NASA Mars probe to land on Red Planet on Sunday

The Phoenix spacecraft is set to land on Mars after a nine-month journey. The American Space Agency is concerned about the landing, as over half of Mars missions since the 1970s have failed. Phoenix will enter the Martian atmosphere at 13,000 mph and has seven minutes to deploy its parachute, extend its legs, and fire thrusters for a soft landing. It aims to land on Mars' Arctic surface, send pictures back to Earth, and use a robotic arm to search for water. A manned mission to Mars could be the next step.

What will Phoenix use its robotic arm for on Mars?

What could be the next challenge after the Phoenix mission?