Moving by Jupiter at 44,000 miles an hour the Voyager 2 spacecraft, today was put on a path that will take it to the distant planet Uranus in 1986.
As things stood today, the 1,8000 pound Voyage 2 will arrive at Saturn in August of 1981 after a trip of almost 500 million miles from Jupiter. On leaving Saturn, the silver-and-black spacecraft will set sail to an uncharter region of space toward Uranus more than one billion miles beyond.
Already 100 million miles ahead of its sister craft, Voyager 1 was still on course today for an encounter with Saturn, its dazzling rins and its mysterious moon Titan in November 1980. If everyting goes will in the next 18 months and Voyager 1 reaches Saturn unscathed, Voyager 2 will be kept on the course it was placed today and targeted for Uranus.
Should Voyager 1 run into trouble or fail to fly close to titan or behind the rings of Saturn, Voyager 2's course will be changed to bring it closer to titan and behind Saturn's rings. If that happens, Voyager 2 will never reach Uranus.
"Our main concern is still Saturn, its rings, and Titan," Voyager Mission Analyst Charles Kohlhase said today at the Jet Propulsion Laboratory where the probe is directed. "We will only target Voyager 2 to Uranus if Voyager 1 makes a successful flight to Saturn."
The maneuver that put Voyager 2 on course for Uranus was a 76-minute slow burn of its small thruster engines. With the spacecraft's nose pointed back toward Earth, this burn slowed it slightly, so that if it stays on course it will sail by Saturn in August 1981 on a path that will bring it to Uranus in January 1986.
This was the first time any spacecraft has been targeted to Uranus, the third planet from the edge of the solar system. Only Neptune and Pluto are farther from the sun than Uranus, which is separated from Earth by two billion miles of space.
Voyager 2's new course is possible because the craft used so little fuel in it two-year journey from Earth to Jupiter. It still has more than enough fuel to allow flight controllers the margins they need to make a choice next year between Saturn and Uranus.
"With the fuel margins we have now, we have a 95 percent chance of now, we have a 95 percent chance of getting to Uranus," mission analyst Kohlhase said. "By this I mean we have enough to navigate there, maintain adequate control when we get there and target and move the cameras around so we can photograph all targets of interest."
If Voyager 2 goes to Uranus, it will fly by Saturn's moon Titan at a distance of about 500,000 miles instead of the 5,000 miles it would have if it were not flying to Uranus. Presumably, Voyager 1 will get so close to Titan -- the only moon in the solar system with an atmosphere as thick as Earth's -- that scientists will be satisfied with that.