The following editorial appeared in the Chicago Tribune on Thursday, Oct. 3:

In 1996, scientists thrillingly theorized that a potato-size meteorite from Mars, discovered in Antarctica, could contain evidence that life had once existed on the red planet. Life on Mars!

That pronouncement provoked a burst of exuberance at NASA and … a volley of skepticism from outside scientists.

One way to approach the question: Send a probe to Mars and sniff around for methane and other elements that could indicate life could still exist there or had once existed.

Enter Curiosity, the Mars probe that nailed its landing on the planet’s surface in August 2012.

Since then, Curiosity, the most advanced machine ever dispatched to another planet, has been trundling across the Martian surface with its laser, drill and soil scooper, carefully seeking signs to answer a key question: Did Mars ever have an environment that could support life as we understand it? The rover did find traces of water in soil that it spent weeks analyzing. And it turned up a volcanic rock that suggests Mars is a lot more geologically similar to Earth than previously thought.

But on the tantalizing question of life on Mars right now, we’re sorry to say that Curiosity has come up empty on the methane hunt. So far, the red planet is more like the dead planet. There are no strong signs that microscopic life, or any other kind, thrives on Mars.

Disappointing? Sure.

But Curiosity’s chief scientist, John Grotzinger, tells us the rover’s mission has been a success. “We’re excited that all of our science instruments worked,” he said. “All things being equal, sure it would be nice to find lots of methane on Mars. But that’s what you get.”

The rover’s failure to find evidence of methane doesn’t mean that life never existed on Mars. Many scientists believe Mars went through a wet and warm period in its early years, about 3.5 billion years ago, and that some forms of life could have existed. In March, an analysis of a rock sample drilled by Curiosity near an ancient stream bed prompted scientists to declare that Mars could have supported microbes in the ancient past.

OK, OK, we’re a long way from the sentient (and menacing) Martians in “War of the Worlds” here. But we say, let’s keep looking. Let’s not lose sight of the amazing fact that there is a rover … on Mars … telling us new stuff about the planet, dismantling old theories, launching new ones. Dreams of life on Mars, tamped down for now, still smolder in our sci-fi-stoked imaginations.

How else to explain the hundreds of thousands of people from around the world who have applied, via a nonprofit organization called Mars One, to colonize the red planet starting in 2023? Yes, hundreds of thousands. You can check out their reasons on the mission website, mars-one.com. Ultimately, four astronauts will be chosen to be among the first group of pioneers, according to the website. Warning: It’s a one-way trip. You get there. You stay there.

We’d advise potential adventurers not to sell their worldly possessions just yet. There’s the technological hurdle of ferrying people on the 154-million-mile journey safely. And shelter will be a challenge: Temperatures on Mars rarely rise above freezing; at night, you’ll shiver in minus-100 Celsius. No wonder that among the characteristics that Mars One seeks in prospective settlers are these: “You are at your best when things are worst … You have a ‘can do!’ attitude.”

Curiosity has kindled a new Mars fever. The exploration is far from over. Maybe there’s no life on Mars now. But one day, we imagine there will be. Human life.