Space Sunday: Curiosity, tardigrades, water and meteors

June 2011: a pristine assembled MSL Curiosity rover sits within its assembly clean room at NASA’s Jet Propulsion Laboratory prior to being stowed and mounted within its delivery system in preparation for its December 2011 launch to Mars. Credit: NASA/JPL

Seven years ago on August 6th, 2012 at 05:17 UTC, NASA’s Mars Science Laboratory rover Curiosity arrived in Gale Crater on Mars. I’ve covered the progress of the mission throughout (just follow my MSL / Curiosity tag), and those articles in fact gave birth to this Space Sunday column; but it’s been a while since I’ve last updated on things.

Since its arrival on Mars, Curiosity has driven a total of 21 km (13 mi) from its landing point to the base of the crater’s central mound, Aeolis Mons, and has ascended 368 metres (1,207 ft) up the side of the mound, which NASA informally call “Mount Sharp” to its current location.

How Curiosity Reached Mars, (1) cruise stage – provided power and data collection during flight from Earth to Mars; (2) aeroshell protecting rover and skycrane during journey and during entry into the Martian atmosphere, with parachute system (6); (3) the skycrane used to winch the rover down to the ground whilst hovering a few metres in the air; (4) the rover in its stowed configuration; (5) the heat shield that protected the vehicle during its entry into the Martian atmosphere. Credit: NASA/JPL

Along the way, Curiosity has revealed a lot about Mars – including confirmation that Gale Crater has been host to multiple bodies of water during its early life, and that the conditions were suitable for microbial life to have potentially arisen on the planet.

Nor did the rover have to wait to make the discovery: it did so literally within weeks of its hair-raising arrival when it had barely started on its journey and was exploring an ancient riverbed on the floor of Gale Crater (dubbed “Yellowknife Bay”), when analysis of samples gathered revealed all the essential ingredients which – if mixed with water (that once flowed through the riverbed)  – might have given life a kick-start and to have been enough to possibly sustain it during the warmer, wet periods of Mars’ early history.

As well as this, Curiosity has revealed much about the ancient conditions on Mars, has found hematite (which requires the presence of water to form), done much to reveal atmospheric processes at work on the planet, and helped track Martian weather and climate processes.

There have been a few causes for concern along the way. Early on in the mission it was revealed that the rover’s six aluminium wheels had suffered more wear and tear than had been anticipated, prompting some changes to the rover’s route as it approached “Mount Sharp”.

Most particularly, the rover’s drill mechanism has had its share of issues, some of which have required changes to how the drill is operated.

However, none of this has really impacted on the rover’s mission – in fact, Curiosity has recently obtained its 22nd drill sample from Mars, as it examines a region the mission team call the “Clay Unit”, one of several closely packed areas with strong differentiators scientists want to examine. Clay forms in the presence of water, and the area has sufficient enough clay deposits to be detected from orbit, and Curiosity has recovered samples with the highest amounts of clay minerals found to date by the mission.

This area is one of the reasons we came to Gale Crater. We’ve been studying orbiter images of this area for 10 years, and we’re finally able to take a look up close.

– Kristen Bennett, U.S. Geological Survey and co-lead for Curiosity’s clay-unit campaign

A panoramic view of “Teal Ridge” in the “Clay Unit” showing sharp differentiations in rock and surface material that suggest the evolution of a lake-like environment. June 18, 2019, the 2,440th Martian day, or sol, of the mission. Credit NASA/JPL

Quite why this particular area is so rich in clay deposits is unclear, but the area is home to complex geologic features, such as “Teal Ridge” and “Strathdon,” a rock made of dozens of sediment layers that have hardened into a brittle, wavy heap. Unlike the thin, flat layers associated with lake sediments Curiosity has studied, these wavy layers in these features suggest a more dynamic environment. Wind, flowing water or both could have shaped this area.

Both “Teal Ridge” and “Strathdon” represent changes in the landscape suggestive of the evolution of the ancient lake environment. This is further exemplified by the area above the “Clay Unit”, and towards which Curiosity is slowly making its way. It’s an area rich is sulphate deposits, indicative that it was drying up or becoming more acidic in ancient times whilst the lower slopes were still rich in water.

The Clay and Sulphate bearing regions on “Mount Sharp” and the proposed path Curiosity is following through them. Credit: NASA/JPL

Cutting down slope through the “Sulphate Unit” is the Gediz Vallis and Ridge, which appears to have been form by water running down “Mount Sharp” at some period after both the Clay Unit and Sulphate Units before spreading into the “Greenheugh Pediment”. This points to the area having seen some considerable changes as a result of climate changes on Mars.

We’re seeing an evolution in the ancient lake environment recorded in these rocks. It wasn’t just a static lake. It’s helping us move from a simplistic view of Mars going from wet to dry. Instead of a linear process, the history of water was more complicated. It’s finally being able to read the paragraphs in a book — a dense book, with pages torn out, but a fascinating tale to piece together.

– Valerie Fox, Division of Geological and Planetary Sciences, Caltech

Curiosity is powered by a radioisotope thermoelectric generator (RTG) that uses a core of plutonium-238. The heat given off by the decay of the isotope is converted into electric voltage by thermocouples and stored within two lithium-ion batteries that directly power the rover’s systems. This ensures the rover obtains constant power during all seasons and through the day and night, with waste heat is also passed through the vehicle’s interior to keep systems and instruments at their operating temperature and without the need for additional electric heating systems.

However, over time, the amount of electrical voltage the RTG can generate decreases. Overall, Curiosity’s RTG is expected to provide sufficient power (100+ Watts) to run all of the rover’s systems for 14 years – so 2019 marks the half-way point. Which is not to say that Curiosity only has seven more years of operations. Rather, it means that in around 7 years power generation is going to fall below the 100 watts mark, and it may become necessary for rationing power between systems on the rover, reducing some of its capacity.

Taridgrades on the Moon?

I’ve previously written about the Israeli attempt to land a vehicle – called Beresheet – on the Moon (see Space Sunday: Mars, the Moon and space hotels and Space Sunday: tourist flights, landers, moons and rovers). Unfortunately, the mission didn’t go as planned, and the lander crashed into the Moon (see Space Sunday: black holes, Falcons and moonshots). However, one of the more curious aspects of the mission is part of the payload.

The mission included the first stage of a privately-funded initiative to transfer living DNA to the Moon – a kind of “Noah’s Ark Mark II”, providing a repository from which plants and animals could be regenerated to repopulate the Earth should a catastrophe akin to a flood of biblical proportions overtake the planet. In particular for this first phases of the project, a 30-million-page archive of human history viewable under microscopes, as well as human DNA were carried by the lander in a DVD-like “Lunar Library” – which also includes tardigrades.

The tardigrade. Credit: 3DStock/Shutterstock

Science fiction fans might recognise this name from the television series Star Trek: Discovery. However, far from being the stuff of sci-fi shows and stories, tardigrades are very real (if a lot, lot smaller than their Star Trek “breathren”) and also exceptionally hardy.

Known colloquially as water bears or moss piglets, tardigrades are a phylum of water-dwelling eight-legged segmented micro-animals that can be found almost anywhere on Earth, from the tops of mountains to the bottoms of the oceans, from the tropical stew of rain forests to the frozen wastes of the polar regions. They can survive extremes of temperature and pressure (both high and low), air deprivation, radiation, dehydration, and starvation and exposure to outer space.

The tardigrades were stored dehydrated tardigrade – which puts them into a state of suspended animation – and “encased in an epoxy of Artificial Amber”. In this state, they could in theory be revived if exposed to heat and moisture. But even without these, the tardigrade could survive for years on the Moon – specimens have been recovered after being in a dehydrated state for decades. Such is the design of the unit in which they are stored, those responsible for the project believe it “highly likely” it survived Beresheet’s impact on the surface of the Moon.

Sadly, it is unlikely we’ll ever get to know if this is the case; the crash point for the Israeli lander puts in it in an area of the Moon’s south polar region far removed from any planned destinations for NASA’s Artemis missions, making recovery very unlikely.

Steam Powered Satellites and Autonomous Exploration

Am August press release from NASA reveals the agency has completed tests of what is effectively the world’s first steam-propelled satellite in Earth’s orbit. Admittedly, it not a particularly big vehicle being tested – it is small enough to compete with a box of tissues – but the test is an important step in examining technologies for future automated space exploration.

The test took place on June 21st, 2019, and was part of a coordinated manoeuvre between two CubeSats operating in low-Earth orbit, carried out as part of NASA’s Optical Communications and Sensor Demonstration (OCSD) mission.

The steam-propelled CubeSat in an artist’s impression. Credit: NASA

The two tiny vehicles were orbiting the Earth around 9 km (5.8 mi) apart when they automatically established a radio communications cross-link with one another. One then ordered the other to fire its thruster and close the gap between them. Rather than using a traditional hypergolic propellant or inert gas, both of the CubeSats carry small tanks of water which can be heated to produce steam that is ejected through an engine nozzle to generate propulsion.

This demonstration is important on two counts. The first is that it shows the potential for a series of small satellite drones to command one another to carry out assorted operations entirely independently of control from Earth. Such a group of drones could work cooperatively on a mission – say a survey of the asteroid belt or the icy moons of Jupiter. They could operate in unison, commanding one another, or under the autonomous control of a “mother ship” that could have facilities for storing (and returning) samples to Earth.

The second is that, in using water as a means of propulsion, these vehicles could in theory be easily fuelled and refuelled with water – water which might in turn be obtained from the frozen bodies these craft are exploring.

Demonstrations such as this will help advance technologies that will allow for greater and more extended use of small spacecraft in and beyond Earth-orbit. It is exciting to think about the possibilities enabled with respect to deep space, autonomously organizing swarms of small spacecraft.

– Roger Hunter, programme manager,
NASA Small Spacecraft Technology Programme

Perseid Meteor Shower

Every July / August, the Earth passes through a haze of stellar debris left by Comet 109P/Swift-Tuttle. The result is of this passage is the Perseid meteor shower (called this because they appear to originate from the constellation of Perseus), is one of the brightest meteor displays one can see in the northern hemisphere. The shower tends to last around a month, from July 17th (ish) through to August 24th.

Observing the Perseids in 2019

This year, the peak period for activity should be August 12th and 13th, when between 60 and 100 meteors an hour might be visible streaking across the night sky. In Europe, the best time to see them is after midnight, while America gets it a little easier and earlier. To check time in your location try timeanddate.com, which should give local observation times.

Unfortunately, the moon will be very close to full on the night of the peak, and this will affect the visibility of the fainter meteors. Of course, you’ll also need to be somewhere that’s dark enough to see the night sky without it being blotted too heavily by surrounding Earthly light pollution.

To help people observe the peak period, there are a number of planned livestreams on the web – including the two below.

Space Sunday: Mars,the Moon and space hotels

It has been some time since my last Mars Science Laboratory (MSL) rover report, so it’s time to play catch up with Curiosity, and take a look at what is happening with Opportunity.

For the last 16 months, Curiosity been engaged is studying “Vera Rubin Ridge”. Originally seen as a measn for the rover to traverse from one area of interest on “Mount Sharp” to another, the ridge became a point of interest itself when the rover imaged a rock formation that could fill a gap in the science team’s knowledge about the mound’s formation.

At the time the rock formation was noticed, engineers had been in the process of trying to overcome a issue with the rover’s drill that had prevented its use for several months. A potential work-around had been tested on Earth, so investigation of the rock formation offered the opportunity to test the updated drilling approach. Curiosity was therefore ordered to reverse course in the hope the tests would be successful and a sample of the rock could be gathered.

While successful, this was actually complicated – the issue with the drill feed mechanism also meant that the usual means of sorting samples post extraction had to be abandoned in favour of a new approach. However, the initial success meant Curiosity could resume drill-based sample gathering and analysis, marking the start of period of exploration around the ridge area – albeit it one interrupted by the 2018 global dust storm. In December 2018, this work concluded with the rover collecting its 19th overall sample on Mars, at a location on the ridge called “Rock Hall”.

Since then, the rover has been completing its work on the ridge, which included taking a “selfie” on January 15th, comprising 57 individual images taken with the Mars Hand Lens Imager (MAHLI) camera on the end of its robotic arm. At the ed of January, Curiosity said farewell to “Vera Rubin Ridge”, resuming its traverse southward towards the “clay bearing unit” it was originally heading to when it stopped at the ridge in September 2017.

The January 2019 “selfie” taken by Curiosity Sol 2291 at the “Rock Hall” drill site, located on “Vera Rubin Ridge”. Note parts of the robot arm have been removed from the completed image due to the fact it would appear in multiple locations in the completed image. Credit: NASA/JPL / MSSS.

At the same time, the science team for the rover released a paper revealing a new mystery about “Mount Sharp” and showing how instruments aboard the rover were re-purposed to allow it to be made.

As I’ve previously reported, previous studies of “Mount Sharp”- more correctly called Aeolis Mons, the 5 km (3 mi) high mound at the centre of the crater – suggested it was formed over two billions years, the result of repeated flooding of the crater laying down bands of sedimentary deposits, some of which were blown away by wind action, others of which settled. Over the millennia, these layers were sculpted by wind action within the crater, until only the central mound was left.

However, this type of water-induced layering should have resulted in the lower slopes of Mount Sharp being heavily compressed; but measurements of the local gravity environment of the terrain Curiosity has been driving over in its ascent up “Mount Sharp”, indicate the layers of the lower slopes are less dense than thought, meaning it is relatively porous. This indicates they were not buried under successive layers as had been thought, and thus some other process must have given rise to the mound.

The measurements were obtained by re-purposing the accelerometers Curiosity uses as a part of its driving / navigation system. Normally, these are used to determine its location and the direction it is facing with enormous precision. But, through a subtle piece of reprogramming, engineers were able to turn them into a gravimeter, allowing Curiosity to measure local gravity every time it stopped driving, and with massively greater precision than can be achieved from orbit.

An image captured by NASA’s Mars Reconnaissance Orbiter (MRO) overlaid with part of Curiosity’s path, including the Bagnold dunes in Gale Crater and up the slopes of Mount Sharp via the Murray Formation. Credit: NASA/JPL

Given the results tend to dispel the idea that water action was primarily responsible for filling the crater with sediments subsequently added to and shaped by wind action, it’s been proposed that “Mount Sharp” has been formed almost entirely as a result of Aeolian (wind-driven) sedimentation. This would leave the layers forming the mound a lot less dense in comparison to layers laid down and built up as a result of water action and settling.

However, this doesn’t entirely explain why the mount was formed, and further study is required before it can be said with certainty that wind played the core part in building and sculpting “Mount Sharp”. In the meantime, the re-purposing of Curiosity’s accelerometers is another example of the flexibility found within NASA’s robot explorers, as Ashwin Vasavada, Curiosity’s project scientist, noted in response to the new information.

There are still many questions about how Mount Sharp developed, but this paper adds an important piece to the puzzle. I’m thrilled that creative scientists and engineers are still finding innovative ways to make new scientific discoveries with the rover.

– Ashwin Vasavada, Curiosity’s project scientist.

New Plan to Contact Opportunity

It is now seven months since communications with NASA’s other operational Mars rover, Opportunity, was lost as a result of the planet girdling dust storm that ran from late May until around the end of July 2018, and which forced the rover to go into a power saving safe mode as there were insufficient sunlight for its solar cells to recharge its batteries.

In late August, ith the skies over Opportunity clearing of dust, NASA initiated an attempt to nudge “Oppy” into trying to resume contact with mission control using what is called the “sweep and beep” method. This involved sending a series of wake up commands throughout the day, then listening for the “beep” signal that would indicated “Oppy” had received the signal and was once again awaiting commands, allowing attempts at recovery to commence.  Unfortunately, this has not been the case.

NASA’s MER rover Opportunity (MER-B) arrived on Mars in January 2004. Contact was lost in June 2018 as a result of a major dust storm on the planet. Since August 2018, attempts to re-establish communications with the rover have been unsuccessful. Credit: NASA/JPL

Originally, it had been intended that if no response was received in  45-day period, NASA would switch to a purely passive means of listening out for “Oppy” in the hope the rover might send a message. But on January 25th, 2019, the space agency indicated they would be taking a different tack.

The new approach means that the “sweep and beep” approach will be continued, but slightly differently. In order to account for the possibility that Opportunity has both and off-kilter clock and both of its primary X-band communications systems, the outward commands designed to nudge a simple “beep” response from the rover will be replace by a command for it to switch away from using its primary communications system(s) to it secondary, the hope being that it would allow the rover to respond, and enable a more detail assessment of Opportunity’s condition to be made.

This effort is expected to continue for “several weeks” before NASA will again reassess the likelihood of re-establishing contact with the rover. However, a new threat is in the offing for Opportunity as winter starts to settle in the hemisphere where it is operating; if its solar panels are not working efficiently, the exceptionally low winter temperatures could damage it beyond recovery.

Continue reading “Space Sunday: Mars,the Moon and space hotels”

Space Sunday: asteroids, telescopes and dust

Credit: Mopic/Shutterstock

Saturday, June 30th marked International Asteroid Day, a global event involving researchers, astronomy groups, space agencies and more talking about asteroids  – and the risk some of them present to Earth.

Since 2013, and the Chelyabinsk event which saw a meteor  roughly 20 metres across, caught on film as it broke up high over the Russian town, the tabloid media has seemingly been obsessed with reporting meteors about to collide Earth and wreak havoc.

Fortunately, the vast majority of the estimated 10 million objects which have orbits passing close to Earth – referred to as NEOs, for Near Earth Objects, are unlikely to actually strike our atmosphere or are of a small enough size not to pose a significant threat if they did, despite all the screaming of the tabloids.

A map showing the frequency of small asteroids entering Earth’s atmosphere between 1994 and 2013. The dot sizes are proportional to the optical radiated energy of impacts measured in billions of Joules (GJ) of energy. A total of 556 events are recorded on the map, representing objects ranging in size from 1m to 20m. Credit: NASA’s Near Earth Object (NEO) programme

Which is not to say NEOs don’t pose a potential threat. Not all of the 10 million objects with orbits passing close to, or intersecting, the orbit of Earth have been properly mapped. Take 2018 LA (ZLAF9B2), for example. As I reported at the start of June, this asteroid, some 2 metres across, was only identified a handful of hours before it slammed into Earth’s upper atmosphere over Botswana at approximately 17,000 kilometres per second, to be caught on film as it burnt up. The energetic force of the accompanying explosion has been estimated to have been in the region of 0.3 to 0.5 kilotons (300 to 500 tonnes of TNT).

To offer a couple of quick comparisons with this event:

  • The 2013 Chelyabinsk superbolide (roughly 10 times the size of 2018 LA (ZLAF9B2) disintegrated at an altitude of around at 29.7 km at a velocity between 60,000-69,000 km/h, producing an energy release equivalent to 400-500 kilotons (400,000-500,000 tonnes of TNT). This was enough to blow out windows and send 1,491 people to hospital with injuries, including several dozen temporarily blinded by the flash of the explosion. The first 32 seconds of the video below convey something of the force of that event.

  • In June 1908 a cometary fragment estimated between 60 and 190 metres cross disintegrated some 5 to 10 km above Tunguska, Siberia. This generated an estimated downward explosive force of between 3 to 5 megatons and an overall force of somewhere between 10 to 15 megatons (again for comparison, all the bombs dropped by allied forces in World War 2 amounted to around 3.4 megatons of combined explosive force). This is believed to have generated a shock wave measuring 5.0 on the Richter scale, flattening an estimated 80 million trees covering an area of 2,150 square kilometres. Were it to occur today, such an event would devastate a large city.

There are two sobering points with these two events. The first is that astronomers estimate only about one-third (1600) of objects the size of the Tunguska event meteoroid which might be among that 10 million NEOs have so far been mapped. The second is that many NEOs can remain “hidden” from our view. the Chelyabinsk superbolide, for example passed unseen as the Sun completely obscured its approach to Earth.

There have been several proposals for trying to deal with the potential risk of a PHA – Potentially Hazardous Asteroid – impact over the years. One currently in development is the NASA / Applied Physics Laboratory (APL) Double Asteroid Redirection Test (DART) mission intended to demonstrate the kinetic effects of crashing an impactor spacecraft into an asteroid for planetary defence purposes.

The target for this mission is rather interesting. DART will be launched on an intercept with 65803 Didymos, an asteroid around 750 metres across – but this will not be the vehicle’s target. That honour goes to a much smaller asteroid – around 170 metres across (so in the size range of the Tunguska object) – orbiting 65803 Didymos and informally referred to as “Didymoon”.

Originally, DART was to be a part of a joint NASA/APL and European Space Agency effort, with ESA supplying a vehicle called the Asteroid Intercept Mission (AIM). This would have been launched ahead of DART on a trajectory that would place it in orbit around the 65803 Didymos / “Didymoon” pairing, allowing it to track / guide DART to its target and record the entire impact and its aftermath.

AIM never received funding, leaving the NASA/APL mission, which is currently scheduled for launch in 2021 and will intercept “Didymoon” in 2022. However, in the last few weeks, ESA has announced a revised mission to 65803 Didymos called Hera. Like AIM, it is designed to orbit the asteroid and is moon, and a call has been made to combine it with DART under a new joint mission called Asteroid Impact and Deflection Assessment (AIDA).

This would require DART to be delayed for a number of years to give ESA time to obtain approval for Hera and design, build and launch the craft – so the intercept would not take place until 2026. While this is a delay, it would mean that scientists would be able to better characterise “Didymoon” ahead of DART’s arrival, and witness the impact and its aftermath in real-time.

The original DART / AIM mission – to study the use of kinetic vehicles to divert an asteroid – now potentially superseded by the DART / Hera mission. Credit: NASA / APL / ESA

It’s not clear whether or not DART will be delayed. If it isn’t, then it has been proposed DART carries a camera equipped cubesat similar to those AIM would have used in support of its mission. This could then be separated from DART ahead of the impact so it could image the event as it flies by “Didymoon”. The Hera mission would then arrive a few years after the impact and assess the outcome, including imaging the impact crater on the asteroid and changes to its orbit and its rotation, which can help scientists determine how efficient the impact was in transferring its energy into “Didymoon”.

Continue reading “Space Sunday: asteroids, telescopes and dust”

Space Sunday: of molecules, meteorites and missions

In 1996, amidst a huge fanfare which included a statement by then US President Bill Clinton, a team of researchers announced they had discovered evidence of past Martian microbial life within a meteorite called ALH84001, discovered in the Allen Hills of Antarctica in 1984.

The claim lead to a high degree controversy, with many scientists disputing the findings of the original team. While that discovery has never been conclusively disproved, it has never been verified, either. However, it has – alongside the controversial results from two of the Viking Lander experiments in the 1970s – encouraged teams researching the potential for microbial life on Mars to be cautious in their work.

So it was with a sense of excitement that on Thursday, June 7th, 2018, NASA announced that the Mars Science Laboratory (MSL) Curiosity rover has once again found potential evidence of both organic molecules and methane on Mars. The news came via two papers Organic matter preserved in 3-billion-year-old mudstones at Gale crater, Mars and Background levels of methane in Mars’ atmosphere show strong seasonal variations.

In the first paper, the authors indicate how Curiosity’s Sample Analysis at Mars (SAM) suite detected traces of methane in drill samples it took from Martian rocks in 2016. Once these rocks were heated, they released an array of organics and volatiles similar to how organic-rich sedimentary rocks do on Earth – where similar deposits are indications of fossilised organic life.

What is particularly exciting is the first paper indicates that the material discovered on Mars is similar to terrestrial kerogen, a solid organic matter found in sedimentary rocks. Comprising an estimated 1016 tons of carbon, Kerogen on Earth exceeds the organic content of all living matter on Earth by a factor of 10,000.

NASA’s Curiosity rover has discovered ancient organic molecules on Mars, embedded within sedimentary rocks that are billions of years old. Credit: NASA Goddard Space Flight Centre

Essentially, want happens on Earth is that organic material gets laid down within the sedimentary layers, then over the aeons, fluid flowing thought the rock initiates chemical reactions to break down the organic deposits until only the insoluble  kerogen is left. It has already been established that Gale Crater was once the home of several liquid water lakes, and also that perchlorate salt – particularly good at breaking down organics – is present on Mars. Hence why the discovery of the kerogen-like material on Mars is a cause for excitement – it could be a similar process to that seen on Earth is present.

While the team responsible for the styudy point out the material SAM has found is similar to an insoluble material discovered in tiny meteorites known to fall on Mars, that it might have formed naturally on the planet is somewhat strengthened by the fact Curiosity has previously confirmed Gale Crater contains the chemical building blocks and energy sources that are necessary for life. However, the legacy of ALH84001 urge caution when dealing with these findings from the rover, as one of the authors of the first paper explained.

Curiosity has not determined the source of the organic molecules. Whether it holds a record of ancient life, was food for life, or has existed in the absence of life, organic matter in materials holds chemical clues to planetary conditions and processes… The Martian surface is exposed to radiation from space. Both radiation and harsh chemicals break down organic matter. Finding ancient organic molecules in the top five centimetres of rock that was deposited when Mars may have been habitable, bodes well for us to learn the story of organic molecules on Mars with future missions that will drill deeper.

Jennifer Eigenbrode, co-author, Organic matter preserved in 3-billion-year-old mudstones at Gale crater, Mars

In the second paper, scientists describe the discovery of seasonal variations in methane in the Martian atmosphere over the course of nearly three Mars years, which is almost six Earth years. This variation was also detected by Curiosity’s SAM instrument suite over the 3-year period.

This image illustrates possible ways methane might get into Mars’ atmosphere and also be removed from it. Credit: NASA Goddard Space Flight Centre / University of Michigan

Water-rock chemistry might have generated the methane, but scientists cannot rule out the possibility of biological origins. Methane previously had been detected in Mars’ atmosphere in large, unpredictable plumes. This new result shows that low levels of methane within Gale Crater repeatedly peak in warm, summer months and drop in the winter every year.

This is the first time we’ve seen something repeatable in the methane story, so it offers us a handle in understanding it. This is all possible because of Curiosity’s longevity. The long duration has allowed us to see the patterns in this seasonal ‘breathing.’

Chris Webster, co-author, Background levels of methane in Mars’ atmosphere show strong seasonal variations

In 2013, SAM detected organic molecules in rocks at the deepest point in the crater. These more recently findings, gathered further up the slopes of “Mount Sharp” add to the inventory of molecules detected in the ancient lake sediments. Thus, finding methane in the atmosphere and ancient carbon preserved on the surface gives scientists confidence that NASA’s Mars 2020 rover and ESA’s ExoMars rover will find even more organics, both on the surface and in the shallow subsurface.

NASA Successfully Transfers Sample

Following my last two Space Sunday updates concerning attempts to resume the collection of rock samples using Curiosity’s drilling mechanism, the US space agency has indicated a successful transfer of material gathered within the rover’s hollow drill bit into the rover’s on-board science suite (which includes the SAM instrument referred to above).

The new drilling capability is referred to as Feed Extended Drilling (FED), designed to bypass a formerly critical, but at risk of failure, piece of the rover’s drill system called the drill feed mechanism. This mechanism also used to form a part of the means by which samples used to be transferred from Curiosity’s arm-mounted turret to the on-board science suite. As it can no longer be used, engineers instead determined the sample could potentially be transferred to the science suite by positioning the drill bit directly over the sample intake ports and then running the drill in reverse, causing the gathered sample to (hopefully) trickle backwards and into one of the hoppers.

Referred to as Feed Extended Sample Transfer, the approach was tested on May 31st, 2018, and successfully saw the transfer of part of a sample obtained on May 19th into the hopper serving the rover’s Chemistry and Mineralogy (CheMin) unit.

Curiosity’s drill bit (upper right) positioned over one of the sample inlets on the rover’s deck leading to the on-board science suite. This image was captured on May 31st, 2018 (Sol 2068) by the rover’s Mast Camera (Mastcam). Credit: NASA / MSSS

The approach had already been successfully tested on Earth, but there were concerns the thin, dry atmosphere of Mars might not produce the same results. There’s also a matter of balance. Previously, any sample gathered by the drill would pass through the rover’s CHIMRA sieving system, which helps ensure the right amount is transferred to the on-board instruments. Without this, transfers become a matter of judgement, as engineer John Moorokian explained following the transfer:

On Mars we have to try to estimate visually whether this is working, just by looking at images of how much powder falls out. We’re talking about as little as half a baby aspirin worth of sample.

John Moorokian, lead developer of the FEST delivery method

The problem here is, were too little materials transferred, and CheMin and SAM would not be able to provide accurate analyses, but transfer too much of the unsorted material, and it could either clog instruments or remaining unused, potentially contaminating measurement of future samples. So far, it appears the first attempt has succeeded, although it will still be a while before the outcome of any analysis is known.
Continue reading “Space Sunday: of molecules, meteorites and missions”

Space Sunday: drills, neutrinos and a spaceplane

In May I wrote about an attempt to return the drill mechanism on the Mars Science Laboratory (MSL) rover Curiosity to operational status. As I noted in that report, use of the sample-gathering drill was suspended in December 2016, after problems were encountered with the drill feed mechanism – the motor used to extend the drill head leading to fears that continued use of the drill feed mechanism would see it fail completely, ending the use of the drill.

At the time of that report, a live test of the drill on Mars had just been carried out, but the results hadn’t been made public. However, on May 23rd, NASA issued an update confirming the test had been successful, and a sample of rock had been obtained.

The new drilling technique is called Feed Extended Drilling (FED). It keeps the drill head extended and uses the weight of the rover’s robot arm and turret to push the bit into a target rock. This is harder than it sounds, as it requires the weight of the rover’s arm to provide the necessary pressure to help push the drill bit into a rock – something it is not designed to do, and risks either breaking the drill bit or cause it to become stuck.

Engineers had spent more than a year developing the technique using Curiosity’s testbed “twin” on Earth before carrying out a preliminary test on Mars in February (see here), which was not intended to gather any sample. For the May 19th, 2018, test the mission team combined the FED approach to drilling with using the drill’s percussive mechanism with the intention of both testing the combined technique with an attempt to obtain a sample of rock.

The sample in question is of specific importance to the mission team, although it required a literal turnaround for the rover. For the last few months, Curiosity has been traversing “Vera Rubin Ridge” on “Mount Sharp”. In doing so, the rover passed a distinct rock formation mission scientists realised could fill a gap in their understanding about how “Mount Sharp” may have formed. However, at the time, there was no way to obtain a sample. Once it looked likely that drilling operations could be recovered, the decision was made in April to reverse the rover’s course and return to the rock formation, where the test was successfully carried out.

The team used tremendous ingenuity to devise a new drilling technique and implement it on another planet. Those are two vital inches of innovation from 60 million miles away. We’re thrilled that the result was so successful.

– Curiosity Deputy Project Manager Steve Lee.

The 5 cm (2-in) deep hole in a target called “Duluth”, captured by the rover’s Mastcam on May 20th, 2018 (Sol 2057) after a successful test allowed a rock sample to be gathered by the rover since October 2016. Credit: NASA/JPL / MSSS

The rover has since resumed its traverse towards an uphill area enriched in clay minerals that the science team is  also eager to explore. The next stage for the engineers it so figure out how to transfer the gathered sample ready for analysis by the rover’s on-board laboratory.

Previously, this would have involved passing the sample through another system on the rover’s “turret”, called CHIMRA (Collection and Handling for In-Situ Martian Rock Analysis). However, transfer into CHIMRA in part requires the use of the drill feed mechanism. As this can no longer be used in case it breaks. the idea – yet to be tested – is to try positioning the drill head over the hoppers feeding the science suite and then running the drill in reverse, allowing the sample  – held within the hollow drill bit – to trickle back out, and hopefully into the hoppers.

If It’s A Particle Jim, Then It’s Not As We Know Them

Neutrinos are elementary particles that interact only via the weak subatomic force and gravity. Their behaviour is explained by the Standard Model of particle physics.

In essence – and very broadly speaking – the Standard Model is a list of particles that go a long way toward explaining how matter and energy interact in the cosmos. Some of these particles – quarks and electrons, for example – are the building blocks of the atoms that make up everything we’ll ever touch with our hands. Others, like the three known neutrinos, are more abstract: high-energy particles which can be created naturally (within the core of stars or during supernova events, for example), or artificially (e.g. in nuclear reactors or nuclear explosions), and which stream through the universe, barely interacting with other matter. Billions upon billions of solar neutrinos pass through each of us every second without ever affecting us.

The LSND. Credit: Los Alamos National Laboratory

These neutrinos can be broken into three known “flavours”:  electron, muon and tau neutrinos. As waves of neutrinos stream through space, they periodically “oscillate,” jumping back and forth between one flavour of the three flavours and another – or that’s the theory.

In the 1990s, the Liquid Scintillator Neutrino Detector (LSND) at the Los Alamos National Laboratory, New Mexico, reported more neutrino detections than the Standard Model’s description of neutrino oscillation could explain, resulting in a new flavour of “heavy” neutrino being posited: the “sterile neutrino”.

At the time, the discovery met with excitement; physicists had long noticed a discrepancy between the predicted and actual number of anti-neutrinos, or the antimatter partners to neutrinos, produced in nuclear reactors. Sterile neutrinos could offer an explanation for the discrepancy. The only problem with the idea is that other than the LSND results, no-one has been able to find evidence for the existence of “sterile neutrinos”.

Until, possibly, now. A paper just published suggests that another neutrino detector – the MiniBooNE, operated Fermilab in Chicago – has also reported a similar result to LSND, resulting in the suggestion some neutrinos are oscillating into the “heavier” sterile neutrinos and then back into one of the recognised flavours. What’s more, combining the results of the MiniBooNE experiment with those of LSND suggests there is just a one-in-500 million chance of both results being a fluke.

Continue reading “Space Sunday: drills, neutrinos and a spaceplane”

Space Sunday: drills, telescopes, pictures and doubts

In March I reported that NASA’s Mars Science Laboratory rover Curiosity had taken an important step in recovering its ability to drill into Martian rocks to collect samples. Now it looks like drilling operations could be resuming.

Use of the sample-gathering drill was suspended in December 2016, after problems were encountered with the drill feed mechanism – the motor used to extend the drill head between two “contact posts” designed to steady the rover’s turret during drilling operations. In particular, there was concern that continued use of the drill feed mechanism would see it fail completely, ending the use of the drill.

Since then, engineers have been trying to develop a means of using the drill without and reliance on the drill feed mechanism, and at the end of February 2018, a new technique was tested. Called Feed Extended Drilling, or FED,  it keeps the drill bit and head extended, and uses the weight of the rover’s robot arm and turret to push the bit into a target rock. This is harder than it sounds,as it requires the weight of the rover’s arm to provide the necessary pressure to help push the drill bit into a rock – something it is not designed to do, and might actually break the drill bit or cause it to become stuck. However, the rover passed the February test with flying colours.

This success meant that engineers could focus on recovering the drill’s percussive action. This assists in both helping the drill cut into a rock and in breaking the contact area under the bit up into a fine powder that can be collected by the collection tube surrounding the bit.

A close-up of the drill mechanism. In the centre is the hollow drill bit, which cuts into rock and gathers sample powder. The drum at the base of the drill is the first part of the sample collection mechanism. Also of this used to be extended up against a rock sample by the drill feed mechanism. Just visible cutting across the bottom right corner of the image is one of the two contact posts. The second post can be seen in part in the top right corner of the image. These are used to hold the rover’s robot arm steady against a target rock surface while the drill is extended for sample-gathering operations. Credit: NASA

On Saturday, May 19th, and following further tests using Curiosity’s Earth-base test bed twin, the command was sent to Mars for Curiosity to carry out a second drilling test using both the FED approach and with the drill percussive action enabled. Unlike the February test, however, this one has an additional goal: to actually recover a special sample of rock.

For the last couple of months, the rover has been making its way along a feature on “Mount Sharp” dubbed “Vera Rubin Ridge”, toward an uphill area enriched in clay minerals that the science team is eager to explore. In doing so, the rover passed a distinct rock formation that could fill a gap in the science team’s knowledge about Mount Sharp and its formation.

Testing the FED / percussion approach to drilling on Earth using Curiosity’s test-bed “twin”. Not how the drill head (centre) is fully extended, so the contact posts cannot be used. Forward pressure on the drill is being provided entirely by the rover’s robot arm. Credit: NASA/JPL

Given the progress made in trying to get the drill working again, the decision was made to reverse Curiosity’s course in mid-April and drive back to the rock formation in the hope that the May 19th test could gather a sample from it. Commenting on the decision, Curiosity principal scientist Ashwin Vasavada  said, “Every layer of Mount Sharp reveals a chapter in Mars’ history. Without the drill, our first pass through this layer was like skimming the chapter. Now we get a chance to read it in detail.”

If the new technique has allowed Curiosity to gather a sample – at the time of writing this article, NASA had yet to provide an update on the operation – the engineering team will immediately begin testing a new process for delivering that sample to the rover’s internal laboratories. This is again a complex process, which in the past has involved the drill feed mechanism to transfer material gathered by the drill to another mechanism called CHIMRA (Collection and Handling for In-Situ Martian Rock Analysis), also mounted on the rover’s turret. CHIMRA sieves and sorts the material, grading it by size and coarseness before transferring it to the rover’s science suite, located in Curiosity’s main body.

Curiosity’s “fingers”: the five instruments on the rover’s turret, including the drill with the feed mechanism motors behind it and the two angled contact posts clearly visible, and the CHIMRA system used for sieving and sorting sample material gathered by both its own scoop (for surface material) and the drill (for rock samples). Credit: NASA 

Success with both the drilling operation and same transfer will mean – allowing for fine-tuning and other adjustments – the drill could be re-entering regular use in the near future.

Continue reading “Space Sunday: drills, telescopes, pictures and doubts”