So we can get people to go at the same speeds as the unmanned probes.

Both countries sent unmanned probes to orbit the moon, photograph it and land on the surface.

They add that unmanned probes and robots could do most of the experiments.

But these experiments could be done just as well from an unmanned probe; their main justification had been to give the crew something to do.

The exploration of Saturn has been solely done by unmanned probes.

Personally, I'd say we should send out more unmanned probes.

An unmanned probe would be sent to Mars next year, he said.

What if it is merely an unmanned probe which has been traveling for centuries?

For whatever reason, many of the unmanned probes we've sent to Mars have failed.

And the unmanned probes were measuring it for years before we arrived here.