LOS ANGELES, Calif. - Drilling into a rock near its landing site, the Curiosity rover has answered a key question about Mars: The red planet long ago harboured some of the ingredients needed for primitive life to thrive.

Topping the list is evidence of water and basic elements that teeny organisms could feed on, scientists said Tuesday.

"We have found a habitable environment that is so benign and supportive of life that probably if this water was around and you had been on the planet, you would have been able to drink it," said chief scientist John Grotzinger of the California Institute of Technology.

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  • Non-Habitable Rock vs. Habitable Rock

    This set of images compares rocks seen by NASA's Opportunity rover (left) and Curiosity rover (right) at two different parts of Mars. The rocks observed by Opportunity were determined to have been uninhabitable due to high acidity, but the rocks observed by Curiosity were likely submerged in a more neutral liquid environment, raising the possibility that they could have once hosted life.

  • Drill Sample

    This image from Curiosity shows the first sample of Mars rock extracted by the rover's drill.

  • X-ray Diffraction Patterns

    X-ray diffraction patterns of samples from two different areas on Mars' surface. On the left, a windswept, rocky environment that was likely uninhabitable; on the right, a lake-bed environment with likely neutral pH that may have been capable of supporting life.

  • Earth Analog

    A modern, Earth analog to the area NASA's Curiosity rover is currently exploring. Left, clay-bearing lake sediments exposed in a pit in southern Australia. Right, a core sample from the lakebed.

  • Soil Quality

    Left, a rock abraded by instruments on the Opportunity rover, showing reddish brown soil indicative of hematite, a substance not especially conducive to hosting life. Right, a hole drilled by Curiosity, showing the greyish, iron-rich rock underneath, which may be more compatible with habitability.

  • Curiosity Neighborhood Map

    This map depicts the area in Gale Crater where the Curiosity touched down. The "John Klein Rock" is where Curiosity drilled its first soil sample.

  • Chemical Analysis

    A chemical analysis of a sample taken by Curiosity indicates the presence of water, carbon dioxide, oxygen, sulfur dioxide, and hydrogen sulfide released on heating.

  • Carbon-Compound Analysis

    The "John Klein" sample reveals the presence of simple carbon-containing compounds chloro- and dichloromethane in Mars' soil. These detections indicate that the analysis instruments are functioning properly and can continue searching for organic compounds.

The discovery comes seven months after Curiosity touched down in an ancient crater. Last month, it flexed its robotic arm to drill into a fine-grained, veiny rock and then tested the powder in its onboard labs.

Curiosity is the first spacecraft sent to Mars that could collect a sample from deep inside a rock, and scientist said they hit pay dirt with that first rock.

Mars today is a frigid desert, constantly bombarded by radiation. Previous missions have found that the planet was more tropical billions of years ago. And now scientists have their first evidence of a habitable spot outside of Earth.

This was an environment where microbes "could have lived in and maybe even prospered in," Grotzinger said.

The car-size rover made a dramatic "seven-minutes-of-terror" landing last August near the planet's equator. As high-tech as Curiosity is, it lacks the tools to detect actual microbes, living or extinct. It can only use its chemistry lab to examine Martian rocks to determine the kind of environment they might have lived in.

The analysis revealed the rock that Curiosity bore into contained a chemical soup of sulfur, hydrogen, oxygen, nitrogen, phosphorus and simple carbon — essential chemical ingredients for life. Also present were clay and sulfate minerals, signs that the rock formed in a watery environment.

NASA rovers Opportunity and Spirit — before it fell silent — also uncovered evidence of a wet Martian past elsewhere on the planet, but scientists think the water would have been too acidic for microbes.

The ancient water at Curiosity's pit stop appears to be neutral and not too salty. It previously found a hint of the site's watery past — an old streambed that the six-wheel rover crossed to get to the flat bedrock.

Curiosity has yet to turn up evidence of complex carbon compounds, fundamental to all living things. Scientists said a priority is to search for a place where organics might be preserved.

The drilled rock isn't far from Curiosity's landing spot in Gale Crater; the rover is ultimately headed to a mountain in the crater's middle. Images from space spied signs of clay layers at the base of the mountain — a good spot to hunt for the elusive organics.

It has been slow going as engineers learn to handle the rover, which is far more tech-savvy than anything that has landed before on Earth's planetary neighbour.

Over the years, Mars spacecraft in orbit and on the surface have beamed back a wealth of information about the planet's geology. Scientists have also been able to study rocks from Mars that have occasionally landed on Earth.

The latest news comes during a lull in the two-year mission. Curiosity has been prevented from doing science experiments as engineers troubleshoot a computer problem.

Scientists still plan to drive toward the mountain but not until Curiosity drills into another rock at its current location. Since flight controllers on Earth will be out of touch with Mars spacecraft for most of next month due to a planetary alignment, the second drilling won't get under way until May.