Category: Space Sunday

Of Martian walkabouts, pictures from a comet, and getting ready to fly

Posted on by Inara Pey

CuriosityIn my last report on the Mars Science Laboratory, I mentioned that Curiosity has been on a geology “walkabout” up the slopes of the “Pahrump Hills” at the base of “Mount Sharp” (more correctly, Aeolis Mons). The zigzagging route up through the area took the rover from “Confidence Hills” and the location of the last drilling operation up to a point dubbed “Whale Rock”, the drive being used to gather information on potential points of interest for further detailed examination.

The exposed rocks in this transitional layering between the floor of Gale Crater, in which Curiosity arrived back in August 2012, and the higher slopes of “Mount Sharp” is expected to hold evidence about dramatic changes in the environmental evolution of Mars. Thus, the “walkabout”  – a common practice in field geology on Earth – was seen as the best means of carrying out a reasonable analysis of the area in order for the rover to be most efficiently targeted at specific locations of interest.

Curiosity’s walkabout, from “Confidence Hills” to “Whale Rock” in October, the rover is now working its way back to various points of interest for further studies

“We’ve seen a diversity of textures in this outcrop,” Curiosity’s deputy scientist Ashwin Vasavada (JPL) said of the drive. “Some parts finely layered and fine-grained, others more blocky with erosion-resistant ledges. Overlaid on that structure are compositional variations. Some of those variations were detected with our spectrometer. Others show themselves as apparent differences in cementation or as mineral veins. There’s a lot to study here.”

During the drive, Curiosity travelled some 110 metres, with an elevation of about 9 metres, using the Mastcam and the ChemCam (Chemistry and Camera) laser spectrometer system to inspect and test potential points of interest for more detailed examination at a later date. Since completing that drive, the rover has been working its way back through Pahrump Hills, this time examining specific targets using the robot-arm mounted Mars Hand Lens Imager (MAHLI) camera and spectrometer. Once this work has been completed, specific targets for in-depth analysis, including drilling for samples will for the core activity of a third pass through the area.

So far, two specific areas have been identified for detailed examination. The first, dubbed “Pelona” is a  fine-grained, finely layered rock close to the “Confidence Hills” drilling location. The second is a small erosion-resistant ridge dubbed “Pink Cliffs” the rover drove around on its way up the incline.

“Pink Cliffs” is roughly a metre (3ft) in length and appears to resist wind erosion more than the flatter plates around it.As such, it offers precisely the kind of mixed rock characteristics mission scientists want to investigate in order to better understand “Mount Sharp’s” composition. This image is a mosaic of 3 pictures captured on October 7th PDT, 2014 (Sol 771 for the rover) by Curiosity’s Mastcam. It has been white balanced to show the scene under normal Earth daylight lighting – click for full size.

Another target of investigation has been the edge of a series of sand and dust dunes right on the edge of “Pahrump Hills”.  In August 2014, Curiosity attempted to use these dunes as a means to more quickly access the “Pahrump Hills” area, but the effort had to be abandoned when it proved far harder for the rover to maintain traction than had been anticipated, particularly given the rover has successfully negotiated sandy dunes and ridges earlier in the mission. As a result, scientists are keep to understand more about the composition of the dunes.

On November 7th, Curiosity was ordered to venture onto the dunes very briefly in order to break the surface of one of the rippled dunes and expose the underlying layers of sand in an effort to better understand why the rover found the sand such hard going the first time around, and what might be within these wind-formed dunes that would prove to be so bothersome to driving over them. Data gathered from the drive is still being analysed.

Spanning roughly 1.2 metres from left to right, a wheel track breaks the surface of a dust sand dune ripple on the edge of “Pahrump Hiils”. The MSL science team hope the exposed material within the ripple will help them understand why Curiosity found these dunes hard-going when trying to cross them in August 2014.

The work in the “Pahrump Hills” area has given rise to concerns over one of the two lasers in the ChemCam instrument. As well as the main laser, known for “zapping” targets on the surface of Mars in order to reveal their chemical and mineral composition, the system uses a second laser, a continuous wave laser, used for focusing the ChemCam’s telescope to ensure the plasma flash of vaporised rock is properly imaged when the main laser fires. Data received on Earth when using the ChemCam to examine rocks on the first pass through “Pahrump Hills” suggests this smaller laser is weakening and may no longer be able to perform adequately.

If this is the case, the laser team plan to switch to using an auto-focus capability with the telescope so it will automatically focus itself on a few “targeting” shots from the main laser ahead of any data-gathering burst of fire, allowing for proper telescope calibration.

Continue reading “Of Martian walkabouts, pictures from a comet, and getting ready to fly” →

The little lander that could – and did

Posted on by Inara Pey
Rosetta,
Rosetta,Philae and, behind them, comet 67P/Churyumov–Gerasimenko seen in an artist’s impression of the mission

It’s been a hectic 48 hours. On Wednesday, November 12th, after 10 years in space, travelling aboard its parent vehicle, Rosetta, the little lander Philae touched down on the surface of comet 67P/C-G/Churyumov–Gerasimenko (67P/C-G). It was the climax of an amazing space mission spanning two decades – and yet was to be just the beginning. Packed with instruments, it was hoped that Philae would immediately commence around 60 hours of intense scientific investigation, prior to its batteries discharging, causing it to switch to a solar-powered battery system.

Unfortunately, things haven’t quite worked out that way. As I’ve previously reported, the is very little in the way of gravity on the comet, so in order for Philae to avoid bouncing off of it when landing, several things had to happen the moment it touched the comet’s surface. As it turned out, two of these things didn’t happen, with the result that the lander did bounce – twice.

Where Philae may be (ESA image via BBC News) – Rosetta has yet to positively locate the lander beyond a rough estimate based on communications and signals received from the CONSERT instrument on the lander

The first time it rose to around 1 kilometre above the comet before descending once more in a bounce lasting and hour and fifty minutes, the second time it bounced for just seven minutes. Even so, both of these bounces meant the lander eventually came to rest about a kilometre away from its intended landing zone. What’s worse, rather than touching down in an area where it would received around 6-7 hours of sunlight a “day” as the comet tumbles through space, it arrived in an area where it was only receiving around 80-90 minutes of sunlight – meaning that it would be almost impossible to charge the solar-powered battery system.

As noted above, the mission was designed so that most of the core science could be carried out in the first 60 hours of the mission, just in case something like this occurred. Even so, in order to prolong the life of the vehicle, it would have been nice to move it into a greater area of sunlight. A means of doing this had also been built-in to Philae: the three landing legs can be flexed, allowing it to “hop”. But as images were returned to Earth by the Lander, it became apparent that one of the legs is not in contact with the ground, making such a hop problematic. After discussion, it was decided not to attempt to move the lander, but focus on trying to achieve the planned science objectives.

In this image released by ESA, a model of the Philae lander has been superimposed on images of the vehicle's shadowy surroundings as captured by the panoramic cameras mounted around the lander (image: Image: Sipa USA/Rex)
In this image released by ESA, a model of the Philae lander has been superimposed on images of the vehicle’s shadowy surroundings as captured by the panoramic cameras mounted around the lander (image: Image: Sipa USA/Rex)

As it turned out, the initial contact between the lander and the comet confused several of Philae’s instruments into “thinking” it had in fact landed, causing them to activate. These included the ROMAP magnetic field analyser, the MUPUS thermal mapper, the CONSERT radio sounding experiment and the SESAME sensors in the landing gear. Data received from these instruments, arriving on Earth some 30 minutes after initial contact with the comet, and the information which followed, help alert mission staff that something had gone wrong, and enabled them to subsequently piece together the events that occurred during the landing sequence, while the instruments continued to gather data and transmit it back to Earth via Rosetta.

On Friday, November 14th, the decision was taken to activate Philae’s sample-gathering drill, officially referred to as SD2. This had been postponed from the previous day, as the drill uses a lot of power. However, obtaining and analysing samples from inside the comet is a central part of the mission, the decision was made to push ahead with drilling operations.

Continue reading “The little lander that could – and did” →

Philae: “I’m here, not there!”

Posted on by Inara Pey
The first image from the surface of a comet, returned to Earth by the Rosetta lander Philae, November 13th, 2014. image: ESA/Rosetta/Philae/CIVA
The first image from the surface of a comet, returned to Earth by the Rosetta lander Philae, November 12th, 2014. image: ESA/Rosetta/Philae/CIVA

Wednesday, November 12th saw a remarkable feat take place over 515,000,000 kilometres from Earth as a small robotic vehicle called Philae, and a part of the European Space Agency’s Rosetta mission, landed on the surface of a comet, marking the very first time this has ever been achieved.

As I reported, immediately following the landing, getting a vehicle to rendezvous with a comet, enter orbit around it and deploy a lander to its surface isn’t easy – Rosetta is a mission 21 years old, with the spacecraft spending a decade of that time flying through space.

Mission control personnel react to the first telemetry received from Philae on it's initial contact with the surface of comet 67P/C-G
Mission control personnel react to the first telemetry received from Philae on its initial contact with the surface of comet 67P/C-G

Immediately following the landing, telemetry revealed things hadn’t gone to plan, although the lander itself was unharmed. Essentially, part of the landing system – a pair of harpoons designed to tether the lander to the comet’s surface as a direct result of the very weak gravity there – failed to operate as expected. Telemetry has shown that the tensioning mechanism and the harpoon activation process started, but the harpoons themselves did not fire. As a result, the vehicle actually “bounced” after its initial touch-down.

The initial touch-down was at 15:33 UT – precisely on schedule and on target. However, as the harpoons failed, the lander rose back up – possibly by as much as a kilometre – above the comet, before finally striking the surface again, two hours later. This means that even while celebrations over the initial landing were going on here on Earth (the initial signal confirming touchdown taking some 30 minutes to reach Earth), Philae had yet to make its second contact with the comet.

Philae (circled in red) en route to its landing site on 67P/C-G (visible top right)
Philae (circled in red) en route to its landing site on 67P/C-G (visible top right)

This eventually happened at 17:26 UT, and was followed by another bounce, this one of a much lesser force, before the lander came to rest at 17:33 UT.

One of the consequences of this bouncing is that the lander is not actually in its designated landing zone – the comet is tumbling through space, and thus turning under the lander as it bounced. This means that while Rosetta and Philae are communicating with one another, the spacecraft’s orbital position around the comet is not optimal for the lander’s position, and is being refined to better suit Philae’s new location. An initial adjustment was made overnight on the 12th/13th November, and further adjust is likely to be made on Friday, November 14th. Currently, communications can occur between the two vehicles for just under 4 hours out of every 13.

Philae mission manager Stephan Ulamec explains where it is belived the lander resides, represented by the blue triangle (ESA press conference, Thursday, November 14th)
Philae mission manager Stephan Ulamec explains where it is believed the lander resides, represented by the blue triangle (ESA press conference, Thursday, November 14th)

This bouncing may explain why there was an initial problem with communications between the lander and the Rosetta spacecraft, as reported immediately after the initial landing telemetry was received: Rosetta was expecting Philae to be at a certain fixed position on the comet, whereas the lander was still in motion, and “moving away” from the landing site as the comet rotated. The task now is for Rosetta to visually locate the lander – which given the current orbital positioning, may take a little time; the next passage of the spacecraft over the region of the landing site will not start until 19:27 UT this evening. Mission planners hope the sunlight reflected by the lander’s solar panels might help in identifying Philae’s exact position.

A core worry for the mission team is that Philae has in fact come down in an area of shadow, possibly in a depression and close to one or two rocky “walls”, and it appears to only be receiving direct sunlight for around 90-120 mins as the comet tumbles, rather than the 6-7 hours planned with the target landing point. This potentially has serious implications for the lander’s power and science regime, although it is hoped that Philae might be able to adjust its position somewhat – the craft actually has the capability of “hopping” around by flexing its landing legs.

Continue reading “Philae: “I’m here, not there!”” →

To touch the origins of the solar system

Posted on by Inara Pey
Brave new world: the surface of comet 67P/C-G, upon which the European space Agency successfully landed a the robot vehicle Philae on Wednesday, November 12th, 2014 as a part of the Rosetta mission
Brave new world: the surface of comet 67P/C-G, upon which the European space Agency successfully landed a the robot vehicle Philae on Wednesday, November 12th, 2014 as a part of the Rosetta mission

“The biggest problem with success is that it looks easy, especially for those of us who have nothing to do.” Thus spoke Jean-Jacques Dordain on Wednesday, November 12th, just moments after it had been confirmed that a tiny robot vehicle called Philae had safely landed on the surface of a comet half a billion kilometres away from Earth.

That simple statement offers a subtle message on the huge achievement this landing represents. The Rosetta / Philae mission is the story of a 6 billion kilometre journey across space which has taken a decade to achieve, and which has involved some 20 countries. Yet the adventure is in many ways only now starting.

The Rosetta mission actually started 21 years ago, in 1993 when it was approved as the European Space Agency’s first long-term science programme. The aim of the mission being to reach back in time to the very foundations of the solar system by rendezvousing with, and landing on, a comet as it travel through the solar system.

An artist’s impression of Rosetta in space. It has already achieved a remarkable set of “firsts”, including the first solar-powered space probe to operate beyond the orbit of Mars. Philae, the lander, is the purple house shape on the front of the vehicle

Comets hold enormous scientific interest because they are, as far as can be determined, the oldest, most primitive bodies in the Solar System, preserving the earliest record of material from the nebula out of which our Sun and planets were formed. While the planets have gone through chemical and (in the cases of places like Earth), environmental and geological change, comets have remained almost unchanged through the millennia. What’s more, they likely played an important role in the evolution of at least some of the planets. There is already substantial evidence that comets probably brought much of the water in today’s oceans – and they may even have provided the complex organic molecules that may have played a crucial role in the evolution of life here.

The target for ESA’s attention is comet 67P/Churyumov–Gerasimenko (aka 67P/C-G), an odd-shaped body comprising two “lobes” joined together one  in what some in the media have at times referred to as the “rubber duck”. The larger of the two lobes measures some 4.1×3.2×1.3 kilometres in size (2.55×1.99×0.8 miles) and the smaller some 2.5×2.5×2 kilometres (1.6×1.6×1.2 miles). It is a “short period” comet, orbiting the Sun once every 6.4 years and most likely originating in the Kuiper belt, a disk of material from the early history of the solar system, orbiting the Sun at a distance of around 30-50 AU

The primary spacecraft in the mission, Rosetta, arrived in the vicinity of 67P/C-G on August 6th, 2014 becoming the first vehicle in history to successfully enter orbit around a comet. The major reason the mission took so long to reach the comet, having been launched in 2004, is that despite having a relatively short orbital period, 67P/C-G is travelling very fast and accelerating as is falls deeper into the Sun’s gravity well heading for perihelion (it is currently travelling at 18 kilometres (11.25 miles) a second and can reach velocities of 34 kilometres a second as it swings around the Sun). As it is impossible to launch a space vehicle is these velocities, Rosetta was launched on a trajectory which allowed it to fly by Earth twice (2005 and the end of 2007) and Mars once (early 2007), using the gravity of both planets to accelerate it and (in the case of the 2nd Earth fly by), swinging it onto an orbit where it would “chase” and eventually catch the comet.

It’s a long way from here to there: Rosetta’s flight from Earth to 67P/C-G (image via extremetech.com) – click for full size

Following its safe arrival, Rosetta settled into an orbit of some 30 kilometres around the comet in September, and began looking for a suitable place where Philae might land – because until the craft actually arrived in orbit around 67P/C-G, no-one had any idea of what it’s surface might look like. On 15 September 2014, ESA announced a region on the “head” of the “duck” had been selected for the landing, christening it Agilkia in keeping with a contest to name the landing site.

Further observations of the comet were carried out throughout September and October as an overall part of Rosetta’s mission and to gain as much information on the landing site itself. At the same time the spacecraft started manoeuvring itself in closer to the comet, dropping its orbit to just 10 km, ready for Philae’s delivery.

This image, captured by Rosetta on Wednesday, November 12th, shows the Philae lander as it starts its descent towards the comet
This image, captured by Rosetta on Wednesday, November 12th, shows the Philae lander as it starts its descent towards the comet

The landing operations commenced around 09:05 UT on Wednesday, November 12th, when Philae detached from Rosetta and started on its long gentle descent. Immediately following the separation, and due to Rosetta’s orbit around the comet, contact was almost immediately lost with the lander, leading to a tense 2 hour wait before communications could be re-established. This happened on cue, with the lander reporting all was OK.

Landing on a comet is no easy task. The gravity is almost non-existent, and there was a very real risk that Philae could, if it struck the surface of 67P/C-G too fast, simply bounce off. Hence the lander’s long, slow drop from the Rosetta spacecraft which the ESA mission scientists dubbed “the seven hours of terror” in recognition of the famous “seven minutes of terror” which marked the arrival of NASA’s Mars Science Laboratory Curiosity on Mars.

Continue reading “To touch the origins of the solar system” →

Of triumph and tragedy

Posted on by Inara Pey

The last week has seen some momentous and tragic events occur in the annals of space flight and space exploration, with tragedy leading the way following the break-up of Virgin Galactic’s SpaceShipTwo vehicle on Friday, October 31st, resulting in the death of co-pilot Michael Alsbury and the serious injury of pilot Peter Siebold.

The loss of SpaceShipTwo came just a few days after an Antares booster, operated by Orbital Sciences and which should have been launching an unmanned Cygnus resupply vehicle to the International Space Station (ISS), was ordered to self-destruct seconds after lifting off of the pad.

Understandably overshadowed by the loss of SpaceShipTwo was the news that China has enjoyed a further success as a part of its ambitious lunar mission plans, and NASA has achieved a further “first” on Mars with Curiosity.

The news from Curiosity came after what has been another period of relative quiet from the MSL team following the successful gathering of a rock sample from a drilling operation into a target rock outcrop dubbed “Confidence Hills” within the “Pahrump Hills” region at the base of “Mount Sharp”.

Since that time, Curiosity has been on something of a “walkabout”, as NASA JPL is calling it (“roll around” probably doesn’t give the right impression…) within the “Pahrump Hills” area whilst simultaneously analysing the samples gathered from “Confidence Hills” at the end of September, and also keeping an eye out for passing comets.

Curiosity’s “walkabout” in the “Pahrump Hills” at the base of “Mount Sharp” in October 2014. The route starts at “Confidence Hills”, the site of a successful drilling operation, and winds up to “Whale Rock”. Red dots indicate points at which the rover paused overnight, white dots denote points at which it stopped to gather images and data, perhaps over several days

As well as the familiar aboriginal reference, “walkabout” is also a term used by field geologists to describe walking across a rocky outcrop in order to determine the best places from which to examine it – which is precisely what Curiosity was ordered to do through October.

During the walkabout, Curiosity made a number of stops for data and image gathering, before arriving at a point dubbed “Whale Rock”, just below another high point which appears to mark the point at which “Pahrump Hills” join the “Murray formation”, the next destination for the rover once studies of “Pahrump Hills” has been completed. The rover will remain parked at “Whale Rock” as the science team analyses the images and data gathered in order to determine where the rover should return to carry out more detailed investigations.

The material obtained from the “Confidence Hills” drilling operation contained in the rover’s sample scoop after being sifted and graduated by the CHIMRA device in the rover’s robot arm turret, and about to be delivered to the input ports ready for analysis by the instruments in the rover’s body. This image was taken by Curiosity’s Mastcam, and has been white-balanced so that lighting conditions match daytime light on Earth

In the meantime, and in the “first” mentioned above, Curiosity has confirmed that the samples gathered from “Confidence Hills” contain mineral deposits what had been mapped from orbit. The mineral in question in Hematite – which has been found elsewhere on Mars by both of the MER rovers, Opportunity, and the now defunct Spirit.

However, the significance of the “Confidence Hills” analysis, carried out by the rover’s on-board Chemistry and Mineralogy (ChemMin) instrument, confirms predictions made from the analysis of data returned by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard the Mars Reconnaissance Orbiter that Hematite deposits would exist within the rocks of the mountain’s lower slopes. This confirmation gives the science team greater confidence that the analysis of orbital data can help them make even better choices of while the rover should carry out drilling operations etc. It also means that the rover’s on-the-spot analysis and observations can be set directly into the broader geologic history of “Mount Sharp” as obtained by orbital data.

Curiosity may spend weeks or months at Pahrump Hills before proceeding farther up into the “Murray formation” and on to “Hematite Ridge”, a further location of interest to scientists. The mineral is of particular interest to scientists not so much because it might be indicative of a water-rich history in the region (as was the case with the discoveries made by Opportunity and Spirit) – Gale Crater has already more than yielded enough evidence of wet conditions being prevalent in its past history. Rather, the hematite on and in “Mount Sharp” helps scientists further understand oxidation conditions within the region. Continue reading “Of triumph and tragedy” →

Between the comets

Posted on by Inara Pey
Siding Spring (circled) passing Mars (the glowing object, bottom left) as seen via the SLOOH telescope at the Pontificia Universidad Católica De Chile (PUC) Chile (images via SLOOH live feed, October 19th, 2014)
Siding Spring (circled) passing Mars (the glowing object, bottom left) as seen via the SLOOH telescope at the Pontificia Universidad Católica De Chile (PUC) – image via SLOOH live feed, October 19th, 2014

It’s now a week since Siding Spring passed by Mars as it hurtled through the inner solar system for what might be the very first time. As I reported on the day of the comet’s flyby, C/2013 A1 – to give the comet its official designation – passed by Mars at a distance of around 136,000km (85,000 miles) and at a speed of some 56 kilometres (35 miles) per second. Since then, the comet reached perihelion – the point of its closest approach to the Sun (Saturday, October 25th, 2014), and it is now on its way back out of the solar system, travelling “up” and out of the plane of the ecliptic as it does so.

It will not be back this way for at least a million years.

Despite some getting their knickers in something of a knot over video footage apparently showing an “explosion”/ “electromagnetic pulse” in the Martian atmosphere around the time of the comet’s closest approach to Mars. In particular, the video footage – some 75 images captured by amateur astronomer Fritz Helmut Hemmerich M.D., captured between 21:00 and 22:00 UT on October 19th, from an altitude of some 1200 metres in Tenerife, have had proponents of the “electric universe” theory (aka Plasma Cosmology) in something of a tizzy.

Quite what caused the artefact in Dr. Hemmerich’s images is unclear – but lens flare cannot be entirely ruled-out. Given that within hours of the comment’s passage the various orbital vehicles around Mars started popping-up and reporting their status, it would appear highly unlikely that the artefact was anything to do with some kind of massive electrical discharge within the Martian atmosphere, simply because it is not unreasonable to suppose had this been the case, it would have adversely affected at least some of the craft.

Siding Spring passing Mars, October 19th, 2014 (image: Scott Ferguson, Florida, USA)
Siding Spring passing Mars, October 19th, 2014 (image: Scott Ferguson, Florida, USA)

As it is, all of NASA’s vehicles reported absolutely no ill effects from the comet’s passage or as a result of the period of “peak dust flux” when they were expected to be at the greatest risk from the passage of very high velocity dust particles (travelling at tens of kilometres per second), and all were back in full operation within hours of the comet’s passage past Mars, as were both India’s MOM and Europe’s Mars Express. NASA’s Mars Reconnaissance Orbiter (MRO) in particular remained in contact with Earth throughout the time the comet passed by Mars and reported nothing to suggest the Tenerife images were showing anything of major significance occurring around Mars at the time of the flyby.

Currently, all of NASA’s orbital assets are continuing to study the comet and how dust and debris ejected from it has affected the Martian atmosphere, although it is expected to be several more days before the data being returned has been analysed and assessed.

In the meantime, on Friday, October 24th, and in a timely move, the European Space Agency reminded the world of another cometary encounter that is taking place. This was via the public premier of Ambition, a short film by Tomek Bagiński, starring Aidan Gillen (“Petyr Baelish” in Game of Thrones) and Aisling Franciosi (“Katie” in The Fall).

The film takes a unique look at the decade-long Rosetta mission, which is only now commencing its primary mission to observe a comet at very close quarters, including landing a robot vehicle on the surface of the comet on November 12th, 2014.

Rosetta and Philae (image: European Space Agency)
Rosetta and Philae (image: European Space Agency)

Continue reading “Between the comets” →