A
robotic spacecraft is an
unmanned spacecraft, usually under
telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a
space probe. Many space missions are more suited to telerobotic rather than
crewed operation, due to lower cost and lower risk factors. In addition, some planetary destinations such as
Venus or the vicinity of
Jupiter are too hostile for human survival, given current technology. Outer planets such as
Saturn,
Uranus, and
Neptune are too distant to reach with current crewed spaceflight technology, so telerobotic probes are the only way to explore them.