Robotic explorers lasting well past their warranty

After decades in space, three intrepid robot explorers seem to have finally reached the end of their lives after living well beyond their original goals. Of course, this is no accident, because scientists plan their missions that way.

The Mars rover Opportunity has been driving around on the red planet for nearly 15 years on a mission planned to last 90 days. The planet hunting Kepler Space Telescope, a four-year mission launched in 2009, was extended to nine years thanks to clever planning, and the Dawn mission to both an asteroid and a dwarf planet lasted 11 years after its mission was extended a couple of times.

If only our cars would run so well beyond warranty

Exploring deep space is expensive, especially with dwindling budgets, so scientists often only ask for funding for short-duration missions. Time is money after all. Most of the science happens at the beginning anyway, when a robot first lands on a planet or passes by another world. But the robots have to be made tough to survive the harsh environment of space, which means they are usually capable of doing much more than the originally stated goal. And the scientists do plan for much more, they just keep quiet about it until the mission is underway.

In the case of the twin rovers Opportunity and Spirit, which landed on Mars in 2004, their primary 90-day mission was accomplished with ease, after which the scientists said the spacecraft are still running perfectly, so could they keep them going? That secured them the extra funding to continue, which ended up going far beyond anyone's expectations. Spirit lasted until 2010 and Opportunity fell silent last June when a dust storm swept over the entire planet and scientists have been unable to make contact with it since. 

In both cases, the rovers did not die because of mechanical problems. Spirit got stuck in soft sand and Opportunity's solar panels are so covered in dust, they can't absorb enough sunlight to keep the batteries charged. If someone could go up there and push Spirit out of the sand then use a broom to sweep Opportunity off, the rovers could probably keep going.  In fact NASA engineers will keep listening for Opportunity until January, just in case winds clear the dust off the little over's solar panels, and it comes back to life.  But Opportunity may well be lost.

It's a huge challenge to fix things that go wrong on a machine that is millions of kilometres away. And if it can't be fixed, the scientists find ways to work around the problem.

Of course it is always a bittersweet moment when they come to the end of their lives, falling silent on an alien world or drifting endlessly through space, but when they do, it is always with an enormous sense of pride that so much has been accomplished with so little.- Bob McDonald, Quirks & Quarks

The ground-breaking Kepler telescope, which has discovered more than 2,500 planets orbiting other stars in our galaxy, ran into problems with its gyroscopes that keep it pointed in space. Normally, that would be game over, but the scientists figured out a way to use the feeble pressure of sunlight to keep the telescope aimed in one direction in space, which they'd rotate between different areas every 80 days, by using the body of the spacecraft like a solar sail to keep it steady. That trick enabled the instrument to continue searching the skies for another five years until it rain out of fuel.

Record-holding spacecraft explorers

The absolute record-holders for extended warranty missions are the twin Voyagers, which left Earth in 1977 with the goal of passing by the giant planets Jupiter and Saturn. Voyager 2 ended up continuing on to Uranus and Neptune. And now both of spacecraft are leaving the solar system entirely, still sending back information about interstellar space more than 40 years later.

Robotic explorers truly go where no one has gone before. They are our artificial senses that open our eyes to worlds humans have never seen before. The scientists who nurse them along for decades, overcoming broken gyros, computers that crash, or jammed wheels, treat them as pets that have been sent very, very far away from home to sniff out new environments. But most of them are on one way trips, never to return home. Of course it is always a bittersweet moment when they come to the end of their lives, falling silent on an alien world or drifting endlessly through space, but when they do, it is always with an enormous sense of pride that so much has been accomplished with so little.