Of rocks and water, swans and falcons

CuriosityCuriosity 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.

“On Earth, we have a pretty good idea how mugearites and rocks like them are formed,” said Professor Martin Fisk from Oregon State University. “It starts with magma deep within the Earth that crystallises in the presence of 1-2% water. The crystals settle out of the magma and what doesn’t crystallise is the mugearite magma, which can eventually make its way to the surface as a volcanic eruption.”

In a curious twist, mugearite was first discovered on the Isle of Skye, Scotland, and is named for a local croft, Mugeary. Jake_M was discovered while the rover was en route to a region dubbed “Glenelg”, which is also the name of a village on Skye.

More Autonomy

I’ve recently covered the updates to Curiosity which allow it greater autonomy when driving. However, while at “Waypoint 1”, the mission team were able to try-out an additional mode of autonomous operation for the rover which involves the accurate placement of the science-laden turret on the end of Curiosity’s robot arm.

The turret includes a highly sensitive Alpha Particle X-ray Spectrometer (APXS) instrument. However, ultra-fine placement of the instrument close to targets of study has, until now, been impossible without risking the instrument actually touching the target (possibly damaging the sensor head) or requiring extra days of fine-tuning the instruments position through back-and-forth checking between Earth and Mars.

On Sol 399 (September 20th, 2013), Curiosity deployed its robot arm and effectively used APXS as a radar to assess the instrument’s proximity to target surface. Signals returned from the instrument were analysed by the rover’s on-board computers, allowing it to move the turret closer to the target and place APXS as an optimum distance to initiate science activities.

APXS as radar: a black-and-white image from the rover’s front Hazard Avoidance Camera (Hazcam) capture on Sol 399 (Sept 20th) shows the position of the turret as APXS is used by the rover to autonomously position the instrument ready for use

Capturing a Swan and Giving Wing to a Falcon

Space-related activities closer to home have been in the spotlight of late. On Sunday September 29th, the unmanned Cygnus “space freighter” was finally captured by astronauts using one of the International Space Station’s robot arms, allowing it and its 700 kg of cargo to be docked with the station’s Harmony module.

Cygnus is the second private-venture US space vehicle to be used in ISS resupply missions, the first being SpaceX’s Dragon vehicle, which made its first trip to dock with the space station in June 2012. Unlike Dragon, which is intended to have a crew-carrying capability, and so can be returned to Earth and re-used, Cygnus, built by Orbital Sciences, is intended purely as a cargo vehicle, and so has no reusable capabilities. Once each Cygnus vehicle departs the ISS in about a month, it will be programmed to re-enter the Earth’s atmosphere and burn-up.

Originally the vehicle, launched on Wednesday September 18th from NASA’s Whallops Flight Facility, Virginia, had been scheduled to approach the station for capture on Sunday September 22nd. This was cancelled after a software glitch left the freighter unable to establish the proper communications and navigation links with the ISS. Cygnus was ordered to “park” itself some 2 kilometres from the station while a software patch was prepared, tested and uploaded, and mission managers waited for a scheduled crew arrival mission aboard a Russian Soyuz space vehicle to take place.

Dragon / Falcon (l) and Cygnus / Antares (r) - images courtesy of the BBC
Dragon / Falcon (l) and Cygnus / Antares (r) – images courtesy of the BBC

Also on Sunday September 29th, SpaceX successfully launched an uprated variant of its Falcon 9 rocket which is the workhorse employed in launching their Dragon space vehicle.

The Falcon 9 v1.1 is larger than the original Falcon 9, which has so far only flown with the Dragon space capsule atop it as the primary payload and which does not require a payload fairing, and has more efficient engines. The fairing allows the vehicle to launch a wide range of payloads, allowing SpaceX to further compete in the commercial launch marketplace.

It is hoped the first stage of the Falcon 9 will splash-down in the Pacific Ocean for recovery
It is hoped the first stage of the Falcon 9 will splash-down in the Pacific Ocean for recovery (image: SpaceX)

Following separation, it is hoped that the vehicle’s first stage will make a safe re-entry into the Earth’s atmosphere and splash-down in the Pacific Ocean, where it will be recovered as part of an initial demonstration of SpaceX’s commitment to developing a reusable Falcon 9 launch system. This particular stage will not be refurbished for future use, however.

Congratulations to both Orbital Science and SpaceX.

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All images courtesy of NASA / JPL unless otherwise stated.