Rock samples analyzed by NASA's Curiosity rover have shown conditions that could have supported ancient life on Mars.
The samples, drilled at a depth of a few centimeters, contained sulfur, nitrogen, hydrogen, phosphorous and carbon -- some of the basic ingredients that are needed to support life, scientists at the U.S. space agency said Tuesday.
"We've discovered a completely different planet," said Chris McKay, senior research scientist at NASA Ames.
The work done by Curiosity represents the first time scientists have been able to drill into any planet other than Earth, said McKay. Previously, analysis of Mars was conducted with samples scooped from the surface.
The rover has been drilling in an area that has been named Yellowknife Bay, which is believed to be the end of an ancient river system or intermittently wet lake bed. The samples from the area show evidence of multiple periods of wet conditions, said NASA.
The drilling also revealed something else about the planet.
"It's the first time we found out the planet isn't red but grey," said McKay. Just a few centimeters below the surface, the sample showed no evidence of oxidization and so didn't have the red color that is so identified with Mars.
Curiosity touched down on Mars in August last year. NASA selected the touchdown point -- an area called Gale Crater -- because it believed the area showed evidence of an old network of stream channels and water. The sample was drilled not far from where the rover landed.
"It shows the future of Mars exploration is down," said McKay. "That's where we have to look."
NASA already has plans to send subsequent missions that will penetrate deeper into the planet.
Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is email@example.com