Not long after I Pressed my last MSL update, Curiosity went ahead and collected its first scoop of Martian sand.
The operation took place over the course of several hours on October 7th (Sol 61), gathered a scoopful of sand and powdery material from the sand ridge the rover had been examining at a location mission managers have dubbed “Rocknest”.
The operation was the first phase in a process which is designed to “clean” the Collection and Handling for In-Situ Martian Rock Analysis (CHIMRA) device mounted on the turret at the end of Curiosity’s robot arm (and which includes the scoop itself). The cleaning process is required to ensure that no contaminants from Earth remain in CHIMRA’s chambers so they do not adversely affect analysis when samples eventually reach the on-board SAM and CheMin instruments.
A Hazcam’s view: Curiosity scoops its first load of Martian surface material
The entire process was carefully monitored using several of Curiosity’s camera systems in order to confirm progress and to make sure everything was operating as expected. This made the gathering of the first scoop of material a protracted affair, with the Hazcams at the front of the rover being used to monitor progress from a low angle and both the Navcam and Mastcam systems imaging progress and results. Once the sample has been gathered, the turret was vibrated gently to level the material in the scoop and shake-off any excess.
A Mastcam image of the scoop filled with material and (arrowed) the FOD – Foreign Object Debris – which halted scoop operations. For scale purposes, the scoop is 7 cm (2.8 inches) long, and 4.5 cm (1.8 inches) wide
It was an image from the Mastcam which brought a halt to operations, when a small, bright object was spotted. Believing the object might be something from the rover, mission managers decided to suspend the scoop operations and use the Remote Micro-Imager of the Chemistry and Camera (ChemCam) instrument to study the object in an attempt to ascertain what it might be.
Following the identification of a further rock target for study, Curiosity spent Sol 54 (September 30th) conducting contact science with the rock, dubbed Bathhurst Inlet by mission personnel, using APXS and MAHLI.
These studies were concluded on Sol 55 when Curiosity used the ChemCam laser, telescope and spectrometer to analyse the chemical / mineral composition of the rock. Following this, the rover manoeuvred some 23.5 metres (77 feet) to an area of sand called Rocknest, which Mastcam images had revealed as a possible location in which to test part of Curiosity’s sample acquisition system.
Studying Bathurst Inlet, a raw image returned by Curiosity’s right Navacam system on Sol 54 (Sept 30th)
Rocknest, an area of wind-blown sand, had initially been imaged on Sol 52, and earmarked as a potential location for sample acquisition tests. The area is around 5 metres by 1.5 metres (16ft by 7ft), and the fact that it appeared to comprise wind-blown deposits suggested it would be an ideal target as the sand is liable to be relatively loosely packed and offer samples which can be acquired relatively easily and which could be used to perform an important task.
Rocknest as imaged by Curiosity’s 100mm Mastcam on Sol 52 (Sept 28). The images in this mosaic have been white-balanced so that colours appear as they would if seen in typical Earth sunlight conditions
Samples can be acquired by Curiosity in one of two ways: using a drill system or via a scoop, both of which are located on the turret at the end of the rover’s robot arm. The activities at Rocknest are focused on the use of the scoop, which can acquire around 20 grams of material at a time for delivery to SAM, the Sample Analysis at Mars system, and CheMin, the Chemistry and Mineralogy system, Curiosity’s two on-board sample analysis systems.
The scoop is part of a complex system called CHIMRA (Collection and Handling for In-Situ Martian Rock Analysis) contained within the turret. This processes samples gathered from both the scoop and the drill system, ready for them to be passed to the rover’s on-board systems. However, before the system can be used, it must be properly prepared and undergo a special “cleaning” process. It is this “cleaning” which is the focus of operations at Rocknest.
The turret science instruments (l) and an internal view of CHIMRA. Note the turret image is inverted in relation to the CHIMRA image (click to enlarge)
On Sol 56, Curiosity further manoeuvred itself a further six metres (20 ft) to get close to a ripple of sand within Rocknest which had been selected for the sample testing. The Dynamic Albedo of Neutrons (DAN) instrument was also used during Sol 56 to measure subsurface hydrogen levels, as was the Radiation Assessment Detector (RAD), designed to characterise the broad spectrum of radiation environment around the rover, and the Rover Environmental Monitoring Station (REMS) – Curiosity’s weather station.
In order to ensure the sand is suitable for the “cleaning” process, mission scientists and engineers needed to understand more about it. To this end, and on Sol 57, Curiosity was commanded to drive onto the ripple, rotate its wheels through 30-degrees and then reverse off. The Purpose of this was two-fold: firstly, it helped to confirm the sand’s consistency and that it is in fact packed loosely enough for the scoop to obtain samples. Secondly, it exposed material beneath the surface layer, allowing it to be further characterised.
Making a mark: a raw image captured by Curiosity’s right Navcam as the rover roll onto the Rocknest sand ripple, prior to leaving a scuff mark designed to help mission scientists examine the particle-size distribution of the material forming the ripple. To give an idea of scale, Curiosity’s wheels are 40cm (16 inches) wide
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This last week has been an interesting one for news on NASA’s Mars Science Laboratory, with the release on the 27th September of news that the rover Curiosity has come across extensive evidence for free-flowing water to have once existed in Gale Crater.
Curiosity examines Jake
Prior to this, on Sol 47 (September 23rd) Curiosity commenced contact science on a rock dubbed Jake Matijevic, using the Alpha Particle X-Ray Spectrometer (APXS), mounted on the turret at the end of the rover’s robot arm. Studies of the rock continued through Sol 48, September 24th, with the ChemCam laser being used once more to assist in analysing the rock’s composition, and MAHLI, the Mars Hand Lens Imager, gathering a range of images of the rock from various distances.
On Sol 49, Curiosity resumed its drive towards Glenelg, a region where three different types of terrain, as observed from orbit, come together. Now over half-way to the region, the rover travelled a further 31 metres (102 ft). During the day, the rover also captured more images of its location and observed the Martian sky.
Sol 50 saw the rover complete its longest single drive to date: 48.9 metres (160 ft), bringing the total distance covered to over 400 metres, or close to quarter of a mile. With the drive came a shift in emphasis for the science team, as they start looking for a location where Curiosity can obtain its first sample of Martian soil. Ideally, the team would like to find a sandy spot with planet of loose Martian fines which can be scooped up by the sample system on the robot arm and then delivered to the on-board SAM and CheMin instruments for detailed analysis.
The road to Glenelg: a mosaic of the land immediately before Curiosity and leading up to Glenelg.
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NASA has released images returned to Earth by the Curiosity rover of what appears to be an ancient stream bed, together with images showing further evidence of liquid water once having flowed freely within Gale Crater.
The images have been captured at separate locations on the route to Glenelg, with the first images being captured on Sol 27 (September 2nd), with additional images of another location being captured on Sol 39 (September 14th).
The Link outcrop images on Sol 27 using the 100mm Mastcam
The first set of these images were of an outcrop of rock dubbed Link, and showed rounded gravel fragments, called clasts, up to a few centimetres in size within the rock outcrop. Too large to have been moved as a result of wind action, these clasts have been deemed to be consistent with a sedimentary conglomerate, or a rock that was formed by the deposition of water and is composed of many smaller rounded rocks cemented together.
A close-up of Link (l) compared with similar rocks seen on Earth (r). Erosion of the outcrop on Mars has resulted in gravel clasts which have fallen onto the ground, creating the gravel pile. The outcrop characteristics are consistent with a sedimentary conglomerate, or a rock that was formed by the deposition of water
On Sol 39, Curiosity imaged a more remarkable outcrop, dubbed Hottah after Hottah Lake in Canada’s Northwest Territories. The exposed bedrock in the images, again captured with the 100mm Mastcam, is made up of smaller fragments cemented together to again form sedimentary conglomerate.
The location of the stream bed lies between the north rim of Gale Crater and the base of “Mount Sharp”, the mound towards the centre of the crater which Curiosity will explore later in the mission. Imaging of the region from orbit shows an alluvial fan of material washed down from the rim, streaked by many apparent channels, sitting uphill of the new finds, further evidence that water was once free-flowing in the region, probably over a reasonably long period of time in Mars’ ancient past. The images of the outcrops themselves show what are referred to as “classic conglomerates”, rocks that are made up of gravels and sand which have been cemented together. The sizes and shapes of stones offer clues to the speed and distance of the ancient stream’s flow.
“From the size of gravels it carried, we can interpret the water was moving about 3 feet [1 metre] per second, with a depth somewhere between ankle and hip deep,” William Deitrich, an MSL science co-investigator said, reviewing the images.
The Hottah outcropping of bedrock – evidence of an ancient stream bed imaged by Curiosity
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Over the course of the last week Curiosity has been busy. Sols 39 through 41 (September 14th through 17th) were driving days in which the rover continued on its traverse towards the area dubbed Glenelg. On Sol 39, Curiosity logged 22 metres (72 feet), and covered a further 37 metres (121 feet) on Sol 40.
Sol 41 saw the rover cover 27 metres (89 feet), during which the Dynamic Albedo of Neutrons (DAN) instrument was incorporated into the rover’s drive sequence. In its active mode, DAN can detect sub-surface minerals associated with water. The instrument has a high sensitivity for finding any hydrogen to a depth of about 50 cm (20 inches) directly beneath the rover. Use of the DAN experiment requires the rover to travel 10 metres (33 feet) before stopping to operate the DAN instrument for 2 minutes, then rolling forward another 10 metres and again operating the DAN instrument, and so on.
On Sol 42, Curiosity travelled a further 32 metres (105 ft), bringing the mission’s total driving distance to about 259 metres (850 ft), reaching the half-way point in the drive to Glenelg. DAN was used at two stops during the drive to check for hydrogen in the soil beneath the rover. During the drive, the rover also paused to take further images of both Phobos and Deimos as they passed in front of the Sun.
Transit of Phobos: had Curiosity been at the top of “Mount Sharp”, this would have been an annular eclipse; Phobos would have been entirely within the disk of the Sun (images from Sol 37 Phobos transit)
Imaging these transits provides accurate data on the orbits of the two moons; although both Phobos and Deimos are very small objects compared with the planet, they still exert a tidal influence on Mars. Having accurate information on their orbits assists scientists in understanding how this tidal influence affects Mars, giving additional clues as to its internal structure. Similarly, the data can also be used in helping to understand the internal structures of the two moons. In addition, measuring the orbits of the two tiny moons helps scientist determine the rate of decay within Phobos’ orbit (Phobos is very gradually slowing down in its orbit and will, at some point in the distant future, break-up and fall onto Mars), and the rate at which Deimos is accelerating in its orbit.
Because so much information can be gathered that can help scientists gain greater insight into Mars and its moons, observing transits by both Phobos and Deimos have previously been a regular activity for NASA’s MER rovers. In fact, Opportunity (as the one remaining operational MER vehicle on Mars) conducted transit observations from its location almost in parallel with Curiosity.
On Sol 43, an unusual rock was identified as a potential target for further tests of the rover’s arm-mounted science instruments – particularly MAHLI, the Mars Hand Lens Imager and APXS, the Alpha Particle X-Ray Spectrometer. During something of an abbreviated day due to the timing of downlink relays on Sol 44, Curiosity took a more detailed look at this rock, as well as observing the early morning atmospheric conditions in Gale Crater and capturing additional images of the instruments mounted on the turret of the robot arm.
A close-in view of the sample acquisition system mounted on the turret at the end of the robot arm
The target rock, roughly the size of a football, was christened Jake Matijevic, in honour of Jacob Matijevic, MSL’s Surface Team Chief Engineer, who passed away shortly after Curiosity arrived on Mars. Matijevic had worked on all three generations of NASA’s Mars rovers, from the tiny Sojourner-class mini-rovers of the 1990s, through the MERs to Curiosity.
Jacob Matijevic, 1947-2012
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Rollin’, rollin’, rollin,
Though the plains are dusty
Keep that rover movin’
NASA. Rocks and wind and cold nights Crossing that ol’ crater On your way to Glenelg now, in style. All things you’re doin’, Sampling, scraping, dating Will help our understanding of Mars.
(With apologies to Ned Washington!)
Over the course of the last several days, NASA has completed initial calibration and characterisation of Curiosity’s robot arm and initial testing of several of the turret-mounted scientific instruments.
These tests have included discovering the arm’s range and accuracy of movement in the low Martian gravity and temperature environs, as well as commissioning the turret-mounted Mars Hand Lens Imager (MAHLI) camera and the Alpha Particle X-Ray Spectrometer (APXS) which is designed to determine the elemental composition of a target rock. Both are now all but cleared for science operations, although some further tests are planned.
On September 11th, Sol 36, the arm went through a series of “reach tests” using MAHLI to ensure that the arm can accurately position equipment over inlet ports on the rover’s body for the transfer of materials gathered from the surface of Mars.
Open wide! The CheMin sample inlet port, imaged by MAHLI on Sol 36. The 3.5cm (1.4 in) diameter mesh-covered funnel will be used to supply Martian “fines” to the CheMin spectrometers for analysis
The Canadian-made APXS has previously been used to gather atmospheric readings, but the tests performed on September 10th, Sol 35, marked its first use on a solid target, using a calibration target mounted on the rover. The results showed APXS to be in excellent health. “The spectrum peaks are so narrow, we’re getting excellent resolution, just as good as we saw in tests on Earth under ideal conditions,” Ralf Gellert, the principal investigator for APXS reported. “The good news is that we can now make high-resolution measurements even at high noon to support quick decisions about whether a sample is worthwhile for further investigations.” This latter point is important, as X-ray detectors best work cold, and so was thought that APXS might find the midday periods of a Martian Sol a little too warm to produce reliable results.
APXS imaged by the 34mm Navcam on Sol 32 (September 7th), during initial visual check-outs of the arm and turret systems. This image confirmed APXS was not caked with dust blown up by the Descent Stage motors during Curiosity’s arrival on Mars.
After its initial check-outs, MAHLI was further tested in its ability to produce 3D images of surface objects, again using the calibration target mounted on the front of the rover. MAHLI is the second imaging system Curiosity carries that is capable of producing colour 3D images, the other being the Mastcam system, which was tested prior to the rover departing Bradbury Landing. Both systems produce 3D images through accurate positioning of the cameras, either by manoeuvring the robot arm (for MAHLI) or the entire rover (for Mastcam).
Transit of Phobos
Earlier this year, I covered the Transit of Venus, an astronomical event only visible from Earth every 105 or 121 years. Mars has similar events, which include transits of the Earth across the face of the Sun and, more particularly, transits of its own small moons, Phobos and Deimos. Transits of Phobos occur twice every Martian year, and on Sol 37 (September 12th), Curiosity’s Mastcam was used to capture images of a Phobos transit. The full-resolution images from this are liable to take a few days to download and be processed, but the plan is to produce a movie of the transit from the images captured.
A raw (unprocessed) low-resolution image of the transit of Phobos – the 11km wide moon, some 6,000km above the surface of the planet can just be seen on the edge of the solar disk
Next Stop: Glenelg – or a rock
With the arm characterisation tests now all but complete, Curiosity was ordered to resume its drive towards Glenelg, an area of Gale Crater some 400 metres from Bradbury Landing. The drive commenced on Sol 38 (September 13th), when the rover completed a drive of 32 metres, a further increment in the daily distance covered as confidence is gained in Curiosity’s autonomous driving capabilities. Even so, it will still be another few weeks before the rover arrives at Glenelg, and the drive may again be interrupted if a suitable rock candidate is identified for direct in situ testing of APXS and MAHLI. If deemed suitable, the rock may also be used to test the rover’s turret-mounted drill, although testing of this may be held-over until Glenelg is reached towards the middle of October.
David Oh from the MSL team provides a superb summary for the week, and insight into working as a part of the Curiosity team.
Not long after I Pressed my last MSL update, Curiosity went ahead and collected its first scoop of Martian sand.
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