Waiting For A Sign: Mars Rover To Land On Its Own

If all goes according to plan, the Mars Science Laboratory, nicknamed Curiosity, will land gently on Mars at 10:31 PDT Sunday night. The rover’s entry, descent and landing will last for a total of seven minutes. During that time, the rover must slow down from 13,000 mph to a dead-stop touchdown on the surface of Mars.

When you’ve spent $2.5 billion on a mission, you probably want to check in on how it’s doing once in a while. So how will scientists be communicating with a spacecraft that’s 154 million miles away?

Richard Kornfeld, a senior engineer on the Mars landing team, says there are two ways to keep in touch: One is a radio system that can transmit a signal directly from the spacecraft to Earth; another requires the radio signal to be relayed through satellites that are orbiting Mars.