A lake that might once have been habitable may have filled a crater for a long time on early Mars, new spacecraft images reveal. NASA's Mars Reconnaissance Orbiter (MRO) captured the images that suggest the debris-strewn Holden Crater once held a calm body of water that could have harbored life. There is so far no convincing evidence life does or ever did exist on Mars, however. The crater debris includes a mix of broken boulders and smaller particles called megabreccia.

Nasa says its Mars rover Spirit has discovered "the best evidence yet" of a past habitable environment on the planet's surface. Spirit has been exploring a plateau called Home Plate, where it discovered silica-rich soil in May. Researchers are now trying to determine what produced the patch of nearly pure silica - the main ingredient of window glass. They believe the deposits came from an ancient hot-spring environment or an environment called a fumarole, in which acidic steam rises through cracks. On Earth, both of these types of settings teem with microbial life, said rover chief scientist Steve Squyres.

A new experiment similar to a pregnancy test but designed to search for signs of life on Mars is now exposed to the vacuum of space above Earth. The European Space Agency's (ESA) postage-stamp-sized experiment, called the "Life Marker Chip" (LMC), was launched last week aboard a Russian rocket launched from Baikonur Cosmodrome, Kazakhstan. Strapped to the ESA's large Foton-M3 capsule, the tiny experiment harbors more than 2,000 life-detecting samples that glow if they encounter life-critical compounds, such as proteins or DNA. Scientists and engineers hope the life-sensing chip can remain viable in the harsh radiation, temperatures and vacuum of space during a trip to Mars.

A Mars-orbiting satellite recently spotted seven dark spots near the planet's equator that scientists think could be entrances to underground caves. The football-field sized holes were observed by Mars Odyssey's Thermal Emission Imaging System (THEMIS) and have been dubbed the seven sisters --Dena, Chloe, Wendy, Annie, Abbey, Nikki and Jeanne--after loved ones of the researchers who found them. The potential caves were spotted near a massive Martian volcano, Arisa Mons. Their openings range from about 330 to 820 feet (100 to 250 meters) wide, and one of them, Dena, is thought to extend nearly 430 feet (130 meters) beneath the planet's surface. The researchers hope the discovery will lead to more focused spelunking on Mars.

Two NASA space probes that visited Mars 30 years ago may have found alien microbes on the Red Planet and inadvertently killed them, a scientist is theorizing. The Viking space probes of 1976-77 were looking for the wrong kind of life, so they didn't recognize it, a geology professor at Washington State University said. Dirk Schulze-Makuch presented his theory in a paper delivered at a meeting of the American Astronomical Society in Seattle, Washington. The paper was released Sunday.

Lab experiments with primitive microbes taken from an Antarctic lake have shown that the hardy single-celled organisms can tolerate at least the warmest of the frigid temperatures found on Mars. And they found that these species of microorganisms "huddled" together in colder temperatures to form a chemically linked unit called a biofilm. The finding marks the first time this phenomenon has been detected in the Antarctic species of so-called extremophiles. The findings provide more evidence for the ideas that liquid found beneath Mars’ surface could harbor microbial life and that life could exist elsewhere in the solar system and galaxy, which is generally incredibly cold.

If future missions are to set the record straight, the study's authors add, scientists may need to change the ways in which they search. NASA's Viking Mission to Mars put two landers on the red planet in 1976. Their experiments uncovered mysterious chemical activity in the Martian soil but no clear evidence of life. Now scientists suggest that telltale signs of life could have been there all along, but Viking's testing methods were not robust enough to recognize them.

A shiny coating found on rocks in many of Earth's deserts suggest a new way to search for signs of life on Mars, scientists said today. The coating, known as desert varnish, binds traces of DNA, amino acids and other organic compounds to desert rocks over the eons. Desert varnish has been found in the Atacama desert in Chile, the Mojave desert in California and Canyonlands National Park in Utah. Prehistoric people carved the varnish away, revealing lighter-colored rock underneat to create petroglyphs. The logic is simple: Samples of Martian desert varnish could perhaps show whether there has been life on Mars at any time during its 4.5-billion-year history.

On an Arctic island 3,000 kilometres north of the nearest city, scientists tested a drill this May that could one day open the next chapter in space exploration the quest to discover what lies beneath the surface of the moon and Mars. Working on the side of a sweeping fiord near the Eureka weather station half-way up Ellesmere Island, the nine researchers from NASA and McGill University bored two metres into a sandstone outcropping with a specialized drill that uses only a lightbulb's worth of power.

Tia Jones peered at the flash cards spread across the stage as her partner, Alexa Jones, slid them back and forth. The girls, both fourth-graders at Ann Arbor's Dicken Elementary, were trying to match cards showing characteristics of Earth with cards showing characteristics of Mars. The activity was part of a visit to Dicken by Doug Lombardi, the education and public outreach manager for Phoenix, NASA's 2007 mission to Mars. Lombardi also visited King Elementary while in town.

For more than a decade, orbiters and landers have assaulted Mars, their handlers driven by the mantra "follow the water." Now, scientists have pulled the results together in the most comprehensive look yet at what the rocks and minerals on the red planet are saying about its climate history and the potential that life may have briefly appeared there.

Nathalie Cabrol will never get to Mars, but the 42-year-old NASA planetary scientist is doing the next best thing. She's climbed almost 20,000 feet into the thin air of an Andes mountain peak, dived into some of the world's highest lakes and sent a robot across a windswept Chilean desert - all in a quest to learn how life once might have existed, or may still exist, on the Red Planet. The French-born Cabrol is one of a growing flock of biologists and geologists - called "astrobiologists" - who are going to the ends of the Earth to find parallels to the cold, dry Martian environment.

At a press conference early this morning, scientists at NASA's Jet Propulsion Laboratory, in Pasadena California announced proof of extraterrestrial life has been discovered on Mars. Last month, while probing rocks on the surface, the "Spirit" rover encountered what appeared to be a smooth flat rock, almost completely covered by sand. "It was the texture of the rock, which drew our attention. It appeared smoother and less weathered than anything else on the surface that we have encountered thus far." When Spirit reached a distance of approximately 1 meter from the object, it was clear that we weren't looking at any ordinary rock. The object lifted from the ground, and began hovering at a altitude of 3 meters. "We had absolutely no expectation that we would ever encounter anything like this!", said JPL's Director Dr. Charles Elachi "We were all speechless." The object remained hovering at 3 meters without any visible sign of propulsion nor support. The features on the lower sections of the object made it very clear that it was an engineered object, and not a naturally occuring phenomenon. Section plates were evident, as well as possible weapons damage of some sort. Spirit has been stationed to observe the object for further signs of intelligent control. No motion other than the hovering has been observed. "We theorize that the object may have been programmed to respond to motion, which is why it is now hovering. Unfortunately, the probes currently on Mars have no way of achieving any further interaction." An anonymous source at the Whitehouse told us that the recently announced moon base is intended as a stepping stone to get scientists close enough to work with the object.

Scientists are ramping up the search for extraterrestrial life with a powerful array of new telescopes and a refined sense of where to look within the vast expanses of our universe. At the annual conference of the American Association for the Advancement of Science last weekend, a panel of experts discussed the key components of life and what it might mean to find them within our own solar system -- or beyond.

Two new studies are challenging the notion that the desolate Martian plains once brimmed with salty pools of water that could have supported some form of life. Instead, the studies argue, the layered rock outcrops probed by NASA's robot rover Opportunity and interpreted as signs of ancient water could have been left by explosive volcanic ash or a meteorite impact eons ago. That would suggest a far more violent and dry history than proposed by the scientists operating Opportunity and its twin rover, Spirit, on the other side of the planet.