Mars lake
© NASA
It's been an exciting weekend of discoveries for NASA and its Mars Curiosity rover.

First, there was an update from NASA engineers operating the one-ton rover, who expressed excitement over a set of rocks discovered in a region dubbed "Yellowknife Bay." The rocks, which are thought to hold evidence that shows Mars was once a much wetter place, were discovered just days before a team of researchers announced findings showing that minerals found underground on Mars are the 'strongest evidence yet that water once flowed across the Red Planet. Meanwhile, on Friday, researchers working in conjunction with the NASA Mars Reconnaissance Orbiter (MRO) team announced they had identified an ancient river system - now considered one of the most important geological sites on Mars.

And that was just the weekend.

Now, NASA has reportedly released an image of an ancient lake bed, saying it was once the site of a massive lake on the Red Planet. According to NASA, the new set of photos of the huge crater on Mars suggest water may still remain in crevices under the planet's surface, possibly increasing the chances that life once resided on Mars. The image, captured by theHigh Resolution Imaging Science Experiment (HiRISE) camera on NASA's MRO, shows a massive crater about 57 miles (92 kilometers) wide and so deep that scientists suspect underground water once flowed into the crater, creating a massive lake.

While the lake bed is now dry, astronomers say future missions to the Red Planet could involve studying the site in more detail. Geologists say the image shows evidence of layered, flat rocks at the bottom of the crater, which contain carbonate and clay minerals that form in the presence of water. Large inflow channels on the side of the crater also seem to indicate that water once flowed into the lake, leaving marks that may show the edge of the lake bed.

"Taken together, the observations in McLaughlin Crater provide the best evidence for carbonate forming within a lake environment instead of being washed into a crater from outside," said study author Joseph Michalski, of the Planetary Science Institute in Tucson, Arizona, and London's Natural History Museum.

The presence of water on Mars increases the odds that life once existed on Mars. A number of astronomers have suggested that space agencies around the world should focus resources on crevices and areas where groundwater may have seeped through the surface. Recent analysis of the Martian surface suggests that life, should it exist on Mars, likely will be discovered underground, where it will be shielded from the harshness of a planet without an atmosphere.

The latest discovery comes as NASA is set to drill into the Martian surface. The U.S. space agency has spent the past several weeks preparing for the drill session in which it will attempt its most complex mission to date.

Launched in 2005, the MRO and its six instruments have provided more high-resolution data about the Red Planet than all other Mars orbiters combined. Data are made available for scientists worldwide to research, analyze and report their findings.