"Let us imagine that such a vehicle is circling Mars," Clarke speculated.

But people didn't believe in it now; ever since we got to the Moon and circled Mars and Venus everybody seemed to agree that we weren't going to find life anywhere.

At this altitude, Surveyor circled Mars once every two hours.

Four tiny planets circled the sun closely-Mercury, Venus, Chung Kuo, and Mars.

So Andrew Lear was hard at work, watching pens twitch on graph paper as we circled Mars.

We've circled Mars twice.

To keep down the spacecraft's weight and cut costs, the plan did not call for Surveyor to go straight to its ultimate 248-mile-high orbit, circling Mars from pole to pole once every two hours.

Satellites circling Mars could help send information back to Earth over an interplanetary Internet.

Presently the music stopped and a voice said: "This is station D-M-S, the Mars Company, Deimos, circling Mars.

At one time it was circling precisely opposite Mars.