Space Sunday: Mars missions and the Soyuz leak

NASA’s Mars 2020 Perseverance rover has started preparations to have some of the samples it has gathered to be returned to Earth for extensive analysis.

Since its arrival on Mars in February 2021, the rover has been exploring Jezero Crater and collecting samples of sub-surface rocks in much the same manner as its older sister, Curiosity, which arrived within Gale Crater half a world away on Mars 12 years ago.

Some of these samples have been subject to on-board analysis by the rover’s internal lab, but for the most part they have been sealed in special tubes stored in an on-board cache, part of a total volume of 43 such tubes it carried to Mars tucked within its underside.

The idea behind the tubes – one of which has been used to collect a sample of the Martian atmosphere, and five more contain various materials intended to capture particulates in the ambient environment – is that they would form one or more sample caches Perseverance could deposit at locations where they could later be collected for return to Earth by a European-American sample-return mission.

Thus, on December 21st, 2022, the rover started building the first of these caches with the “drop” of the first tube to be selected for surface caching. The operation involved the rover parking at a recognisable feature within Jezero crater – dubbed “Three Forks” – and then rotating the rotunda of sample tubes so that the selected tube – containing samples of igneous rock collected at the start of 2022 – could be released and dropped to the Martian surface. Then, to confirm the operate had succeeds, and the tube wasn’t snagged somewhere in the mechanism, NASA commanded the rover to use its robot arm to peer down between its wheels and use the camera mounted on the end of the arm to confirm the position of the tube and check its overall condition.

Somewhat resembling a light sabre from the Star Wars franchise, the sample tubes are made up of a mix of materials designed to protect their contents from the rigours of being placed out in the harsh Martian environment and and rick of contamination by solar radiation or by the future process of transferring them to the vehicles that will be used to return them to Earth.

Resembling a Star Wars light sabre, a sample tube dropped by the Mars 2020 rover Perseverance on December 21st marks the start of an operation to place 10 sample tubes in a cache for collection by a future mission which will return them to Earth. Credit: NASA

This resemblance to a light sabre is something that has not been lost on the mission team at NASA’s Jet Propulsion Laboratory.

I’ve been holding out my hand to my computer screen to see if the tube will be transported from Mars, since as director, I’m pretty sure the Force is with me, right? OK, so no joy so far, but I’ll keep trying!

– Laurie Leshlin, NASA’s Jet Propulsion Laboratory director

A photo of the “Three Forks” cache site in Jezero Crater, Mars, depicting the points at which the ten sample tubes will be dropped by the Perseverance rover. Credit: NASA

In all, ten of the 22 tubes so far used by the rover will be dropped around the “Three Forks” location – each one in its own drop point to facilitate easier pick-up. The second of the ten – containing the longest core sample thus far collected by the rover, comprising sedimentary rock taken from the edge of an ancient outflow delta in the crater – was dropped on December 22nd. A second cache of tubes will be established elsewhere in the crater at a later period in the rover’s mission to offer an alternate collection point for samples.

The current plan for the sample-return mission (July 2022) requires an orbiter / return vehicle to be supplied by the European Space Agency and delivered to Mars orbit in May 2028. At around the same time, a Sample Retrieval Lander built for NASA, will also arrive on Mars relatively close the the selected sample cache and carrying an sample ascent vehicle and two small helicopters similar to Ingenuity, already operating on Mars in concert with Perseverance.

The Mars Sample-Return Mission elements. top: the ESA- built orbiter / return vehicle; right: the sample lander with the ascent vehicle above it, carrying the sample back to the orbiter; left: the Perseverance rover and an Ingenuity-class Mars helicopter, one or other of which will be used to transfer sample tube to the lander vehicle, which will load them into the ascent vehicle. Credit: NASA / ESA.

Perseverance, which will have returned to the cache site in the interim, will then collect the sample tubes and pass them to the lander vehicle, which will then use a special robot arm to stow them in the ascent vehicle. Should Perseverance be unable to carry out the collection and transfer, the two helicopters will do so instead. Once all the samples have been collected, the ascent vehicle will launch to a rendezvous with the orbiter, and the containment unit with the sample transferred to it for the return to Earth, arriving in 2033.

Goodnight, InSight

As one team at NASA’s Jet Propulsion Laboratory were celebrating the success of the latest phase of their mission, another team was saying a final “farewell” to their mission vehicle.

Having operated for a total of four years on Mars – two years longer than its primary mission period – the NASSA InSight lander’s mission was officially brought to an end on December 21st, 2022, its mission team no longer able to communicate with it.

InSight on Mars, December 1 2018, on Flickr
Three images captured by the HiRISE camera on NASA’s Mars Reconnaissance Orbiter, released on December 13th, 2018. Left: the lander’s aeroshell and parachute. Right: the heat shield, discarded after EDL and ahead of parachute deployment on November 26th, 2018. Centre: InSight itself with a surrounding ring of regolith blasted by the lander’s landing motors. The teal colour is not genuine, but the result of sunlight being reflected off of the lander and its parts saturating the HiRSE imaging system. Credit: NASA/JPL

Whilst not as exciting as an ambulating rover mission, InSight – short for  INterior exploration using Seismic Investigations, Geodesy and Heat Transport – was a massively ambitious mission, full details of which can be found in Space Sunday: insight on InSight. As the name suggests, the overall aim of the mission was to gain information on the processes going on deep within Mars.

To achieve this, the lander notably included two experiments it had to transfer from its deck to the surface of Mars, post-landing. One of these experiments, the Heatflow and Physical Properties Package (HP3) and involving a self-propelled “Mole” designed to investigate how much heat is emanating from Mars’ core, did not fare too well, the Mole becoming stuck very early in its attempt to burrow into the ground.

However, the second surface package, SEIS (Seismic Experiment for Interior Structure) – the primary mission element for the lander – proved to be highly successful in its goal of recording details of “marsquakes” and other sound-generating events within and on the planet (such as recording meteor impact later traced to a new 150m diameter crater on the planet), allowing scientists build up a clearer understanding of the planet’s internal structure and activity.

In all, SEIS measured over 1300 seismic events in 4 years, marking Mars as still being geologically active deep below its surface. Fifty of these events were “loud” enough to reveal information about their location on Mars, with a large cluster of them coming from Cerberus Fossae, a region of the planet having been thought to be geologically active relatively recently in its 4.5 billion year history, with many “young” surface features.

SEIS also showed that the Martian core is molten but is larger than thought and less dense than the lower crust. Lighter elements mixed with molten iron in the core lower its density, which explains how the core can still be molten even after cooling considerably.

By reading how vibrations from impacts and Marsquakes travelled through the planet, SEIS gave scientists the data they needed to understand Mars’ interior structure. Image Credit: S. Cottaar, P. Koelemeijer, J. Winterbourne, NASA

As a static lander, InSight always had a limited lifespan; as a solar-powered vehicle, its panels would inevitably become so coated in dust and subject to deterioration in the harsh Martian environment that they would no longer be able to generated sufficient power to charge the lander’s batteries.  However, it had been hoped that dust devils, tiny Martian tornadoes created during the changing of the Martian seasons, might help “clean” the panels in much they same way they have with the solar-powered MER rovers. Unfortunately, this was not the case – possibly because the 2m diameter solar arrays used by the lander were simply too big for passing dust devils to effectively blow accumulated dust off of them.

The mission time had been expecting the end of the mission for some time; by December of 2021, the ability of the arrays to generate power had dropped from 4.6 kilowatt-hours when InSight arrived on Mars to just 285 watt-hours, indicating that they would full below the minimum level of power production needed to keep the lander operating within 12-14 months of that point in time.

However, to try and extend operations, some of the lander’s instruments were turned off in 2022. However, on December 15th, 2022, communications became intermittent before failing completely on December 18th. Despite attempt to re-establish contact over the next three days, InSight failed to respond and missed a further schedule communications link of its own in the process. On December 19th, NASA tweeted what appears to be the last message “from” the lander, together with a final image:

My power’s really low, so this may be the last image I can send. Don’t worry about me though: my time here has been both productive and serene. If I can keep talking to my mission team, I will – but I’ll be signing off here soon. Thanks for staying with me.

– NASA InSight on Twitter (@NASAInSight)

Possibly the final image returned by NASA’s InSight Lander, showing the SEIS science package (centre) and the HP3 package (left). Note the accumulated dust on both. Credit: NASA

It is believed that the loss of communications indicate the lander reached a “dead bus” condition, a state where the batteries can no longer supply the lander’s main power bus with sufficient energy to drive even basic operations, such as communications. Thus, the mission was declared as being at an end.

InSight has more than lived up to its name. As a scientist who’s spent a career studying Mars, it’s been a thrill to see what the lander has achieved, thanks to an entire team of people across the globe who helped make this mission a success.

– Laurie Leshin, NASA’s Jet Propulsion Laboratory director


Soyuz MS-22 Leak Update

In my previous Space Sunday update, I covered the ammonia leak from Soyuz MS-22, docked at the International Space Station (ISS), which may have crippled the vehicle.

Used to cool the vehicle’s systems and interior, the ammonia leak on December 14th ran for several hours, and resulted in both Russian and America spacewalks at the ISS to be cancelled or postponed for several days while the situation was assessed. It’s still unclear what caused the leak, but one suspect has been ruled out: a strike by a Geminid meteor.

Ammonia coolant spews from the Soyuz MS-22 vehicle docked against the Rassvet module of the International Space Station. Credit: NASA TV

The Geminids are a prolific meteor shower which occurs every December as the Earth’s orbit passes through a trail of debris caused by the object 3200 Phaethon, This can give rise to a 2-week period of spectacular “shooting stars” in night skies, which can reach 120+ sighting per hour as they reach their peak on December 14th. While they make for superb time-lapse photographs, these tiny motes of dust are nevertheless a potentially severe hazard to orbiting spacecraft, which they can strike at speeds of several thousand kilometres per hour, potentially causing significant damage.

However, the Geminids were rule out as a possible culprit after trajectory teams working independently at the two control centres for ISS operations – the Johnson Space Centre, Texas, and the RKA Mission Control Centre, Moscow Oblast –  confirmed that the side of the Soyuz on which the leak occurred was never exposed to any risk of impact by an incoming meteor.

Time lapse photo showing Geminid meteors over Pendleton, Oregon. Credit: Thomas W. Earle

However, on December 18th, as my previous report was being written, NASA was able to complete a close-up study of the stricken vehicle using cameras on the Canadarm2 robotic arm. These confirmed the Soyuz has a hole in its hull which may have triggered the leak, but no determination has yet been made as to its cause. In the meantime, Roscosmos is continuing to assess the extent of the damage to Soyuz MS-22 and whether or not it is capable of crewed use. In addition, work has also started to fast-track the Soyuz MS-23 vehicle and launcher, in case a replacement vehicle is required.

This is not because the three crew of MS-22 (or any of the other 4 crew currently on the ISS) are in any danger or in any way stranded at the station long-term. Rather, it is a precautionary move: were an evacuation needed, the Crew Dagon docked a the station cannot return all seven crew to Earth, so having a second “lifeboat” on-hand would be preferred.

Following an initial assessment of MS-23 – which is fully capable of being launched without a crew and making an automated docking with the ISS – Roscosmos indicated the earliest it could launch would be in February 2022, although a more complete assessment may yet reduce this lead time. While this time frame would leave the ISS short one lifeboat vehicle for around 6 more weeks, barring emergencies, it also confirms that the 3-man crew who initially flew to the station on MS-22 (cosmonauts Sergey Prokopyev and Dmitry Petelin and NASA astronaut Francisco Rubio) will likely be able to return to Earth within the anticipated time frame for the end of their mission, even when using a back-up vehicle.

In the meantime, and given no further leaks have occurred, scheduled operations at the ISS have resumed, notably the delayed US spacewalk to install further ROSA – Roll-Out Solar Arrays – which are being used to replace the station’s older, bigger, and less-efficient solar arrays used to generate its electrical power.