Mariner 10:
Mariner 10 was the first spacecraft to use a gravity assist trajectory, accelerating as it
entered the gravitational influence of
Venus, then being flung by the
planet's gravity onto a slightly different course to reach
Mercury. It was also the first
spacecraft to encounter two planets at close range.
Placed into orbit around the
Sun going in the opposite direction
from Earth's orbit, Mariner 10's orbit crossed Mercury's the first time at a distance of
703 kilometers (437 miles) from the planet, the second time at 48,069 kilometers (29,870
miles), and a third time at 327 kilometers (203 miles). In total, Mariner 10 imaged about
half the planet. Mercury was revealed to have a very cratered,
Moon-like surface and a faint,
mostly helium atmosphere.
Read More About Mariner 10
Visit the Mariner 10 Website
