Comet Siding Spring

A fleet of robotic spacecraft orbiting Mars got a front row seat to space history and lived to tell about it, giving scientists their first close-up look at a comet fresh from a cloud of primordial mini-worlds at the outer reaches of the solar system.

The red planet’s brush with Comet Siding Spring was a close encounter of the best kind for science, a once-in-a-lifetime chance to study a pristine remnant of the solar system’s birth 4.6 billion years ago as it makes its first and possibly last visit to the warmth of the inner solar system.