He says that one of the greatest legacies of the two rovers is how they’ve made Mars familiar.
“It’s no longer this strange distant alien world. My team goes to work on Mars every day. That’s one of the greatest intangibles these rovers have given us. Our universe is larger now.”
When the twin rovers were launched, they were designed to last 90 days. And that was just over six years ago.
Callas calls the extra time on the planet and the accompanying data a bonus.
“We do recognize that they are older. They are a bit more frail and a little bit more arthritic, but they are still tremendously capable resources,” Callas says, “and they’re on the surface of another world. Right now it is the only presence on the surface of another world anywhere in the solar system. So as long as they have capability, we can explore. The great thing about a rover, you’re not stuck in the same location looking at the same real estate or the same rock.”
Each day, the rovers take images and send them back to NASA and Callas’ team to be studied.
“We get about 100 images a day from each rover and that translates only out to about 100 megabits of data, so stuff that would easily fit within your cell phone or your thumb drive, so it’s not a huge amount of data, but the fact that it’s from this exotic location is what makes each one of those little bits count so much.”
During each Mars winter, the rovers enter a hibernation period in order to store energy.
Before the past Mars winter (the rovers’ fourth on the planet) Spirit became what Callas called “embedded”.
“We weren’t able to reposition (Spirit) favorably for the deep dark days of winter so it didn’t generate enough energy each day during the depths of the winter to power all it’s systems so it powered down into a hibernation state. It’s not talking to us, so we haven’t heard from the rover in many, many weeks.”
Callas says they hope to hear from Spirit sometime in the fall, but he knows the extreme cold temperatures could affect the rover.
“(Spirit) is going to get colder than it’s ever been before on Mars because it’s shut down. We’re talking about temperatures colder than Antarctica, without any heaters being on. So think of leaving your laptop out at night in the winter time in Antarctica and expecting it to work the next day.”
The rovers are located on opposite sides of the planet from one another. So while Callas’ team waits for Spirit to respond again, Opportunity is busy heading towards Endeavor Crater.
“We want to get (to Endeavor Crater) because it’s scientifically exciting. There are these plain minerals that are found around this crater that we see from orbit that formed a long time ago in neutral pH water. This is very exciting because we found evidence of acidic water on Mars, but not neutral water. This is exciting to the astrobiologist because if you’re looking for life, you’re expecting life to have formed in a neutral pH environment.”
When launched, each rover was designed to travel approximately one kilometer. Opportunity has already traveled close to 22 kilometers in the past six years. While there is still about 10-12 kilometers before Opportunity reaches Endeavor Crater, Callas is optimistic about the information they can obtain from the area.
Callas is also very excited about what lies ahead for both the rovers and for his team at NASA.
“Even as old as these two rovers are, there is still an exciting future ahead for each one. Opportunity is headed toward Endeavor Crater. For Spirit, once we recover from the winter, we’re going to use that rover as a way to investigate the interior of the planet by tracking it’s radio signal.”
“Because the rovers will be stationary, or near stationary, by tracking its radio signal, we actually measure the motion of the planet Mars. And measuring that motion, we can look for the subtle wobble in the spin of the planet which tells us about not only the distribution of mass inside the planet, like the size of the core, but whether the core is liquid or solid. So both rovers will be very busy for as long as we can make them busy on the surface.”
For information on NASA’s Mars Rover Project, click here.