1.   At any point on the ellipse between apogee and perigee a spacecraft will have both a horizontal and a radial velocity.

2.   Because of this distance, the spacecraft will have to guide itself through the flyby, executing sequences of commands at preset times.

3.   But Mars-bound spacecraft have a habit of disappointing.

4.   If it was some common malfunction on board, the spacecraft had instructions on how to call on backup systems to restore operations.

5.   The aim is to have spacecraft in orbit around Mars spot such sites, either active or fossilized.

6.   The Apollo spacecraft had yet to make its first spaceflight, and the deaths served as dramatic evidence of serious design problems.

7.   The one thing such a spacecraft would have plenty of, he said, is time.

8.   The spacecraft had to be maneuvered gingerly into its planned circular orbit for the primary mission of mapping the entire planet.

9.   The spacecraft does have a teammate, however.

10.   Mission Control ordered Chilton to remain in orbit until Sunday, when the spacecraft will have the option of landing at Kennedy or at Edwards.