides to be found within these vapours (assuming they could survive in the tumult), it could dramatically increase the potential for one of these moons to be harbouring microbial life in its waters.

I’ve written about the issues of orbital space debris several times in these pages. It is estimated that there are 150 million pieces of space junk surrounding Earth. The vast majority of this debris is too small to be readily detected – minute pieces smaller than a centimetre; still large enough to do mischief to a satellite or other orbital vehicle, particularly if a cloud of them happen to strike – but of no significant threat to those of us on Earth or flying through the sky.

However, there are between 25,857 and 56,450 large object orbiting the Earth; of these, between 10,000 and 12,500 are operational satellites (the numbers vary based on the collective orbital regions studied), and the rest defunct satellites, rocket stages, payload fairing and other debris large enough to pose a range of issues. These present a range of problems, some of which are obvious, others perhaps less so.

For example, satellites and rocket stages in low-Earth orbit (LEO) can be directed to re-enter the atmosphere so that any parts surviving re-entry “safely” fall into the Pacific Ocean at “Point Nemo” (officially called the oceanic pole of inaccessibility), the furthest point from land in any ocean or sea, and a place 400 km from the nearest air or marine route. However, as “safe” as this is, as I recently noted – they result in an increase in high-altitude pollutants such as aluminium oxides that is on the increase (as I noted in that article, SpaceX’s Starlink is now responsible for some 40% of debris burning-up in the upper atmosphere and creating up to 5 tonnes of (mostly) aluminium oxide dumped in the mesosphere and stratosphere per day).

There are others who are less considerate in what happens to their satellites and the expended stages of their rockets. Russia, for example, has a habit of taking pot-shots at its own satellites, blowing them up (and thus increasing the amount of fast-moving debris and adding to the general confusion, whilst China just tends to leave rocket stages to make an uncontrolled re-entry which, whilst pointing in the general direction of Point Nemo, could equally result in debris striking populated areas.

Even SpaceX has been a little cavalier; three of their service modules – or “Trunks” – from Crew Dragon missions have survived re-entry to come down near populated areas. The first was largely glossed over (it fell on Australia); the next two came down in America – one within a glamping centre, the other actually striking a house in Florida (fortunately without loss of life or injury). These two were enough to persuade NASA and SpaceX to move Crew Dragon splashdowns from the Atlantic to the Pacific Ocean, so the vehicles would not be re-entering the atmosphere over the continental United States.

However, this is just the tip of the iceberg. Not only is there a vast amount of debris occupying the various orbital planes – low Earth orbit (LEO), medium Earth orbit (MEO), Geostationary orbit (GEO), Sun synchronous orbit  (SSO) – over the years all of the smaller debris previously mentioned has come to be spread more broadly around the Earth and across different altitudes. And the amount of potential junk we’re casually lobbing up in the form of smallsats viewed as “no bother” as even in an uncontrolled re-entry at the end of their useful life, they will completely burn up, together with the rocket stages used to get them there, is now accelerating. In 2024, for example, there were 263 launches world-wide, most of them delivering multiple satellites to various orbits and leaving upper stages in what are called “superspreader orbits” – orbit beyond those occupied by satellites, so as to minimise collision risks between them. Taken together, all of this increases the risk of collisions – and not just between a couple of objects; there is a very real risk of one or more collisions leading to an event referenced under the term Kessler syndrome.

Also called collisional cascading, the Kessler syndrome envisages a  single collision between two fast-moving orbital objects generating debris which goes on to strike other orbital objects, shattering them, causing more debris, and so on through a cascading set of collisions that could destroy entire networks of satellites – and orbital facilities like space stations together with orbiting crewed space vehicles.  If you’ve seen the 2013 film Gravity starring and Sandra Bullock and George Clooney, you’ll have seen a visualisation of a Kessler syndrome event.

Kessler syndrome is particularly relevant to the crowded domain of low Earth orbit which is currently getting packed out thanks to the arrival of megaconstellations such as Starlink (currently 7,000 active and inactive, with a plan for 12,000 potentially rising to 40,000 in both LEO and MEO, together with China’s planned 14,000 strong Qianfan (“Thousand Sails”). Because of these and the overall increase of commercial activities in LEO, the risk of a Kessler syndrome event occurring is seen as being on the rise – as is its potential range of impact (no pun intended).

In particular, a study conducted by a team from the University of British Columbia (UBC) and published in Scientific Reports noted that a widespread collisional cascade could result in multiple large-scale debris elements entering the atmosphere to rain down fragments across wides areas, not only putting lives on the ground at risk but also causing potential disruptions to air travel and airspace closures, even when there is no direct threat to people on the ground.

In this latter regard, the report additionally notes that even without a Kessler syndrome event, particularly busy concentrations of air routes – like southern Europe, the Mediterranean Sea and Middle East; the Caribbean and Central America; south-east Asia through the Philippines and around the South China Sea – now have a 1 in 4 risk of suffering significant disruption as a result of orbital debris falling through them, and this could rise to 1 in 3 in the next few years (although the chances of an individual aircraft actually being struck by debris will remain around 1 in 430,000).

The report also notes that this potential for disruption is not limited to just space debris re-entering the atmosphere; the increasing number of launches around the world could see something of an increase in vehicle losses at high altitudes during ascent, also causing short-term airspace restrictions and aircraft diversions. In this, the report references the loss of the Starship vehicle during the January 16th, 2025 IFT-7 sub-orbital flight by SpaceX.  The vehicle in question exploded at an attitude of 124 km, with wreckage falling over the airspace of the Caribbean and Greater Antilles, resulting in aircraft being diverted and airspace being temporary restricted to avoid the risk of aircraft passing through clouds of small debris which could be ingested by their engines with unwanted results. Also, and as a by-the-by, this mishap resulted in 85.5 tonnes of pollutants in the form of metal oxides and nitrogen oxides oxides dumped into the upper atmosphere – that’s 1/3 of the annual levels of such pollutants dumped on us from meteorites burning up in the atmosphere.

All of which underlines the fact that whilst space companies point towards their use of more environmentally-friendly propellants for the launch vehicles – notably with the move away from using kerosene – this is actually a very small step in tackling increasingly complex problems resulting from spaceflight.

Boeing Warn of SLS Layoffs

Following my last piece concerning NASA Project Artemis and – particularly – the Space Launch System (SLS) and Orion crew vehicle – Boeing has formally notified employees working on the SLS programme that there could be lay-offs coming.

To align with revisions to the Artemis program and cost expectations, today we informed our Space Launch Systems team of the potential for approximately 400 fewer positions by April 2025. This will require 60-day notices of involuntary layoff be issued to impacted employees in coming weeks, in accordance with the Worker Adjustment and Retraining Notification Act.

– Boeing Statement in the possible layoffs notification

The notification is seen as evidence that the Trump administration is moving towards an immediate cancellation of SLS – and possibly Orion. However, the wording of the Boeing statement might indicate otherwise. The company and its partners in Artemis, Lockheed-Martin and ULA have been under pressure from NASA to reduce costs, and have agreed to do so. With the SLS production line maturing the notification might by in line with that goal, Boeing having the confidence they can reduce the SLS workforce without impacting the programme. As it is, the vehicles  – both SLS and Orion – due to be used in the next three Artemis missions (2 through 4) are already well advanced: 

• The Artemis 2 SLS is being stacked at Kennedy Space Centre, and the Orion vehicle for that mission is awaiting final testing.
• Construction of the core stages for the SLS vehicles to be used with Artemis 3 and Artemis 4 have been under construction in parallel by Boeing at NASA’s Michoud Assembly Facility, and work has commenced on the Artemis 5 rocket’s core stage.
• The Orion vehicles for Artemis 3 and Artemis 4 are at Kennedy space centre, undergoing assembly and integration.
• The European Service Module (ESM) for Artemis 3 was shipped to Kennedy Space Centre from Germany in August / September 2024 while the ESM for Artemis 4 is currently under construction in Bremen, Germany.

However, if the Boeing notice has been issued over concerns about cancellation, then as I pointed out last time out, it would likely only serve to severely delay Artemis, because there just isn’t anything available to readily replace SLS or SLS + Orion. Also, there is an argument to be made that whilst Artemis in its current form with the fully expendable SLS is unsustainable, continuing with it for the time being might actually help move the programme towards any SLS replacement without the need to completely disrupt the entire Artemis programme.

Right now, only Artemis mission 2 through 5 are funded to any degree; 6 through 10 have yet to receive serious budget allocations – although this will have to start soon. As such, it would seem to make more sense to continue with Artemis 2 preparations and the development of the Artemis 3-5 flight hardware whilst redirecting funds that would otherwise go into the vehicles required for Artemis 6 onwards into the development of a more cost-effective architecture, such as modifications to New Glenn and the Orion launch Abort System to allow the one to launch the other, and the development of a means for Orion to dock with ULA’s Centaur upper stage whilst on-orbit (required to get Orion to cislunar space, New Glenn being unable to do so on its own).

Such an approach would both allow Artemis to meet current goals – and even provide a buffer if mission dates have to again slip – whilst the alternate hardware is modified, tested, rated, and called for flight. Thus, by the time Artemis 6 rolls around, the new architecture could be ready to make its debut in place of SLS, and no significant ground has been lost in moving Artemis forward. Additionally, the specific use of New Glenn / Centaur would both fit with the current Lunar Gateway architecture (possibly the one thing NASA really should abandon but likely won’t) and avoid the need to cancel and squander Orion.

However, this is pure conjecture. Whether the Boeing notification was issued in expectation of SLS cancellation or not, is something that is likely to become clear within the next month or two.