VoyagerAt a distance of nearly 60,000,000 miles from Earth, NASA’s Voyager 1 and Voyager 2 spacecraft cross the orbit of Mars as the twin space probes continue their outbound race toward Jupiter. Moving at 13 miles per second, Voyager 1 will overtake its identical twin, Voyager 2, at the end of 1977, with both spacecraft expected to reach Jupiter in 1979. From here, they will plunge through the asteroid belt between Mars and Jupiter, though fears of damage occurring in this part of space have been allayed by the successful asteroid belt passage of Pioneers 10 and 11 in the early 1970s.