Category: Space Sunday

Space Sunday: Kepler, China, and a voyage to the Sun

Posted on by Inara Pey
An artist’s rendering of Kepler in its heliocentric orbit. Credit: NASA

In March 2018, I reported that NASA’s exoplanet hunting Kepler mission might be drawing to a close. The end of the mission was threatened when engineers confirmed that the observatory was showing signs of running out of fuel.

Responsible for locating 70% of the 3,750 exoplanets discovered to date, Kepler was launched in 2009 and has been one of the most successful missions NASA has run. Unfortunately, as a result of a change to its operational parameters following the failure of two of the four reaction wheels used to hold it steady while observing distant stars, the observatory has had to increase its use of its propellant reserves. As a result, on July 2nd, 2018, NASA Kepler was ordered into a “no-fuel-use safe mode” after telemetry reported an “anomalous” drop in fuel pressure in the spacecraft.

The observatory will remain in this mode until August 2nd, 2018, when it is due to use its manoeuvring jets to orient itself so it can transmit the data collected on its last observational campaign – the 18th in its extended mission – to Earth via the Deep Space Network. During the time between now and August 2nd, engineers will attempt evaluate the status of the spacecraft’s propulsion system to determine if it has sufficient fuel left to allow it to resume observations in what is called Campaign 19, scheduled to begin August 6th, 2018.

Kepler has been tremendously successful by any measure. In addition to its impressive raw planet tally – liable to raise as there are still more than 2,000 planet candidates still to be vetted – the data gathered by Kepler since 2009 seems to suggest that 20% of Sun-like stars host a roughly Earth-size planet in the habitable zone — that just-right range of distances where liquid water could exist on a world’s surface.

During its primary mission, from 2009 through May 2013, Kepler stared at about 150,000 stars simultaneously, hunting for periodic dipping in their brightness that might indicate a planetary body moving in front of them. Since 2014, it has been engaged on its extended K2 mission, comprising a series of observational campaigns lasting 80 days apiece, each focused on a slightly different area of sky.

However, if this is the beginning of the end for Kepler, it’s not the end of our exoplanet hunting efforts: if all is proceeding as planned, the Transiting Exoplanet Survey Satellite, launched in April, 2018, should be taking over the task – although admittedly, news on its “first light” image, which was due in June, has yet to be released.

China’s Super-Heavy Launch and Reusable Rocket Capabilities

Speaking during an event in China at the end of May 2018, Long Lehao, a chief designer with the China Academy of Launch Vehicle Technology (CALT), gave an update on two of China’s new launch vehicles: the Long March 9 super booster and the partially reusable Long March 8 rocket.

The Long March 9 – referred to as the CZ-9, or Changzheng 9 in Chinese – is slated to enter service in 2030, and is central to China’s interplanetary ambitions. It is also a huge increase in scale a capability for the nation’s launch systems. The core three-stage rocket will stand 93 metres tall, using a 10-metre diameter first stage. It will be assisted at launch by four 5-metre diameter strap-on boosters – these alone being the same diameter as China’s Long March 5, currently the country’s most powerful rocket. The most powerful variant of the vehicle will be capable of launching 140 tonnes to low-Earth orbit (LEO), 50 tonnes to the Moon and around 44 tonnes to Mars.

China’s Long March 9 (CZ-9), flanked by launch vehicles past and present, including Russia’s never successfully flown N-1 lunar rocket from the 1960s. Via: Wikipedia

By comparison, NASA’s Space Launch System (SLS) vehicle will have a core stage 8.4 metres in diameter, with its most powerful variant (Block 2) capable of placing 130 tonnes into LEO, and SpaceX’s BFR with a 9-metre diameter core and be capable of putting 150 tonnes into LEO.

In his presentation, Long confirmed the first CZ-9 is slated for launch in 2030 – around the time the Block 2 variant of the SLS is due to fly. One of the first missions earmarked for the super booster is an automated Mars sample return mission, with crewed lunar missions also on the cards for the vehicle. In addition, the CZ-9 could be used to deploy a system of solar power satellites the Chinese government and military are said to be considering.

Meanwhile, the Long March 8, based on the core of China’s current mid-range launcher, the Long March 7, is expected to make its first flight in 2021. Capable of lifting a more modest 8 tonnes to LEO, the first stage of the booster is designed to be reusable, employing a similar methodology to SpaceX’s Falcon 9 first stages to return to Earth and land.

An artist’s impression of the Long March 8 first stage about to make a soft-landing at the end of a launch flight. Credit: Shanghai Academy of Spaceflight Technology

While the payload capacity of the Long March 8 might sound small, it is ideal for typical satellite payloads. More to the point, the use of the Long March 7 first stage means the system could be “upgraded” to work with that vehicle, which is capable of placing 13 tonnes into LEO.

Continue reading “Space Sunday: Kepler, China, and a voyage to the Sun” →

Space Sunday: asteroids, telescopes and dust

Posted on by Inara Pey
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: stations, Ceres, doubts and rockets

Posted on by Inara Pey
Tiangong-2, with one of the two docking ports visible. Credit: China News

China may be preparing to de-orbit its Tiangong-2 orbital laboratory, possibly to avoid a situation similar to that relating to the so-called “uncontrolled” re-entry of their Tiangong-1 facility, which re-entered the Earth’s atmosphere and broke-up / burnt-up in April 2018.

Orbital information published by the U.S. Strategic Command’s Joint Force Space Component Command, through the Joint Space Operations Centre, indicates that Tiangong-2 has moved from an altitude of around 380 by 386 km down to 292 by 297 km.

No official announcement regarding the status of the Tiangong-2 space lab has been made by the China Manned Space Engineering Office (CMSE), however, China has made no secret of its plans to establish a permanent orbital presence over the Earth in the 2020s – and that to do so, they would discontinue operations with both Tiangong-1 and Tiangong-2. and de-orbit both.

Measuring 10.4 metres in length and some 3.3 metres in maximum diameter, Tiangong-2 weighs 8.6 metric tonnes – making it the same overall size and weight as Tiangong-1, launched in 2011. The re-entry of that unit came after a series of alarmist headlines claiming it would “crash” to Earth after it was reported the Chinese only had partial control over it. Because of that tabloid farrago, some have speculated the alteration in Tiangong-2’s orbit is to allow China to retain full control over the facility, including when it re-enters the atmosphere.

Jing Haipeng (l) and Chen dong (r) aboard Tiangong-2. The only crew to visit the facility Credit: CCTV

Launched in September 2016, Tiangong-2 hosted a single crewed visit that same year, which lasted 30 days. In 2017 served as a test-bed for verifying on-orbit automated docking and refuelling capabilities  – two aspects of operations vital to the Chinese ambitions of developing their large-scale space station – using the Tianzhou-1 cargo spacecraft.

Tiangong-2 carried a range of science payloads, including POLAR, a gamma-ray burst detector developed by an international collaboration including Swiss, Chinese and Polish institutes. According to principal investigator Nicolas Produit, this astro-particle experiment collected excellent data during six months of operations, with science results to be published shortly. It is the kind of international collaborative effort China would like to develop with its new station.

Artist’s impression of the planned Chinese space station complex. Credit: CCTV

China is aiming to launch the first module of the space station proper, named Tianhe, around 2020. This mission first requires the nominal return-to-flight of the heavy lift Long March 5 launch vehicle, which suffered a launch failure in July 2017. When completed, the space station will mass between 60 and 100 metric tonnes, including two experiment modules due for launch in 2022. It will be capable of hosting three astronauts in rotations of up to six months at a time. A further element of the station will be a free-flying Hubble-class space telescope capable of docking with the station to receive propellants and undergo maintenance and repairs.

More on Ceres and the Building Blocks of Life

In February 2017, I wrote about the discovery of the basic building blocks of life on Ceres, which has been the subject of the joint NASA / ESA Dawn mission since March 2015.

The discovery of aliphatic compounds on the surface of Ceres was made by an international team of scientists who had been reviewing data from the Visible and Infra-red Mapping Spectrometer (VIMS) aboard the spacecraft. Now, a new study conducted by a team of researchers from Brown University suggests that these patches contain more organic material than previously thought.

Dawn spacecraft data show a region around the Ernutet crater where organic concentrations have been discovered (labelled “a” through “f”). The colour coding shows the strength of the organics absorption band, with warmer colours indicating the highest concentrations. Credit: NASA/JPL / UCLA / ASI / INAF / MPS / DLR / IDA

Aliphatics are a type of compound where carbon atoms form open chains that are commonly bound with oxygen, nitrogen, sulphur and chlorine – all of which are necessary for the evolution of life. This doesn’t actually mean that Ceres supports life, because these molecules can also arise from non-biological processes. Nevertheless, the presence of these compounds does raise the questions.

The team behind original discovery of the aliphatics, found within a 1000 km² region around of the Ernutet crater, concluded that between 6 and 10% of the spectral signature detected on Ceres could be explained by organic matter. As hydrothermal activity had been detected on Ceres, the researchers hypothesised that the molecules were endogenous in origin – that is, they came from inside the protoplanet. Given that ammonia-bearing hydrated minerals, water ice, carbonates, and salts have also been detected on Ceres, there is the suggestion that it may have an interior environment that can support prebiotic chemistry.

Dawn mission (NASA / JPL) – click for full size

However, rather than relying on Earth rocks on which to base their work and findings, the team from Brown University used carbonaceous chondrite meteors, which have been shown to contain organic material that is slightly different from what we are familiar with here on Earth. As a result, they determined that the organics found on Ceres were distinct from their terrestrial counterparts – and the up to 40 to 50% of the spectral signal we see on Ceres is explained by organics – far more than originally estimated.

If this latter estimate is correct, it raises the question about where it came from – 40% is a lot for the compound to be entirely endogenous in origin. Rather, the high concentrations seem to be more consistent with being deposited by a comet impact.

Given that the asteroid belt is composed of material left over from the formation of the Solar System,  determining where these organics came from could shed light on how organic molecules were distributed throughout the Solar System early in its history, and the role this distribution may have played in the development of life here in Earth.

If, however, the compound deposits are endogenous in origin, there is still the question of what mechanisms were / are in play to result in such high concentrations emerged in Ceres’ northern hemisphere, and then preserve them in these locations. This is a question unlikely to be answered without follow-up missions able to obtain and analyse samples gathered from the surface of the protoplanet.

Continue reading “Space Sunday: stations, Ceres, doubts and rockets” →

Space Sunday: the sands of Mars and Planet Nine

Posted on by Inara Pey
The spread of the 2018 dust storm as seen by NASA’s Mars Reconnaissance Orbiter between May 31st and June 10th. The black gaps in the images indicate parts of the planet’s surface not captured in the individual images making up this time-lapse view. Note the position of the Opportunity and Curiosity rovers. Credit: NASA / MSSS

Dust storms on Mars are not unusual event; they occur in both hemispheres with the changing of the seasons, and can even grow to encompass the entire planet.

Just such world-girdling dust storm occurred in 1971, and was caught by the cameras on NASA’s Mariner 9 space vehicle when it arrived in the vicinity of Mars in November of that year. The images Mariner 9 returned from Mar as it entered orbit (becoming in the process the first man-made object to orbit another planet) show the entire surface of Mars totally obscured by a blanket of dust that reached high up into the atmosphere. It took some two months for the storms to abate – although scientists were treated to Mars gradually revealing itself to Mariner 9’s camera as the dust slowly settled, starting with the high peaks of Olympus Mons and the Tharsis Ridge volcanoes, which rise up to 25 kilometres above the mean surface level of Mars.

In 2001, the Hubble Space Telescope (HST) reveal just how all-encompassing these more massive storms on Mars can be, when it took two images of Mars just three months apart. In one, surface features are clearly visible; in the second, Mars appears to be devoid of any detail.

These two images, captured 3 months apart by the Hubble Space Telescope in 2001, shoe how all-encompassing the more extreme dust storms on Mars can be. Note that in both images, south is at the top . Credit: NASA / The Hubble Heritage Team

Now, another dust storm is engulfing a huge swathe of Mars. It grew quickly in the opening week and a half of June, While it has not – as yet – engulfed the entire planet, it is raising massive mounts of dust high into the Martian atmosphere, marking it as the “thickest” dust storm witnessed on Mars.

Of to two rovers currently operating on Mars, the Mars Exploration Rover Opportunity is particularly impacted by storms of this nature as it is solar-powered. Such is the volume of dust lifted into the Martian atmosphere when these more extreme storms occur that they can severely limit Oppy’s ability to gather sunlight to charge its batteries.

This is not the first such dust storm Oppy has encountered; in 2007, a large-scale storm resulted in a severe degradation in the amount of sunlight reaching the Martian surface where the rover was operating. At that time, we were treated to some remarkable images of just how all-pervasive the dust can become when lifted into the tenuous Martian atmosphere.

This series of images show the onset of a severe dust storm, as seen by NASA’s Opportunity rover in 2007. On the left, Sol 1205, is “normal” daylight conditions. The remain shots show the reduction in daylight between Sol 1220 and Sol 12035. Credit: NASA / Cornell University

Even so the current storm is perhaps the most severe Oppy has had to face. So much so that even though the decision was quickly made to suspend all science gathering operations as it explores Endeavour Crater, and so reduce its power output, the rover has since switched itself into a further “safe” mode of power conservation.

This  kind of more massive storm is particularly prone to occurring when summer comes to one of the hemispheres (in this case, the southern hemisphere). At this time, the increased sunlight warming the atmosphere causes an increase in wind activity, which results in more dust being lifted into the atmosphere. For so reason, this dust causes the winds to persist  – and even increase, lifting more dust, and a feedback loop is created, turning the process into a self-driving storm that can take weeks or months to die down.

A couple of interesting points with these dust storms is that firstly, and for those familiar with the Matt Damon vehicle The Martian, the winds are nowhere near as violent as portrayed by that film. While wind speeds during these storms can reach speeds of 96-160 km/h (60-100 mph), the Martian atmosphere is so tenuous, the overall effect of such wind speeds is akin to a stiff breeze here on Earth. The second point is that while they do reduce the amount of sunlight reaching the surface of Mars, the dust is an effective insulator, both reducing the amount of heat being radiated away from Mars whilst simultaneously absorbing solar radiation, both of which serve to raise ambient surface temperatures.

This latter point is in part good news for Oppy, as it helps reduce the rover’s power outlay in keeping itself and its instruments warm. However, given that such intense storms can last for periods of several weeks to months at a time, there is genuine concerns as to how well Opportunity might survive if this storm is particularly drawn out, leaving the MER team on Earth reasonably confident the rover will be able to survive the storm without its systems becoming too cold to be restarted.

By June 10th, the storm had grown to a size where it was starting to make itself felt in Gale Crater, where NASA is operating the Mars Science Laboratory rover Curiosity, although the effects haven’t been as great as around Endeavour Crater, which Opportunity has been exploring. When it comes to dust storms, Curiosity has a significant advantage over Opportunity in that it is nuclear powered and is thus its power systems aren’t affected by any loss of  sunlight.

The dust storm reaches Gale crater: on the left, a true colour image from Curiosity’s Mastcam taken of the east-north-east rim of Gale Crater taken on June 7th, 2018 (Sol 2074). On the right, the same view seen three days later, on June 10th, 2018 (Sol 2077). Credit: NASA / MSSS

By the time the dust storm reach Gale Crater, it was blanketing to 35 million square kilometres (14 million sq miles) of the Martian surface – or roughly one-quarter of the entire planet, and it was still growing. As well as bing observed by the two surface rovers, it is also being watched from space by the combined network of NASA’s Mars Reconnaissance Orbiter (MRO), Mars Odyssey and MAVEN space vehicles, as well as Europe’s Mars Express mission and India’s Mars Observer Mission.

Observing and probing this kind of storm is seen as vital on a number of counts. In the first place, the precise mechanism that causes the feedback loop of wind and dust mentioned above isn’t really understood, so seeing storms like the develop and abate can help scientists to fill-in the blanks. In addition, and as NASA’s Mars Programme Office chief scientist Rich Zurek explains:

Studying their physics is critical to understanding the ancient and modern Martian climate. Each observation of these large storms brings us closer to being able to model these events, and maybe, someday, being able to forecast them. That would be like forecasting El Niño events on Earth, or the severity of upcoming hurricane seasons.

This latter point is particularly important in terms of planning for future missions – including any human mission to Mars. Being able to predict the rises and potential scope of these storms could go a long way to ensuring human safety on Mars. However, for the duration of this storm, all eyes are on little Opportunity, caught in the midst of it, with the hope that the rover will come through the storm able to resume its record-breaking 14+ years of operations on Mars.

Continue reading “Space Sunday: the sands of Mars and Planet Nine” →

Space Sunday: of molecules, meteorites and missions

Posted on by Inara Pey

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

Posted on by Inara Pey

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” →