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.
“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.
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.
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.