How Mars may have looked about four billion years ago

How Mars Lost Its Magnetic Field—and Then Its Oceans

Chemical changes inside Mars's core caused it to lose its magnetic field. This, in turn, caused it to lose its oceans. But how?
The view south from Viking 2, one of two probes sent to investigate the surface of the planet Mars for the first time, September 6, 1976

We Might Have Accidentally Killed the Only Life We Ever Found on Mars Nearly 50 Years Ago

In one experiment, the Viking landers added water to Martian soil samples. That might have been a very bad idea.
Martian Moon Deimos

Deimos: A Chip Off the Old Martian Block?

A new space probe suggests that the moonlet Deimos isn’t a captured asteroid after all.
Carl Sagan holding a globe model of the planet Mars, 1970s.

Should We Go to Mars? Carl Sagan Had Thoughts

It'd be "a step more significant than the colonization of land by our amphibian ancestors some 500 million years ago." But Sagan had reservations.
An artist concept of a NASA astronaut on Mars

Why Hasn’t NASA Sent Anyone to Mars?

The Perseverance mission to Mars represents a considerable step forward for the space program. But are rovers as good as it gets?
The Mars Curiosity Rover

The Meaning of Methane on Mars

Curiosity rover's recent report of methane on Mars isn't the first time the gas has been indicated. Does it necessarily mean that Mars harbors life?
Zooming in on Schiaparelli components on Mars

Why Getting to Mars is Not So Easy

There is a reason Mars has a reputation as a graveyard for spacecraft.
Bacteria

Protecting Mars From Earthly Contaminates

Now that water has been discovered on Mars, the next step is to ensure we don't contaminate the planet with Earthly microbes and bacteria.
Credit: NASA/JPL/University of Arizona
Caption: Alfred McEwen

The Canals of Mars

We now know there's liquid water on Mars, according to NASA. But at the turn of the 20th century, we believed something else: that Mars had canals.
Black and white mapping of canals

The Extinct Civilization of Mars

Liquid water has been detected on Mars. We explore the history of the search, and the astronomer, Percival Lowell, who shook the public imagination.