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

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.

Rosetta and Philae

This mosaic from Rosetta’s OSIRIS camera captures the descent of Philae towards comet 67P/C-G, as seen in the timestamped magnified images. The pair towards the top right, labelled 15:43 and 15:18 show the landing point, the 15:43 clearly showing impact marks in the centre of the landing point area, which were not visible in the image of the same spot capture around 30 minutes before touchdown. The final insert, far right, show Philae rising on it’s first “bounce” off the comet.

From November 12th 2014, ears and ears around the world were on news concerning a tiny science probe as it set out to try to land on a comet over 515,000,000 kilometres from Earth. The Philae lander, a part of the European Space Agency’s Rosetta mission, departed it’s parent space craft on the morning of Friday November 12th, and commenced a slow drift down to the surface of comet 67P/C-G.

As I’ve reported in these pages, the landing didn’t quite go as planned, and Philae eventually entered a state of hibernation very early in the morning of Saturday, November 15th (UK / European time), being unable to charge its solar batteries. But in that time, the lander managed to achieve almost all of its primary mission goals, sending back a wealth of data to Earth via Rosetta.

That data is now being analysed, and has already revealed that on its first touch-down on the comet, Philae’s harpoons and the ice screws in its three landing pads, all designed to quickly anchor it to the surface of the comet, failed to operate as anticipated.

A 3D image of the comet created by overlapping two images captured by Philae's ROLIS camera as it descends toward the surface
A 3D image of the comet created by overlapping two images captured by Philae’s ROLIS camera as it descends toward the surface

Philae’s final resting place, after two bounces across the comet, appears to be dust-covered ice, the thermal probe of the MUPUS science instrument detecting temperatures of around –153°C under the lander.

One aspect of the mission which may not have succeeded, despite initial data returned to Earth, is the drilling operation. While data was received showing the dill had fully deployed, and there was an apparent transfer between the drill sampling mechanism and the on-board science instruments, there is a chance that because the lander wasn’t anchored on the comet, the drill may have actually lifted it, rather than cutting into the ground under it. Further analysis of data from the on-bard science instruments is required before this is known for sure, and members of the mission team are working through images returned from Philae’s ROLIS camera, which may show whether or not the drill cut into the ice and dust under the lander.

A mosaic of four images captured by Rosetta showing 67P/C-G in detail. The white smudging against the backdrop of space is the gas and dust of the comet#s coma as it catches and reflects sunlight
A mosaic of four images captured by Rosetta showing 67P/C-G in detail. The white smudging in the darker areas of the images is the gas and dust of the comet’s coma as it catches and reflects sunlight

Since the landing, Rosetta continues to studies the comet, and has, amidst all the science returns, delivered some stunning images – such as the one shown above.

Orion Readies for Flight

NASA’s next generation crewed launch vehicle, Orion, is fast approaching its first test flight. Exploration Flight Test -1 (EFT-1) will be an uncrewed mission that will see the first flight-ready Orion capsule launched from Kennedy Space Centre’s launch complex 37 on Thursday, December 4th, 2014.

The Orion capsule, hidden under the protective shroud of the Launch Abort System, and with the simulated Service Module  beneath it similarly hidden by cylindrical payload fairings, was mated to its Delta IV launch vehicle earlier in November
The Orion capsule, hidden under the protective shroud of the Launch Abort System, and with the simulated Service Module beneath it similarly hidden by cylindrical payload fairings, was mated to its Delta IV launch vehicle earlier in November

During the 4.5-hour flight, Orion will orbit the Earth twice, rising to a maximum altitude of 5,800km (3,600 miles) – the furthest any space vehicle designed to carry humans has travelled away from the surface of the Earth since the Apollo lunar missions – by comparison, the space station orbits at approximately 420km (260 miles) above the Earth.

This altitude will allow the vehicle to return through the atmosphere at around 80% of the velocity of a return flight from the Moon – one of Orion’s intended future targets – a speed of around 3,2000kp/h (20,000 mph), generating temperatures of some 2,200°C as it does so.

The mission is intended to validate many of Orion’s flight systems, all of which must perform flawlessly to guarantee safe, successful missions in the future when the vehicle will be carrying up to six crew well beyond Earth orbit.  As such, EFT-1 will provide critical data that will enable engineers to improve Orion’s design and reduce risk for the astronauts it will carry on future missions.

At the conclusion of the flight, Orion will splash down in the Pacific Ocean off the coast of California, where it will be recovered for examination.

This initial launch will utilise a Delta IV rocket. However, its second flight – slated for 2017 – will introduce a rocket specifically built to launch Orion missions, called the Space Launch System (SLS). Together Orion and SLS are intended to form the backbone of NASA-led missions around the Moon, to an asteroid, and eventually to Mars in the 2030s.