Answer: inspace

AnswerCrossword Clue
INSPACE

Lost ...

INSPACE

Where the Robinsons were lost

INSPACE

Heading for Mars

INSPACE
Orbiting
INSPACE
On a shuttle, maybe
INSPACEWhere we're weightless
INSPACEWhere one is weightless
INSPACEWhere the Robinsons were lost on 1960s TV