Following our mechanical pets to the planets

In January 2004, I had the privilege of being at mission control at NASA's Jet Propulsion Laboratory in Pasadena, California for the landing of the Opportunity rover on Mars.

We were told the rover would run for three months. If anyone back then had predicted it would last a decade and a half, they would have been laughed out of the room. To our surprise and delight, it did exactly that.

Opportunity was one of a twin pair of rovers — Spirit was its companion — that landed on different parts of Mars just a day apart. The rovers are quite large, about the size of an office desk. Curiosity, which landed in 2012, is even larger, about the size of a subcompact car and is still driving on Mars. In the picture below, my hand is resting on the stereo camera mast, which is about at eye level, so the images we get from Mars are what a person would see standing there.

These driverless cars we send to Mars are treated like pets by the people who build and operate them on their alien worlds. Each rover is meticulously built and assembled by hand. Every part is precision made, tested rigorously for durability, then carefully packed into the nose cone of a rocket and sent off into a very hostile environment.

Sending the intrepid robotic explorer to Mars

Once the rocket blasts off, the robots are entirely on their own for the journey. They must survive the stresses of launch, seven months in the cold vacuum of space and a fiery "seven minutes of hell" landing, so just getting there is reason to celebrate. And celebrate we did when the signal came down that Opportunity was safely on the ground.

Only minutes after touchdown, the first images showed up on the monitors, and the "wow" factor kicked in as we gazed upon a scene never before seen by human eyes. The geologists were excited by the sight of exposed bedrock right beside the lander, and off in the distance, rolling red hills under a pink Martian sky.

During the press conference after the landing, we were shown an image of the landing area that had been taken by another robot looking down from orbit. I asked, "How much of this image will the rover cover during its mission?" A scientist answered with a slight smirk, "Oh, not very far, probably less than a kilometre."

To be fair, that was all the mission called for. They figured that the ubiquitous Martian dust, which is always blowing around and gives the sky its salmon colour, would coat the solar panels after 90 days so they would no longer be able to charge the batteries. Little did they know that those same winds would occasionally blow the dust away and breathe new life into the rover for years to come.

Keeping in touch with "Oppy" to direct exploration

The distance between Mars and Earth is so great it can take up to 20 minutes for a radio signal from Earth to get there, and an equal amount of time for a signal from the rover to return. So the robots cannot be driven in real time like radio controlled toy cars. Instead, they are given instructions when they wake up each morning, carry out those instructions throughout the day, and report back the results before going to sleep at night.

That means they have to be smart enough to say, drive over to a particular rock a few metres off to the right and take a close-up picture without running into anything along the way, or to drill into that rock and see what is inside.

In the same way that a dog knows how to chase a stick thrown by the owner, rovers on Mars know how to navigate around on their own following instructions from their owners on Earth. And that is why the scientists and engineers become attached to these mechanical pets as they continue to perform way beyond expectations. And in the case of Opportunity, or "Oppy" as it is affectionately known, it was a journey of more than 40 kilometres, up over the distant hills, down into large craters, and across vast plains.

Our eyes in places where we cannot go

Along the way, it provided magnificent panoramas and conducted geological work proving that once, billions of years ago, Mars was a blue planet like the Earth, with lakes, rivers and possibly even an ocean. It's quite an accomplishment, considering almost all of it was done well past warranty.

Our robotic emissaries have now been to every planet in the solar system, as well as a few asteroids and comets. They are the true explorers, literally going where no one has gone before, and in some cases, where humans will never go, such as into the poisonous clouds of Jupiter.

For Mars, they are mapping the lay of the land for humans that may follow. But beyond that, they are providing insights into our own planet. Opportunity showed how Mars was once warm and wet like the Earth, but then it entered an ice age and never recovered — talk about climate change! The Earth has entered several ice ages in the past, but our climate has managed to come back from the cold. In fact, lately we've been warming up a little faster than we should.

Understanding how other planets can change over time is looking at the Earth in its full environmental context, as only one member of a family of planets orbiting the sun.

Saying goodbye to a trusty robot is always a sad day, because they don't come back. Opportunity was hit by a global dust storm so dense those solar panels were finally covered to the point where they were unable to charge the batteries. Now that the instruments have gone quiet, Oppy, will rest silently alone, frozen in the cold Martian desert.

Unless, of course, a Martian explorer in the future finds Opportunity and brushes off those solar panels…