NASA’s Curiosity Mars rover experienced a technical glitch in its stored memory last week, causing it to temporarily lose its sense of direction and freeze in its tracks. But the talented rover repair team back on Earth enabled a fix, and Curiosity is now back in action.
“Partway through its last set of activities, Curiosity lost its orientation,” Dawn Sumner, a planetary geologist at UC Davis and Curiosity science team member, wrote in a blog post update on January 20. “Some knowledge of its attitude was not quite right, so it couldn’t make the essential safety evaluation.”
Specialized fault protection software runs throughout the rover’s
modules and instruments (somewhat similar to the ground fault circuit
interrupter in your bathroom), and when a problem occurs, the rover stops and
sends data called ‘event records’ to Earth. When this happens, Curiosity is
programmed not to move or perform any scientific experiments until it hears
back from Earth.
The event records include images taken of its surroundings that provided details about the nature of the terrain and clues where the rover was. Other information allowed the team to determine what happened so they could develop a recovery plan.
“The engineers on the team built a plan to inform Curiosity of its attitude and to confirm what happened,” Sumner said in the blog post. In a subsequent post on January 21, MSL team member Scott Guzewich from NASA’s Goddard Space Flight Center wrote that the plan enacted to ensure Curiosity had enough knowledge of its orientation to proceed with arm activities and mobility was successful. Curiosity is now back to its regularly scheduled science activities.
In an email to Universe Today, Sumner she said she was not sure what caused the fault, and that the team at JPL are still analyzing the data, as well as working to prevent a similar problem in the future.
Since the engineering team can’t go to Mars and repair a problem, everything is fixed either by sending software updates to the rover or by changing operational procedures. Over the years since Curiosity landed on Mars in August of 2012, the rover team has upgraded the rover’s software with much more efficiency, fault protections, and system robustness.
Detailed in Emily Lakdawalla’s excellent book, “The Design and Engineering of Curiosity: How the Mars Rover Performs Its Job,” Curiosity has two redundant sets of avionics controlling all of its functions, referred to as the A-side and B-side. Two redundant rover power analog modules (RPAMs) function like the rover’s cerebellum, controlling all of its essential life support functions: power distribution, system fault protection, and wakeups/shutdowns.
This recent event is not the first time the rover team has had to work through memory problems. As early as the rover’s 200th day on Mars, a rover had a problem with its flash memory on the A-side, and the rover couldn’t properly shut down for the day. In order not to deplete the batteries, the rover team worked around the problem by instructing the A-side computer not to use half of its flash memory.
“The software was updated to handle these conditions more
gracefully,” Lakdawalla wrote. “The rover has used the B-side rover compute
element as its primary computer ever since. Engineers patched the flight
software to return the A-side computer to service as a reliable backup after
During the seven-and-a-half-year mission, Curiosity has
overcome other issues such as a short in the electronics for its drill,
problems with the wheels and other memory problems.
“It’s really impressive how well the team can diagnose and
recover from glitches in rover operations on another planet,” Sumner told
Universe Today. “I have immense respect for our engineering team. In
particular, they have really effective processes for working together to
identify the best path forward when faced with something unknown.”
Sumner added that when she has sat through the engineering
team’s discussions, she has been fascinated by how they share data, create
hypotheses, challenge each other’s assumptions, and focus on solving the
problem, identifying the uncertainties, and deciding what action to take.
The ingenuity of the team and the resilience of the rover has allowed the mission to be so successful for so long, allowing the rover to be the eyes and hands for an international team of about 500 earthbound scientists. Their goal is to figure out how Mars evolved over billions of years and determine if it once was — or even now is — capable of supporting microbial life.
Curiosity is currently climbing a 3.4 mile (5.5 km) -high Mars mountain scientists call Mt. Sharp (formally known as Aeolis Mons) that sits in the middle of Gale Crater, a 96-mile (155-km) diameter impact basin.
Follow more mission updates at NASA’s Curiosity mission update site.
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