Space Sunday: of moons and Mars

The Artemis 2 mission profile. Credit: Canadian Space Agency (CSA)

NASA has announced that Artemis 2 – the first mission of the programme to send a crew to cislunar space – is now targeting a launch for the period between February 5th, 2026 and the end of April 2026.

The 10-day mission will carry a crew of four – three Americans and one Canadian – to the vicinity of the Moon and then back to Earth aboard an Orion Multi-Purpose Crew Vehicle (MPCV) in what will be the final test of that vehicle and its systems, together with the second flight of NASA’s Block 1 Space Launch System (SLS) rocket. The latter – SLS – is currently undergoing the final steps in its assembly process. Earlier this year the core and upper stages of the rocket were stacked at Kennedy Space Centre’s Vehicle Assembly Building (VAB), where the two solid rocket boosters also stacked within the VAB were then attached to either side of the rocket’s core stage.

Meanwhile, and as I noted in August 2025, the Orion vehicle for the mission, together with its European-built Service Module, moved from NASA’s Multi-Payload Processing Facility (MPPF) to the Launch Abort System Facility (LASF), where it is being mated with its launch abort system tower. Once completed, the combination of Orion and launch abort system will be transferred to the VAB for installation on the SLS vehicle.

Two images of NASA engineers installing the Orion Stage Adapter  (just visible, top left) onto the the top of the mission’s SLS launch vehicle, inside the High Bay of the Vehicle Assembly building (VAB), Kennedy Space Centre, September 2025. Credit: NASA

To this end, at the end of September 2025, NASA integrated the Artemis 2 Orion Stage Adapter with the rest of the SLS system. As its name suggests, the Orion Stage Adapter is the element required to mate Orion to the launch vehicle. In addition, the adapter will be used to deploy four CubeSats containing science and technology experiments into a high Earth orbit after Orion has separated from the SLS upper stage and is en route to the Moon.

Also at the end of September, the four crew due to fly the mission – Reid Wiseman (mission commander), Victor Glover, and Christina Koch all from NASA, and Canada’s Jeremy Hansen – revealed the name they had chosen for their Orion capsule: Integrity.

A couple months ago, we thought, as a crew, we need to name this spacecraft. We need to have a name for the Orion spacecraft that we’re going to ride this magical mission on. And so we got the four of us together and our backups, Jenny Gibbons from the Canadian Space Agency and Andre Douglas from NASA, and we went over to the quarantine facility here, and we basically locked ourselves in there until we came up with a name.

– Artemis 2 mission commander, Reid Wiseman

The Artemis 2 crew (l to r: Canadian Space Agency astronaut Jeremy Hansen and NASA astronauts Christina Koch, Victor Glover, and Reid Wiseman) outside the Astronaut Crew Quarters inside the Neil Armstrong Operations and Checkout Building during an integrated ground systems test at Kennedy Space Centre, September 20th, 2023. Credit: Kim Shiflett

Integrity will be the second Orion capsule to join NASA’s operational fleet, the first being the still unnamed craft flown during the uncrewed Artemis 1 mission in 2022. That mission revealed an issue with the initial design of the vehicle’s re-entry heat shield, which received more and deeper damage than had been anticipated (see: Space Sunday: New Glenn, Voyager and Orion). This delayed Artemis 2 in order for investigations into the cause to take place and solutions determined.

In short: a return from the Moon involves far higher velocities than a return from Earth orbit (entering the atmosphere at 40,000 km/h compared to 28,000 km/h), resulting in far higher temperatures being experienced as the atmosphere around the vehicle is super-heated by the friction of the vehicle’s passage through it, further leading to increased ablation of the heat shield. This could be offset by using a very substantial and heavy heat shield, but as Orion is also intended to be launched on vehicles other than SLS and for other purposes (e.g. just flying to / from low Earth orbit), it is somewhat mass-critical and in need of a more lightweight heat shield.

As a result, rather than making a single plunge back into Earth’s atmosphere at the end of lunar missions, Orion was supposed to perform a series of initial “skips” or “dips” in and out of the denser atmosphere. These would allow the vehicle bleed-off velocity ahead of a “full” re-entry whilst also reducing the amount of plasma heating to which the ablative material of the heat shield would be exposed.

However, post-flight analysis of the heat shield used in the Artemis 1 mission of 2022, it was found that the heat shield had suffered extensive and worryingly deep material loss – referred to as “char loss”, resulting in a series of deep pits within the heat shield. Investigation revealed the cause of this being the initial “skips” the vehicle made into and out of the denser atmosphere.

While these “skips” did indeed reduce the load on the outer layers of the heat shield, they also had the unintended impact of heating-up gases trapped inside the ablative layers of the heat shield during its construction, causing the underlying layer of the material in the heat shield to expand and contract and start to crack and break. They, when the capsule entered its final plunge through the atmosphere prior to splashdown, the material over these damaged areas ablated away as intended, exposing the damaged material, which then quickly broke-up to leave the pits and holes.

Two of the official NASA images showing the severe pitting and damage caused to the Orion heat shield following re-entry into Earth’s atmosphere at the end of the uncrewed Artemis 1 mission, December 11th, 2022. Credit: NASA / NASA OIG

To mitigate this, Artemis 3 and 4 will fly with a redesigned heat shield attached to their Orion capsules. However, Artemis 2 will fly with the same design as used in Artemis 1, but its re-entry profile has been substantially altered so it will carry out fewer “skips” in and out of the atmosphere before the final entry, and will do so at angles that will reduce the amount of internal heating within the heat shield layers.

Ahead of its launch, the complete Artemis 2 launch vehicle and payload should be rolled-out from the VAB to the launch pad early in 2026. It will then go through a series of pre-flight demonstration tests, up to and including a full “wet dress rehearsal”, wherein the rocket will be fully fuelled with propellants and go through a full countdown and lunch operation, stopping just short of actually igniting the engines. These test will then clear the way for the crewed launch.

Flying over Mars with Mars Express

When it comes to exploring Mars, NASA understandably tends to get the lion’s share of attention, simply by volume of its operational missions on and around the Red Planet. However, they are far from alone; Mars is very much an international destination, so to speak. One of the longest continuous missions to operate around Mars, for example, is Europe’s Mars Express mission, an orbiter which has been studying Mars for more than 22 years, marking it as the second-longest running such mission after NASA’s Mars Odyssey mission (now in its 24th year since launch).

During its time in orbit, Mars Express has provided the most complete map of the Martian atmosphere and its chemical composition currently available; produced thousands of high-definition images of the planet’s surface, revealing many of its unique features whilst also helping scientists understand the role of liquid water in the formation of the ancient Martian landscape; acted as a communications relay between other Mars missions and Earth, and it has even studied the innermost of Mars’ two captive moons, Phobos.

An infographic released by the European Space Agency in 2023 to celebrate 20 years of continuous operations by Mars Express around Mars. Credit: ESA

It is through the high-definition images returned by the orbiter that ESA has at times promoted the mission to the general public, notably through the release of galleries of images and the production of detailed “flyover” videos of the planet, revealing its unique terrain to audiences through the likes of You Tube. At the start of October 2025, ESA released the latest of these movies featuring the remarkable Xanthe Terra (“golden-yellow land”). Located just north of the Martian equator and to the south of Chryse Planitia where Viking Lander 1 touched-down on July 20th, 1976, and a place noted for its many indications that water played a major role in its formation.

The images used in the film were gathered using the orbiter’s High Resolution Stereo Camera (HRSC) during a single orbit of the planet. Following their transmission to Earth, these were combined with topography data gathered in the same pass to create a three-dimensional view of a part of the region centred on Shalbatana Vallis, a 1300 km-long outflow channel running from the southern highlands into the northern lowlands on the edge of Chryse Planitia. The film also includes passage over Da Vinci crater. Some 100 km across, this crater is intriguing as it contains a smaller, more recent impact crater within it, complete with debris field.

Uranian Moon Ariel the Latest Moon to have an Ocean?

Jupiter’s Galilean moons of Europa, Ganymede and Callisto, together with Saturn’s Enceladus and Titan are all thought to have (or had) oceans of icy slush or liquid water under their surfaces. In the case of the Galilean moons, the evidence is so strong, Both NASA and ESA are currently sending probes to Jupiter to study them and their interiors. Similarly, the evidence for Enceladus – as I’ve covered numerous times in these pages – having a liquid water ocean under its ice is so powerful that calls for a mission to visit it are equally as strong.

Now Uranus is getting in on the act of having moons with what could be (or could have been) liquid water oceans under their surfaces, the latest contender being Ariel, the planet’s fourth largest and second closest of Uranus’s moons in hydrostatic equilibrium (i.e. largely globular in shape) to the planet, after Miranda.

Measuring just 1,160 km in diameter, Ariel is a comparatively tiny moon and not too much is known about it, other than it its density suggests it is made up of a mix of rock and ice, with a lean towards the latter. It orbits and rotates in Uranus’s equatorial plane, which is almost perpendicular to the planet’s orbit, giving the moon an extreme seasonal cycle. But the most remarkable aspect of  Ariel is its extreme mix of geological structures: massive surface fractures, ridges and grabens – part of the moon’s crust that have dropped lower than its surroundings—at scales larger than almost anywhere else in the solar system.

The southern hemisphere of Ariel as imaged be NASA’s Voyager 2 in 1986, showing some of the extreme surfaces features – graben – along the line of the terminator. Credit: NASA; post-processing clean-up by Kevin M. Gill.

Only one space mission has come close to visiting Ariel. NASA’s Voyager 2 zipped by the moon in 1986 at a distance of 127,000 km. This allowed the probe’s camera system to gather images of around 35% of the moon’s surface that were of sufficient spatial resolution (approx. 2 km) so as to be useful for geological mapping. It has been these images which have allowed a team of researchers led by the Planetary Science Institute and Johns Hopkins University Applied Physics Laboratory to embark on an effort to understand Ariel’s likely interior structure and how its dramatic surface features might have been produced.

First, we mapped out the larger structures that we see on the surface, then we used a computer program to model the tidal stresses on the surface, which result from distortion of Ariel from soccer ball-shaped to slight football-shaped and back as it moves closer and farther from Uranus during its orbit. By combining the model with what we see on the surface, we can make inferences about Ariel’s past eccentricity and how thick the ocean might have been.

– Study co-author  Alex Patthoff, Planetary Science Institute

Captured on July 26th, 2006 by the Hubble Space Telescope, this infrared image of Uranus showing tiny Ariel making a rare visible-from-Earth transit of its parent planet and casting a shadow on Uranus’ upper atmosphere. Credit: NASA / Space Telescope Science Institute

The movement of the moon towards and away from Uranus – its orbital eccentricity –is important, because it represents how much the moon is being affected by different gravitational forces from Uranus and the other four globular moons dancing around the planet. Forces which can causes stresses within the moon which might act as engines for generating the kinds of surface features imaged by Voyager 2.

Overall the team calculate that in the distant past, Ariel’s eccentricity was likely around 0.04. This doesn’t sound much, but it is actually 40 times greater that Ariel’s current eccentricity, suggesting that its orbit around Uranus was once more elliptical than we see today, but over the aeons it has gradually moved toward becoming more circular.

However, and more particularly, an eccentricity of 0.04 is actually four times greater than that of Jupiter’s Europa – a moon in an almost constant state of flux thanks to the gravitational influences of Jupiter and the other Galilean moons that it may well have a deep subsurface liquid ocean kept warm by geothermal venting powered by similar gravitational forces that may have been / are affecting Ariel.

Thus, if Ariel conforms to the Europan model, the team suggest that it could potentially harbour a liquid or semi-liquid water ocean, and that at one time, during the period of greatest orbital stresses, this ocean could have been entirely liquid in nature and some 170 kilometres deep. Such an ocean, the modelling revealed, would be fully capable of helping to produce surface features on Ariel of the same nature as those seen by Voyager 2, thanks to the internal stresses and movement of such a volume of water.

This same team carried out a similar study of tiny (just 470 km in diameter) Miranda. It also has curious surface features, a density suggesting it likely has an icy interior and a position where it is subject to contrasting gravitational forces courtesy of Uranus and the other moons. Applying their modelling to the available images data of Miranda also taken by Voyager 2, the team concluded there is a strong potential that at some point in the past, it may have had a subsurface liquid water ocean, although this may have long since become partially or fully frozen.

The highest-resolution Voyager 2 colour image of Ariel, captured in 1986. Canyons with floors covered by smooth plains – their smoothness believed to be the result of cryovolcanism – are visible at lower right. The bright crater Laica is at lower left. Credit: NASA/JPL

Whether or not either of these tiny moon does have any remaining subsurface liquid water, or whether their interiors have long since frozen, is obviously unknown. The team also admit that their work is entirely based on data gathered by Voyager 2 on the southern hemispheres of Miranda and Ariel; the nature of their northern hemispheres being entirely unknown. As such, a future study on both northern hemispheres might reveal factors and features that could dramatically change our understanding of both moons and their possible formation, and thus change the findings in both studies.

But for the meantime, two more potentially subsurface hycean moons in the solar system can be added to the list of such bodies.

Space Sunday: New Glenn, Voyager and Orion

Blue Origin’s New Glenn first stage rolls past NASA’s Vehicle Assembly Building (VAB) for its first trip to the launch facilities at SLC-36, Cape Canaveral Space Force Station in February 2024. Credit: NSF

In the world of commercial space development, there is a tendency to pooh-pooh the efforts of Blue Origin, the company founded by billionaire Jeff Bezos. This is chiefly done through comparisons with SpaceX, a company which has achieved a lot over the last decade in particular, albeit (and contrary to what SpaceX fans will insist as being the case) largely at the largesse of the US government, from whom the company receives the lion’s share of its revenue.

However, this may all be about to change. Whilst much of the public focus on Blue Origin has been on their sub-orbital New Shepard vehicle catering to the space tourism industry, the company is now gearing-up in earnest for the (somewhat overdue) launch of its massive New Glenn launch system.

Originally targeting a maiden flight in 2020, the 98-metre tall vehicle is now due to launch in November 2024 from Cape Canaveral Space Launch Complex 36. The payload for this mission was to have been NASA’s Mars EscaPADE mission. However, that mission was removed from the flight by NASA over concerns that Blue Origin might miss the required launch window. As a result, the company switched its attention to the second planned flight for New Glenn, a demonstration flight for the United States Space Force’s National Security Space Launch (NSSL) programme, with the payload taking the form of a prototype of Blue Origin’s Blue Ring spacecraft platform.

New Glenn is classified as a heavy lift launch vehicle with a maximum payload capacity to low-Earth Orbit (LEO) of 45 tonnes, with a fully reusable first stage. This compares favourably with Falcon Heavy’s 50 tonnes with all three of its core stages recoverable (although the latter can lift up to 63 tonnes to LEO when all three core stages are discarded).  In addition, New Glenn is designed to deliver up to 13.6 tonne to geostationary transfer orbit (GTO) and up to 7 tonnes to the Moon, as well as the ability to send payloads deeper into the solar system.

As well as the first stage of the rocket being designed from the ground up to be reusable, Blue Origin plan to replace the current expendable upper stage of the system with a reusable stage called Jarvis; however, little has been heard on this front since 2021. If it happens, it will make New Glenn fully reusable.

In September 2024, the company carried out static fire tests of the expendable upper stage of the rocket, and on October 30th, Blue Origin rolled-out the first stage for the maiden launch from its Exploration Park complex at Cape Canaveral Space Force Station for a 37 km, multi-hour road trip to Launch Complex 36 “having to go the long way round” as Dave Limp, Blue Origin’s CEO put it.

The route taken from Blue Origin’s Exploration Park and SLC-36 at Cape Canaveral Space Force Station.

The long journey was the result of the sheer size of the booster and its transporter: a 94.5 metre long behemoth comprising a powerful tractor and two trailers with a total of 22 axles and 176 tyres. Simply put, it’s not the most manoeuvrable transport, with or without a 57.5 metre first stage on its back; as such, the route from factory facility to pad had to reflect this.

The stage in question comprised an engine module which also includes the landing legs, the core tank section and am upper interconnect – the section of a booster onto which the upper stage connects. After being delivered to the vehicle integration facility at SLC-36, Limp confirmed it will be participating in an integrated hot-fire test.

The first stage of the inaugural New Glenn booster rolls into the the vehicle integration facility at SLC-36 on the back of GERT – the Giant Enormous Rocket Transport (yes, really). Credit: Blue Origin

Each New Glenn first stage is designed to be re-used 25 times, with Blue Origin planning a cadence of up to 8 launches per year, and already have a growing list of customers. While this cadence might not sound as extensive as SpaceX and Falcon 9, it should be remembered that the larger percentage of SpaceX Falcon 9 launches are non-commercial / non-government / non-revenue generating Starlink launches; as such, New Glenn’s cadence is potentially in step with the current state of the US commercial and government launch requirements.

As noted, for the inaugural launch, New Glenn will be carrying a prototype Blue Ring satellite platform capable of delivering up to 3 tonnes of payload to different orbits, and capable of on-orbit satellite refuelling (as well as being refuelled in orbit itself) and transporting them between orbits, if required.  It is “launch vehicle agnostic”, meaning it can be flown with payloads aboard any suitable vehicle – New Glenn, Vulcan Centaur, Falcon 9.

An artist’s impression of the Blue Ring space tug. Credit: Blue Origin

The prototype will be flown as the Dark Sky-1 (DS-1) mission, intended to demonstrate the vehicle’s Blue Origin’s flight systems, including space-based processing capabilities, telemetry, tracking and command (TT&C) hardware, and ground-based radiometric tracking in order to prove the craft’s operational capabilities in both commercial and military uses. To achieve this, the vehicle will operation in a medium Earth orbit (MEO), ranging between 2,400 km by 19,300 km.

In addition, the flight will be used to check the New Glenn upper stage’s ability to re-light its motors multiple times. After the launch, the first stage will attempt to make a return to Earth and a landing at sea aboard the company’s Landing Platform Vessel 1 (LPV-1) Jacklyn, as shown in the video below.

The company is targeting the end of November for New Glenn’s inaugural launch. However, given the work still to be completed, it is possible this might slip to December 2024. If successful, the flight will for one of two certification launches for the USSF NSSL programme, both of which are required to clear New Glenn for classified lunches.

As well as these projects – all of which have been directly funded by Bezos himself outside of a modest contract payment made under a Defense Innovation Unit (DIU) payment – Blue Origin is well on the way to developing its Blue Moon Mark 2 lunar lander, capable of supporting up to four astronauts on the surface of the Moon for up to 30 days.

An artist’s impression of the Blue Moon Mark 2 crew lander. Credit: Blue Origin

A cargo variant of the lander, able to deliver between 20 and 30 tonnes (non-reusable) to the lunar surface is also in development. Both versions are intended to be part of NASA’s sustainable lunar architecture to follow the use of the SpaceX HLS vehicle (Artemis 3 and 4). However, there is some speculation that Blue Moon – due to be used with Artemis 5 onwards – is much further along in its development that the SpaceX HLS, and Artemis 5 might fly in the slot in Artemis 3 mission. Time will tell on this as well.

Voyager 1: Communications Issues

I’ve covered the Voyager mission, and its twin spacecraft Voyager 1 and Voyager 2 numerous times in these pages. After 47 years, both craft are now operating beyond the heliopause, and whilst technically still within the “greater solar system” and heading for the theorised Oort Cloud, both craft are now operating in the interstellar medium. However, they are obviously aging, and this is impacting their ability to operate.

As I recently reported, as a result of both vehicles’ declining ability to generate electrical power, NASA has, since 1998, been slowing turning off their science instruments in the hope that they can eke out sufficient electrical power from the RTGs powering both craft to allow them to continue to operate in some capacity into the early 2030s. However, this is far from a given, as again demonstrated in October 2024.

As a part of the “power saving” activities with both Voyager craft, mission engineers periodically power down one of vehicles’ on-board heaters, reducing the electrical load on the RTGs, and then ordering the heater to power-back up as and then powering-down another. On October 16th, 2024, a command was sent to Voyager 1 to power-up one such heater. Due to the distances involved, confirmation that the command had been received and executed would not be received for almost 48 hours. However, on October 18th, NASA’s Deep Space Network (DSN), responsible for (among other things) communicating with all of NASA’s robotic missions, reported it was no longer receiving Voyager 1’s “heartbeat ping” periodically sent from the vehicle to Earth to confirm it was still in communications.

A drawing of a Voyager space craft with the high-gain antenna prominent. The X- and S-band communications systems, located at the centre of the dish, use it to send / receive communications. Credit: NASA/JPL

Both Voyager craft have two primary communications systems: a high-power X- band (8.0–12.0 GHz frequency) for downlink communications from the craft to Earth and a less power-intensive S-band (2 to 4 GHz frequency) for uplink communications from Earth to the craft. However, each also has a back-up S-band capability for downlink communications, but because it is of a lower power output than the X-band, it hasn’t been used since around 1981.

Realising the loss of X-band communications had effectively come on top of the command to turn on a heater, engineers theorised that in trying to power on the heater, Voyager 1 had exceeded its available power budget and entered a “safe” mode, turning off the power-hungry X-band communications system to provide power to the heater. They then trained over to the much lower-power S-band downlink frequency, as any loss of the X-band system should have triggered an automatic switch-over – and sure enough, after a while, Voyager 1’s “heartbeat ping” was received.

This allowed a test to be carried out in sending and receiving commands and responses entirely via S-band, and on October 24th, NASA confirmed communications with the vehicle had been re-established. The work of diagnosing precisely what triggered the “safe” mode & shut down of the X-band system is now in progress, and the latter communications system will remain turned off until engineers are reasonably confident that re-activating it will not trigger a further “safe” mode response.

NASA Confirms Root of Orion Heat Shield Issues – But Won’t (Yet) Disclose

There are, frankly, multiple issues with the US-led Artemis Project to return humans to the surface of the Moon by 2030. They encapsulate everything from the vehicles to be used to reach the Moon and its surface (NASA’s Space Launch System rocket and the SpaceX Human Landing System and its over-the-top mission complexity of anywhere between 10 and 16 launches just to get it to lunar orbit) the supporting Lunar Gateway space station and its value / cost, etc. However, from a crew perspective, one of the most troubling had been with the heat shield used on the Orion vehicle – the craft intended to carry crews to cislunar space and, most particularly, return them to Earth.

Orion has thus far made one, unscrewed, flight to the Moon and back, in November / December 2022 (see here and here for more). While the system as a whole – capsule and service module – operated near-flawlessly, with the capsule making a successful return to Earth and a splashdown on December 11th, 2022, post-flight examination revealed that the craft’s heat shield had suffered a lot more damage – referred to as “char loss” – that had been anticipated.

The moment of splashdown for Artemis 1, December 11th, 2021. Credit: NASA

As with most capsule systems, Orion uses an ablative heat shield which is designed to carry away heat generated during re-entry into the atmosphere through the twin process of melting and ablating to dissipate the initial thermal load, and pyrolysis to produce gases which are effectively “blown” over the surface of the heat shield to form a boundary layer between the heat shield and the plasma generated by the frictional heat of the capsule’s passage into the denser atmosphere, producing a “thermal buffer” again the heat reaching the vehicle.

Ablative materials do not necessarily melt / ablate (the “char loss” process) evenly and can lead to gouges and strakes in the surviving heat shield. However, this is not what happened with the heat shield used in the Artemis 1 mission. Rather than melting and ablating, the heat shield material, known as Avcoat, appeared to crack and break away in chunks, creating a visible debris trail behind the craft during re-entry and leaving the heat shield itself pock-marked with holes and breaks looking like someone had taken a hammer to it.

While the damage was not severe enough to put the capsule itself at risk, it was clearly of concern as it indicated a potential for some form of burn-through to occur in a future flight and put vehicle and crew at risk of loss. NASA and its contractors have therefore been seeking to understand what happened as Artemis 1 Orion capsule was re-entering the atmosphere, and what needs to be done to avoid such deep pitting and damage in future missions.

Most of this work has been carried out well away from the public eye; in fact, the only images of the damage caused to the heat shield were published as part of a report produced by NASA’s Office of Inspector General (OIG) in May 2024.

Two of the official NASA images showing the severe pitting and damage caused to the Orion MPCV heat shield following re-entry into Earth’s atmosphere at 36,000 km/h at the end of the uncrewed Artemis 1 mission, December 11th, 2022. These were made public within the NASA OIG report on the readiness or Orion for the Artemis 2 mission. Credit: NASA / NASA OIG

On October 24th, 2024 NASA indicated, by way of two separate statements, that they now understand what caused to Artemis 1 heat shield to ablate as it did, and know what needs to be done to prevent the problem with missions from Artemis 3 onwards. However, the agency has said it will not disclose the problem or its resolution, as they are still investigating what needs to be done with the Artemis 2 heat shield.

We have conclusive determination of what the root cause is of the issue. We have been able to demonstrate and reproduce it in the arc jet facilities out at Ames. We know what needs to be done for future missions, but the Artemis 2 heat shield is already built, so how do we assure astronaut safety with Artemis 2?

– Lori Glaze, acting deputy associate administrator, NASA Exploration Systems Development Mission Directorate

Artemis 2 was slated for a 2024 launch, but was pushed back to no earlier than September 2025 in order to allow time for the heat shield investigations, and for the upgrade of various electronics in the Orion capsule’s life support systems. Glaze’s comments suggest that NASA might have to completely replace the heat shield currently part of the Orion capsule slated to be used in the Artemis 2 flight. If this is the case, then it could potentially further delay the launch.

Space Sunday: lunar aspirations

A depiction of China’s Chang’e 6 mission landing on the far side of the Moon, June 1st (UTC), 2024. Credit: CCTV

China’s sixth robotic mission to the Moon successfully touched down on the lunar far side at 22:23 UTC on Saturday, June 1st, marking four out of four successful landings on the Moon (the early Chang’e missions being orbiter vehicles).

Chang’e 6 is the most ambitious Chinese lunar surface mission yet, charged with placing a lander and rover on the Moon, collecting samples from around itself, and then returning those samples to Earth for analysis by scientists around the world. It’s not the first sample return mission to the Moon – nor even the first by China; that honour went to the previous surface mission, Chang’e 5. However, it will be the first lunar mission to return samples gathered from the Moon’s far side and from the South Polar Region of the Moon, which is the target for human aspirations for establishing bases on the Moon, as currently led by China (the International Lunar Research Station (ILRS) project) and the United States (Project Artemis).

As I’ve previously noted, the mission – launched on May 3rd – took a gentle route out to the Moon and comprises four elements: an orbiter charged with getting everything to the Moon and bringing the sample home; and lander responsible for getting the sample gathering system, the sample return ascender and a small rover down to the Moon in one piece; the ascender, charged with getting the samples back to lunar orbit for capture by the orbiter, and the returner, a re-entry capsule designed to safely get the samples through Earth’s atmosphere and to the ground.

China’s ability with its robotic landers is impressive. Chang’e 6, for example, carried out its landing entirely autonomously – the only way for it to communicate with mission control is via two Queqiao (“Magpie Bridge-2”) communications relay satellites operating in extended halo orbits around the Moon and with a time delay that while measured in seconds was still too long for mission control to manage the lander directly.

Instead, the vehicle used a variable-thrust motor to descend over its target landing location close to Apollo crater. On reaching an altitude of 2.5 kilometres, the vehicle started scanning its landing zone using imaging systems to find an optimal landing point and then continue its descent towards it. Then at 100 metres altitude, the vehicle entered a short-term hover and activated a light detection and ranging (LiDAR) system alongside its cameras to assess the ground beneath and around it and manoeuvre itself directly over the point it deemed safest for landing.

Following landing, mission control started a thorough check-out of the lander’s systems, including the sample gathering scoop and drill in readiness for operations to commence. The first order of business will be to gather up to 2 kg of surface and subsurface material for transfer to the ascender vehicle, which could be launched back into orbit within the first 48 hours of the start of operations.

An artist’s rendering of a Change 5/6 lander on the Moon’s surface (the craft being almost identical), the ascender vehicle sitting on top of it. Credit: China News Service

As well as this, the lander will carry out an extensive survey of its landing zone, in which it will be supported by its mini-rover. The latter is apparently different to the Yutu rovers carried by Chang’e 4 and Chang’e 3 respectively, being described as an “undisclosed design”. Overall mission time for the lander and rover is unclear, but will be at least a local lunar day.

Chang’e 6 marks the end of the third phase of China’s efforts to explore the Moon.  The next two surface missions, Chang’e 7 (2026) and Chang’e 8 (2028) form the fourth phase, and will be geared towards preparing China to undertake its first crewed landings on the Moon in the early 2030s, and with the development of a robotic base camp on the South Polar Region which can then be extended into a human-supporting base.

Starliner Hits Further Delay

June 1st was the latest target launch date to be missed by the Boeing CST-100 Starliner on its maiden crewed flight after a computer issue caused the attempt to be scrubbed just under 4 minutes prior to a planned 16:25 UTC lift-off.

As I’ve been reporting over the last few Space Sunday updates, Boeing and NASA are attempting to clear the “space taxi” designed to fly crews to and from orbiting space stations for normal operations by having it complete a week-long flight to, and docking with, the International Space Station (ISS). However, the vehicle and its launcher, the veritable Atlas V-Centaur combination, have hit a further series of hitches.

An image captured from one of the video camera at Launch Complex 41 (LC-41), Cape Canaveral Space force Station, showing the Boeing CST-100 Calypso sitting atop its Atlas Centaur V-N booster with just under 8 minutes to go in the countdown towards the June 1st launch attempt, and just under 4 minutes out from the GLS system aborting the launch. Credit: NASA / ULA

If there is light at the end of the tunnel, it is that this and one of the previous causes for a launch delay sit not with the Starliner vehicle, but with a ground-based computer system or with the launch vehicle’s Centaur upper stage respectively. In the June 1st launch attempt everything was proceeding smoothly right up until some four minutes prior to launch, when there was an apparent error in one of the Ground Launch Sequencer (GLS) computers housed within the launch pad.

The GLS is a triple redundant system charged with overseeing all the actions the launch pad must make in sequence with the launch vehicle at lift-off. These include things like shutting off vent feeds from the space vehicle through the umbilical support system, separating and retracting the umbilical systems as the vehicle lifts off, and firing the pyrotechnics holding in place the launch clamps keeping the vehicle on the pad, and so on.

These events have to happen rapidly and in a precise order, and all three GLS computers must concur with themselves and one another that everything is set and ready and they can collectively give the command for the launch to go ahead as the countdown reaches zero. In this case, one of the three GLS systems failed to poll itself as rapidly as the other two, indicating it had a fault in one of its subsystems. Such an issue is regarded as a “red line” incident during a vehicle launch, and so the GLS computers triggered an automatic abort call, ending the launch attempt.

Mission commander Barry “Butch” Whitmore and pilot Sunita “Suni” Williams depart the Neil A. Armstrong Building at NASA’s Kennedy Space Centre before boarding the crew bus that would take them to neighbouring Canaveral Space Force Station and their CST-100 starliner. Credit: John Raoux via Associated Press

United Launch Alliance (ULA) who operate the launch pad and the launch vehicle, traced the fault to a single card within one of the GLS computers, and initially hoped to perform a rapid turn-around swap/out so as to have the pad ready for a further launch attempt on Sunday, June2nd. However, at the time of writing, it appears the launch has now been postponed until no earlier than Wednesday, June 5th.

Orion: Heat Shield Woes

On May 2nd, 2024, NASA’s Office of Inspector General (OIG) released a report titled NASA’s Readiness for the Artemis 2 Crewed Mission to Lunar Orbit, a determination of the space agency’s readiness to undertake its circumlunar crewed Artemis 2 mission currently slated for 2025. It did not make for happy reading for some at NASA.

In particular, the report notes that following the Artemis 1 uncrewed flight test around the Moon in November / December 2022 the vehicle’s heat shield suffered numerous issues despite carrying out its primary role of protecting the craft through re-entry into the atmosphere to allow it to achieve a successful splashdown at the end of the flight.

November 28th, 2022: an image capture by a camera mounted on one of the solar arrays of the Orion MPCV of Artemis-1 as it reaches its furthest distance from Earth (432,210 km) and well beyond the Moon. On December 5th, the craft passed around the Moon at an altitude of just 128 km, where it performed and engine burn to start it on its way back to Earth. Credit: NASA

The heat shield is a modern take on the ablative shielding used on capsule-style space vehicles, as opposed to the thermal protection systems seen on the likes of the space shuttle and the USSF X-37B, SpaceS Starship and Sierra Space’s upcoming Dream Chaser. The latter are designed to absorb / deflect the searing heat of atmospheric entry without suffering significant damage to themselves. Ablative heat shields however, are designed to slowly burn away, carrying the heat of re-entry with them as they do so.

However, in Artemis 1, the heat shield – which should “wear away” fairly evenly (allowing for the space craft’s overall orientation) –  showed more than 100 instances where it in fact wore away very unevenly, in places leading to fairly wide and deep cavities pitting the heat shield, potentially pointing to the risk of the structure suffering a burn-through which might prove catastrophic.

NASA and heat shield manufacturer Lockheed Martin have not been unaware of the problem; they have been working to try and locate the root cause(s) for well over a year; however, the OIG shone a potentially unwelcome light on the situation, both highlighting the extent of the damage – something NASA had hitherto not revealed publicly – and also drawing attention to additional issues that collectively threaten the agency’s attempt to try an complete the Artemis 2 mission by the end of 2025.

An image captured from a camera inside the Orion capsule during atmospheric re-entry, December 11th, 2022. Black lumps of material torn from the heat shield, rather than being ablated, can be seen in the vehicle’s wake. Credit: NASA

The additional issues include the fact during the Artemis 1 uncrewed flight, problems saw in Orion’s power distribution system which lead to electrical power being inconsistently and unevenly delivered to many of the vehicle’s critical flight systems. Again, NASA has stated the power issues issues were the result of higher than expected radiation interference during the Artemis 1 flight, and has sought to implement “workarounds” to operational procedures for the vehicle, rather than addressing the problems directly – something which has drawn a sharp warning from the OIG:

Without a permanent change in the spacecraft’s electrical hardware, there is an increased risk that further power distribution anomalies could lead to a loss of redundancy, inadequate power, and potential loss of vehicle propulsion and pressurisation.

– OIG Report into the Orion MPCV flight readiness for Artemis 2

Following the release of the OIG report, NASA responded with what can only be called a statement carrying a degree of petulance within it, with associate administrator for Exploration Systems Development Mission Directorate Catherine Koerner apparently referencing the OIG’s report as both “unhelpful” and “redundant” – an attitude which raised eyebrows at the time it was issued.

In this, some at NASA might have been angered by the OIG not only underlining problems they have been struggling to deal with, but by the fact the report included images showing the extent of the damage to the heat shield which until the OIG report, has remained out of the public domain – and they are rather eye-popping.

Two of the official NASA images showing the severe pitting and damage caused to the Orion MPCV heat shield following re-entry into Earth’s atmosphere at 36,000 km/h at the end of the uncrewed Artemis 1 mission, December 11th, 2022. These were made public within the NASA OIG report on the readiness or Orion for the Artemis 2 mission which the agency has said will take place by the end of 2025. Credit: NASA / NASA OIG

In the wake of the OIG report and NASA’s somewhat petulant response, Jim Free, the NASA associate administrator in overall charge of the agency’s ambitions to return to the Moon with a human presence has stepped into the mix, stating the heat shield issue will now be additionally overseen by an independent review panel charged with assisting both NASA and Lockheed Martin and guiding them towards a solution that will hopefully rectify the problem and safeguard the lives of those flying aboard Orion in the future. But whether this result in the mission going ahead in 2025 or being pushed back into 2026 remains to be seen.

Dear Moon – We’re Not Coming

In what comes as no surprise, Japanese billionaire Yusaku Maezawa has cancelled his booking to use a SpaceX starship to fly him and eight others around the Moon and back to Earth. First announced in 2018, the flight – called “dearMoon” – was seen by Maezawa as an “inspirational” undertaking that would see him and a mix of artists, musicians and writers make the trip and then produce pieces of work based on their experience. It was announced with great fanfare in 2018, with the flight slated for 2023 – which, as I noted at the time, just wasn’t going to happen.

I signed the contract in 2018 based on the assumption that dearMoon would launch by the end of 2023. “It’s a developmental project so it is what it is, but it is still uncertain as to when Starship can launch. I can’t plan my future in this situation, and I feel terrible making the crew members wait longer, hence the difficult decision to cancel at this point in time. I apologise to those who were excited for this project to happen.

– Statement from Yusaku Maezawa, June 1st, 2024

The dearMoon crew (with two back-ups). Left to right: Kaitlyn Farrington (USA – backup); Brendan Hall (USA); Tim Dodd (USA); Yemi A.D. (Czechoslovakia); Choi Seung-hyun (South Korea); Yusaku Maezawa (Commander – Japan); Steve Aoki (Pilot – USA); Rhiannon Adam (Ireland); Karim Iliya (UK); Dev Joshi (India); and Miyu (Japan – back-up)

At the time the announcement of the flight was made in 2018, starship hadn’t even flown, so the idea the entire system could be designed, finalised, tested, flight, achieve a rating to fly humans and be capable of making a trip around the Moon and back was nothing short of a flight of fancy – which is why, in part, that little mention of it has been made since.  However, the mission concept served to boost Starship / Super Heavy in the public eye and bring and bring undisclosed (but described by Elon Musk as “very significant”) sum of money to SpaceX.

It’s not clear if the money has or will be refunded to Maezawa, who subsequently turned to more conventional means to reach space, flying aboard a Soyuz vehicle as a “space tourist” to spend 12 days at the ISS in December 2021.

Space Sunday: SLS WDR-2; FRBs, JWST and UAPs!

Artemis 1 SLS on the Mobile Launcher 1 inside the Vehicle Assembly Building. Credit: NASA

Artemis 1, the planned first flight of NASA’s huge Space Launch System (SLS), is back on Pad 39B at Kennedy Space Centre and being prepared for another try at a full Wet Dress Rehearsal in what many are framing as a make-or-break for the new launch system. At the same time, the SLS programme has come under further critique by NASA’s own Office of Inspector General (OIG).

As I’ve noted in the past, the Wet Dress Rehearsal (WDR) is the final critical test for the SLS system, putting absolutely everything involved in a launch through its paces right up to just nine second before the rocket’s core RD-25 engines would light-off. The test is to ensure everything – the pad systems, the propellant loading systems, the rocket’s computers and avionics, the launch control systems, etc., are commissioned and ready for operational launch, with the data gathered from this first rocket going on to provide a baseline for checking future SLS vehicles as they go through pad preparations and launch in the future.

A graphic showing the tank filling which forms a core element of the WDR, currently scheduled for or around June 17yh, 2022. Credit: NASA

The first attempt at a WDR, back in April started with fanfare a high-profile roll-out of the pad by the first SLS, where it successfully completed a battery of tests prior to the WDR commencing, only to be followed by a series of issues that forced rocket and Mobile Launcher (ML-1) tower to be ignominiously rolled back to the Vehicle Assembly Building (VAB).

The June 6th roll-out was far more low-key, the rocket and ML own leaving the VAB atop the veritable crawler-transporter just after midnight and arriving at the pad in the morning sunlight. Since then, the vehicle and launcher have been going through check-out and connection to all the ground support systems, and a second WDR attempt is provisionally set for on or around June 17th, 2022.

In the meantime, NASA’s OIG has issued a report critical of another aspect of the programme: Mobile Launcher 2 (ML-2).

ML 1 was originally built for launching Saturn 1B and Saturn V rockets in the 1960s. It was then modified for space shuttle launches and again to handle SLS Block 1 launches. However, it is incapable of supporting launches of the bigger and more powerful SLS Block 1B and Block 2 vehicles (assuming the latter are built). So in 2018/19, NAS awarded a US $383 million contract to engineering firm Bechtel to supply a new Launcher – ML-2 – capable of supporting SLS Block 1B and beyond launches, with delivery slated for 2024, ahead of the then planned launch of Artemis 4, the first SLS Block 1B vehicle.

However, the OIG report reveals that ML-2 is spiralling out of control, with costs already exceeding US $440 million, and set to hit at least US $960 million, with doubt cast on Bechtel’s ability to deliver the Launcher in time for Artemis 4, even though that mission is unlikely to fly before later 2027 or early 2028.

Comparing ML-1 and ML-2. Credit: NASA

The report is primarily critical of Bechtel for multiple failures and lapses, but also points out NASA’s own folly in playing “yes man” to an accelerated Artemis programme. Originally, the US return to the Moon was to commence in 2028, but the Trump administration pulled that date forward to 2024; while that was clearly unachievable, NASA attempted to meet the goal. As a result, the ML-2 contract was awarded as “cost plus”, meaning that overruns would be met out of NASA’s pocket, rather than fixed price, which would leave Bechtel holding the purse for errors and delays on their part. NASA further compounded the issue by awarding the contract for the ML-2 design before the SLS Block 1B design had been finalised. As a result, the space agency immediately became liable for continued changes to the ML-2 design as the SLS Block 1B design evolved.

Currently, NASA is attempting to move the contract to a fixed price basis; unsurprisingly, Bechtel appear somewhat resistant to doing so.

FRBs: Far, Far Away – or a Lot Closer to Home?

First discovered in 2007, FRBs are intense, brief flashes of radio-frequency emissions, lasting on the order of milliseconds, thought to emit as much energy in a millisecond as our Sun does over three days – although such are the vast distances they must cover, by the time they reach us their signal strength is around 1,000 times less powerful than a mobile ‘phone signal being received from the Moon.

What causes FRBs is unknown. Most have been thought to originate outside our galaxy – although some have clearly originated within it. Many are heard only once; others appear to repeat on a highly random basis. By listening for and measuring some of the latter, it has been possible to localise their likely point of origin to an area of space. Then, using their dispersion measurement (DM) and overall red-shift, it has been possible to calculate their approximate distance.

ive hundred-metre Aperture Spherical radio Telescope (FAST. Credit:

The DM a measurement of the period between the high-frequency range of a radio burst reaching us and the lower frequencies, which tend to get more dispersed more the first they travel, and so take longer to reach us. It’s a small, but measurable amount. As the composition of interstellar space is known, this difference can be used to calculate signal attenuation over distance, and thus the approximate distance of the originating object from Earth.

This measurement can then be combined with the overall red shift exhibited by the signal to yield a similar distance result, thus allowing reasonable certainty as to how far away the originating object is. But that’s not the case with FRB 20190520B.

First detected in May 2019 by the Five hundred-metre Aperture Spherical radio Telescope (FAST) in Guizhou, China, in 2019, it was later picked up again by the Very Large Array (VLA) in New Mexico, USA in 2020 and subsequently by the Subaru telescope, Hawaii.

What is particularly interesting about this FRB is that taken on its own, its DM suggests it originates in a small galaxy beyond our own. However, when the DM / red-shift relationship is extrapolated, the result suggests the originating point is a lot closer to Earth – as in possibly within our own galaxy.

This might make 20190520B some weird outlier among FRBs – but as some have pointed out, it might also indicate to our entire assumptions about extra-galactic FRBs and the use of dispersion measurements as a kind of “cosmic yardstick” as being totally wrong; that we could actually be mistaking events occurring within our own galaxy that result in FRBs for something far more distant and exotic.

Right now, it’s too early to tell either way, but 20190520B has caused a considerable stir among astronomers, with many looking to step-up the search for more of these strange events.

Continue reading “Space Sunday: SLS WDR-2; FRBs, JWST and UAPs!”

Space Sunday: “super Earth”, “supermoon”, and Orion’s future

An artist's impression of a "super Earth" type planet in orbit around a red dwarf star. Credit: NASA / Dana Berry.
An artist’s impression of a “super Earth” type planet in orbit around a red dwarf star. Credit: NASA / Dana Berry.

In a couple of recent Space Sunday reports, I covered the discovery of an Earth-size planet orbiting  our nearest stellar neighbour, the red dwarf Proxima Centuari (see here and here). Red dwarfs  are a class of star which has proven rich ground for planet hunters  –  and this has once again proved the case.

The European Southern Observatory ESO), one of the leading hunters of exoplanets, has  reported the discovery of a “super Earth”, a sold planetary body with roughly five times the mass of Earth. It is orbiting GJ 536, an M-class red dwarf star some 32.7 light years from the Sun. The planet is orbiting its parent once every 8.7 days, at a distance of 0.06661 AU.

The planet was discovered using a pair of instruments operated by ESO: the High Accuracy Radial velocity Planet Searcher (HARPS), mounted on ESO’s 3.6 metre telescope at the La Silla Observatory in Chile, and its sister instrument, HARPS-N, at the La Palma Observatory in Spain. The findings from these instruments were combined with photometric data from the All Sky Automated Survey (ASAS), which has observatories in Chile and Maui, to confirm the existence of the planet.

Red dwarf stars are entirely convective in nature, making them extremely volatile in nature, and subject to massive stellar flares. Credit: NASA/CXC/M.Weiss
Red dwarf stars are entirely convective in nature, making them extremely volatile in nature, and subject to massive stellar flares. Credit: NASA/CXC/M.Weiss

However, its was no rapid-fire discovery. In all, data from over eight years of observations of the star went into confirming the presence of the planet. Such is the extended period of observations, that the science team were able to gather a huge amount of spectroscopic data on the star. This has revealed it has a rotational period of about 44 days, and magnetic cycle that lasts less than three years. By comparison, the Sun has a rotational period of 25 days and a magnetic cycle of 11 years.

This indicates that GJ536 is, in keeping with most red dwarf stars, exceptional volatile. Such stars are so small, all activity within them is entirely convective in nature, which gives rise to massive stellar flares. So while the new planet may well have “earth” in its description, it is unlikely to be “Earth like”, particularly given its relatively close proximity to its parent star.

Not much more is known about the planet at this point, but this is liable to change over time, and in the meantime, the survey team will continue to gather data on GJ 536 to see if it is home to other planets, such as gas giants further away from it.

November’s Supermoon

A dramatic supermoon is seen behind the Christ the Redeemer statue in Rio de Janeiro, in May 2012. Credit: AP Photo/Victor R. Caivano
A dramatic supermoon is seen behind the Christ the Redeemer statue in Rio de Janeiro, in May 2012. Credit: AP Photo/Victor R. Caivano

The last three months of 2016 are marked by three so-called “supermoons”, and the biggest will be in the night skies on Monday 14th November 2016.

The Moon is in an elliptical orbit around the Earth, at apogee, the point furthest from the Earth, it is between 404,000–406,700 km (252,500-254,187 mi) from Earth. At perigee, the point closest to the Earth, the Moon is between 356,400–370,400 km (222,500-231,500 mi) away. A “supermoon” occurs when the Moon is both full and at perigee, when it can appear up to 14% large in diameter than “normal” full moons.

Apogee and preigee in the Moon's orbit around Earth. Credit: NASA
Apogee and perigee in the Moon’s orbit around Earth. Credit: NASA

“Supermoons” aren’t actually rare events; they take to occur once every 14 months on average.  However, the supermoon on November 14th, scores double. Not only will be “just” 356,509 kilometres (221,524 miles) from Earth, pushing it to that 14% increase in apparent size, but also because the Earth/Moon system is approaching the time of year when it is closest to the Sun (which will occur on January 4th, 2017). Therefore, the Moon will be receiving more sunlight than average, further boosting its apparent brightness.

Together, these two events mean that the Moon will be at its “largest” and brightest in the sky since 1948. The next comparable event will not occur again until 2034 – although there will be a further “supermoon” on December 14th, when the Moon again reaches its full phase, but it will be slightly further away from the Earth in its orbit at that time, so not quite as “super”.

How the Moon can appear to differ i size at apogee (the point furthest from Earth in its orbit) and perigee (the point in its orbit closest to Earth). Credit: Catalin Paduraru
How the Moon can appear to differ in size at apogee (the point furthest from Earth in its orbit) and perigee (the point in its orbit closest to Earth). Credit: Catalin Paduraru

Continue reading “Space Sunday: “super Earth”, “supermoon”, and Orion’s future”

Space Sunday: Jupiter and Juno

 Update, July 5th: The insertion burn on July 4th/5th was successful, and Juno is safely in its initial orbit around Jupiter. I’ll have an update on the mission in the next Space Sunday.

rAt 20:18 PDT on Monday, July 4th (03:18 UT, Tuesday, July 5th) a spacecraft called Juno will fire its UK-built Leros-1b engine to commence a 35-minute burn designed to allow the spacecraft  enter an initial orbit around the largest planet in the solar system, ready to begin a comprehensive science campaign.

As I write this, the craft is already inside the orbit of Callisto, the furthest of Jupiter’s four massive Galilean satellites,  which orbits the planet at a distance of roughly 1.88 million kilometres. During the early hours of July 4th, (PDT), the vehicle will cross the orbits of the remaining three Galilean satellites, Ganyemede, Europa and Io, prior to commencing its orbital insertion burn.

In the run-up to the burn, Juno will complete a series of manoeuvres designed to correctly orient itself to fire the Leros-1b, which will be the third of four planned uses of the engine in order to get the craft into its final science orbit. Two previous burns of the engine – which NASA regards as one of the most reliable deep space probe motors they can obtain – in 2012 ensured the craft was on the correct trajectory from this phase of the mission.

Getting into orbit around Jupiter isn’t particularly easy. The planet has a huge gravity well – 2.5 times greater than Earth’s. This means that an approaching spacecraft is effectively running “downhill” as it approaches the planet, accelerating all the way. In Juno’s case, this means that as the vehicle passes north-to-south around Jupiter for the first time, it will reach a velocity of nigh-on 250,000 kph (156,000 mph), making it one of the fastest human-made objects ever.

An Artist's impression of Juno approaching the Jovian system. Credit: NASA
An Artist’s impression of Juno approaching the Jovian system. Credit: NASA

Slowing the vehicle directly into a science orbit from these kinds of velocities would take an inordinate amount of fuel, so the July 4th manoeuvre isn’t intended to do this. Instead, it is designed to hold the vehicle’s peak accelerate at a point where although it will be thrown around Jupiter and back into space, it will be going “uphill” against Jupiter’s gravity well, decelerating all the time. So much so, that at around 8 million kilometres (5 million miles) away from Jupiter, and travelling at just 1,933 kph (1,208 mph), Juno will start to “fall back” towards Jupiter, once more accelerating under gravity, to loop around the planet a second time on August 27th, coming to within (4,200 km (2,600 mi) of Jupiter’s cloud tops, before looping back out into space.

On October 19th, Juno will complete the second of these highly elliptical orbits, coming to within 4,185 km (2,620 mi) of the Jovian cloud tops as it completes a final 22-minute burn of the Leros-1b motor. This will be sufficient for Jupiter’s gravity to swing  Juno into an elliptical 14-orbit around the planet, passing just 4,185 km from Jupiter at its closest approach before flying out to 3.2 million kilometres (2 million miles) at it’s furthest from the planet.

Juno's journey to Jupiter, with a flyby-of Earth in 2013
Juno’s journey to Jupiter, with a flyby-of Earth in 2013

The July 4th insertion burn is also significant in that it marks the end of a 5-year interplanetary journey for Juno, which has seen the vehicle cover a distance of 2.8 billion km (1.74 billion miles).

It’s a voyage which began on August 5th, 2011, atop a United Launch Alliance (ULA) Atlas V, launched from Cape Canaveral Air Force Station, Florida.

As powerful as it is, the Atlas isn’t powerful enough to send a payload like Juno directly to Jupiter. Instead, the craft flew out beyond the orbit of Mars before dropping back to Earth, passing us again in October 2013 and using Earth’s gravity to both accelerate and to slingshot itself into a Jupiter transfer orbit.

While, at 35 minutes, the engine burn for orbital insertion is a long time, the distance from Juno to Earth means that confirmation that the burn has started will not be received until 13 minutes after the manoeuvre has actually completed. That’s how long is takes for a radio signal to travel from the vehicle back to Earth (and obviously, for instructions to be passed from Earth to Juno.  Thus, the manoeuvre is carried out entirely automatically by the vehicle

Juno is not the first mission to Jupiter, but it is only the second orbital mission to the giant of the solar system.

The Jovian system was first briefly visited by Pioneer 10 in 1973, followed by Pioneer 11 a year later. Both of these were deep space missions (which are still continuing today), destined to continue outward through the solar system and into interstellar space beyond. They were followed by the Voyager 1 and Voyager 2 missions in January and July 1979 respectively, again en route for interstellar space by way of the outer solar system.

In 1992 the Ulysses solar mission used Jupiter as a “slingshot” to curve itself up into a polar orbit around the Sun. Then in 2000, the Cassini mission used Jupiter’s immense gravity to accelerate and “bend” itself towards Saturn, its intended destination. New Horizons similarly used Jupiter for a “gravity assist” push in 2007, while en route to Pluto / Charon and the Kuiper Belt beyond.

It was in 1995 that the first orbital mission reached Jupiter and its moons. The nuclear RTG-powered Galileo was intended to study Jupiter for just 24 months. However, it remained largely operational until late 2002 before the intense radiation fields around the planet took their final toll on the vehicle’s systems. Already blind, and with fuel supplies dwindling, Galileo was ordered to crash into the upper limits of Jupiter’s atmosphere in 2003, where it burned up.

In the eight years it operated around Jupiter, Galileo complete changed our perspective on the planet. Juno has a 20-month primary mission, and it is hoped its impact on our understanding of Jupiter will be greater than Galileo’s. However, it is unlikely the mission will be extended.

Unlike all of NASA’s previous missions beyond the orbit of Mars, which have used RTG power units, Juno is entirely solar-powered, making it the farthest solar-powered trip in the history of space exploration. However, the three 8.9 metre (29 ft) long, 2.7 metre (8.9 ft) wide solar panels are particularly vulnerable to the ravages of radiation around Jupiter, and it is anticipated that by February 2018, their performance will have degraded to a point where they can no longer generate the levels of electrical energy required to keep the craft functioning – if indeed, its science instruments and electronics haven’t also been damaged beyond use by radiation. This being the case, Juno will be commanded to fly into Jupiter’s upper atmosphere and burn up.

Juno's science instruments - click for full size. Credit: NASA / JPL
Juno’s science instruments – click for full size. Credit: NASA / JPL

Continue reading “Space Sunday: Jupiter and Juno”