Have we heard the last from NASA's Mars Opportunity rover?
Wednesday, February 13, 2019, 10:52 AM - After over 15 years on Mars, NASA's Opportunity rover remains silent after enduring an intense planet-wide dust storm last year. Have we heard our last from this venerable explorer? NASA is set to update us today.
On January 25, 2004, a brand new solar-powered robot geologist began roving around on the surface of the Mars. Mars Exploration Rover Opportunity had just arrived after a six-month journey through space, and it wasted no time in setting off on its 90-day mission to look for signs that the planet was once a much wetter place, which could have hosted life.
A view of Opportunity's shadow against the Martian landscape, taken by the rover's front hazard avoidance camera, looking out between the rover's front wheels, on March 20, 2014. Credit: NASA/JPL-Caltech
Nearly 15 years later, and after many, many mission extensions, this veteran rover appears to have finally given up.
At 2 p.m. ET, on Wednesday February 13, NASA is hosting a briefing from the Jet Propulsion Laboratory, in Pasadena, Calif., to update us all on their attempts to contact Opportunity.
Over the years of its exploration of Mars, Opportunity had racked up some amazing discoveries, but it had also developed problems. Primarily, the aging rover's memory wasn't what it used to be, which required its NASA handlers to come up with some inventive solutions from millions of kilometres away (there's no way to send a repair team to Mars!). Otherwise, though, the robot was still fully operational, with all of its instruments functioning.
So, what happened to cause the rover to fall silent, and apparently be lost?
Two 'selfies' of Opportunity's solar panels. With dust buildup as of January 2014 (left) and after a 'dust clearing event' in March 2014 (right). Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ
Towards the end of May 2018, shortly after spring began in Mars' southern hemisphere, both Opportunity and its cousin, Curiosity, began to notice more and more dust in the air.
According to Jim Green, NASA's Chief Scientist, Martian dust storms typically begin in southern spring, when Mars is near perihelion (its closest distance to the Sun). As the more intense sunlight causes carbon dioxide ice to sublimate from the south-polar ice cap, pulses of the gas spread northward. These waves of carbon dioxide loft dust from the ground up into the air, and while the dust does begin to settle after each waves passes, the next one lofts the dust higher, and draws more dust from the ground as well.
What makes the difference between seeing a localized or planet-wide dust storm, Green added, is exactly how the dust settled from the previous dust storm, and how it may have shifted around based upon surface winds in the time since.
Opportunity had weathered dust storms before. This impacted the rover's ability to recharge its batteries, but it seemed that they could always count on Mars' 'windy season' (which typically happen for a few months after a dust storm) to clear off Opportunity's solar panels.
The storm that kicked up in May of 2018 was different, though.
Watch below to see just how bad Mars' latest global dust storm was.
In the span of just 10 days, the sky over Opportunity became so obscured with dust that it blotted out the Sun.
The views from Opportunity's cameras show the sky filling with dust between May 30 and June 10, 2018. The final frame, on the right, is a simulation based on the rover's data. Credit: NASA/JPL-Caltech/TAMU
The level of 'atmospheric opacity', or how obscured the sky is, which scientists denote as "tau", reached a value of 10.8. That is the highest tau value ever recorded by a mission on Mars!
Since solar-powered Opportunity is dependent on the Sun to charge its batteries, the rover's power levels dropped to their lowest on record, and on June 10, it fell silent.
With the dust keeping the air and surface around Opportunity reasonably warm, the hope of the NASA team was that the rover could endure for the duration of the storm. Then, once they regained contact afterward, they could correct any computer faults it suffered during its down time, and they could continue on with its mission.
Unfortunately, even after the skies cleared in September, Opportunity remained silent.
Repeated attempts have been made to revive the rover since, with over 600 commands sent in the months after the storm abated, but as of February 12, 2019 - the date of NASA's final planned attempt at contact - there has still been no reply from Opportunity.
As of now, the windy season, which started up in November 2018 and lasted through January 2019, has passed. If Opportunity was going to see a dust-clearing event, it was expected during that time.
From here, Mars is getting farther away from the Sun as it approaches aphelion, which reduces the intensity of sunlight that reaches the surface of Mars. Also, autumn is coming for the southern hemisphere in roughly a month, and winter follows starting in October. Even with Opportunity located just south of Mars' equator, these changes mean that temperatures at Opportunity's location are going to drop dramatically in the months to come. Without power to warm itself, it's highly unlikely that the rover's components will survive until spring returns in April of 2020.
So, we are very likely looking at the end of this incredible, overachieving mission. Watch the NASA briefing, starting at 2 p.m. ET, for more.