A look at NASA's Mars venture

PASADENA, Calif. -- NASA's robot rover, Curiosity, has spent 8 1/2 months hurtling through space toward its anticipated arrival Sunday on Mars. NASA's 19th mission and eighth landing attempt, it is to land near the foot of a mountain rising from a giant crater.

Why Mars again? Scientists want to know if any form of life ever existed there, meaning microscopic organisms. Since the 1960s, spacecraft have zipped past, orbited or landed on Mars in this quest. Two small NASA rovers that arrived in 2004 explored different craters and one is still functioning.

Curiosity is the most ambitious effort ever, but it's not the be-all and end-all. During its two-year exploration, it will try to answer whether the giant crater where it lands had the right conditions to support microbes.

Curiosity carries a toolbox of 10 instruments, including a rock-zapping laser and a mobile organic chemistry lab. Its long robotic arm can jackhammer into rocks and soil to hunt for basic ingredients of life, including carbon-based compounds, nitrogen, phosphorus, sulfur and oxygen, as well as minerals that might provide clues about possible energy sources.

The spacecraft is formally called the Mars Science Laboratory but, in 2008, NASA held a naming contest open to students and selected Curiosity, proposed by a sixth-grader from Lenexa, Kan.

The mission is costing $2.5 billion, $1 billion over its original budget because development took longer than expected.

President Barack Obama has set a goal for astronauts to orbit Mars by the mid-2030s followed by a landing. The plan is first to send astronauts to an asteroid. -- AP