Photograph courtesy Paul E. Alers, NASA

Read Caption

John Grotzinger, Curiosity's chief scientist, with a model of the Curiosity rover.

Photograph courtesy Paul E. Alers, NASA

One Year on Mars: A Chat With Curiosity's Chief Scientist

Looking for organics and planning the next landing site are on the agenda.

One year ago today, a one-ton, SUV-sized rover named Curiosity touched down on Mars after a daring landing maneuver that involved deploying a parachute at supersonic speeds and using a rocket-powered "sky crane" for the final soft touchdown. (Read: "Mars Curiosity Milestones: Top 5 First-Year Discoveries.")

Viewers around the world tuned in to witness Curiosity's "seven minutes of terror" and then cheered along with NASA scientists and engineers in mission control when news finally arrived that the landing was successful.

We caught up with Curiosity's chief scientist John Grotzinger during an anniversary celebration event at NASA's Jet Propulsion Laboratory in California on Monday to ask him what the past year has been like, what still lies ahead for Curiosity's scientific mission, and how the rover is helping lay the groundwork for a manned mission to Mars. (Related: "Curiosity Finds Evidence for a Habitable Ancient Mars.")

What has been the most exciting part of the mission for you so far?

The landing and the launch—those were all thrills. There was one very special opportunity, though. The night before launch, I stumbled my way onto Kennedy [Space Center] and found my way to the base of the launch vehicle. And then I ran into a photographer who had a pass for a guest, and I wound up standing literally toe-to-toe with the rocket. That was amazing.

In our culture, it's commonplace to see a rocket launching, but when you're next to one it's awe inspiring. And when you know it's carrying the payload that you've helped to develop, that makes it extraordinary. (Watch video of the Mars rover Curiosity.)

What questions about the red planet was Curiosity designed to help answer that are still outstanding?

We have an instrument that's able to detect complex organic molecules, and we've had a couple of sniffs that suggest there might be organics [on Mars]. But we haven't been able to confirm it, so we're looking for a stronger signal.

What we're hoping is we might eventually find an environment that's not only habitable but also has the right chemistry to preserve the organics that we think should be there. And the reason we think they're there is organics are always arriving from outer space onto every planetary surface. We would think that there's some chance to preserve them [on Mars]. (Related: "Meet One of Mars Rover Curiosity's Earthbound Twins.")

In the 1970s, some tantalizing results from experiments performed by NASA's Viking lander missions suggested there might be microbes in the Martian soil that were producing carbon dioxide or methane, but those results were later dismissed. Has Curiosity been able to help settle the debate about whether the Viking landers did or did not find evidence of life?

So far we haven't seen anything. We keep making measurements, and we've seen no methane down to the parts-per-billion level.

How is the Curiosity mission informing NASA's plans for a 2020 rover mission, which is expected to include sample returns of Martian rocks to Earth?

There will be a competition to select the final landing site [for the 2020 rover], and Curiosity's results will surely feed into that by helping us as a community understand better how Mars works. (See: "Mars Gets Its Close-Up.")

You've talked before about how Curiosity is helping lay the groundwork for a manned mission to Mars by measuring radiation on the surface of the red planet. Can you elaborate?

Of course, everybody knows that radiation is not a good thing and can cause cancer. And all astronauts have what are called career limits in terms of what they're exposed to. What Curiosity does is it can actually measure directly the radiation on Mars that astronauts would receive if they were on the planet.

One of the big questions is ... how does the atmosphere interact with the radiation and cause it to be dissipated? We know it'll be dissipated by some amount but not as much as on Earth. We can make these measurements on a regular basis and just see how much radiation an astronaut would experience over that time.

That's never been done before?

Nope. This is the first time ever. We turned on an instrument on Curiosity [called RAD] ten days after we launched so we could measure the radiation dose that an astronaut would get on the flight to Mars while protected by a spacecraft.

And then once we landed, the instrument sits on the deck of the rover, so it's unshielded and you can measure directly what the impact is of the atmosphere on controlling radiation.

Follow Ker Than on Twitter.