Category: Other Worlds and Tech

One of the most expansive space programmes, both national and commercial, is that of China. I’ve covered multiple missions carried out by the Chinese national space programme both in terms of human spaceflight and the establishment of an orbital space station, and robotic missions to the Moon and Mars. I’ve also touched on the country’s growing commercial space sector, some of which seemingly “borrowing” heavily from the likes of SpaceX in terms of vehicle design and development – particularly with regards to reusable boosters.

At the top of the list for the latter is Jiangsu Deep Blue Aerospace Technology. Founded in 2016, the company has been recognised for developing a family of semi-reusable launch vehicles called Nebula – which bear a remarkable resemblance to the SpaceX Falcon 9.

The smaller Nebula-1 vehicle-capable  of lifting payloads in the 2-8 tonnes range – has been undergoing increasingly ambitious launch and landing tests of the vehicle’s first stage over the last several years. The company had been planning to lunch the vehicle on its first orbital flight, including the booster returning to a landing, be the end of 2024. However, the loss of a Nebula-1 first stage during a high altitude launch and recovery flight in late September has now put this in doubt.

The Nebula-2 vehicle, meanwhile, not only resembles Falcon 9 with very similar landing legs and grid fins, but is also a very similar payload capability, including up to 20 tonnes to low-Earth orbit (LEO) in a full expendable mode (compared to Falcon 9’s 22 tonnes when fully expendable). It is due to make its orbital debut in late 2025.

Whether either vehicle can be considered a direct “rip off” of Falcon 9 is perhaps debatable: form follows function when it comes to flight dynamics; but it’s hard to imagine Deep Blue reaching their rocket design and propulsion choice without them taking a long, hard look at SpaceX.

This is perhaps even more true when looking at the latest announcement concerning the company’s other planned area of operations: sub-orbital tourist flight to the edge of space. On October 23rd, 2024, the company’s CEO,  Huo Liang, announced these sub-orbital flights will start in 2027, and ticket reservations are now open.

The flights will, according to Huo, be akin to Blue Origin’s New Shepard flights: lift-off using a recoverable booster (in this case, the Nebula-1 first stage), carrying a capsule capable of sitting up to 6 people in two rows of back-to-back seats, prior to the booster separating and returning to a safe landing.

Once separated, the capsule will coast ballistically, passing through the Kármán line at 100km altitude, the passengers getting to enjoy around 5-minutes in weightlessness, prior to gravity making its presence felt once more as the capsule commences its fall back to Earth. Parachutes will be used to slow the descent until just above the ground, when four pairs of mid-mounted motors will be fired for a soft landing. It’s not clear if the capsule will include either a “crush ring” at its base designed to absorb the final impact with the ground (like the New Shepard capsules) or utilise some form of inflatable cushion, as with Boeing’s CST-100 capsules.

What is interesting is the capsule’s uncanny resemblance to the SpaceX Crew Dragon. The two are so similar in overall looks and dimensions, one might be forgiven for thinking they are the product of the same company. The only at-a-glance difference (outside of the paint scheme) being Crew Dragon had two viewports on one side of the vehicle, and the Deep Blue vehicle – which at the October 24th announcement bore the somewhat clumsy name of “Rocketaholic” in slides and literature – has six primary viewports, three on either side and aligned to give all six passengers a view out of the vehicle, and one more to either sides of the seating, for a total of eight.

Internally, the differences are likely to be more noticeable, including the back-to-back seating arrangement of the Deep Blue vehicle and the fact that whilst slightly smaller than Crew Dragon, it potentially has a larger internal volume available to passengers as it does not have any docking and hatch mechanisms in the nose area.

Whether or not operations do commence in 2027 remains to be seen; it is entirely unclear as to where development of the capsule stands or when practical testing will commence (if it hasn’t already).

Deep Blue is actually the second Chinese entity to “borrow” from SpaceX for space tourism flights. In 2021, CAS Space – a private venture spin-off of the Chinese Academy of Sciences (CAS) – announced they would start conducting fare-paying space tourism flights in 2024, after a (surprisingly) short 3-year flight development and test cycle of a capsule and booster system.

In this, CAS Space perhaps borrowed even more heavily from SpaceX. Not only do full-scale mock-ups of its capsule show it to be another to borrow heavily from Crew Dragon (and which shares pretty much the same dimensions as the Deep Blue capsule), the booster somewhat resembles Blue Origin’s New Shepard –  but is designed to make a return to the launchpad, a-la the SpaceX Starship / Super Heavy – where it is to be grabbed by arms on the launch tower, rather than landing on the ground.

Since the initial announcement, CAS Space has (unsurprisingly) revised the date on which they plan to start fare-paying flights, moving it back to (currently) 2028, in order to allow sufficient time for vehicle development and testing. However, they have also indicated plans to operate it not from a spaceport, but from a dedicated “Aerospace theme park”, with one flight taking place roughly every 4 days. Flights on either Deep Blue or CAS are rumoured to be in the US $210,000 per person, and be interesting to see whether either will come to pass.

Space Evasion and Detection Avoidance

In my previous Space Sunday article I wrote a little about the increasing issue of space debris in orbit around Earth and the increasing need for satellites to manoeuvre away from chunks of dead satellites which beak-up in orbit, used rocket parts and so on. However, that’s not the only reason for some satellites requiring an ability to adjust their orbit. Another is to evade or avoid detection.

This is something particularly used by so-called “spy” satellites, like the various families operated over the decades by the US National Reconnaissance Office (NRO). Many of these include the ability to be “re-tasked” – have their orbital periods and inclinations changed – so as to be able to overfly targets of interest or to take longer to pass over a country in order to gather more detailed intelligence. However, the degree to which this is possible has always been somewhat constrained in terms of how much propellant these satellites might carry and how much they can use to achieve orbital adjustments without unduly shortening their anticipated operational life. But that might all be changing in the future, thanks to the US Space Force’s X-37B automated spaceplane.

Also known as the Orbital Test Vehicle (OTV), the X-37B is a highly-secretive vehicle programme capable of exceptionally long-duration missions in orbit. For example, OTV-6 launched on May 17th, 2020 and returned to Earth on November 12th, 2022, spending a little under 3 hours shy of 909 complete days in space. The USSF / Department of Defense is pretty quiet about the purpose of the two X-37B vehicles, other than stating they are for carrying out research into advanced technologies for space application and the fact that they do carry experiments related to NASA as a part of their payloads.

But in October 2024, the USSF was a little more forthcoming, revealing that the current X-37B flight, which launched in December 2023, has been carrying out a series of aerobraking tests in Earth’s atmosphere to examine the use of such capabilities to radically alter an orbital vehicles trajectory and inclination around Earth.

Aerobraking – using the frictional heat of the upper layers of an atmosphere as a means to both decelerate a space vehicle and / or to alter its orbit – is a process that is well understood on paper and has been used by both NASA and the European Space Agency. The former has used it on their of its Mars missions:  Mars Global Surveyor (MGS), Mars Odyssey and Mars Reconnaissance Orbiter; whilst ESA has used aerobraking in conjunction with its ExoMars Trace Gas Orbiter mission to Mars and its Venus Express mission.

Data from all of these missions was used in the preparations for X-37B to make use of Earth-based aeorbraking to significantly alter its orbital period and orbital shape around the Earth. The attempt – carried out some time between October 10th and October 15th – was designed specifically to lower the overall perigee of the vehicle’s elliptical orbit and make its orbit more circular without the use of propellants, and bring the craft into a position where it can carry out the next phase of the mission.

Whilst the manoeuvre was fairly basic, it is seen as a precursor to more complex manoeuvres by the vehicle on future missions as the USSF researches the use of aerobraking as a strategic tool which could be employed by future generations of MilSats as well as vehicles like the X-37B.

By carrying out an atmospheric dip of this nature, the X-37B demonstrates its ability to become a very effective operational, rather than experimental vehicle.  Having such a craft that could in theory be deployed to orbit reasonably rapidly and equipped with a range of intelligence-gathering equipment would be exceptionally worrying to another military power.

Under normal circumstances, satellites are highly predictable; locate one, track it for a while, and you can predict when it is going to be below the horizon (and therefore unable to see / hear you) and when it is going to pop back up again. Thus, it is very easy to determine when you might be able to carry out an operation you’d rather others didn’t know about immediately – such as the large-scale movement of troops and materiel to a foreign border or the deployment of a fleet to open sea.

However, if you can never be sure exactly where those eyes are or whether then are looking at your forces, things get a lot more complicated, resulting in potential second-guessing, delay or even backing away from what might be seen as overly aggressive actions.

[The X-37B is] fascinating [because it] can do an orbit that looks like an egg and, when it’s close to the Earth, it’s close enough to the atmosphere to turn where it is. Which means our adversaries don’t know – and that happens on the far side of the Earth from our adversaries – where it’s going to come up next. And we know that that drives them nuts. And I’m really glad about that.

– Former USAF Secretary Heather Wilson

Of course, the flipside of this is the further militarisation of space and the risk of it becoming a future combat environment.

The aerobraking is not the only unique aspect of this mission. During their first 6 flights the two OTV vehicles operated in low Earth orbit. Prior to the mission launching, the USSF indicated that in part it would involve testing the effects of radiation on various materials and technologies whilst in an elliptical orbit sufficient for the vehicle to pass through the Van Allen radiation belts. However, it was not until February 2024 that amateur sleuths who track orbital craft were able to confirm the vehicle’s exact orbit: an inclination of 59.1 degrees to the equator, and ranging between 300 km and 38,500 km from the surface of the planet!

This discovery led to speculation as to how the vehicle would survive re-entry when coming home, as it would be entering Earth’s atmosphere at a speed closer to that of a vehicle returning from the Moon or Mars than from LEO, and thus experience much higher temperature regimes  on a direct passage back into the atmosphere in order to land. Now, with these orbital adjustments carried out, the vehicle has no need to make such a high-speed re-entry, as it is once again operating at a significantly lower orbital velocity.

Quite when the vehicle will return, however, is unclear. Until now, each successive X-37B mission has been longer than the last – but there is no absolute requirement for this. Also the USSF has said on the matter than now it is established in it new LEO, the vehicle will commence the next phase of its mission.

A Second from Disaster

Whatever one’s view of the SpaceX Starship / Super Heavy launch system (and there are multiple reasons to doubt its actual viability as a genuine flight system / revenue earner), the capture of the Super Heavy booster at the landing facility during the recent Integrated Flight Test 5 (IFT 5) on October 13th was a remarkable achievement. However, audio accidentally released on October 25th reveals the flight of the booster almost ended in it striking the ground in close proximity to the launch tower and stand.

I gotta be really up-front about scary shit that happened …We had a misconfigured spin gas abort …and we were one second away from that tripping and telling the rocket to abort and try to crash into the ground next to the tower. We had a whole bunch of new aborts and commit criteria that we tried to double-check really well, but, I mean, I think our concern was well-placed, and one of these came very close to biting us.

– Unnamed SpaceX official

The audio was released inadvertently as a result of SpaceX CEO Elon Musk taking a call from his engineers about a post-flight engineering review whilst apparently more interested in a video game he was playing, and then subsequently releasing a clip of his game-play which included audio of the discussions.

What is striking about the audio is that it is made clear that the engineers had plenty of data indicating the flight was on the edge, and that some of the issues could have been addressed before the flight (fore example, they have evidence the vehicle could lose one or more of the triangular chines running vertically up the booster to protect essential external equipment during its descent – and that’s precisely what happened), and they knew there had been an insufficient amount of time given to a full pre-flight review ahead of IFT5.

We were scared about the fact that we had 100 aborts that were not super-trivial … which were routed in we didn’t do as good a review for pre-flight one lift-off.

– Another SpaceX official discussing the review of IFT5

The audio also includes a hint that the engineers are concerned about the next flight is turning into a struggle between trying to get it ready in a short a period of time as possible and actually having the time to properly address and mitigate the problems identified with IFT5.

Obviously, given the brevity of the recording, it is not clear was was said in the rest of the meeting, or what Musk’s overall response to the concerns raised might have been. However, later the same day he did take to Twitter / X.com to state IFT6 would be happening sooner rather than later.

NASA finally got its flagship Europa Clipper mission away on Monday, October 14th, with the lift-off of its Falcon Heavy booster having been delayed four days, courtesy of Hurricane Milton.

The launch occurred at 16:06 UTC from the SpaceX launch facilities at LC-39A, Kennedy Space Centre. It marked the start of a 5.5 year flight to Jupiter for the spacecraft, which as I covered in a recent Space Sunday article will study Jupiter’s icy moon of Europa for about 4 years. It will be joined in this effort by Europe’s JUICE mission, which although launched 18 months ahead of the NASA mission, will arrive a year after it, and will also study Jupiter’s two other “icy world” moons: Ganymede and Callisto.

Once at Jupiter, Europa Clipper – the spacecraft – will orbit the planet, not the moon, making periodic fly-bys of the latter. As I previously explained, this is to both minimise its exposure to the extremely harsh radiation regime immediately surrounding Jupiter (and enclosing Europa) which would burn-out the vehicle’s electrical systems in about 6 months, and also to maximise the time available for it (between 7 and 10 days, rather than mere minutes were it orbiting Europa) to transmit the data gathered during each fly-by back to Earth.

The mission is one of NASA’s most expensive robotic undertakings yet, with an estimated total lifecycle cost (including the four years of operations studying Europa) of US $5.2 billion.

Following launch, none of the three core stages of the rocket – all of them Falcon 9 first stages – were slated for recovery, and five minutes after lift-off the upper stage of the rocket separated and fired its engine whilst also jettisoning the payload shroud protecting the Europa Clipper spacecraft, as it continue to carry the latter up to an initial orbit.

This parking orbit was used to carry out checkouts on the space vehicle as it coasted around the Earth for some 40 minutes prior to the upper stage motor re-lighting for a three minute burn to push its payload onto its initial trajectory away from Earth. Payload separation then came just over an hour after launch, temporarily breaking communications with the spacecraft which had up until that point been using the communications relay on the Falcon upper stage to report its status.

Signal acquisition took five minutes as the spacecraft had to first “warm up” its communications systems via its onboard batteries. Once the signal had been obtained, initial flight data information and vehicle operating telemetry were returned to mission control at the Jet Propulsion Laboratory, California, the  latter revealing a minor problem in the spacecraft’s propulsion system, but which was not interfering with general operations.

We could not be more excited for the incredible and unprecedented science NASA’s Europa Clipper mission will deliver in the generations to come. Everything in NASA science is interconnected, and Europa Clipper’s scientific discoveries will build upon the legacy that our other missions exploring Jupiter — including Juno, Galileo, and Voyager — created in our search for habitable worlds beyond our home planet.

– Nicky Fox, associate administrator, Science Mission Directorate at NASA Headquarters,  Washington

With the initial check-out complete, the command was sent for the vehicle to start unfurling its two huge solar array “wings”, the largest NASA has ever flown on a deep space mission (with a total vehicle/ array span  just slightly smaller than that of Europe’s Rosetta mission). This was a gentle operation, finally completed some 6 hours after launch, allowing the craft to start generating up to 600 watts of electrical output.

The spacecraft is now heading away from Earth on a heliocentric orbit which will allow it to fly-by Mars in March 2025 prior to a return to Earth in December 2026. It will use Earth’s gravity to assist it on its way to Jupiter, which it will reach in April 2030.

Skyrora First UK Vertical Launch?

Scottish rocket start-up, Skyrora Now looks to be taking pole position in the race to be the first entity to launch a commercial rocket from British soil. In October, the company announced that after months of delay – not all of them related to itself – it expects to receive a launch vehicle license from the UK’s Civil Aviation Authority (CAA) in December 2024 or January 2025. This will allow its first launch to take place in the spring of 2025, from the UK’s SaxaVord Spaceport located on the Lamba Ness peninsula of Unst, the most northerly of the inhabited Shetland Islands.

Based in Edinburgh, Scotland, Skyrora has been operating since 2017, and already has something of an impressive record, developing two sub-orbital test bed vehicles Skylark Nano and Skylark Micro, which helped pave the way for their Skylark L two-stage sub-orbital rocket, capable of lifting payloads of up to 60 Kg to attitudes of around 100km for micro-gravity research.

The company is also working on the tree-stage version of the vehicle, called the Skylark XL, capable of placing payloads of up to 315 kg into a 500-km low-Earth orbit (LEO). In addition, Skyrora has also been developing its own 3D printed engines for its rockets, and plans to offer a “space tug” vehicle along with Skylark XL. This tug will be capable of remaining in orbit post-launch and used to either remove space debris from orbit, and / or replace / maintain satellites in orbit by giving them a little boost.

I’ve covered Skyrora a couple of times in this column, notably in October 2022, when the company attempted its first Skylark L launch. This actually took place from Iceland (as regulatory approval for hosting launches from UK soil had not at that time been granted), and whilst it was ultimately unsuccessful as a result of a software error, it did demonstrate a further unique aspect of Skylark L: a fully mobile launch platform and control facility allows the company to ship a rocket and its launch systems pretty much anywhere in the world and complete a launch without the need for any permanent supporting launch infrastructure.

As well as flying the Skylark L from SaxaVord, Skyrora also intend to use the facilities at the spaceport for its Skaylark XL original launcher, thus becoming one of a number of commercial ventures set to use SaxaVord, which gained its operator’s license from the CAA in May 2024.

In fact, at the time the license was granted, it was widely anticipated that Germany’s Rocket Factory Augsburg (RFA) would be the first to launch from the site. Holding a long-term lease on the facilities most northerly launch pad – called Freddo – RFA commence static fire tests of the first stage of the rocket they hoped to fly, in June 2024, with an initial test of 4 of the nine motors. They then planned a further test of all nine engines in August 2024, with the aim of then assembling the entire vehicle and launching at the end of summer. Unfortunately, and as I reported at the time, the second static fire test resulted in the complete loss of the stage 38 second after motor ignition. RFA now expect to make their first launch attempt from SaxaVord in August 2025.

Starliner: 1st Operational Flight Postponed

Following the uncrewed return for Boeing’s CST-100 Starliner Calypso at the end of a frustrating Crew Flight Test (CFT) which saw significant issues with the vehicle’s service module and its propulsion systems, NASA has confirmed it will not have the vehicle participate in either of the planned crew rotation flights planned for 2025.

The news is hardly surprising; NASA wants to give Boeing and their propulsion system partner Aerojet Rocketdyne as much time as possible to fully diagnose and correct a multitude of problems with the service module propulsions systems – from overheating, through leaks in purge systems to unexpected wear-and-tear on valves – and then determine how best to get the system properly certified for operational use.

In July 2024, prior to Calypso returned to Earth, the US Space Agency made an initial decision to swap the planned crew flights for 2025. Originally, Starliner 1, carrying a crew of four to the ISS, had been due to fly in February 2025 – but NASA swapped that out in favour of SpaceX Crew 10. This left Starliner 1 occupying the late July / early August slot; however, as well as swapping the slots over, NASA also instructed SpaceX to bring forward preparations for its 2026 Crew 11 flight, thus allowing the agency to to seamlessly swap to flying a crew on SpaceX Crew Dragon if Starliner was not in a position to fly a full mission.

Now, in the wake of further deliberation, NASA has opted to fly the July/August 2025 mission using SpaceX Crew 11, meaning the earliest Starliner is likely to fly an operational mission to the ISS will be 2026. However, this does not mean Starliner will not fly at all in 2025; rather it means that NASA have given themselves and Boeing additional space in which to fly a further Crew Flight Test of the vehicle, should the agency decided one is warranted ahead of any final vehicle certification, and to be able to plan and fly any such mission again with minimal disruption to existing schedules.

Space Debris and Re-Entry: Hazards and Pollution

There is an estimated 150 million pieces of space junk / debris orbiting the Earth ranging in size from around 1 cm across to entire satellites and spent rocket stages, all of which constitutes a growing hazard for space operations, crewed and uncrewed. An increasing number of operational satellites routinely have to change altitude / velocity to avoid collisions with such objects – or at least, with those that can be accurately tracked.

On top of that there are hundreds of millions of pieces of debris in the millimetre(-ish) range zipping around the Earth we simply cannot track, but which pose and equal amount of danger – witness what happened to Soyuz MS-22 in December 2022, which what is believe to be a millimetre-sized piece of Micrometeoroid and Orbital Debris (MMODs) punched its way through a vital cooling system radiator.

Things like MMODs are really hard to mitigate, and while getting rid of larger debris is a problem multiple companies are actively working on, by far the most common means of disposing of unwanted satellites and used bits of rockets and spacecraft is to push them back into the upper atmosphere and let them burn up. However, there is now growing evidence that this approach is neither wise or sustainable, with studies revealing increasing signs that doing so beginning to have a lasting detrimental impact on the atmosphere, and by extension, the climate, both of which are already subject to other aspects of space launch activities.

In just 10 years, the volume of satellites and rocket elements burning-up in the upper atmosphere has doubled. In their wake they leave soot from engine exhausts, aluminium oxides capable of altering the planet’s thermal balance in favour of faster greenhouse warming (as well as the return of ozone destruction). In particular, three separate studies have shown that concentrations of aluminium oxides in the mesosphere and stratosphere — the two atmospheric layers above the lowest layer, the troposphere have been measurably rising in the same period. One of these reports goes so far as to note that if the current rate of disposal of space junk through atmospheric burn-up continues for as little as 20-30 more years, the volume of  aluminium oxides in the upper atmosphere could increase by 650%.

And this rate of disposal is not to much likely to continue in the next couple of decades – but increase, thanks to the ever increasing number of “megaconstallations” of thousands of satellites in low Earth orbit.

To take Starlink as an example (and as cited by UK-based Space Forge). Since 2019, SpaceX has launch thousands of Starlink satellites which are supposed to be able to remain in orbit for 5 years before re-entering the atmosphere. However, such has been the pace of development, SpaceX has been actively disposing its older, unwanted Starlink units by de-orbiting them to to make space for newer units, reaching a point where they are now responsible for some 40% of all debris re-entering the Earth atmosphere and being incinerated. This equates to half a tonne of incinerated trash – much of it aluminium oxide – being dumped in the mesosphere and stratosphere every day, just by Starlink. And that’s just with an operational fleet of 6,000 satellites; what – researchers ask – will it be like if SpaceX are allowed their requested 40,000 units in orbit?

And while they are singled-out, SpaceX are not alone, both One Web and Amazon are deploying their own (admittedly fewer in number) constellations which will also likely go through the same continuous evolution at Starlink; then there are military constellations, European constellations and the potential huge Chinese Thousand Sails megaconstellation. Thus, the issue is not going to be diminishing any time soon.

Already researchers have calculated that the amount of ozone depletion directly related to space launch operations is slowly increasing. Not only are there far more satellites being pushed back into the atmosphere – there are more rocket stages going the same way, filled with soot, aluminium oxides, alumina particles in general and chlorine, which are all being dispersed in the upper atmosphere. Again, to take SpaceX as an example: they are performing some 100 launches a year when less than a decade ago the total number of global launches was maybe two dozen. That’s 100 extra upper stages burning up in the atmosphere – from just one company. Add that to the pollutants pushing into the atmosphere during launch from the liquid kerosine SpaceX uses with Falcon 9 and Falcon Heavy, and it is understandable why researchers pin around 12% of ozone depletion from space related activities just on SpaceX.

But again, the company is hardly alone – and through a switch to methane (which despite itself being a greenhouse gas, burns so cleanly in rocket motors so as to produce very little measurable pollution in the scheme of things), they are attempting to reduce that aspect of their footprint. ESA, Roscosmos, JAXA, ULA, NASA, the Indian space industry – even the likes of Virgin Galactic  – continue to dumping harmful waste products into the atmosphere through their use of solid rocket motors and hybrid propellants in their launch vehicles / space planes. These perhaps doe the most significant damage to the atmosphere each and every time they are used.

The problem here, of course is how to regulate without suffocating. And it that, the issue of atmospheric pollution as a result re-entry burn-up is particularly thorny. For while there are multiple national requirements and international agreements relating to environmental protection in countries operating launch services, none of them extend to protecting the atmosphere against the potential harmful impact of using it as a convenient trash incinerator.

Update: October 6th: Two hours after this article was published, NASA announced launch operations for the Europa Clipper mission are standing down, and the launch postponed due to Hurricane Milton. A new target launch data will be announced once the hurricane has cleared the Florida Space Coast and any damage to facilities at Cape Canaveral Space Force Station’s SLC-41 launch pad assessed.

If all goes according to plan, October 10th should see the launch of the second of NASA’s Large Strategic Science Missions of the 21^st century (formerly called Flagship missions, and the first having been the James Webb Space Telescope): Europa Clipper.

The launch will see a SpaceX Falcon Heavy carry a NASA space probe bearing the same name as the mission on the first leg of a 5.5 year journey to Jupiter to study the Galilean moon of Europa. In order to achieve this goal, the spacecraft will be directed towards Mars, which it will reach in February 2025. Using the Martian gravity as a brake, the spacecraft will fall back toward the Sun and encounter Earth again in December 2026, using our planet’s gravity to fling it out on a trajectory to reach Jupiter in April 2030.

On arrival at Jupiter, the vehicle will enter an initial orbit that will then be refined, allowing it to make some 44 fly-bys of Europa varying between just 25 km above the surface and 2,700 km. The reason fly-bys will be made rather than the craft entering orbit around Europa directly is large due to radiation. Europa lies well within Jupiter’s extreme and intense radiation belts, an environment so harsh that it would fry the spacecraft’s electronics and electrical component – notably the huge solar arrays which generate its power – in just a few months after its arrival.

In addition, the spacecraft is carrying a significant science payload which can gather data much faster than the communications system can transmit it to Earth; were it to be placed in orbit around Europa, the opportunities to transmit the data its has would be subject to a a range of limitations (such a when Jupiter is between the probe and Earth), risking data loss due to existing data being overwritten before it could be transmitted.

By taking up an orbit around Jupiter and simply swinging by Europa, the space craft may lose opportunities for gathering data, but it increases the time available for the successful transmission of the data it does collect safely. Rather than having mere minutes or hours in which to send information, the probe will have between 7 and 10 days at a time. Further, by orbiting Jupiter rather than Europa, the spacecraft “dips” in and out of the harshest radiation, rather than being subjected to it all the time,  thus preserving its electronics for much longer, and allowing it a primary science mission of an initial 3.5 years.

To assist it whilst orbiting Jupiter, Europa Clipper will use 24 thrusters connected to a hypergolic propulsion system with 2.7 tonnes of propellants. Up to 60% of this mass will be used during the initial orbital insertion phase around Jupiter in April 2030, with the rest used in stabilising the spacecraft and orienting it during Europa fly-bys and communication periods with Earth to maximise data gathering and transmission.

The suite of nine instruments on the vehicle will be used to study Europa’s interior and ocean, geology, chemistry, and habitability. The science payload accounts for some 82 kg of the vehicle’s mass and includes a pair of imaging cameras operating in visible light wavelengths, and both a thermal imaging system and a near-infrared imaging system which will search for the likes of dynamic activity on the icy-covered surface of Europa (e.g. vents venting water and sub-surface material into space) and the distribution of organic material across the moon’s surface.

The vehicle also carries an instrument called REASON – the Radar for Europa Assessment and Sounding: Ocean to Near-surface (NASA still reign supreme in the acronym stakes!) – an ice-penetrating radar designed to characterise the 10-30 km (estimated) thick ice crust of the moon, seeking information on its composition and any indications of water pockets within it, any exosphere existing just above it as a result of venting, and – hopefully – reveal something of the nature of the upper limits of the liquid water ocean sitting under the lowest extent of the ice, between it and Europa’s rocky mantle.

Whilst it has launched some 18 months after ESA’s JuICE (Jupiter Icy Moons Explorer – see: Space Sunday: a bit of JUICE, a flight test & celebrating 50) mission, Europa Clipper will arrive in Jupiter orbit more than a year ahead of it by virtue of being launched atop a more powerful launch vehicle. In doing so, it will take over from the Juno mission as NASA’s lone research spacecraft orbiting Jupiter (the Juno mission is expected to come to an end in September 2025, the vehicle having exhausted the vast majority of its propellants, leaving only sufficient for it to make a controlled entry into Jupiter’s upper atmosphere and burn-up).

During its fly-bys of Jupiter, the Juno spacecraft has also been able to study the Galilean moons as well, and while the mission’s overall science goals have been very different to those of the Europa Clipper and JuICE missions, they are nevertheless somewhat foundational, helping both NASA and ESA better understand the environment in preparation for JuICE and Europa Clipper. Once both craft are in orbit around Jupiter, the respective science teams will work closely together, JuICE being tasked with studying Europa as well as the other two potentially water-bearing moons of Jupiter, Ganymede and Callisto.

In all, should the October 10th launch opportunity be missed (e.g. due to weather), the Europa Clipper launch window will remain open for a further 20 days.

Vulcan Triumphs despite SRB Anomaly

United Launch Alliance (ULA) completed the second launch of its new Vulcan Centaur rocket on Friday, October 4th, and despite a significant issue with one of its Northrop Grumman GEM-63XL solid rocket boosters (SRBs), the vehicle went on to ace the flight.

Vulcan Centaur is a ULA’s replacement for both the veritable Atlas and Delta families of launchers, and like them it is currently fully expendable. I covered its successful maiden flight for the vehicle, sending the ill-fated private lunar lander Peregrine One by in January 2024 (see: Space Sunday: lunar losses and delays; strings and rings). Following that flight, ULA had hoped to launch Vulcan again in April 2024, carrying aloft Tenacity the first of the Dream Chaser cargo space planes being developed by Sierra Space; however, delays with Tenacity’s final preparations now means this launch has been pushed back until at least March 2025. Instead, ULA decided to go ahead with flight designed to certify it for DoD launches, using a payload mass simulator in place of an actual payload.

Launch came at 11:25 UTC on October 4th, the vehicle lifting-off from Launch Complex 41 (SLC-41) at Cape Canaveral Space Force Station in after around a 30-minute delay. After clearing the tower, it became obvious that the right-side GEM-63XL booster was suffering an anomaly: the exhaust plume was broader than it should have been and it appeared that ignited propellants might have been escaping the SRB just above the engine bell.  Then, roughly 37 seconds into the launch as the vehicle was about to commence its roll programme to pitch itself out over the Atlantic, and just before passing through clouds, the base of the right-side SRB disintegrated.

On emerging from the cloud, cameras revealed the damaged SRB now had a very “off-nominal” exhaust plume, with pieces falling away as the launch vehicle continued its ascent. And here is where the overall robustness of the GEM-63XL came into play and the superb flight avionics and capabilities of the Vulcan Centaur were demonstrated. Rather than simply unzipping and exploding, taking out the entire rocket, as might reasonably be expected with the rocket was entering and passing through “max Q”, the period when it faces the maximum dynamic stresses imposed on its structure during ascent, the GEM-63XL held together and continued to provide at least some semblance of thrust all the way up to the engine cut-off point.

Meanwhile, the Vulcan Centaur sense the asymmetric thrust pushing it off of its flight trajectory and commenced compensating for it by gimballing the two Blue Origin BE-4 engines of the first stage and adjusting their thrust. At the same time, the vehicle started looking downrange and recalculating flight parameters in order to achieve a successful orbital insertion for its upper stage and payload. This entirely automated response also included calculating the likely drop-zone for the two SRBs following separation as a result of the off-nominal performance of the right side SRB.

This actually resulted in the rocket “holding on” to the two SRBs for 20 seconds beyond their expected release time. In doing so, this pretty much ensured both SRBs had sufficient upward momentum to complete their ballistic trajectory and then fall back to the Atlantic Ocean without exceeding any downrange parameters. Similarly, the rocket performed a recalculation of the required burn time on its main engines, and for the same reason.

Thus, the two BE-2 motors ran for an additional 6-7 seconds beyond their designated cut-off time. This was enough to ensure the Centaur upper stage received the kick it needed and the first stage to also remain within the parameters of its specified descent trajectory into its targeted (and shipping-free) splashdown area. Once separated, the Centaur stage was able to light its motor and go on to deliver its mass simulator almost exactly in the centre of the “bull’s-eye” of its intended orbital track.

And that is a remarkable success, all things considered. Sadly it did not stop some SpaceX cultists proclaiming FAA “bias” against SpaceX because a) Vulcan has not been “grounded” following the “failure” and b) the FAA signalled no requirement for a Mishap investigation on the grounds that, despite the SRB issue, the vehicle performed precisely as called for within its flight plan, and at no time exceeded the limits of it launch license.

Obviously, the GM-63XL failure needs to be thoroughly investigated by Northrop Grumman (potentially with FAA oversight) and the causes understood together with any significant issues – if found – rectified.  However, this in itself require a “grounding” of Vulcan Centaur nor does it illustrate any kind of “bias” towards SpaceX on the part of the FAA. Why? Firstly, because the conflict between SpaceX and the FAA relate pretty much to the later exceeding the limitations imposed in the launch licenses issued to it by the latter. That’s not the case with the Vulcan Centaur flight.

More to the point, Vulcan Centaur’s launch cadence is fairly relaxed; the next launch will not occur until mid-November, for example. Ergo, there is more than enough time for the SRB issue to be investigated and a decision taken as to whether there is any kind of fault endemic to the GEM-63XL which precludes further Vulcan Centaur launches until such time as the problem has been rectified, and without the need for the FAA weigh-in on the matter pre-emptively.

Voyager 2 Loses Further Science Instrument

The two Voyager mission spacecraft have been hurling themselves away from Earth since their launches in 1977. In doing so, they are the first human-made craft to reach interstellar space, and are truly voyaging into the unknown. But even though both are powered by three radioisotope thermoelectric generators (RTGs) – essentially “nuclear batteries” generating electricity through the decay of plutonium 238 – their ability to produce the electricity they need to operate is constantly declining.

At launch the three RTGs on each of the Voyager vehicles generated some 470 watts of electrical power on a continuous basis. However, by 2011, that had been reduced to just 268 watts per vehicle. To combat the loss of electricity production NASA has, since 1998, been gradually turning off systems and instruments that are no longer essential to either vehicle’s mission.

For example, in 1998, NASA turned off the imaging system on the two spacecraft because the amount of light reaching them was insufficient for them to be able to produce meaningful images. Over time, this policy has continued to the point were, at the start of October 2024, of the 11 instruments aboard each of the vehicles, Voyager 1 had just four operating and Voyager 2 had just five, all dedicated to examining the interstellar space through which both vehicles are travelling.

However, on October 2nd, 2024, NASA announced that a further instrument on Voyager 2, the Plasma Spectrometer, has now been turned off, again to meet the dwindling amount of energy the RTGs are producing. This means that both craft are now operating the same four instruments each, allowing for solid comparative science to be carried out as they continue to move out into interstellar space. These instrument comprise a magnetometer gathering data on the interplanetary magnetic field; a low energy charged particle instrument for measuring the distributions of ions and electrons in the interstellar medium; a cosmic ray system that determines the origin of interstellar cosmic rays; and a plasma wave detector.

Unfortunately, overall power issues mean that the rate at which instruments must be turned off is likely to accelerate over the next few years, and that by 2030 it is likely the last science instrument on both Voyagers will be turned off, although there may be sufficient power for the communications systems to continue to transmit system reports beyond that, if NASA opt to allow them. But even if this is the case, by 2036, the signals from the two spacecraft will be so weak, they will not be heard by facilities on Earth.

But the loss of communications, when it eventually comes, will not be the end of the voyage for either of the spacecraft: in 300 years they should reach the “inner edge” of the theorised Oort cloud. It will take each of them some 30,000 years to cross it and arrive at the cosmographic boundary of the solar system. Ten thousand years after that, Voyager 2 will pass “just” 1.7 light-years away from the first star relatively close to its trajectory since departing the Sun: Ross 248. At roughly the same time, Voyager 1 will pass within 1.6 light-years of the star Gliese 445.

If you want to keep abreast of the Voyager mission status then check the official “where are they now” page for the mission.