NOEL KING, HOST:
Tonight, a European space probe will fly past the Earth on its way to Mercury, the planet closest to the sun. That mission will ping around the inner solar system before getting to its destination. Here's NPR's Joe Palca.
JOE PALCA, BYLINE: Normally, when a mission milestone like a fly-by occurs, scientists gather at Mission Control to monitor the spacecraft's progress - not this time.
JORN HELBERT: We will all be at home. We all do this from our living rooms, kitchens - wherever we are.