Tag Archives: MSL

Short circuits on Mars and mapping asteroids

CuriosityFollowing my last Curiosity update, which noted that other than for one potential drilling / sampling target, work was wrapping-up for the Mars Science Laboratory in the “Pahrump Hills” location on the lower slopes of “Mount Sharp”, the decision was taken to indeed gather one more sample.

The selected target had been dubbed “Telegraph Peak”, and sits towards the top end of “Pahrump Hills”. It was selected because Alpha Particle X-ray Spectrometer (APXS) measurements carried out by the rover during its 5-month “walkabout” in “Pahrump Hills” revealed the rocks in the area to be relatively enriched in silicon when compared to the corresponding amounts of aluminium and magnesium, which is somewhat different to rocks sample prior to the rover arrival at the basal slops of “Mount Sharp”. This enrichment has also shown to increase the further up the slopes of “Pahrump Hills” the rover climbed, which is of interest to the science team.

“When you graph the ratios of silica to magnesium and silica to aluminium, ‘Telegraph Peak’ is toward the end of the range we’ve seen,” Curiosity co-investigator Doug Ming explains. “It’s what you would expect if there has been some acidic leaching. We want to see what minerals are present where we found this chemistry.”

Sampling took place on February 24th, 2015 (PDT) or Sol 908 for the rover on Mars. For the first time in Curiosity’s time on Mars, it was carried out with no preliminary “mini-drill” operation. Instead, the science team judged that analysis of the rock by APXS indicted it was of a very similar nature to the previous two sample drilling sites in “Pahrump Hills”, and the new lower percussion drilling capabilities the rover now has were judged as sufficiently safe enough to go ahead with a direct sample gathering operation.

How the drill works: On the left, a view of the drill mechanism mounted on the rover's turret, with the drill bit centre bottom. On the right a cutaway showing the sample collection mechanism in the drill bit

How the drill works: On the left, a view of the drill mechanism mounted on the rover’s turret, with the drill bit centre bottom. On the right a cutaway showing the sample collection mechanism in the drill bit

As I’ve covered previously in these pages, obtaining a sample for analysis is a multi-part operation. First the rock is drilled, and a core sample forced up through the drill bit into a one of two sample collection chambers at the top of the drill mechanism. From here, the sample is “shaken” through a feed to another device in the rover’s robot arm turret called CHIMRA – the Collection and Handling for In-Situ Martian Rock Analysis system, used to separate the tailings through a series of sieves, ready for different sizes of sample grains to be passed through the the rover’s on-board laboratory systems.

Both of these operations require the use of the drill’s percussive system to vibrate the turret, forcing material both from the drill’s sample collection chamber and through CHIMRA. However, on February 27th, during the initial operation to move the sample tailings from the drill chamber to CHIMRA, Curiosity’s on-board fault protect system identified a transient short circuit within the robot arm’s electronics. The immediately resulted in all arm-related activities being shut down, and the arm and turret locked into position ready for diagnostic operations to commence.

A transient short can occur for a number of reasons, and can pass without significant problems. However, it may also indicate a potential issue which might require some measure of action, such as a change in operating procedures or a restriction on how a mechanism is used, in order to avoid the issue becoming a serious problem in the future. To this end, following the fault report, mission engineers started diagnosing the problem, with almost all rover operations halted while they did so.

A monochrome image from Curiosity’s Navigation Camera (Navcam) shows the position in which the rover held its arm for several days after a transient short circuit triggered on-board fault-protection programming to halt arm activities on February 27th, 2015 PDT, the 911th Sol of the rover’s work on Mars.

On Thursday, March 5th, as a part of the investigative process, the rover was commanded to carry out a series of vibration tests of the kind performed while forcing the transfer of samples from the drill to CHIMRA. The vibrations were carried out with the robot arm and turret in the same orientation and position which caused the initial triggering of the fault protection system, and in the third of 180 repeat motions, a similar transient short occurred, lasting less than one one-hundredth of a second, enough to trigger the rover’s fault protection systems, and confirming there does appear to be some kind of electrical issue.

Tests are now under-way to determine whether or not the short will occur with the turret in different orientations, and may be followed by additional tests to see if it occurs with the arm in different positions. If no shorting occurs with either a change in the orientation or position of the turret / arm, then the most obvious step in preventing any recurrence of the issue is to avoid placing the turret / arm in the same orientation for sample transfer operations during future drilling activities.

It is hoped that the tests can be completed in the course of the next week. If they show that operations can be resumed safely, it is anticipated that the sample transfer operations will be completed, and Curiosity will then be ready to resume its climb up “Mount Sharp”, leaving “Pahrump Hills” via a narrow valley the science team have dubbed “Artist’s Drive”.

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Avatars on Mars, Falcons in Florida and oceans in space

CuriosityCuriosity, NASA’s Mars Science Laboratory (MSL), has been wrapping things up in the “Pahrump Hills” region at the base of “Mount Sharp”, the mountain-sized mound of deposited material occupying the centre of Gale Crater.

For the last several months, the rover has been engaged on what geologists on Earth call a “walkabout”, zigzagging back and forth across the area, looking for targets of interest for follow-up investigations, and allow the science team to better understand the geology and form of the region.

This method of activity is a change from how Curiosity has largely operated to date, which has seen the rover primarily move from point-to-point along its route, only re-visiting sites as a part of its onward movement towards the goal of reaching and climbing “Mount Sharp” (such as when travelling into, and then back out of the “Glenelg” and “Yellowknife Bay” regions Curiosity first explored in 2012 / 2013).

Curiosity's wandering through "Pahrump Hills", which started with one of the tree lines into the region at the top of the image

Curiosity’s wandering through “Pahrump Hills”, which started with one of the tree lines into the region at the top of the image

In this respect, and as Aileen Yingst, the Deputy Principal Investigator with the Mars Hand Lens Imager (MAHLI) on the rover, describes, Curiosity has been demonstrating just how much of an avatar it is for the science team, allowing them to careful investigate, examine and catalogue “Pahrump Hills” in a rich, practical way using the very human technique of the “walkabout”, which will serve the mission well as the ascent up “Mount Sharp” continues.

Most recently, and since collecting samples from “Mojave 2″, the area of rock displaying interesting crystalline elements within it, Curiosity has been looking at an area geologists dubbed “pink cliffs”, which shows further signs of the crystalline structures, and might be a candidate for further investigation. If so, it will be the last stopping point in “Pahrump Hills” before Curiosity continues its climb up “Mount Sharp”.

Oppy Reaches 11

January 25th, 2015 saw NASA’s Mars Exploration Rover, Opportunity, reach it’s eleventh anniversary on Mars. The rover, one of two MER vehicles, arrived on Mars at January 25th, 2004 (Universal Time), ready to start a mission initially planned to last just 90 days.

Since then, and up to its anniversary, “Oppy” has travelled a distance of some 41.7 kilometres (25.9 miles). While this doesn’t sound that much (and in truth, a human science team could have travelled that far in just a few days, including time for any science carried out along the way), remember that “Oppy’s” forward speed is measured in centimetres per hour.

As one of two solar-powered MER rovers (the second, Spirit having finally succumbed to the hostile environment on Mars around March 215th, 2011), Opportunity has carried out an incredible amount of work, and greatly contributed to our understanding of the planet, returning compelling evidence about wet environments on ancient Mars.

A panoramic view of Endeavour Crater as seen from “Cape Tribulation” an uprising close to the crater’s rim, the summit of which Opportunity reach in January 2015, marking its 11th anniversary on Mars (click for full size)

The rover marked its anniversary by reaching the summit of “Cape Tribulation”, an uprising close to the rim of 20 kilometre (13.7 mile) wide Endeavour Crater, which the rover has been gradually circumnavigating. This involved a change in elevation for “Oppy” of about 135 metres (440 feet), and afforded it a panoramic view of the crater and the land around it, presenting a unique opportunity for geological observations of the crater and its rim.

 A New Mars Mystery

That night, too, there was another jetting out of gas from the distant planet. I saw it … That night another invisible missile started on its way to the earth from Mars, just a second or so under twenty-four hours after the first one.

- The narrator, H.G. Wells’ The War of the Worlds

Okay, so it’s unlikely to be the sign of an impending invasion of Martians possibly ticked-of at the way we’re cluttering-up their planet with our probes and landers and rovers, but recent events high in the atmosphere of Mars have given rise to some excitement.

The images, originally capture in 2012, show huge plumes rising some 250 kilometres (156 miles) into the most tenuous reaches of Mars’ thin atmosphere.

Martian high-altitude plumes

Martian high-altitude plumes (image: ESA)

The plumes occurred on two separate occasions in March and April 2012, and were spotted by amateur astronomers. Each time, they developed with relative rapidity, rising upwards and outwards to cover areas of some 1000 x 500 kilometres (625 x 312.5 miles) in a period of around 10 hours before remaining visible for up to 10 days at a time, their structure and form changing on a daily basis.

Unfortunately, neither event was seen from orbit about Mars, occurring so high on the planet’s limb as to be effectively out-of-sight for the NASA and ESA orbital vehicles, and by the time word had spread sufficiently about the observations, the events were largely over.

However, investigations into images of the planet taken by the Hubble Space Telescope in orbit around the Earth have revealed similar plumes being imaged in the past. However, with the exception of an image captured in 1997, none have been anywhere near as high or dramatic as the 2012 events.

So what might have caused this plumes to occur? The answer to that question is uncertain.

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“I spy with my big eye…” and landing a rocket on Earth

CuriosityNASA’s Curiosity rover has been a busy bunny on Mars. Currently still parked in the “Pahrump Hills” terrain on the lower slopes of “Mount Sharp”, the Mars Science Laboratory (MSL) rover has now completed its latest drilling activity, collecting samples from a rock dubbed “Mojave 2″.

This isn’t actually the rock from which the science team had originally hoped to gather samples. That rock, dubbed “Mojave” broke apart as a result of the percussive action of the rover’s drill during a “mini-drill” test. As a result, the rock was ruled out as a sample gathering target. “Mojave” was of particularly interest to scientists as Curiosity had images tiny, rice-grain sized crystalline minerals that might have resulted from evaporation of a drying lake, thus presenting the science team with a further insight into environmental conditions within Gale Crater.

To counter this loss, the team relocated Curiosity to  “Mojave 2″, another rock within the same outcrop as “Mojave”, and which exhibits similar crystalline features. In doing so, the team were able to bring into play software improvements only recently uploaded to the rover as a part of an overall systems upgrade, which was deployed to one of the rover’s two computer systems at the end of January.

The software improvements for the drill are the result of investigations into the fracturing of a rock during a previous attempt to obtain samples prior to the rover arriving on “Mount Sharp”. Like an Earth-based hammer drill, the rover’s drill uses a percussive action, so that as well as drilling into a rock, the drill bit effectively hammers its way into the rock. In all, there are six settings governing the amount of percussive energy used during drilling, which range from a gentle tapping (level 1) through to hammering at the rate of 30 times a second with a 20-fold increase in energy imparted (level 6).

During early drilling operations the software monitoring these percussion settings “learned” that defaulting to the “level 4″ setting best met the needs of gathering samples in the harder rock types the rover initially encountered. However, this was proving too forceful for the softer rocks closer to, and on, “Mount Sharp”, but the software was unable to switch down to a lower setting.

The drill hopes on "Mojave 2" captured by Curiosity's Mastcam. Towards the top is the small, "mini drilling" test bore, just a couple of centimetres deep, created on Sol 881 (January 28th, 2015, PDT) and some 10 centimetres below it, the sample-gathering bore hole, some 6.5 centimetres deep, cut on Sol 882 (January 29th, 2015, PDT).

The drill holes on “Mojave 2″ captured by Curiosity’s Mastcam. Towards the top is the small, “mini drilling” test bore, just a couple of centimetres deep, created on Sol 881 (January 28th, 2015, PDT) and some 10 centimetres below it, the sample-gathering bore hole, some 6.5 centimetres deep, cut on Sol 882 (January 29th, 2015, PDT).

The new update causes the drill software to reset to “level 1″ after each drilling operation, and then step through the levels incrementally until the ideal is found. As a result, a sample was gathered from “Mojave 2″ without the drill needing to step beyond the “level 2″ percussion action.

Drilling operations on “Mojave 2″ took place on Sol 881 and Sol 882 (January 28th and 29th, PDT, respectively). As per standard operating procedure, the first drilling operation was a test “mini drilling” to see how the rock responded to encroachment and cutting. The second, which took the dill to a depth of around 6.5 centimetres (2.6 inches). The gathered samples were then sifted and sorted through the CHIMRA system in the rover’s turret, prior to being transferred via the surface scoop to Curiosity’s primary laboratory systems, ChemMin and SAM.

At the same time as Curiosity was carrying out its initial analysis of the “Mojave 2″ rock, NASA released an image captured by the HiRise (High Resolution Imaging Science Experiment) carried aboard the orbiting Mars Reconnaissance Orbiter (MRO), which forms the mainstay of the rover’s communications with Earth. The image, which was taken on December 13th, 2014, reveals Curiosity mid-way through its “walkabouts” in “Pahrump Hills”, when it was seeking potential targets of interest for further study.

While not the first time the rover has been imaged from orbit, this is one of the clearest pictures from the rover yet capture from an altitude of around 280 kilometres (175 miles) above the surface of Mars.

"I see you!" - MRO's HiRise image of the curiosity rover, obtained on December 13th, 2014, as the rover explores the "Pahrump Hills" region on a basal slopes of "Mount Sharp"

“I see you!” – MRO’s HiRise image of the curiosity rover, obtained on December 13th, 2014, as the rover explores the “Pahrump Hills” region on a basal slopes of “Mount Sharp”

Initial results from ChemMin (the Chemical and Mineralogy) instrumental has shown that the rock was likely effected by water that was much more acidic in nature than evidenced through the analysis of other rock samples obtained by the rover. The still-partial analysis shows a significant amount of jarosite, an oxidized mineral containing iron and sulphur that forms in acidic environments. This raises the question of whether the more acidic water was part of environmental conditions when sediments were being deposited to form “Mount Sharp”, or the result of fluids soaking the rocks at a later time.

ChemMin was also unable to identify a clear candidate mineral for the crystalline deposits which first attracted the science team to the outcrop; this presents the possibility that the minerals responsible for originally forming the crystals may have been leached away over time and replaced by other minerals during later periods of wet environmental conditions.

It is hoped that SAM – the Sample Analysis at Mars – suite of instruments may be able to reveal more about the nature and composition of the samples once they have completed their round of analysis. Depending on the outcome of this work, Curiosity may be ordered to gather a further rock sample from “Pahrump Hills”, or may be ordered to continue upwards and into new territory on “Mount Sharp”.

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All change, getting virtual on Mars and watching the asteroid go by

CuriosityThe start of the year has brought – and is bringing – some changes to the Mars Science Laboratory mission. The first change has occurred here on Earth. On January 5th, 2015, John Grotzinger from the California Institute of Technology stepped down as the mission’s principal Project Scientist in overall charge of a team of some 500 people from across the globe who are operating the rover and its suite of scientific instruments.

Recently promoted to chair Caltech’s Division of Geological and Planetary Sciences, Grotzinger will still be involved in the mission, but his new responsibilities mean he cannot reasonably continue in such a lead role within the project. Stepping into his shoes, therefore, is Ashwin Vasavada of NASA’s Jet Propulsion Laboratory. He has been serving in the role of Deputy Project Scientist since the mission’s inception 2004, and has been intimately involved in both the development of the mission’s science packages and the rover itself. As such, he is ideally placed to take over from Grotzinger.

“John Grotzinger put his heart and soul into Curiosity for seven years, leaving a legacy of success and scientific achievement,” he said on taking over the role. “Now I look forward to continuing our expedition to Mars’ ancient past, with a healthy rover and a dedicated and passionate international team. And yes, this is all just incredibly cool.”

Ashwin Vasavada of NASA’s Jet Propulsion Laboratory, Pasadena, California, took over has the MSL’s Project Scientist from John Grotzinger at the start of January, 2015

Meanwhile, on Mars, Curiosity is engaged in further studies of rocks within the “Pahrump Hills” area on the lower slopes of “Mount Sharp”. These studies will involve drilling for rock samples from at least one more target of interest,  prior to the rover continuing its climb up the flank of the mountain.

The initial target for sample gathering has been dubbed “Mojave”, which appears to be rich in crystalline minerals. Slightly smaller than grains of rice, the structures first appeared on early images of the rock captured by the rover, and have caused intense – no pun intended – curiosity among mission scientists.

“We don’t know what they represent,” Vasavada said of the mineral forms and the decision to target “Mojave” for drilling. “We’re hoping that mineral identifications we get from the rover’s laboratory will shed more light than we got from just the images and bulk chemistry.”

Prior to drilling for actual samples, Curiosity was first ordered to carry out a “mini drilling” operation. This is a routine test to ascertain a number of things prior to committing to a full-on sample gathering exercise. These include making sure the rock is stable enough for a full drilling operation, gathering data of the reaction of the drill to penetrating the rock surface, ensuring any drilling operation will not cause undue vibration within the rover’s mechanisms, and so on.

A unique view of the "mini drilling" operation on "Mojave". Captured by Curiosity's Hazcam navigation cameras, the image shows the rover's "hand" oriented such that the dril (visible with its two steadying arms) is placed against the rock

A unique view of the “mini drilling” operation on “Mojave”. Captured by Curiosity’s Hazcam navigation cameras, the image shows the rover’s “hand” oriented such that the drill (visible with its two steadying arms) is placed against the rock, with the peak of “Mount Sharp” forming a backdrop.

The initial mini-drilling operation took place on January 13th 2015, during the 867th Martian day, or Sol, of Curiosity’s work on Mars. It marks the third phase of science operations in the “Pahrump Hills” area, having been preceded by a “walkabout” of the area in which potential target sites for detail investigation were noted prior to follow-up examinations of several of them using some of the rover’s on-board systems, such as the Alpha Particle X-Ray Spectrometer and the Mars Hand Lens Imager (MAHLI), both of which are also mounted on the “hand” or turret at the end of the rover’s robot arm.

Once samples from “Mojave” have been collected, they’ll be passed through the CHIMRA system inside the turret, which will prepare them for delivery to the rover’s main on-board science suits, SAM and ChemMin. The latter (standing for Chemistry and Mineralogy instrument), will hopefully reveal a lot more about the chemical composition of the crystals. Additionally the drilling operation itself should reveal whether the crystals are only at the surface, like a salty crust, or are also deeper in the rock, which itself might lead to clues about their origins

“There could be a fairly involved story here,” Vasavada said. “Are they salt crystals left from a drying lake? Or are they more pervasive through the rock, formed by fluids moving through the rock? In either case, a later fluid may have removed or replaced the original minerals with something else.”

Two other potential targets for drilling operations are also under consideration before the rover moves out of the “Pahrump Hills” area.

The view is a mosaic of four focus-merge images created by Curiosity from 40 images acquired using MAHLI on Sol 809 (November 15th, 2014 PDT). It shows an area of the “Mojave” rock which has been cleaned by the rover’s dust removal tool in order to reveal the tiny rice-like crystalline deposits. The penny in the lower left is to scale with the mosaic

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