Category: Other Worlds and Tech

Russia’s uncrewed Soyuz MS-23 launched for the International space station on February 24th, 2023, on its way to replace the Soyuz MS-22 vehicle struck by a major coolant leak in December 2022, leaving it incapable of returning crew members Sergey Prokopyev, Dmitri Petelin and Frank Rubio to Earth as planned at the end of their 6-month rotation.

Due to the lack of any return capability, NASA and Roscosmos had worked on an emergency scenario whereby the Soyuz seat for Rubio had been transferred to Crew Dragon Endurance to allow his return with the 4-person members of NASA’s Crew 5 in the event of an emergency evacuation being called for ahead of MS-23’s arrival; the theory being that this would reduce the heat load in the Soyuz return capsule, allowing Prokopyev and Petelin to survive a return to Earth in that vehicle.

Having arrived at the ISS on February 25th, the crew started work in off-loading the ~430 kg of cargo MS-23 carried to the ISS and then moving the flight seats for the MS-22 crew into the newly-arrived Soyuz. It is not clear when MS-22 will be undocked from the ISS to attempt an automated return to Earth; however, its crew will now spend almost a year in space, as MS-23 will not make a return to Earth until September 2023, giving Roscosmos time to completely reshuffle crew rotations.

In the meantime, NASA’s Crew 6 mission launched from Kennedy Space Centre on March 2nd, aboard SpaceX Crew Dragon Endeavour delivering NASA astronauts Stephen Bowen and Warren Hoburg, cosmonaut Andrey Fedyaev and Emirati astronaut Sultan Alneyadi to the space station on March 3rd, after a one-hour delay in docking whilst a faulty sensor on the docking system was corrected.

Bowen is due to take over the role of ISS commander from Prokopyev, marking the start of NASA Crew Rotation 69. Following handover, the Crew 5 mission, comprising NASA astronauts Nicola Mann and Josh Cassada, together with JAXA astronaut Koichi Wakata and cosmonaut Anna Kikina (the first Russian to fly a US commercial crew programme flight, and the first Russian to fly on a US spacecraft since 2002) will depart the ISS aboard Endurance for Earth, possibly around March 8th.

Crew 6 almost marks the last flight of Crew Dragon under the initial contract between NASA and SpaceX which pegged launch fees at US $220 million / US$55 million per seat.  From the August Crew 7 launch through until Crew 14 (~2028), SpaceX Crew Dragon flights will average US $288 million / US $72 million per seat.

Giving the Moon its Own Time Zone

A human return to the Moon and the potential for establishing a permanent presence there involves many things. Most of the time, efforts are focused on the technologies required: launch and landing systems, communications system, life support, etc. However, one thing people likely do not consider is the matter of how time will be kept.

Until now, missions to the Moon have operated on a time frame based on their country of origin, with their onboard chronometers synchronised with terrestrial time. However, this will not work going forward, when there will be multiple missions – crewed and robotic – operating on and around the Moon.

To facilitate these missions, NASA and the European Space Agency (ESA) are developing new orbital services such as the Lunar Communications Relay and Navigation System and Moonlight, both of which might be thought of a combination of communications as GPS data services such as the US GPS and European Galileo systems.

The latter have their own timing systems, but they possess offsets relative to one another of just a few billionths of a second, allowing them to operate on concert. In particular, they are fixed to the Universal Coordinated Time (UTC) global standard, which is also used by the internet and aviation, as well as scientific experiments that require highly precise time measurements. This allows both networks to remain fully in synch with one another and with ground-based units.

Having a universal time standard for the Moon and cislunar space is important because clocks run slower on the Moon’s surface than on Earth by 56 millionths of a second per terrestrial day, whilst clocks placed in different orbits around the Moon will run at different rates to one another and those on the lunar surface. Over time, this can result in communications and data errors to be introduced, so having a singular reference point – time zone – unique to lunar operations is essential for such time-keeping and allowing for things like accurate navigation across the surface of the Moon and when in orbit around it.

To this end, and following meetings hosted by ESTEC, the European Space Research and Technology Centre, space organisations such as NASA, ESA and JAXA, have agreed to develop LunaNet. Based on the core concepts of GPS and Galileo, LunaNet is intended to provide a set of mutually agreed-upon standards, protocols and interface requirements for inter-operability between multiple space and surface units operating around on the Moon, all utilising the same time standard.

Exactly how this standard will be defined and will be responsible for maintaining it or what it should be called has yet to be determined. UTC, for example, is not maintained by any one nation, but by the intergovernmental International Bureau of Weights and Measures (IBWN) based in Paris, France. One suggested name for the new time zone is “selenocentric reference frame” (SRF), which doesn’t exactly roll off the tongue. It has also yet to be decided whether or not it should be synchronised with time zone on Earth. However, as a necessary requirement, developing and defining it could help with future deep-space missions.

UK Treated to Almost Nationwide Auroral Display

On February 24th and again of February 25th, the Sun gave off a pair of coronal mass ejections (CMEs) – massive eruptions of material throwing billions of tonnes of energetic material from the corona and free of the Sun’s gravity well. CMEs are a common event and can move in any direction relative to the Sun. As it so happened, this pair fired Earthward, travelling at around 3 million km/h, each arriving at a time when they were ideal viewing in the evening skies over the UK.

After a journey of 150 million km, the material from the first CME slammed into the Earth’s magnetosphere over an UK just settling down for a quiet evening under clear skies on Sunday, February 26th. The result was a sizeable geomagnetic storm in which electrons in the magnetosphere were accelerated into the atmosphere by the blunt force of the CME material, sparking intense auroral displays which rapidly spread far further south than is usually the case, giving people across Britain with a glorious display.

Twenty-four hours later, the second CME struck, this time coinciding with lunchtime in the UK and largely overcast skies. However, such was the nature of the resultant geomagnetic disturbance, coming hard on the heels of the first, resulted in a second extensive auroral display which was still visible  in the evening across many parts of the UK as the skies darkened – and the weather cleared again.

Continue reading “Space Sunday: ISS, a lunar time zone and an aurora” →

International work on near-Earth asteroid detection systems is again ramping up as, coincidentally, a very small asteroid caused a stir in northern Europe and the UK.

2023 CX₁ (originally known as Star2667 prior to its impact) was broadly similar in nature to the type of object such systems would attempt to seek out, in that it was entirely unknown to astronomers the world over until a mere seven hours before it entered Earth’s atmosphere on February 13th, 2023. Fortunately, it was small enough and light enough – estimated to be around 1 metre across its largest dimension and weighing about 1 kilogramme – to pose no direct threat, although its demise was seen from France, the southern UK, Belgium, The Netherlands and northern Spain.

Thus far, over 30,600 asteroids and comets of various classes have been identified as having some risk of striking Earth’s atmosphere, with around 8% know to be of a size (+100m across) large enough to result in significant regional damage should it to so. However, even asteroids and comet fragments of just 20-40m across could cause considerable damage / loss of life were one to explode in the atmosphere over a population centre, whilst the total number of potential threats remains unknown.

A major problem in identifying these objects from Earth’s surface using visual or infra-red means is that the Sun tends to sharply limit where and when we can look for them, whilst radar has to be able to work around 150,000 satellites and all debris and junk we have put in orbit (excluding military satellites and “constellations” of small satellites such as SpaceX Starlink and OneWeb).

To bypass such problems, the European Space Agency plans to deploy NEOMIR, the Near-Earth Object Mission in the Infra-Red, a spacecraft carrying a compact telescope and placed at the L1 Lagrange point between Earth and the Sun (where the gravitational attraction of the two essentially “cancel each other out”, making it easier for a craft occupying the region to maintain its position). From here, Earth and the space around it would be in perpetual sunlight and the Sun would be “behind” the satellite, meaning that any objects in orbit around Earth or passing close to it will also be warmed by the Sun (and so visible in the infra-red), whilst sunlight would not be able to “blind” the satellite’s ability to see them.

The half-metre telescope carried by NEOMIR will be able to identify asteroids as small as 20m in size, and would generally be able to provide a minimum of 3 weeks notice of a potential impact with Earth’s atmosphere for objects of that size (although under very specific edge-cases the warning could be as little as 3 days), with significantly longer periods of warning for larger objects.

Currently, NEOMIR is in the design review phase, and if all goes well, it will be launched in 2030. In doing so, it will help plug a “gap” in plans to address the threat of NEO collisions with Earth: NASA’s NEO Surveyor mission, planned for launch in 2026, will also operate from the L1 position – but is only designed to spot and track objects in excess of 140m in diameter. Thus, NEOMIR and NEO Surveyor will between them provide more complete coverage.

At the same time as an update on NEOMIR’s development was made, China announced construction of its Earth-based Fuyan (“faceted eye”, but generally referred to as the “China Compound Eye”) radar system for detecting potential asteroid threats is entering a new phase of development.

The first phase of the system – comprising four purpose-built 16m diameter radar dishes – was completed in December 2022 within the Chongqing district of south-west China. Since then, the system has been pinging signals off of the Moon to verify the  system and its key technologies.

The new phase of work will see the construction of 25 radar dishes of 30m diameter, arranged in a grid. When they enter service in 2025, they will work in concert to try to detect asteroids from around 20-30m across at distances of up to 10 million km from Earth, determining their orbit, composition, rotational speed, and calculate possible deflections required to ensure any on a collision course with Earth do not actually strike the atmosphere.

As this second phase of Fuyan is commissioned, a third phase of the network will be constructed to extend detection range out to 150 million km beyond Earth. At the same time, China is planning to run its own asteroid deflection test similar to the NASA Double Asteroid Redirection Test mission, although the precise timeline for this mission is not clear.

In the meantime, 2023 CX₁ was of the common type of near-Earth asteroids to regularly strike Earth’s atmosphere (at the rate of one impact every other week). It was discovered by Hungarian astronomer Krisztián Sárneczky, at Konkoly Observatory’s Piszkéstető Station within the Mátra Mountains, less than 7 hours before impact.

At the time of its discovery it was 233,000 km from Earth (some 60% of the average distance between Earth and the Moon), and travelling at a velocity 9 km per second. It took Sárneczky a further hour to confirm it would collide with Earth, marking 2023 CX₁ as only the 7th asteroid determined to be on a collision with Earth prior to its actual impact.

The object – at that time still designated Star2667 – was tracked by multiple centres following Sárneczky’s initial alert, allowing for its potential entry into and passage through the upper atmosphere to be identified as being along the line of the English Channel, close to the coast of Normandy. It was successfully tracked until it entered Earth’s shadow at around 02:50 UTC on February 13th, just 9 minutes before it entered the upper atmosphere

As both the media and public were alerted to the asteroid’s approach, it’s demise was caught on camera from both sides of the English channel. It entered the atmosphere at 14.5 km/s at an inclination 40–50° relative to the vertical. As atmospheric drag increased, it started to burn up at an altitude of 89 km, becoming a visible meteor. At 29 km altitude it started to fragment, completely breaking apart at 28 km altitude as a bright flash as its fragments vaporised, finally vanishing from view at 20 km altitude, although meteorites fell to Earth in a strewn field spanning Dieppe to Doudeville on the French coast, sparking a hunt for fragments to enable characterisation of the object.

At the time of flash-fragmentation, the object released sufficient kinetic energy to generate a shock wave which was heard by people along the French coast closest to the path of the meteor and recorded by French seismographs.

Following its impact, study of 2023 CX₁ s orbital track revealed it to be an Apollo-type asteroid, crossing the orbits of Earth and Mars whilst orbiting the Sun at an average distance of 1.63 AU with a period 2.08 years. It last reached perihelion on 13th February 2021, ad would have done so again on March 15th, 2023 had it not swung into a collision path with Earth in the interim.

Continue reading “Space Sunday: asteroid impacts; ISS update” →

SpaceX has completed the largest static fire test for this Starship / Super Heavy launch system, with the 70-metre tall Booster 7 – expected to be part of the first orbital launch attempt – completing a “full duration” 5-7-second test of 31 of its 33 Raptor 2 engines.

The test was made on Thursday, February 9th, amidst on-going work at the orbital launch facilities at the company’s Boca Chica, Texas Starbase site. It had been intended to be full 33-engine test, but one engine was “turned off” during a pause in the countdown at the T -40 second mark, presumably due to an issue being detected, and a second automatically shut down at, or immediately following, ignition.

Even so, the burn was enough for the SpaceX CEO to proclaim the 31 firing engines developed sufficient thrust that, if sustained throughout an 8-minute ascent, it would be enough for Super Heavy to push a fully laden Starship to an altitude where it could reach orbit under the thrust of its six engines.

Ignition came at 21:13:53 UTC, after a partial filling of the booster’s liquid methane and liquid oxygen tanks – Starship 24 had already been destacked from the booster earlier in the month, leaving just the booster on the launch table. Everything appeared to go well, with SpaceX afterwards reporting the engines reached a peak thrust of 7,900 tonnes, or almost twice that generated by the Space Launch System Block 1/1A launcher, and 3,000 tonnes more than the Block 2 SLS cargo launcher.

However, such comparisons need to be put into context: Super Heavy must lift 1200+ tonnes of Starship to low-earth orbit (LEO), carrying 100 tonnes of cargo. SLS is already capable of lifting 95 tonnes of payload to LEO if required, which will increase to 105 tonnes and then 130 tonnes. It is also capable of delivering 27 tonnes to cislunar space, which will increase up to 46 tonnes. The flipside is that Starship and its booster are fully reusable, lowering launch costs; SLS is not. Also, if the booster is not re-used, they Starship could in theory life up to 250 tonnes to LEO; conversely, SLS can reach cislunar space, whereas Starship cannot, not without a complex series of on-orbit refuelling operations.

The test came after extensive work had been carried out at the launch facility after the first two Super Heavy static fire tests (with 7 and 14 Raptor motors respectively) literally stripped the concrete from the base of the launch stand, peppering the launch mount and its surroundings with high velocity cement debris and necessitating extensive repairs to the site.

The problem was one of basic engineering (and frankly, something SpaceX should have considered): the launch table legs and apron underneath the rocket are coated in concrete. A key ingredient of concrete is water, some of which is retained in the concrete as pockets of moisture. Heat concrete to 600°C or more, that moisture flash vaporises into expanding gases, causing the concrete to violently explode.

As I’ve previously noted, this risk is usually negated by the inclusion of a water deluge system which delivers thousands of litres of water to a launch facility, serving a dual purpose: it both absorbs the enormous heat generated by multiple rocket motors by flashing into stream by the force of that exhaust, and it also absorbs the sound waves generated by the motors, further preventing that sound being deflected back up against the rocket and potentially damaging it at launch.

Following the 14-engine test, SpaceX replaced the concrete at the launch facilities with a type designed to withstand very high temperatures. At the time of writing, it is not clear how well this mix withstood the engine test, however the test came at a time when SpaceX is – belatedly – attempting to install a water deluge system to work alongside the existing (and minimal) sound suppression system already part of the launch table.

Many – including the SpaceX CEO – are proclaiming the way is now clear for an orbital launch attempt to be made in March. However, this actually depends on a number of factors – the most key of which is whether or not the FAA is satisfied that SpaceX has done / is doing enough to ensure its compliance with all 75 remedial actions specified in its Programmatic Environmental Assessment (PEA).

NASA Tests Upgraded RS-25 Motor

The SpaceX static fire test overshadowed NASA’s test of its updated RS-25 engine for the Space Launch System.

The initial four SLS launches utilise a total of 16 refurbished RS-25 motors originally used with the space shuttle system and referenced as the RS-25D. However, beyond Artemis 4, NASA will be switching to a version of the RS-25 which has been extensively updated. Called the RS-25E, it will deliver 30% more thrust; allowing SLS achieve the upper end of its payload capabilities noted above.

The test, which took place at NASA’s Stennis Space Centre in Mississippi, saw a test stand mounted RS-25E motor fire at 111% of its rated thrust for a total of 8.5 minutes – the amount of time the engines would be used in an actual launch.

The RS-25E will commence operations with the Artemis 5 mission in 2028. They will operate alongside the new Exploration Upper Stage (EUS) which will also help raise the SLS system’s performance. EUS itself will entire service with Artemis 4.

Image of the Week

The image below is a computer-generated top-down view of Jupiter and the orbits of its (currently) 92 moons. At the centre of the image is Jupiter and (purple) the orbits of its four most famous Galilean moons – Io, Europa, Ganymede and Callisto. Beyond them, predominantly shown in red, are the remaining 88 moons.

Until recently, Saturn held the record for the greatest number of moons (82), the majority of which (43) have been discovered by a team led by astronomer Scott Sheppard. However, Sheppard’s team have also been busy over the years seeking moons orbiting Jupiter – racking up and impressive 70, including the most recent batch of 12 which handed the moon record back to the largest planet in the solar system.

The newest moons were discovered over a period of observations by Sheppard and his team using a number of observatories around the world across 2021 and 2022. They range in size from 1 to 3.2 km across. Most have very large orbits, with nine having periods of more than 550 days. None have been named as yet, as all are awaiting further independent verification.

Continue reading “Space Sunday: rockets, moons, leaks and a ring” →

In my previous Space Sunday, I covered some of the renewed interest in nuclear propulsion for space missions – and it certainly is a hot topic (no pun intended). Just 24 hours after that article was published, NASA and the US Defense Advanced Research Projects Agency (DARPA) announced they had signed an interagency agreement to develop a nuclear-thermal propulsion (NTP) concept.

Referred to as the Demonstration Rocket for Agile Cislunar Operations (DRACO), the three-phase programme will look to develop and enhance an NTP propulsion system capable of operating between Earth and the Moon and eventually Earth and Mars, potentially enabling fast transit times to the latter measured in weeks rather than months. Nor is this simply a computer modelling exercise: the agencies plan to fly a demonstrator of the propulsion unit in early 2027.

As I noted in my previous piece, NTP uses a nuclear reactor to heat liquid hydrogen (LH2) propellant, turning it into ionized hydrogen gas (plasma) channelled through engine bells similar to those seen in chemical rockets to generate thrust. As I also noted, NTP for space vehicle propulsion is not new; both the US and the former Soviet Union both pursued NTP projects in the early days of the space race – most notably for the US with the Nuclear Engine for Rocket Vehicle Application (NERVA) project, successfully tested on the ground in 1963/64.

Per the agreement, NASA’s Space Technology Mission Directorate (STMD) will lead the technical development of the nuclear thermal engine, which will be integrated into a vehicle built by DARPA, with that agency leading the overall programme as the contracting authority. Both agencies will collaborate on the overall design of the engine.

DARPA and NASA have a long history of fruitful collaboration in advancing technologies for our respective goals, from the Saturn V rocket that took humans to the Moon for the first time to robotic servicing and refuelling of satellites. The space domain is critical to modern commerce, scientific discovery, and national security. The ability to accomplish leap-ahead advances in space technology through the DRACO nuclear thermal rocket program will be essential for more efficiently and quickly transporting material to the Moon and eventually, people to Mars.

– DARPA director Dr. Stefanie Tompkins

Meanwhile, on January 27th, 2023, the UK’s famed Rolls Royce teased details of its own foray into the space-based nuclear power / propulsion systems: the micro-nuclear reactor (MNR), an extremely robust, self-contained nuclear fission plant which could be used to supply power to bases on the Moon or Mars, or used as a core element in vehicle propulsion systems either individually or as multiple units to provide both thrust and system redundancy, if required.

Development of the MNR started as a result of a 2021 agreement between the United Kingdom Space Agency (UKSA) and Rolls Royce (RR) to study future nuclear power options in space exploration. However, the design for the unit builds on RR’s decades-long expertise in developing power plants for the Royal Navy’s nuclear submarine squadrons and, more particularly a project the company has been developing since 2015 to develop and build small modular reactor (SNRs) to meet the UK’s energy needs (SNRs are self-contained, less complex and lower cost alternative to current nuclear reactors).

Precise details of the size of the unit and its output have not been revealed, although images released by RR suggest a single MNR is around 3 metres in length. In discussing the system, the company indicated its designs have reached a point where it plans to have a full-scale demonstrator / prototype running by 2028.

The MNR forms a part of a broader space strategy from Rolls Royce, which also includes systems for high Mach propulsion systems (e.g. ramjets) which could be combined with rocket propulsion to reach orbit, and a new generation of radioisotope thermal generators (RTGs) for power generation on robotic explorer craft and surface system on the Moon and Mars. The overall aim of the strategy is to offer space agencies and the private sector the ability to easily integrate selected elements of RR’s product offerings into their space projects and programmes.

Returning to NASA, as well as considering the nuclear option, the US agency has been researching the next generation of rocket engines – the rotating detonation rocket engine (RDRE) – and on January 24th, carried out a series of sustained ground tests of a prototype unit.

In a conventional rocket motor, fuel is expended by deflagration combustion – fuel and oxidiser are burnt to produce an energetic gas flow which is then directed through exhaust bells to generate subsonic thrust. With rotating detonation, fuel and oxidiser are injected into a circular channel (annulus). An igniter within the annulus then detonates the initial incoming mix, generating a shockwave which travels around the channel, returning to the point of injection.

At this point, more fuel is injected into the channel to be detonated by the existing shockwave. This increases the shockwave’s speed and force, and the cycle repeats over and over, the shockwave accelerating to supersonic speed, generating high pressures which can be constantly be directed out of the channel to form thrust through an exhaust system even as the shockwave maintains its momentum within the channel.

Whilst this may sound complicated, the upshot is that rotating detonation engines (RDREs) theoretically generate around 25% more thrust than conventional rocket motors, which directly translates to greater delta-V being imparted to vehicles departing Earth, so reducing flight times to the Moon and Mars and elsewhere in the solar system. RDEs could also be inherently less complex than subsonic brethren, reducing the mass of a launch vehicle’s propulsion system.

However, there are drawbacks; for example, the very nature of containing the growing force of the shockwave puts an RDRE under tremendous stress and they have been known to explode. They are also incredibly noisy when built at scale.

Both Russia and Japan have experimented with RDRE technology; in 2018, former Roscosmos chief Dmitry Rogozin claimed Russia had successfully developed the first phase of a 2-tonne class of liquid-fuelled RDRE, although this has yet to be substantiated. In 2021, Japan successfully tested a small-scale (112.4 lbf) RDRE in space, using it to propel the upper stage of a sounding rocket.

The NASA test, carried out at the Marshall Space Flight Centre, Alabama, is the first verified test of a full-scale RDRE. The demonstrator motor operated for a total of 10 minutes, reaching peak thrusts of some 4,000 lbf. This is fairly lightweight by rocket standards, but the aim of the test was not just to generate thrust, but to test the engine’s ability to withstand multiple firings and confirm that a copper alloy referred to as GRCop-42 developed by NASA specifically for use in RDRE engines, was up to the task of reducing the stress on the motor by more efficiently carrying the heat generated by the shockwave away from the annulus structure.

While tests with this motor will continue, NASA is now also moving to the construction of a large unit capable of a sustained 10,000 lbf – the same as mid-range rocket motors – to better understand the potential for RDREs to out-perform “traditional” rocket motors. If successful, it could pave the way for RDRE motors capable of match the output of large-scale engines like the RS-25 used by the Space Launch System (SLS) rocket (418,000 lbf).

Continue reading “Space Sunday: propulsion, planets and pictures” →