Space Sunday: drills, flares and monster ‘planes

NASA’s Mars Science Laboratory (MSL) rover Curiosity has taken a further step along the way to retrieving and analysing samples gathered by its drill mechanism, which hasn’t been actively used since December 2016, after problems were encountered with the drill feed mechanism.

Essentially, the drill system is mounted on Curiosity’s robot arm and uses two “contact posts”, one either side of the drill bit, to steady it against the target rock. A motor – the drill feed mechanism – is then used to advance the drill head between the contact posts, bringing the drill bit into contact with the rock to be drilled, and then provide the force required to drive the drill bit into the rock. However, issues were noted with this feed mechanism, during drilling operations in late 2016, leading to fears that it could fail at some point, leaving Curiosity without the means to extend the drill head, and thus unable to gather samples.

To overcome this, MSL engineers have been looking at ways in which the feed mechanism need not be used – such as by keeping the drill head in an extended position. This is actually harder than it sounds, because the drill mechanism – and the rover as a whole – isn’t designed to work that way. Without the contact posts, there was no guarantee the drill bit would remain in steady, straight contact with a target rock, raising fears it could become stuck or even break. Further, without the forward force of the drill feed mechanism, there was no way to provide any measured force to gently push the drill bit into a rock – the rover’s arm simply isn’t designed for such delicate work.

Curiosity’s drill mechanism, showing the two contact posts (arrowed) used the steady the rover’s robot arm against a target rock, and the circular drill head and bit between them – which until December 2016, had been driven forward between the two contact posts by the drill feed mechanism, which also provided the force necessary to drive the drill bit into a rock target. Credit: NASA/JPL / MSSS

So, for the larger part of 2017, engineers worked on Curiosity’s Earth-based twin, re-writing the drill software, carrying out tests and working their way to a point where the drill could be operated by the test rover on a “freehand” basis. At the same time, code was written and tested to allow force sensors within the rover’s robot arm – designed to detect heavy jolts, rather than provide delicate feedback data – to ensure gentle and uniform pressure could be applied during a drilling operation and also monitor vibration and other feedback which might indicate the drill bit might be in difficulty, and thus stop drilling operations before damage occurs.

At the end of February 2018, the new technique was put to the test on Mars. Curiosity is currently exploring a part of “Mount Sharp” dubbed “Vera Rubin Ridge”, and within the area being studied, the science team identified a relatively flat area of rock they dubbed “Lake Orcadie”, and which was deemed a suitable location for an initial “freehand” drilling test. The rover’s arm was extended over the rock and rotated to gently bring the extended drill head in contact with the target, before a hole roughly one centimetre deep was cut into the rock. This was not enough to gather any samples, but it was sufficient to gauge how well robot arm and drill functioned.

“We’re now drilling on Mars more like the way you do at home,” said Steven Lee, a Curiosity deputy project manager on seeing the results of the test. “Humans are pretty good at re-centring the drill, almost without thinking about it. Programming Curiosity to do this by itself was challenging — especially when it wasn’t designed to do that.”

The test drill site of “Lake Orcadie”, “Vera Rubin Ridge”, imaged by Curiosity’s Mastcam on February 28th, 2018, following the initial “freehand” drilling test. Credit: MASA/JPL / MSSS

The test is only the first step to restoring Curiosity’s ability to gather pristine samples of Martian rocks, however. The next test will be to drive the drill bit much deeper – possibly deep enough (around 5 cm / 2 inches) to gather a sample. If this is successful, then the step after that will be to test a new technique for delivering a gathered sample to its on-board science suite.

Prior to the drill feed mechanism issue, samples were initially graded and sorted within the drill mechanism using a series of sieves called CHIMRA – Collection and Handling for In-Situ Martian Rock Analysis, prior to the graded material between deposited in the rover’s science suite using its sample scoop. This “sieving” of a sample was done by upending the drill and then rapidly “shaking” it using the feed mechanism, forcing the sample into CHIMRA. However, as engineers can no longer rely on the drill feed mechanism, another method to transfer samples to the rover’s science suite has had to be developed.

This involves placing the drill bit directly over the science suite sample ports, then gently tapping it against the sides of the ports to encourage the gathered sample to slide back down the drill bit and into the ports. This tapping has been successfully tested on Earth – but as the Curiosity team note, Earth’s atmosphere and gravity are very different from that of Mars. So whether rock powder will behave there as it has here on Earth remains a further critical test for Curiosity’s sample-gathering abilities.

More Evidence Proxima b Unlikely To Be Habitable

Since the confirmation of its discovery in August 2016, there has been much speculation on the nature of conditions which may exist on Proxima b, the Earth-sized world orbiting our nearest stellar neighbour, Proxima Centauri, 4.25 light years away from the Sun.

Although the planet – roughly 1.3 times the mass of Earth – orbits its parent star at a distance of roughly 7.5 million km (4.7 million miles), placing it within the so-called “goldilocks zone” in which conditions might be “just right” for life to gain a foothold on a world, evidence has been mounting that Proxima b is unlikely to support life.

Comparing Proxima b with Earth. Credit: Space.com

The major cause for this conclusion is that Proxima Centauri is a M-type red dwarf star, roughly one-seventh the diameter of our Sun, or just 1.5 times bigger than Jupiter. Such stars are volatile in nature and prone stellar flares. Given the proximity of Proxima-B its parent, it is entirely possible such flares could at least heavily irradiate the planet’s surface, if not rip away its atmosphere completely.

This was the conclusion drawn in 2017 study by a team from NASA’s Goodard Space Centre (see here for more). Now another study adds further weight to the idea that Proxima b is most likely a barren world.

In Detection of a Millimeter Flare from Proxima Centauri, a team of astronomers using the ALMA Observatory report that a review of data gathered by ALMA whilst observing Proxima Centauri between January 21st to April 25th, 2017, reveals the star experienced a massive flare event. At its peak, the event of March 24th, 2017, was 1000 times brighter than the “normal” levels of emissions for the star, for a period of ten seconds. To put that in perspective, that’s a flare ten times larger than our Sun’s brightest flares at similar wavelengths.

An artist’s impression of Proxima b with Proxima Centauri low on the horizon. The double star above and to the right of it is Alpha Centauri A and B. The ALMA study suggests that it is very unlikely that Proxima b retains any kind of atmosphere, as suggested by this image. Credit: ESO

While the ALMA team acknowledge such ferocious outbursts from Proxima Centauri might be rare, they also point out that such outbursts could still occur with a frequency that, when combined with smaller flare events by the star, could be sufficient enough to have stripped the planet’s atmosphere away over the aeons.

“It’s likely that Proxima b was blasted by high energy radiation during this flare,” Meredith A. MacGregor, a co-author of the study stated as the report was published. “Over the billions of years since Proxima b formed, flares like this one could have evaporated any atmosphere or ocean and sterilised the surface, suggesting that habitability may involve more than just being the right distance from the host star to have liquid water.”

Which is a bit of a downer for those hoping some form of extra-solar life, however basic, might be sitting in what is effectively our stellar back yard – but exoplanets are still continuing to surprise us, both with their frequency and the many ways in which they suggest evolutionary paths very different to that taken by the solar system.

Continue reading “Space Sunday: drills, flares and monster ‘planes”

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Space Sunday: Mars rover round-up

Curiosity, NASA’s Mars Science Laboratory (MSL) continues its exploration and examination of “Vera Rubin Ridge” on the slopes of “Mount Sharp”.

Most recently, star- and swallowtail-shaped tiny, dark bumps in fine-layered bright bedrock have been drawing the attention of the rover’s science team due to their similarity to gypsum crystals formed in drying lakes on Earth – although multiple possibilities for the features are being considered alongside their potential for being formed as a result of water action.

The features pose a number of puzzles: where they formed at the same time as the layers of sediment in which they sit, or were formed later as a result of some action? Might they have been formed inside the rock sediments of “Mount Sharp” and exposed over time as a result of wind erosion? Do they contain the mineral that originally crystallised in them, or was it dissolved away to be replaced by another? Answering these questions may point to evidence of a drying lake within Gale Crater, or to groundwater that flowed through the sediment after it became cemented into rock.

“Vera Rubin Ridge” stands out as an erosion-resistant band on the north slope of lower Mount Sharp inside Gale Crater. It was a planned destination for Curiosity even before the rover’s 2012 landing on the crater floor near the mountain. The rover began climbing the ridge about five months ago, and has now reached the uphill, southern edge. Some features here might be related to a transition to the next destination area uphill, which is called the “Clay Unit” because of clay minerals detected from orbit.

In addition to the deposits, the rover team also is investigating other clues on the same area to learn more about the Red Planet’s history. These include stick-shaped features the size of rice grains, mineral veins with both bright and dark zones, colour variations in the bedrock, smoothly horizontal laminations that vary more than tenfold in thickness of individual layers, and more than fourfold variation in the iron content of local rock targets examined by the rover.

A mineral vein with bright and dark portions distinguishes this Martian rock target, called “Rona,” near the upper edge of “Vera Rubin Ridge” on Mount Sharp. The MAHLI camera on NASA’s Curiosity Mars rover took the image after the rover brushed dust off the grey area, roughly 5cm by 7.5 inches. Click for full size. Credit: NASA/JPL / MSSS

The deposits are about the size of a sesame seed. Some are single elongated crystals. Commonly, two or more coalesce into V-shaped “swallowtails” or more complex “lark’s foot” or star configurations. They are characteristic of gypsum crystals, a form of calcium sulphate which can form when salts become concentrated in water, such as in an evaporating lake.

“These tiny ‘V’ shapes really caught our attention, but they were not at all the reason we went to that rock,” said Curiosity science team member Abigail Fraeman of NASA’s Jet Propulsion Laboratory. “We were looking at the colour change from one area to another. We were lucky to see the crystals. They’re so tiny, you don’t see them until you’re right on them.”

“There’s just a treasure trove of interesting targets concentrated in this one area,” Curiosity Project Scientist Ashwin Vasavada of NASA’s Jet Propulsion Laboratory, adds. “Each is a clue, and the more clues, the better. It’s going to be fun figuring out what it all means.”

In January, Curiosity examined a finely laminated bedrock area dubbed “Jura”, thought to result from lake bed sedimentation, as has been true in several lower, older geological layers Curiosity has examined. This tends to suggest the crystals formed as a lake in the crater evaporated. However, an alternate theory is that they formed much later, as a result of salty fluids moving through the rock during periodic “wet” bouts in the planet’s early history. This would again be consistent with features previous witnessed by Curiosity in its past examination of geological layers, where subsurface fluids deposited features such as mineral veins.

The surface of the Martian rock target in this stereo, close-up image from the Curiosity rover’s MAHLI camera includes small hollows with a “swallowtail” shape characteristic of gypsum crystals. The view appears three-dimensional when seen through blue-red glasses with the red lens on the left. Click for full size. Credit: NASA/JPL / MSSS

That the deposits may have formed as a result of fluids moving down the slopes of “Mount Sharp” is pointed to by some of them being two-toned – the darker portions containing more iron, and the brighter portions more calcium sulphate. These suggest the minerals which originally formed the features have been replaced or removed by water. The presence of calcium sulphate suggests salts were suspended in any water which may have once been present in the crater. If this is the case, it could reveal more about the past history of Mars.

“So far on this mission, most of the evidence we’ve seen about ancient lakes in Gale Crater has been for relatively fresh, non-salty water,” Vasavada said. “If we start seeing lakes becoming saltier with time, that would help us understand how the environment changed in Gale Crater, and it’s consistent with an overall pattern that water on Mars became more scarce over time.”

Even if the deposits formed inside the sediments of “Mount Sharp” and were exposed over time as a result of wind erosion, it would reveal a lot about the region, providing evidence that as water became more and more scarce, so it moved underground, taking any minerals which may have been suspended within it along as well.

“In either scenario – surface or underground formation –  these crystals are a new type of evidence that builds the story of persistent water and a long-lived habitable environment on Mars,” Vasavada notes.

As well as offering further evidence of Gale Crater having once being the home of multiple wet environments, the presence of iron content in the veins and features might provide clues about whether the wet conditions in the area were favourable for microbial life. Iron oxides vary in their solubility in water, with more-oxidized types generally less likely to be dissolved and transported. An environment with a range of oxidation states can provide a battery-like energy gradient exploitable by some types of microbes.

Opportunity’s Mystery

As Curiosity explores “Vera Rubin Ridge”, half a world away, NASA’s Mars Exploration Rover (MER) Opportunity has reached 5,000 Sols (Martian days) of operations on Mars in what was originally seen as a 90-day surface mission.

A view from the front Hazard Avoidance Camera on NASA’s Mars Exploration Rover Opportunity shows a pattern of rock stripes on the ground, a surprise to scientists on the rover team. It was taken in January 2018, as the rover neared Sol 5000 of what was planned as a 90-Sol mission. Credit: NASA/JPL

Currently, Opportunity is investigating a mystery of its own: a strange  ground texture resembling stone striping seen on some mountain slopes on Earth that result from repeated cycles of freezing and thawing of wet soil. The texture has been found within a channel dubbed “Perseverance Valley” the rover is exploring in an attempt to reach the floor of Endeavour crater. This 22 km (14 mi) diameter impact crater has been the focus of Opportunity’s studies since it reached the edge of the crater in October 2011.

The striping takes the form of soil and gravel particles appearing to be organised into narrow rows or corrugations, parallel to the slope, alternating between rows with more gravel and rows with less. One possible explanation for their formation is that on a scale of hundreds of thousands of years, Mars goes through cycles when the tilt, or obliquity, of its axis increases so much that some of the water now frozen at the poles vaporises into the atmosphere and then becomes snow or frost accumulating nearer the equator and around the rims of craters like Endeavour.

Continue reading “Space Sunday: Mars rover round-up”

Space Sunday: images of Mars, comets and giant planets

Looking across Gale Crater as it might appear from NASA’s Mars Science Laboratory rover Curiosity. Render created by Kevin M Gill.

Kevin M. Gill is a software engineer, planetary and climate data wrangler at NASA’s Jet Propulsion Laboratory. He’s been working with digital terrain models and ortho images from the HiRISE imaging system aboard NASA’s Mars  Reconnaissance Orbiter (MRO) to create some stunning computer models and images of Endeavour and Gale craters, where the Opportunity and Curiosity rovers are exploring, as well as other regions of Mars. These have caused a stir on social media this week, and rightly so.

Kevin provides a detailed description of how he produces the images, which involves a range of software tools including ImageMagick, Maya and Photoshop. For those interested in creating computer renderings, his post makes a fascinating read; for those who love images of Mars, his images offer a stunning new perspective on the planet. The images utilise a slight vertical height exaggeration and false colour / lighting adjusted to Earth daylight standards, but the results are undeniably stunning.

A view along a volcanic fissure in the Cerberus Palas region of Mars. Rendering by Kevin M. Gill

Some of the images offer a unique perspective on surface features, such as the one above, showing a volcanic fissure in Cerberus Palas in the north-eastern Elysium quadrangle of Mars.

For those interested in producing vistas of Mars in a platform such as Linden Lab’s Sansar, Kevin’s work and notes could offer a starting point. In turn, Sansar could offer the perfect VR visualisation platform for allowing people to “visit” and learn about Mars.

“Mount Sharp” (Aeolis Mons), the mound of material deposited against the central impact peak of Gale Crater. Render by Kevin M Gill.

Meanwhile, the MSL team are moving closer to resuming drilling operations with the Curiosity rover.

These were suspended in December 2016. Prior to that, Curiosity had used the drill system mounted on its robot arm a total of 15 times between 2013 and 2016. On each of those occasions, two contact post, one either side of the bit, were placed on the target rock before the bit was extended by the drill feed mechanism, helping to gauge and support the drill. It was reliability issues with the feed mechanism which led to the suspension of all drilling operations.

Engineers have been investigating ways to use the drill without any reliance on the feed mechanism. This requires the drill to remain extended, the rover’s arm bringing it directly in contact with the rock to be drilled, without any support from the stabilising arms. In order for this to work, it is essential the drill bit  – which not only cuts into rocks, but gathers samples from within them – can be placed with minimal downward or side-to-side pressure or motion on it, to ensure it is not damaged or becomes stuck.

The issue here is that when supported by the stabilisers, the drill had only one axis of movement, without them, it could be subject to fix degree freedom of movement as vibrations from the drilling process feed back into the rover’s arm. To minimise this risk, tests are being carried out to determine if sensors in the robot arm are sensitive enough to detect potentially damaging motions in the drill when in use, and shut down the drilling operation.

On October 17th, 2017, NASA conducted the first test with Curiosity’s robot arm aimed at resuming the rover’s ability to gather rock samples with the drill mounted on the arm. Credit: NASA/JPL

To this end, on October 17th, 2017, Curiosity was commanded to place the drill bit in contact with a rock for the first time in ten months and without the use of the stabilisers. The bit was then gently pressed downward and moved slightly from side-to-side to see how well the sensors responded, the idea being that when the drill resumes operations, the sensors can be used to automatically detect potentially harmful movements in the drill head which could result in the bit being damage or becoming stuck.

It’s still likely to be several months before Curiosity resumes drilling operations, with further tests in the planning. However, mission managers are optimistic the rover will at some point be able to resume use the drill to gather samples from within rocks for analysis.

Deep Space Gateway Gains Momentum

On November 1st, 2017, NASA awarded contracts to five companies to examine how they can develop a power and propulsion module as the initial element of the agency’s proposed Deep Space Gateway.

As currently envisioned, the power and propulsion module will generate electrical power for the gateway, provide a communications relay and use a solar electric engine for manoeuvring the station in cislunar space. NASA had been examining their own ideas for the module, but it is hoped that the contracts will allow industry the chance to present their own ideas and technologies in support of the module’s development.

Part of the NASA studies involve the use of a 50-kilowatt solar electric propulsion (SEP) motor for the module, the idea being that if successful, the system could be scaled-up for use on missions to Mars.  While SEP systems can’t generate much thrust, they can run for long periods and are far more efficient than chemical systems.

Artist’s concept of the Deep Space Gateway passing close to the Moon. Credit: NASA

NASA had planned to test the SEP concept on the robotic portion of the now-cancelled Asteroid Redirect Mission (ARM), in which a robotic spacecraft would obtain a boulder-sized sample of a near Earth asteroid and return it to cislunar space for examination by astronauts. With the cancellation of that mission, the SEP programme has been in limbo; so issuing the contracts might both help revive the SEP project and allow commercial organisations weigh-in on the work.

These contracts are separate from those issued in 2016 to examine development of habitat modules for the gateway. However, all five of the companies that received contracts for Power and Propulsion Element studies also either have a habitat award or are partnered with a company that does.

How NASA plans to proceed with development of the station, including how it procures it from industry, will depend on the outcome of the studies as well as NASA’s overall exploration planning. At this point in time – and despite the October 5th, 2017 directive from the inaugural meeting of the re-invoked US National Space Council (NSC) concerning an American return to the Moon – the Deep Space Gateway remains a concept, not a formal NASA programme.

Also interested in participating in the programme is the European Space Agency. They are hoping to have a dedicated module forming part of the station, and are offering to develop a resupply system potentially capable of delivering up to nine tonnes of supplies to the Gateway.

The resupply vehicle would likely use the Ariane 6 launcher and solar electric propulsion system, rated around 60 kilowatts. ESA representatives believe the system could be ready for operation in 2025 or 2026, which fits with the time frame for the station’s development – which could see the power and propulsion module launched in 2022, as part of NASA’s Exploration Mission 2 mission for the Orion / Space Launch System. In the meantime, the first launch of the Ariane 6 booster is currently scheduled for 2020.

Continue reading “Space Sunday: images of Mars, comets and giant planets”

Space Sunday: Curiosity’s 5th, Proxima b and WASP-121b

On August 6th 2016, NASA delivered the Mars Science Laboratory (MSL) to the surface of Mars in what was called the “seven minutes of terror” – the period when the mission slammed into the tenuous Martian atmosphere to begin deceleration and a descent to the surface of the planet which culminated in the Curiosity rover being winched down gently from a hovering “sky crane” and then lowered until its wheels made firm contact with the ground.

The “seven minutes of terror” actually had a double meaning. Not only did it represent the time MSL would smash into Mars’ atmosphere and attempt its seemingly crazy landing, at the time of the event, the distance between Earth and Mars meant it took seven minutes to be returned to mission control from the red planet. Thus, even as the initial telemetry indicating the craft was entering the upper reaches of Mars’ tenuous atmosphere was being received, mission controls knew that in reality, the landing had either succeeded or failed.

Obviously, the attempt succeeded. Everything worked flawlessly, and Curiosity was delivered to the surface of Mars at 05:17 GMT on August 6th, 2012 (01:17, August 6th EDT, 22:17 PDT, August 5th). In the five years since that time, it is helped revolutionise our understanding of that enigmatic world – as well as adding somewhat to its mystery.

To call the mission a success is not an exaggeration; within weeks of its arrival inside the 154 kilometre (96 mile) wide Gale Crater, Curiosity was examining an ancient riverbed en route to a region of the crater dubbed “Yellowknife Bay”. It was there the rover made its first bombshell discovery: analysis of the area showed that billions of years ago it was home for the ideal conditions to potentially kick-start microbial life. It was, in essence, the achievement of mission’s primary goal: to identify if Mars may have once harboured the kind of conditions which might have given rise to life.

This 360-degree view was acquired on August 6th, 2016, by Curiosity’s Mastcam as the rover neared the “Murray Buttes” on lower “Mount Sharp”. The dark, flat-topped mesa seen to the left of the rover’s arm is about 15 metres (50 ft) high and about 61.5 metres (200 ft) long. Credit: NASA/JPL / MSSS

For the first year following its arrival on Mars, Curiosity continued to survey the regions relatively close to its landing zone, finding more evidence of a benign ancient environment. Then it started out on the next phase of its mission: the long traverse towards the massive bulk of “Mount Sharp” – officially called Aeolis Mons. A huge mound of rock deposited against the crater’s central impact peak, “Mount Sharp” rises from the crater floor to an altitude of some 5.5 km (3 mi), and imagining from orbit strongly suggested its formation was due, at least in part, to the presence of water in the crater at some point in Mars’ past.

The 8 km (5 mi) trip took the rover a year to complete, in part due to its relatively slow speed, in part due to the fact is had to travel a good way along the base of “Mount Sharp” to reach a point where it could commence an ascent up the slope; but mostly because there were a number of points of interest along the way where the mission scientists  wanted to have a look around, investigate and sample.

Mount Sharp as seen from Curiosity, on January 24th, 2017. The light grey banding befpre the sandy coloured slopes is the clay unit the rover will reach in about 2 years. In front of it is the “Vera Rubin Ridge”, the next location for study by the rover. Credit: NASA/JPL / MSSS

For the last three years, the rover has been slowly making its way up “Mount Sharp”, climbing around 180 metres (600ft) vertically above the surrounding crater floor and visiting numerous points of interest – such as “Pahrump Hills”, the mixed terrain where “Mount Sharp” merges with the crater floor. Along the way, Curiosity has both confirmed that “Mount Sharp” was most likely the result of sedimentary deposits laid down during several periods of flooding in the crater before the water finally receded and wind action took over, sculpting the mound into its present shape down through the millennia.

The lakes within Gale crater may have actually been relatively short-lived, perhaps lasting just 1,000 years at a time, but Curiosity has shown that even during the dry inter-lake periods, water was very much a feature of Gale Crater, finding evidence of compressed water channels within the layers of rock which sit naturally exposed on “Mount Sharp’s” flanks.

In December 2014, NASA issued a report on how “Mount Sharp” was likely formed. On the left, the repeated depositing of alluvial and wind-blown matter (light brown) around a series of central lakes which formed in Gale Crater, where material was deposited by water and more heavily compressed due the weight of successive lakes (dark brown). On the right, once the water had fully receded / vanished from the crater, wind action took hold, eroding the original alluvial / windblown deposits around the “dry” perimeter of the crater more rapidly than the densely compacted mudstone layers of the successive lake beds, thus forming “Mount Sharp”

Alongside the sedimentary layering of the mudstone comprising “Mount Sharp” and the compressed and long-dry water channels, a further sign that the region was once water rich comes in the form of the mineral hematite, which Curiosity has found on numerous occasions. Right now, the rover is making its way towards a feature dubbed “Vera Rubin Ridge” which orbital analysis shows to be rich in this iron-bearing mineral which requires liquid water to form. Beyond that is a clay-rich unit separating the hematite rich ridge from an area which show strong evidence for sulphates. These are also indicative of water having once been present, albeit less abundantly than along “Vera Rubin Ridge”, and thus hinting at a change in the local environment. Currently, Curiosity is expected to reach this area in about two years’ time, after studying “Vera Rubin Ridge” and the clay unit along the way.

Selfies from Mars: how Curiosity has weathered the dust on Mars over five years – the dates are given as Sols – Martian days, top left and the locations where the pictures were taken. Credit: NASA/JPL

Throughout the last five years, Curiosity has remained relatively healthy. There has been the odd unexpected glitch with the on-board computers, all of which have been successfully overcome. There has been some damage to the rover’s aluminium wheels. This did give rise to concern at the time it was noted, resulting in a traverse across rough terrain being abandoned in favour of a more circuitous and less demanding route up onto “Mount Sharp”. But overall, the wheels remain in reasonably sound condition.

The one major cause for concern at present lies with Curiosity’s drill mechanism. Trouble with this first began when vibrations from the drill percussive mechanism was noted to be having a negative impact on the rover’s robot arm.

More recently – since December 2016, in fact – all use of the drill has ceased, limiting Curiosity’s sample gathering capabilities. This has been due to an issue with the drill feed motor, which extends the drill head away from the robot arm during normal drilling operations, preventing the arm physically coming into contact with targets. Attempt to rectify the problem have so far been unsuccessful, so engineers are loot at ways to manoeuvre the rover’s arm and place the drill bit in contact with sample targets, avoiding the need to use the feed motor.

So with five years on Mars under its belt, and barring no major unforeseen incidents, Curiosity will continue its mission through the next five years, further enhancing our knowledge of Mars.

Continue reading “Space Sunday: Curiosity’s 5th, Proxima b and WASP-121b”

Space Sunday: Flying over Mars, JUICE for Jupiter and black holes

An impact crater which formed between July 2010 and May 2012 and imaged by the HiRISE camera on the Mars Reconnaissance Orbiter, is one of the locations featured in “A Fictive Flight Above Real Mars” by Jan Fröjdman. Credit: Jan Fröjdman; original anaglyph image NASA/JPL / University of Arizona

Ever wondered what it would be like to actually fly over Mars? I have – although I admit, I’m utterly entranced by that red world and the potentials it presents. Finnish film-maker Jan Fröjdman has as well – only he’s taken the idea a step further and produced a remarkable video,  A Fictive Flight Above Real Mars. Last just over 4.5 minutes, the film takes us on a flight over some of the must remarkable scenery imaginable, using high-resolution images and data returned by NASA’s Mars Reconnaissance Orbiter (MRO).

It’s a stunning piece showing many of the more intriguing features of Mars: the recent impact crater see in the still at the top of this article; the ice walls and melt holes of the Martian poles; gullies and cliffs rutted and marked by RSLs – recurring slope lineae – which might or might not be the result of liquid activity; the ripples of sand dunes, and the winding forms of channels which might have been shaped by the passage of water.

To make the film, Fröjdman used 3-D anaglyph images from HiRISE (the High Resolution Science Imaging Experiment aboard MRO), which contain information about the topography of Mars surface. The work involved manually picking more than 33,000 reference points in the anaglyph images, and then processing the results through six pieces of software to achieve a sense of motion and panning across the surface of Mars.

In putting the film together, Fröjdman  wanted to create a real feeling of flying over Mars and of recapturing the feel of video footage shot by the Apollo astronauts as they orbited the Moon. To help with the latter, he overlaid the video with image cross-hairs of the kind seen in some of the Apollo footage, and added little bursts of thruster firings to simulate a vehicle manoeuvring in the thin atmosphere. The film concludes with a main engine firing, presumably to lift the vehicle back into orbit.

NASA and SpaceX Consider Red Dragon Landing Site

And staying with Mars: NASA and SpaceX have started the process of selecting a landing site for SpaceX’s planned Red Dragon mission to Mars in 2020. The ambitious mission will see the company attempt to land a 10-tonne Red Dragon capsule on Mars purely by propulsive means. While paid for entirely by the company, the mission will feature a science suite provided by NASA.

There are two major criteria governing any landing site location: scientific interest, and the potential for colonisation – the 2020 mission being the first of a number which SpaceX plans to uses as precursors for human missions to Mars. As such, it had initially been decided that any landing sites put forward must be near the equator, for solar power; near large quantities of ice, for water and at low elevation, for better thermal conditions.

NASA initially identified four potential locations on Mars’ northern hemisphere which meet the broad criteria for the mission – but examination of three of them using the HiRISE system on the Mars Reconnaissance Orbiter showed they are rocky enough to pose a threat to landing a vehicle the size and mass of Red Dragon. This currently leaves a short-list of one, in the shape of Arcadia Planitia, a smooth plain containing fresh lava flows and which has a large region that was shaped by periglacial processes which suggest that ice is present just beneath the surface.

Acadia Planitia is the current sole contender to be the landing site for the SpaceX Mars 2020 mission

However, negating this is the plain’s relatively high northern latitude (40-60 degrees north), which would reduce the amount of sunlight a base of operations there would receive in the winter months. While Amazonis Planitia to the south offers a similar youthful surface, much of which is relatively smooth, it is largely volcanic in origin and unlikely to harbour sub-surface water ice which can be easily accessed.

Given both of these point, it is likely other possible landing sites will be proposed in the coming months.

Curiosity Reveals More Wheel Damage

It’s been a while since my last report on NASA’s Mars Science Laboratory rover, Curiosity. This is mostly being the updates coming out of JPL have slowed mightily in recent months.

At present, Curiosity is examining sand dunes on the lower slopes of “Mount Sharp”. Once finished, it will proceed up higher to a feature known as “Vera Rubin Ridge”, inspecting a layer that is rich in the mineral hematite. From there, it will proceeded to even higher elevations to inspect layers that contain clays and sulphates. This will require a drive of some 6 km (3.7 mi) uphill, and so will require time to complete.

A recurring area of concern for the mission – albeit not serious at this point – is the wear and tear on the rover’s wheels. In 2013, Curiosity suffered greater than expected damage to its six wheels while traversing some exceptionally rough terrain.  Although the damage was nowhere near severe enough to impeded the rover’s driving abilities, it did result in engineers keeping a much closer eye on the condition of Curiosity’s wheels using the imaging system mounted on the rover’s robot arm.

The latest of these checks was performed on  Sunday, March 19th, 2017, and it revealed two small breaks in the raised treads (“grousers”) on the rover’s left middle wheel. These seem to have occurred since the last wheel check at the end of January, 2017. These treads perform two major tasks: bearing the brunt of the rover’s weight and providing most of the traction for a wheel.

The broken “grousers” (“treads”) on one of Curiosity’s six wheels, together with older puncture holes through the wheel, as imaged on March 19th, 2017. Credit: NASA/JPL

Following the 2013 damage, testing on Earth suggested that significant breaks in three “grousers” on a wheel would indicate it has passed 60% of its expected lifespan. However, the mission team emphasise the rover has already driven more than 60% of the total distance needed for it to make it to all of its scientific destinations. As such, while the breaks will be monitored, they are not a cause for immediate or grave concern.

Overall, confidence remains high that Curiosity will achieve all of its expected science goals and will likely make an extended traverse up the side of “Mount Sharp”.

A rover’s progress: the 16 km (10 mi) travelled by Curiosity so far, and potential for future explorations up the side of Aeolis Mons. Credit: NASA/JPL / T. Reyes

Continue reading “Space Sunday: Flying over Mars, JUICE for Jupiter and black holes”

Space Sunday: Moon flights and the winds of Mars

The Dragon 2 crew capsule attached to its service module. Credit: SpaceX
The Dragon 2 crew capsule attached to its service module. Credit: SpaceX

While most private space tourism companies are busily going about various routes to offer sub-orbital flights to those who can afford them, Elon Musk’s SpaceX has stepped into the arena – and, as might be expected, made the bold announcement it will go one better: fly paying passengers around the Moon and back. And they plan to do it in 2018.

The announcement was made by Musk on Monday, February 27th during a press teleconference. If the flight goes ahead, it will allow two fare-paying passengers the opportunity to undertake a week-long journey out to and around the Moon, before returning to Earth. The flight would use a “free return” profile which would see it skim over the surface of the Moon and continue outward beyond it, possibly as far as 480,000 Km (300,000 mi) from the Earth (the average distance of the Moon from Earth is around 384,400km /  240,000 mi), before Lunar gravity takes over and hauls the vehicle back towards the Earth, where it would splash down.

It’s not clear how much the passengers would pay to be on the flight – but the going price for a seat aboard the Dragon 2 vehicle, which would be used for the flight, will be around US $58 million a pop to get to the International Space Station, once it enters service. It’s also far from clear if SpaceX can actually deliver on the goal of launching the flight in late 2018.

SapceX plan to use the Falcon Heavy as the launch vehicle for the lunar flight. When it enters service later in 2017, the Falcon Heavy will be the most powerful launch vehicle in the world today
SpaceX plan to use the Falcon Heavy as the launch vehicle for the lunar flight. When it enters service later in 2017, the Falcon Heavy will be the most powerful launch vehicle in the world

In order to take place, the flight first and foremost needs a launch vehicle and a suitable space vehicle. SpaceX plan to use their mighty Falcon Heavy and – as noted – their new Dragon 2 crewed vehicle. There’s just a couple of problems with both.

The Falcon Heavy is not due to fly until some time later in 2017, and even then it will not be rated for crewed launches. For that to happen, it will have to be certified for crew use, and depending on how the initial flights go, that could take time. In terms of the Dragon 2, that is not scheduled to enter service until 2018 – and even then, its primary function is to fly crews to and from  the International Space Station (ISS).

Ferry flights to the ISS are vastly different to going out around the Moon and back. To start with, the outward flight from Earth to the ISS can be measured in just a couple of days – around a quarter of the time needed for the lunar trip.  The velocity (delta vee)  imparted to a spacecraft going to the ISS (28,000 km/h / 17,500 mph) is also a lot less than required to go to the Moon (40,000 km/h / 25,000 mph).

Elon Musk unveils a mock-up of the Dragon V2 capsule in May 2014. SpaceX now has their firs NASA contract to fly a crew to the ISS aboard the vehicle, probably in 2018
Elon Musk unveils a mock-up of the Dragon 2 capsule in May 2014.Credit: SpaceX

This means a returning Dragon 2 will be re-entering the Earth atmosphere a lot faster than the same craft coming back from the ISS, and will have to face much higher re-entry temperatures and a harsher deceleration regime. While the Dragon 2 can in theory do so, it is likely that significant testing on uncrewed vehicles will be required before the Federal Aviation Authority and NASA agree to any such flight taking place. On top of this, it will have to be demonstrated that the Dragon 2 can be outfitted for a deep space mission and keep a crew alive and well for around 7-8 days.

Given all this, there are widespread doubts the company can meet a 2018 deadline for such a mission – and SpaceX has tended to be ambitious with its time frames for achieve goals. They had originally slated 2013 as the year in which the Falcon Heavy would make its first flight – although in fairness, setbacks following the loss of two Falcon 9 vehicles also contributed to its launch being pushed back to 2017.

Red Dragon Delayed

As further evidence of SpaceX presenting time frames which are perhaps a little ambitious, on February 17th, the company announced its mission to land a variant of the Dragon 2 – dubbed Red Dragon – on Mars has been pushed back from 218 to 2020.

The aim of the mission so to fly an uncrewed 10-tonne Dragon 2 vehicle to Mars and land it safely. In doing so, the company hopes to gain valuable data on landing exceptionally heavy vehicles on Mars using purely propulsive means. This is because crewed landing vehicles on a Mars mission are liable to have a mass of at least 40 tonnes – far too much to be safely slowed in a descent through the thin Martian atmosphere by parachutes.

A SpaceX / NASA infographic outlining the Red Dragon mission - now slated for 2020
A SpaceX / NASA infographic outlining the Red Dragon mission – now slated for 2020

The planned mission would be undertaken entirely at the company’s own expense, although it would can science instruments and experiments supplied by NASA. For Musk it, and possibly three further Red Dragon mission which could follow it in the 2020-2024 time frame, is a vital precursor to greater ambitions for Mars.

As he outlined in September 2016 (see: Musk on Mars), Musk plans to start launching crewed missions to Mars, possibly before 2030. The initial missions will doubtless be modest in size in terms of crew and goals. However, his overall stated goal is to kick-start the colonisation of Mars. To do that, he plans to use vehicles massing at least 100 tonnes and which can make a propulsive landing on Mars. Whether he can succeed in even the step to land a crew on Mars  – and bring them back to Earth – remains to be seen. However, his Red Dragon mission is an important first step.

Continue reading “Space Sunday: Moon flights and the winds of Mars”