Mars 101: What we know of our celestial neighbor

This artist's animation of the NASA Mars Reconnaissance Orbiter.
This artist's animation of the NASA Mars Reconnaissance Orbiter.

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KPCC reporters have been talking to Southland scientists and engineers and counting down the days until NASA's most ambitious rover yet — Curiosity — prepares to land on the Martian surface. Follow the series online.

NASA rover Curiosity is scheduled to touch down on Mars this Sunday, after which the mobile science lab will hopefully start analyzing Martian dirt and rocks to look for signs of life. But this rover is just the latest knot in a very long string of attempts to better understand our rust-colored neighbor.

Galileo was the first to peer at Mars through a telescope way back in 1609. Fifty years later, a Dutch astronomer named Christiaan Huygens mapped the planet. And two hundred years later, in the 1870s, an American named Aseph Hall discovered its two moons, Phobos and Deimos.

Then, in 1894, a man named Percival Lowell built an observatory in Flagstaff, Arizona. He focused it on Mars and saw something shocking: a complex series of canals feeding water to Martian farms.

Lauren Amundson works at the observatory Lowell founded. She says he and his colleagues were convinced that an advanced civilization was thriving on the red planet.

“They would talk about seeing vegetation up there," Amundson says. "How the vegetation would change depending on the season. They thought they had it pretty figured out what those Martians were doing up there."

No one knows what Lowell and company were really looking at, but it shows how hard it was to get reliable information about a place so far away.

Decades later, in 1964, scientists were still trying to get a closer look at Mars, using probes to fly by the planet and snap pictures. After several failures, NASA sent a pod called Mariner 4 and for the first time, the world saw Mars up close.

“The first pictures that came back were of the southern parts of Mars, which is ancient, heavily cratered highlands," says Bethany Ehlmann, a planetary scientist at Cal Tech. "And people were bummed. There was all this hope that Mars was different and there was another intelligent civilization.”

Ehlmann says that after several more missions, scientists learned all sorts of things. For instance, Mars’ atmosphere is mostly carbon dioxide, so forget about dropping in and taking a breath of fresh Martian air.

As for the weather, Mars is really cold. As in, 75 degrees below zero is an average day there.

But many questions remained: was there ever blue water on the red planet? Is the white patch at the northern pole an ice cap?

“It is,” says Scott Hubbard, former head of NASA’s Mars program.

He says NASA sent a lander called Phoenix to the Martian north pole in 2007 and it found solid evidence of water on Mars.

“There is probably billions and billions of tons of ice water in the top three feet of the Martian surface at the North pole," Hubbard says. "We have dug it up, we put it in our chemistry set. We tested it. What we saw from orbit was confirmed on the ground in the Phoenix mission.”

Other missions have suggested that not only does Mars have frozen water, but the planet was actually once warm and wet. In fact, billions of years ago the red planet may have been similar to Earth — a perfect breeding ground for life.

Hubbard says that’s where Curiosity comes in.

“Curiosity has the most sophisticated analytical laboratory we have ever sent to another world," he points out. "[Its job is] to see if we can’t find that missing piece, the organic materials, the fingerprints of life on Mars.”

Hopefully, Curiosity will begin that work after a successful landing. It's scheduled to arrive on Mars at 10:31 p.m. on Sunday.