The search for signs of life on Mars. NASA'S Mars rover makes its final approach to the red planet ahead of a planned landing Sunday for a mission that hopes to unlock clues as to whether there was ever life on Mars.br br NASA Engineer Adam Steltznerbr br (SOUNDBITE) (English) NASA ENGINEER ADAM STELTZNER ON THE MISSION, SAYING:br br "The purpose of this is that we are taking a big rover to the surface of Mars. We are looking to do big science and big science requires big instruments, requires big rover and novel entry, descent and landing system which I just spoke about. The science, the goal is to understand the past environment and present environment of Mars, to see if it has a possibility for being habitable for life."br br The rover, also known as Curiosity, has been careening towards Mars since its November launch. The nuclear-powered rover -- the size of a compact car is expected to end its 352-million-mile journey on August 6.br br Earth and Mars are so far apart that radio signals, which travel at the speed of light, take 13.8 minutes for a one-way journey.