The conference featured Jim Green, director, Planetary Science Division, NASA Headquarters, Washington, John Grotzinger, Curiosity project scientist, California Institute of Technology, Pasadena and Kathryn Stack, Curiosity Rover mission scientist, NASA’s Jet Propulsion Laboratory, Pasadena. California, and marked the first direct conference on the mission hosted by JPL since the start of the year.
The focal point for the briefing was to announce that just over two years since its arrival on Mars, having covered a distance of some 6 kilometres and having already fulfilled its primary mission objective – to locate a region on Mars which shows both chemical and geological indications that it may once have been amenable to development and support of microbial life – the rover had, again in geological terms, arrived at its primary exploratory target: Aeolis Mons, which NASA refers to as “Mount Sharp”.
Curiosity still has around two kilometres left to drive before it can be said to be actually “on” or climbing Mount Sharp, but the changes in geology and terrain which it is now encountering are sufficiently clear for the science team to state the rover is effectively traversing the “boundary” between the floor of Gale Crater and the slopes of Aeolis Mons itself.
Originally, it had been intended to drive the rover further south from its current location near an uprising dubbed the “Pahrump Hills” – originally seen as a potential target site for further sample drilling – to a series of low buttes named after the late co-founder of The Planetary Society, Bruce Murray. From orbit, this had been seen as the best route by which the rover could skirt an extended line of sand dunes lying between it and “Mount Sharp” and commence a climb up onto the lower slopes.
However, further examination of the terrain adjacent to the Pahrump Hills / Zabriskie Plateau has revealed it to be softer than the terrain than the rover has been crossing, and potentially more suited to driving onto the slopes of the mound. Dubbed the “Murray Formation”, this terrain also forms a visible boundary between the Mount Rainer-sized mound of “Mount Sharp” and the crater floor sediments, and so offers the potential for further science discoveries. Thus, from a driving characteristics point of view and a science perspective, it offers a shorter, more interesting route onto the mountain proper.
As well as being geologically different to the sediments of the crater floor, the Murray Formation is topographically different as well, which is driving a lot of interest in the science team in terms of what it might indicate about the way in which “Mount Sharp” was formed. The floor of Gale Crater – more correctly known as Aeolis Palus – bear the marks of considerable cratering which can be seen from orbit. However, the layers of the Murray Formation – essentially a scarp between the crater floor and Aeolis Mons – have almost no visible cratering at all.
During the course of the next few weeks, the rover will pass over / around Pahrump Hills, hopefully gathering a suitable rock sample using the “compressed drilling” routine,. Then it will turn more sharply southwards than originally planned, travelling directly onto the Murray Formation, rather than continuing in a more south-westerly direction to Murray Buttes before turning onto the slopes of the formation. The rover will still study the area of the Murray Buttes, but will now do so at their eastern extremes, allowing the science team to also investigate some nearby sand dunes.
While “Bonanza King” proved to be unsuitable for drilling for an actual sample for analysis, it did provide sufficient data to help the team in determining a revised science programme, and in their decision to traverse the Murray Formation and onto “Mount Sharp” proper sooner rather than later. This is because spectral analysis for the rock revealed it to have very high silica content (the only location on Mars so far studied with similar levels of silica is half a world way and was studied by the Spirit MER), which stands a marked contrast to rock samples so far gathered by the rover.
This is a significant find, as it means that the rover is entering an environment which has a very different geological history to that of the crater’s plains – and one in which it is possible that water has played a very significant role, one which many have led to the development of an environment rich in chemicals and minerals which may have been conducive to live forming, as was the case at “Yellowknife Bay”. The difference being, while the environment at “Yellowknife Bay” was likely no more than a few metres thick, the Murray Formation is liable to be up to 200 metres thick, representing an evolutionary period of several million years, rather than the few tens of thousands, offering a far greater time period in which life might have been able to form.
The “Murray Buttes” region remains a target for exploration because, rather than being elements of the transitional rocks of Murray Formation which have been eroded into their current form over the eons, they are believed to be elements of the crater floor rising up through the softer layers of the Murray Formation, thus they present an environment where the geology from the crater floor can be studied directly alongside the geology of “Mount Sharp”.
The transitional region of the Formation is also of interest because while it appears somewhat uniform from orbit, with few visible indications sedimentary layering, it does exhibit some very bright banding. It’s currently not clear if these bands in fact relate to different sedimentary layers within the formation, or whether they were formed as a part of the overall formation of the mound, or whether they have been created by some other process subsequent to the formation of “Mount Sharp”. Thus there are some significant questions surrounding the bands and how they might or might not contribute to the potential of the region having perhaps once been a suitable habitat for microbial life.
Sitting above the Murray Formation is the Hematite Ridge. This is again of interest to scientists because it does show significant layering when imaged from orbit, which suggests very different processes may have been involved in its creation when compared to the Murray Formation below it, and the slopes of Mount Sharp above it. So scientists are again keen to find out more about it.
All of this means that Curiosity is now entering an entirely new phase of its mission, one which potentially offers entirely new and quite exciting opportunities for scientific discovery, including the potential to find further environments which may have once not only have been benign to the support for microbial life but which, like “Yellowknife Bay”, have all the essential requirements needed for microbial life to have arisen – the right chemical combinations and compounds, a suitable energy source, a suitable environment in which these could mix, and so on.
The immediate target for Curiosity over the course of the next week or so is to move more directly onto the transitional terrain marked by “Pahrump Hills”, where rock sampling may still take place, and then onto what might be termed “Murray Formation proper”. This will then see further analysis of the environment take place from ground level, which will be combined with images of the region obtained from the Mars Reconnaissance Orbiter (MRO), to further refine the revised route up and across the Murray Formation, and in the identification of potential science targets.
A further mission goal for Curiosity going forward, particularly as a result of the Mars 2020 mission being confirmed, and which will look for direct evidence of microbial having existed on Mars (rather than seeking signs of environments which may have been conducive to life perhaps having arisen, as with the MSL), is to write what might be referred to as a the rubric by which future robotic missions can define and refine their own mission objectives based upon their own mission requirements and on their own findings during their operations on Mars.
Thus, the coming months will see less in the way of relentless driving of the kind we’ve seen through most of 2014, and more a return of to the kind of activities (and possible reporting) seen during the early investigations of “Glenelg” and “Yellowknife Bay”.
Orion Readies for Maiden Flight
NASA’s new generation crewed space vehicle, the Orion Multi-purpose Crew Vehicle (MPCV) passed its own mile stone also on September 11th. Mated to its service module, contained within the cylindrical mating adapter that will connect the vehicle to its Delta IV launch vehicle, the first Orion unit scheduled to fly into space was moved out of the Neil Armstrong Operations and Checkout Building at NASA’s Kennedy Space Centre in Florida, and driven to the Payload Hazardous Servicing Facility, a new NASA installation where the vehicle will undergo fuelling with ammonia and hyper-propellants ready for its flight test. When this has been done, the Launch Abort System will be fitted to the vehicle, at which point it will be ready to be connected to its launch rocket.
The first flight of Orion will be uncrewed, and is set for December 4th, 2014. Designated Exploration Flight Test-1, the mission will last some 4.5 hours and will see the vehicle push itself to an orbit of some 5,800 km (3200 miles) before circling the Earth twice and then making a re-entry for splashdown. At the time of re-entry, the vehicle will be travelling at around 32,000 kph (20,000 mph), which is close to that of a vehicle returning from either a lunar mission or a mission to Mars. As the Orion system is intended for deep space missions, the re-entry test at the end of the flight is seen as a critical element in preparing the system for future activities.
Assuming all goes as planned, the second flight of Orion will take place in 2017/18. This will involve the European-build Service Module, and see another uncrewed system launched by the Space Launch System (SLS) specifically developed for Orion fly around the Moon and back.
Following that, in 2022, the first crewed mission is scheduled to take place, which is currently planned to rendezvous with a near-Earth asteroid.
All images and video courtesy of NASA KSC and NASA / JPL