Curiosity spent the Christmas and New Year period parked in at “Grandma’s House”, a point of geological interest within the “Yellowknife Bay” area of Gale Crater. With most of the mission team on Earth taking a break over the holiday period, the rover was left largely to its own devices for an 11-day period. This was not only to accommodate the holidays – which saw some NASA / JPL personnel available to step-in should problems be reported – but also to test the rover’s capabilities for upcoming times when it will be completely out-of-communication with Earth.
The times occur during what is known as periods of solar conjunction, which place Earth and Mars on opposite sides of the Sun. During these periods, which can last some two weeks, communications between Earth and vehicles operating on and around Mars are severely disrupted / curtailed due to interference from the Sun.
As a result, vehicles like Curiosity need to have sufficient instructions stored onboard so that they can continue to operate when it is impossible to upload commands on a daily basis, and to ensure their safety systems / processes are properly primed should anything untoward happen and the vehicle is forced to “safe” itself. The Christmas / New Year break was an ideal time for NASA / JPL to test Curiosity’s ability to operate in an effectively autonomous mode in preparation for the first such conjunction, which will occur in April 2013.
In all, two days were spent uploading 11 days’ worth of instructions and mission activities to the rover. These included instructions for Curiosity to record panoramic images of its surroundings and also images of potential targets of interest for the next phase of the mission. With “full” mission operations resuming on the 3rd January, 2013, mission project manager Richard Cook of JPL said of Curiosity’s first extended period of autonomous operation, “We had no surprises over the holidays,” before turning attention to the next immediate step in the mission: to commission the rover’s onboard drill.
“Yellowknife Bay” has been selected for the first test of the rover’s drill because it comprises terrain which is substantially different to that traversed by Curiosity during its 4-month journey to the region. Examination of soil samples gathered while en route to “Glenelg” and “Yellowknife Bay” have provided considerable insight into the processes that drive the dry and cold environment that dominates Mars today. However, “Yellowknife Bay”, a depression of broken terrain and what appears to be the remains of a stream bed, is much older, and thus could provide a glimpse of the process which held sway in ancient times, when water may have been one of the defining factors in Mars’ history.
“The place where Curiosity is right now is a small stack of layers – very impressive – and they could be 3-3.5 billion years old,” the mission’s Principal Investigator, John Grotzinger said, speaking to the BBC’s Science in Action programme. “We’re very excited about this because unlike the soil which we were analysing before the holiday season – a loose, windswept patch of dirt on the surface of Mars – we’re now going to start digging down into the very ancient bedrock which we really built the rover to look at.”
Mission personnel have most recently been examining what appears to be an ancient stream / river bed the rover had to traverse before Christmas in order to reach “Grandma’s House”, and which Curiosity imaged on December 20th (Sol 133).
Dubbed “Snake River”, the area is one possible target for drilling, although there are others the rover will be examining prior to a final target being selected. “Snake River” is of interest, as it It has a crosscutting relationship to the surrounding rock and appears to have formed after the deposition of the layer that it transects.
The first operation taken on resuming full mission operations at the start of 2013 (Sol 147, January 3rd, 2013) was to have the rover complete a 3-metre (10 ft) drive to allow it to get a much closer look at “Snake River”. The manoeuvre, which marked the first of which is going to be a major year of driving for the rover, brought the total distance travelled by Curiosity on the surface of Mars to 702 metres (2,303 ft).
Speaking to the BBC, Grotzinger stated, “We’re down at the very lowest layer – what would be the oldest layer that we would see in this succession that might be five to eight metres thick, and that is very likely where we are going to choose our first drilling target, because suddenly we’ve come into an area that represents a very high diversity of things we haven’t seen before.”
He went on, “We use these layers as a sort of recording device of past events and conditions, and the rover has the same kind of analytical capability that we would use here on Earth to tell us about the early environmental conditions; and, if life had ever evolved, [whether it would] be the kind of environment that would have been conducive towards sustaining that life.”
The percussive drill mounted on the turret at the end of Curiosity’s robot arm is the last major piece of equipment on the rover to be commissioned. Mission managers have held-off on deploying the drill sooner in a desire to ensure it is used on targets of clear scientific interest due to concerns about the drill’s operational lifespan. A fault in the drill’s design means that with repeated use, vibrations created by the percussive action will eventually cause a bond in the mechanism to break, shorting out the drill. While it is felt there is little risk of this happening in the two years of the rover’s primary mission, that the bond will break in time is viewed as a certainty, and there is obviously a desire to keep the drill functioning for as long as possible as the mission is extended into the future.
Currently, and subject to final target selection, it is expected that the drill will be deployed for use very soon – possibly during week 2, 2013.
It is not clear how long Curiosity will remain in the “Yellowknife Bay” / “Glenelg” region; much depends on what is found when analysing samples obtained from inside one or more rocks by the drill. However, the mound towards the centre of the crater NASA have dubbed “Mount Sharp” (more correctly, Aeolis Mons) remains the rover’s eventual target, one which will take Curiosity most of 2013 to reach in order to start detailed scientific investigations.
As a part of NASA’s public outreach, a New Year’s message “from” Curiosity was displayed in New York’s Times Square on New Year’s Eve, 2012.
All images courtesy NASA / JIPL / Malin Space Science Systems