It’s been fairly quiet as the Mars Science Laboratory (MSL) rover Curiosity continues driving towards the point at which it is hoped the rover can traverse between a line of low-lying sand dunes and start exploring the lower slopes of Aeolis Mons, which NASA has dubbed “Mount Sharp”.
However, Thursday November 7th saw an unexpected hiccup in proceedings as Curiosity unexpectedly performed a “warm reset” (software reboot). This occurred around four and a half hours after the new flight software uploaded to the rover (see my last mission report) had been temporarily loaded into memory as a part of the uploading and commissioning of the software, and while the rover was also transmitting data to the Mars Reconnaissance Orbiter (MRO) for later transmission to Earth.
A warm reset is executed when the flight software identifies a problem with one of the operations it is executing which may adversely affect the rover’s operations, and is a standard fault protection mode on all automated craft operated by NASA. It resets the software to its initial state, preventing further issues occurring. While there have previously been problems with Curiosity’s on-board computers, this was actually the first time since the rover’s arrival on Mars 16 months ago that a fault-related software warm reset had been executed.
Curiosity, seen here in an artist’s impression working on Mars, suffered its first software reset on November 7th
Following the reset, the rover resumed communications, but the mission team initiated a root cause analysis for the reset using the ground testbed unit (essentially, Curiosity’s Earthside “twin”). This revealed an error in a catalogue file for the existing onboard software was triggered when the catalogue file was executed by the newly uploaded flight software, causing the reset. As a result of this analysis, the flight software team were able to determine the steps required to recover the rover to its operating state prior to the reboot. These were successfully uploaded to Curiosity, and on Sunday November 10th, the rover set confirmation to mission controllers that it has successfully transitioned back to a nominal surface operations mode.
“We returned to normal engineering operations,” software and systems engineer Rajeev Joshi from the Curiosity team at JPL reported following the transition. “We are well into planning the next several days of surface operations and expect to resume our drive to Mount Sharp this week.”
Following the successful reinstatement of normal operations for the rover, the mission science team resumed planning for the next stage of Curiosity’s surface activities, which were due to restart on Thursday November 14th.
No, this isn’t a return to coverage of Wars of the Worlds in SL. November marks the start of the next round of missions to Mars, with two new orbiters about to depart Earth as a part of our efforts to better understand the Red Planet and its atmosphere. Meanwhile, and despite a lack of headline news, NASA’s Mars Science Laboratory (MSL) continues its own explorations of the Red Planet, as does its little cousin Opportunity, half a world away.
Driving Forward
During the last week of October, the MSL rover Curiosity chalked up another achievement making its first pair of back-to-back autonomous drives using its on-board capabilities rather than relying on assistance from Earth.
I’ve covered the benefits of Curiosity’s ability to “self navigate” and how it works in previous MSL reports. However, up until now the system has only been used after the rover has initially traversed a course carefully plotted by the drive team on Earth using images taken by the rover and from overhead passes of the Mars Reconnaissance Orbiter (MRO).
This was the case with the rover’s drive on Sunday 27th October, when it completed an autonomous drive after a plotted drive. However, on Monday 28th October Curiosity immediately resumed its autonomous drive without any input from Earth, heading for the next waypoint along the route which will eventually bring it into the lower slopes of “Mount Sharp”.
Next stop “Cooperstown”, the raised outcrop in the centre of this image from Curiosity’s Navcams, captured at the end of the rover’s back-to-back autonomous drives on October 28th, 2013 (Sol 437).
This waypoint, dubbed “Cooperstown”, is a rocky outcrop which had been identified as a candidate for examination by the rover in MRO images of the route to “Mount Sharp”. It is anticipated that Curiosity will spend no more than a day examining the outcrop, which is liable to be done predominantly using the instruments mounted on the turret at the end of the rover’s robot arm.
“What interests us about this site is an intriguing outcrop of layered material visible in the orbital images,” said Kevin Lewis of Princeton University and a participating scientist for the mission responsible for planning the “Cooperstown” activities. “We want to see how the local layered outcrop at ‘Cooperstown’ may help us relate the geology of ‘Yellowknife Bay’ to the geology of ‘Mount Sharp’.”
A high-resolution raw image of part of the “Cooperstown” outcrop captured using Curiosity’s Mastcam on Sol 440 (November 1st, 2013)
“Yellowknife Bay” is an area of Gale Crater which, alongside that of “Glenelg”, the rover spent some 6-months examining various rock formations and gathering samples for analysis.
The planned duration of the “Cooperstown” stop is in marked contrast to the rover’s last waypoint stop, and coupled with the testing of back-to-back autonomous drives, is aimed at accelerating Curiosity’s progress towards the desired destination of “Mount Sharp”. So far, the rover has traversed around one-third of the 8.6 kilometres (5.3 miles) separating the “Yellowknife Bay” area, which it left in July 2013, from the entry point to the lower slopes of “Mount Sharp”.
The ability for the rover to safely store data necessary for it to resume self-navigation in its onboard memory is also vital for future planning for Curiosity’s progress over the upcoming holidays, when it is hoped that multi-day operations for the rover can be planned and uploaded, allowing the rover to continue in a range of activities, including driving, rather than necessarily spending the entire holiday periods parked-up and performing static science.
The next key activity for the rover is the uploading of the third new version of the on-board software. Such uploads are periodically needed in order to both prepare the rover for upcoming aspects of the mission and to improve its capabilities. This next update will see improvements in the information the rover is able to store overnight for the purposes of autonomous driving, updates to the software controlling the robot arm which should further increase the ability to use the arm when the rover is parked on a slope – something which is likely to be needed once Curiosity starts exploring “Mount Sharp”.
Curiosity has resumed its long drive towards the point where it can begin its examination of the huge mound sitting at the centre of Gale Crater which NASA has dubbed “Mount Sharp” (its official name is Aeolis Mons).
The rover recently stopped-off at an area dubbed “Waypoint 1”, the first of several potential stop-over points on the rover’s route, where it will carried out various studies of the surroundings.
Curiosity departed the area on September 22nd after spending some 10 days examining rocks at “Waypoint 1”, and is once more travelling slowly but steadily towards the point mission managers have identified for it to bypass a dune field lying between it and “Mount Sharp”. Along the way, it is liable to make around four more stops.
While at “Waypoint 1”, the rover spent time examining a rocky outcrop dubbed “Darwin”, using a range of instruments to gather images and data which again showed that Gale Crater was once the scene of considerable water activity.
A mosaic of four images taken by the Mars Hand Lens Imager (MAHLI) camera shows detailed texture in a ridge on the rock outcrop dubbed “Darwin” the rover studied at “Waypoint 1”. The images were obtained shortly before sunset Sol 400 (Sept. 21, 2013) with the camera 25 cm (10 inches) from the rock. Scale is indicated by the Lincoln penny from the MAHLI calibration target, shown beside the mosaic.
“We examined pebbly sandstone deposited by water flowing over the surface, and veins or fractures in the rock,” said Dawn Sumner of University of California, Davis, a Curiosity science team member with a leadership role in planning the stop. “We know the veins are younger than the sandstone because they cut through it, but they appear to be filled with grains like the sandstone.”
While much of the outcrop was covered in the all-too-familiar oxidised Martian dust, there were a patches of bare rock scattered across its surface in which sand deposits and pebbles could be seen, and it was these that drew the attention of the science team.
A mosaic of nine images, taken by the MAHLI camera, shows detailed texture in a conglomerate rock bearing small pebbles and sand-size particles. Again, these images were captured on Sol 400 (Sept. 21, 2013) with the camera positioned about 10 cm (4 inches) from the rock. Scale is indicated by the Lincoln penny from the MAHLI calibration target, shown beside the mosaic.
Following extensive studies of the outcrop, the science team interpret the sand and pebbles in the rock as material that was deposited by flowing water, then later buried and cemented into rock, forming conglomerates. Research will now focus on the textures and composition of the conglomerates as Curiosity continues onward, to understand its relationship to stream bed conglomerate rock found closer to Curiosity’s landing site. Doing so, together with studies to be undertaken at the remaining waypoints, should help scientists to piece together the relationship between rock layers at “Yellowknife Bay” where the mission found evidence of an ancient freshwater-lake environment favourable for microbial life, and the rock layers at the main destination on lower slopes of “Mount Sharp”.
Water, Water, Everywhere
On September 27th, the Curiosity team published five reports in the journal Science which discuss the mission’s findings during the first four months of the rover’s time on Mars. A key finding from this work is that water molecules are bound to fine-grained soil particles, accounting for about 2 percent of the particles’ weight at Gale Crater. This result has global implications, because these materials are likely distributed around the Red Planet.
The presence of water was discovered as a result of samples of surface material being heated to the point of vapourisation within a small oven inside Curiosity – and the most abundant vapour detected was H2O. The quantity of water molecules bound-up in the Martian soil suggest that as much as two pints of water could be obtained through the heating of one cubic foot of Martian dirt.
This discovery potentially has major implications for any long-term human presence on Mars in the future. The water – once subjected to appropriate treatment to remove unwanted minerals, such as a perchlorate, which has also been found in small amounts within Martian soil samples and can interfere with the thyroid function – could be used for cleaning and drinking purposes. It could also be electrolysed and used in the creation of oxygen and hydrogen. The hydrogen could then be used for a variety of purposes, including as a raw fuel, or in the production of fuel in the form of methane (created by combining the hydrogen with carbon dioxide from the Martian atmosphere), which could be used with oxygen to power surface vehicles.
An interesting part of the study is that the analysis of the chemicals and isotopes in the gases released during the analysis of soil samples indicates that the water molecules are the result of an interaction between the soil on Mars and the current atmosphere of the planet; so the process of depositing the water molecules is ongoing, rather than the result of some past mechanism. Even the discovery of perchlorate in the samples is of significance; previously, this had only been found in soil samples examined at the high latitude Phoenix Lander site. That they’ve now also been found in a near-equatorial latitude suggests they have a global distribution as well.
The other papers released by the science team further confirm earlier studies into the mineral composition of samples gathered and studied during the rover’s initial four months on Mars using its full suite of sample analysis tools: MAHLI, APXS, ChemCam, SAM, and CheMin, all of which can perform a range of complementary as well as disparate analyses.
One of the papers additionally focuses on a rock I covered back in the early days of the mission – Jake_M. Named in memory of NASA / JPL engineer Jacob Matijevic, who worked on all three generations of NASA’s Mars rovers and who passed away shortly after Curiosity arrived in Gale Crater, Jake_M was thought to be quite unlike any other rock on Mars – not because of its pyramid-like shape, but because of its composition.
“Jake_M”, the remarkable rock examined by Curiosity on September 22nd 2012, and believed to be a mugearite type of rock. The markings show where ChemCam and APXS were used to examine it
The paper published in Science confirms that Jake_M is most like a mugearite, a type of rock found on islands and rift zones on Earth.
In what has been something of a surprise to scientists around the world, findings from the Mars Science Laboratory (MSL) suggest the amounts of methane present in the Martian atmosphere, at least at near-ground levels, are at best negligible.
While it can be produced by non-organic, as well as organic means, methane has long been regarded as one of the tell-tale signs that life may have once existed on Mars – or even may still exist somewhere beneath the planet’s arid surface.
Using the highly sensitive Tunable Laser Spectrometer, a part of the Sample Analysis at Mars (SAM) science package aboard Curiosity, MSL has subjected six samples of the atmosphere gathered between October 2012 and June 2013 to analysis – and failed to detect any signs of methane, trace or otherwise.
The Tunable Laser Spectrometer (TLS) shoots laser beams into a measurement chamber filled with Martian atmosphere. By measuring the light absorption at specific wavelengths, the TLS can measure concentrations of gases, including methane, as well as different isotopes of the gases. In this images of a TLS demonstrator, visible lasers are being used to show how the lasers bounce between the mirrors in the measurement chamber. The actual TLS uses infrared lasers.
This has come as a surprise because previous data gathered by US and international scientists via a range of means have suggested that while not present in abundant amounts, methane is very detectable within the Martian atmosphere. So much so that some of those involved in MSL were extremely confident ahead of the mission that the rover would find clear evidence of the gas as a part of its analysis of atmospheric samples.
Europe’s Mars Express, for example, which started on-orbit operations in 2004, and is still functioning today, found strong evidence for methane within the atmosphere of Mars. Not long after this, NASA’s own Mars Global Surveyor (the precursor to the Mars Reconnaissance Orbiter which relays communications between Curiosity and Earth today), which operated in Mars orbit from September 1997 through to November 2006, also detected methane to a point where scientists where able to map its annual ebb and flow.
Map showing the relative concentrations of methane on Mars, 2004. Yellow indicates the highest concentrations of the gas, which coincide with the upland regions of the northern hemisphere, including the once volcanic regions of the Tharsis Bulge and Elysium
On Earth, methane (CH4) is largely the by-product of two distinct activities: geological, such as through volcanic eruptions – and Mars certainly has a fair few volcanoes, some of the largest in the solar system in fact; and via organic means. Either way, it tends to break down relatively quickly, so even trace amounts of it within Mars’ atmosphere suggest that it is being renewed somehow. Given that an erupting volcano on Mars is a tad hard to miss (see “some of the largest in the solar system”, above), a renewable source of methane has seen as evidence that either there is some as yet unknown chemical reaction going-on to create methane – or it may just be the result of outgassing from Martian microbes.
Possible sources of methane on Mars
The amount of methane in the Martian atmosphere has never been particularly high; even the best analyses over the years have placed it at a peak of around 70 parts per billion, However, the TLS on Curiosity is a very sensitive piece of equipment. So sensitive that any trace amounts of methane in the Martian atmosphere must be below 1.3 parts per billion (around 10,000 tonnes in total throughout the atmosphere) in order for the TLS to miss it.
Responding to the findings, published on Thursday September 19th in Science Express, NASA has pointed out that the chances of future missions finding evidence of microbial life on Mars, past or present, aren’t entirely dashed. “This important result will help direct our efforts to examine the possibility of life on Mars,” Michael Meyer, NASA’s lead scientist for Mars exploration, said in a press release accompanying the report’s publication. “It reduces the probability of current methane-producing Martian microbes, but this addresses only one type of microbial metabolism. As we know, there are many types of terrestrial microbes that don’t generate methane.”
TLS forms a part of the Sample Analysis at Mars package of instruments, one of the most comprehensive and compact science experiments sent into space, shown here being installed into Curiosity
On Sol 376, August 27th 2013, Curiosity achieved another mission milestone: the first use of the autonomous driving capabilities to fully drive itself through a potentially hazardous zone.
The autonomous navigation software – autonav – was uploaded to the rover following the April 2013 period of solar conjunction. It is designed to allow the rover to decide how best to handle driving safely on Mars, rather than constantly relying on command updates from Earth – something which can severely limit the rover’s daily progress if there are significant obstacles in the rover’s path or if the mission team want the rover to drive beyond the limits of what the Navcams can see at the start of a day’s drive without routes having to be constantly re-plotted from Earth.
The drive of August 27th saw Curiosity successfully use autonomous navigation to cross ground that could not be confirmed safe before the start of the drive. While the drive team were able to establish a “bounding box” in which the rover was expected to keep during the day’s progress, a significant depression in the ground some 10 metres (33 feet) across could not be imaged in advance of the rover’s arrival, and so autonav was enabled in order for the rover to make its own way through the depression.
“We could see the area before the dip, and we told the rover where to drive on that part. We could see the ground on the other side, where we designated a point for the rover to end the drive, but Curiosity figured out for herself how to drive the uncharted part in between,” said JPL’s John Wright, a rover driver.
The road ahead: a mosaic panorama captured by Curiosity’s Navcams after the Sol 376 traverse. The rise on the left of the image is part of “Mount Sharp”; the more distance highlands to the right are the walls of Gale Crater (click to enlarge)
Crossing the depression required the rover to take several sets of stereo images of the terrain, compare them, determine potential routes to reach a the designated way-point, and then select the safest course to take.
While autonav has been used a number of times already in recent weeks, these have always been under controlled conditions and limited in scope. The Sol 376 traverse marks the first time Curiosity has been left entirely to its own devices to cross what has essentially been unknown ground for the mission team. The drive means that the rover has now travelled about 1.39 kilometres (0.86 miles) since departing “Glenelg” and “Yellowknife Bay” early in July, and has a little over 7 kilometres (4.46 miles) to go before reaching the lower slopes of “Mount Sharp”.
Rapid Transit Route
To assist the rover’s progress, NASA have marked-out a “rapid transit route” using images from the High Resolution Imaging Science Experiment (HiRISE) camera aboard the orbiting Mars Reconnaissance Orbiter. This plots a rough course for the rover from “Glenelg” to the designated entry-point into the lower slopes of “Mount Sharp”, and which runs alongside a dune field which lays between the terrain the rover is on and the slopes of the mound itself. Several potential waypoints have been identified along the route where the rover may stop for a few days at a time to allow further science work to be carried out.
The “Aeolis Mons expressway”: NASA’s “rapid transit” route Curiosity is following in order to reach the lower slopes of “Mount Sharp”, with potential science waypoints marked. The mound is towards the bottom of the image and the black diagonal band is a dune field which runs along the foot of the hill
On the 5th/6th August 2012, an aerodynamic capsule large enough to hold compact family car separated from its cruise stage “life support” system after an eight-month journey from Earth and blazed a trail across the high, thin atmosphere of Mars at the start of what those responsible for it had dubbed the “seven minutes of terror”.
Inside that aeroshell was the most advanced remote science system yet sent into interplanetary space by humankind, 80 kg (around 180 pounds) of science equipment packaged neatly into a rover vehicle itself just under a tonne in weight and powered by a “nuclear battery”. If all went well, those “seven minutes of terror” would end with NASA’s latest and most ambitious mission to the planet Mars safely on the surface of that world. If things went badly, a lot of people would be looking at almost a decade of their endeavours smashed to pieces along with the rover.
The Mars Science laboratory spacecraft systems: (1) Cruise Stage; (2) aeroshell back shell; (3) Skycrane; (4) Curiosity rover; (5) Heat shield; (6) Parachute system
Of course, things did go well. The rover, dubbed “Curiosity” by an 11-year-old girl called Clara Ma following a nationwide competition held by NASA in 2008, landed safely and so wrote the first lines in what have been a remarkable year of operations on Mars.
Just over half-way through its primary phase of a full Martian year (about 1.8 times longer than a year here on Earth), Curiosity and the Mars Science Laboratory mission has already achieved a major part of its mission goal: to discover if Mars demonstrates any evidence for once having the kind of environment conducive to the formation of life.
And with the mission indefinitely extended beyond that primary mission phase (the rover’s RTG power system should be able to power it for around 14 years or so, so only the unforeseen accident or failure might now curtail the mission in less than that time frame), the opportunities for Curiosity to write many more new chapters in our understanding of Mars are considerable.
Over the last year, as an aside to my reporting on Second Life and virtual worlds (as well as one or two other things!), I’ve tried to provide a steady narrative on the mission in these pages (with more than a little help from NASA JPL!), I’ve done so as space exploration is of interest to me for assorted reasons, and because the reports seem to have resonated with some of you who regular read this blog (and thank you on both counts, for reading the blog and the reports!).
Obviously, as with all things fresh and exciting, coverage of the mission in the early months was easy; such was the media interest in the story that information was flooding out of NASA’s Jet Propulsion Laboratory as the rover went through its month-long post-landing commissioning activities, and then started its first hesitant operations on the dusty, wind-swept floor of Gale Crater.
With the passing of a year, media interest has moved on. As a result, the science and engineering teams responsible for the mission have been able to focus more on their day-to-day work, and the updates coming out of NASA have slowed somewhat.
Curiosity is now well into the eight kilometre (five miles) drive to its next target: the lower slopes of Aeolis Mons (“Mount Sharp”), the mound surrounding the central peak of the crater. In the six weeks since departing “Glenelg” and “Yellowknife Bay”, where it had been engaged in science activities for almost six months, the rover has travelled almost a full kilometre.
Traversing Mars: from the arrival point of “Bradbury Landing” to Curiosity’s position on Sol 365 (August 16th, 2013) this map traces a remarkable journey (click to enlarge)
That the rover is making “rapid” progress is down to two things: there are no planned science objectives for this phase of the mission (unless Curiosity happens across something completely unexpected and interesting), and the rover’s drive team have gained considerable confidence in the upgraded autonomous driving capability I reported on last time around.
Curiosity’s primary mission is not to find direct evidence of life, past or present, on Mars, but rather to see if ancient Mars once had the right conditions present in or on it for life to have possibly arisen. Gale Crater was chosen as a landing site with this in mind; since well before the mission it has been the subject of study from orbit by the likes of NASA’s Mars Odyssey and Mars Reconnaissance Orbiter and Europe’s Mars Express. That it has surface features which appear consistent with free-flowing water once having existed on Mars have been well-known, including the fact that “Mount Sharp” itself shows signs of having been in part formed from water-borne sedimentary deposits (it is thought Gale Crater may have once been filled with a lake). As such, it was anticipated that the rover would find evidence of free-flowing water having once been present within the 194-kilometre wide crater.
What wasn’t expected was the overwhelming evidence the rover came across in terms not only of sedimentary deposits, but also in what look to be ancient river beds sitting exposed on the floor of the crater, and rock and soil samples the on-board science systems have found to contain mineral and chemical elements and traces which point to a wet history in this part of Mars. What has been more exciting is that the mix of elements and minerals suggest the environment in the crater was once very benign towards life, so much so, that John Grotzinger, the mission’s Principal Investigator, was given to comment:
It’s been fairly quiet as the Mars Science Laboratory (MSL) rover Curiosity continues driving towards the point at which it is hoped the rover can traverse between a line of low-lying sand dunes and start exploring the lower slopes of Aeolis Mons, which NASA has dubbed “Mount Sharp”.
Inara Pey: Living in a Modemworld 