Friday, November 15, 2013
The past several weeks have been a busy time for the Mars rover Curiosity. Events included stops at two waypoints on the way to Mount Sharp, the longest one-day drive of its journey so far and the discovery of the apparent absence of methane in the Martian atmosphere.
Add to that list an unexpected software reboot on Nov. 7 and you have an exciting few weeks.
Back on July 4, Curiosity left the area near its landing site called Yellowknife Bay and started its 5.3-mile journey to the base of Mount Sharp.
One of Curiosity’s main science goals is to explore the sedimentary layers of this 3-mile-high mountain to gain a better understanding of the geological history of Mars.
A six-month investigation of the Yellowknife Bay area has yielded many insights about its history, and we envision many more insights as Curiosity studies the layers of Mount Sharp. But it is also important to understand how the rocks at Yellowknife Bay relate to those at Mount Sharp.
To aid in this understanding, Curiosity is collecting data along the way. The science team selected five geologic waypoints along the route to Mount Sharp, using images taken by the Mars Reconnaissance Orbiter to select potentially interesting science locations.
The plan is for Curiosity to stop at each waypoint for a day or two to collect data with two of its instruments: the alpha particle X-ray spectrometer, which identifies what chemical elements are present, and the Mars hand lens imager, which takes close-up images that show the texture, shape and color of the surface.
Information collected at the waypoints can be used to stitch together a timeline of the history of Gale Crater. Which layers are older and which are younger? What is the history of water in the crater? Did water flow at the waypoints at the same time it was present at Yellowknife?
In the past few weeks, Curiosity has collected data from the first two waypoints. This data will be used to help answer these questions.
The longest single-day drive so far in the 13-month-old mission occurred on Sept. 5, when Curiosity traveled 464 feet. For the first part of the drive, engineers chose the path, as Curiosity traveled in directed mode.
The rover then went into autonomous mode, where it chooses its own path based on images taken during the day’s drive.
On Oct. 28 Curiosity completed another first — a two-day autonomous drive. It began on Oct. 27 with a normal combined drive, starting with a directed-mode drive of 180 feet and finishing with an autonomous mode drive of 125 feet. But the next day Curiosity continued another 105 feet in autonomous mode with no directed driving.
Curiosity is now about one-third of the way to Mount Sharp. If the rover can use the autonomous mode more often, it will accelerate its progress. Curiosity needed a software update to enable more autonomous driving, so a new version of the onboard software was uploaded during the week of Nov. 4.
This new software includes improvements in the rover’s ability to store information overnight, which is needed for multiple-day autonomous driving.
It also expanded the capabilities for using the robotic arm while parked on slopes, a feature that will be needed to explore Mount Sharp.
An unexpected event occurred on Nov. 7. Curiosity’s onboard computer did an unplanned software reboot and went into safe mode. The reboot occurred about 4½ hours after the new flight software had been uploaded.
Curiosity is designed to perform a warm reboot whenever it has an unanticipated event. From information sent back to Earth, it has been determined that a software error caused the reboot, so updates have been sent to repair the problem.
Curiosity now appears to be operating normally and has returned to normal engineering operations, with science operations resuming this week. Curiosity should be back on the road to Mount Sharp by this weekend.
Another significant event during this same period was the release of results from the analysis of the Mars atmosphere. When six samples by Curiosity taken between October 2012 and June 2013 were analyzed, there was no detectable trace of methane.
Methane is a byproduct of many of the biological processes of life, so finding it in the atmosphere would have been a potential sign of life on Mars.Methane would persist in the atmosphere for hundreds of years, so the lack of it reduces the likelihood that there was any form of life on Mars in the recent past.
Not a bad few weeks’ work for our robot on Mars!
Marty Scott is the astronomy instructor at Walla Walla University, and also builds telescopes and. He can be reached at firstname.lastname@example.org.