The hunt for evidence of life on Mars will go underground next year when a NASA probe digs beneath the surface of the red planet's arctic northern plains, US scientists revealed Monday. In a departure from previous missions -- which have seen robotic vehicles explore the planet's hills and craters -- NASA's Phoenix Mars Lander will instead dig into Martian soil for conditions favorable to past or present life. US scientists want Phoenix to try and determine whether frozen water near the planet's surface might periodically melt enough to sustain a viable environment for microbes.
