The European Space Agency launched its Giotto spacecraft yesterday on the first leg of an eight-month journey that will take it to a violent, suicidal rendezvous with Halley's Comet between the sun and Earth next March.
The launch, Europe's first venture into interplanetary space, took place yesterday at 7:13 a.m. EDT from the Kourou Space Center in French Guiana on the northeast coast of South America. The launch was the ninth straight success for the agency's unmanned Ariane 1 rocket.
Placed by Ariane in a "parking orbit" 22,300 miles above the equator, the 2,112-pound spacecraft was to use an onboard "kick" motor to move it out of Earth orbit into what engineers call the cruise phase towards deep space. During its cruise, Giotto will take a curved path through space that will cover an estimated 360 million miles before it intercepts the comet next year.
One of three instrumented spacecraft that will greet Halley's Comet next year, Giotto is the one that will come the closest. On March 13 next year, Giotto is expected to come within 310 miles of the comet's five-mile-diameter nucleus of ice and rock.
When the spacecraft reaches its rendezvous, agency scientists expect it to be sandblasted into oblivion by billions of high-speed dust particles pouring off the comet's nucleus. But before being destroyed, the ship is to perform approximately 10 experiments examining the image, chemistry, magnetism and other aspects of the comet and its tail.
The Giotto spacecraft gets its name from 14th-century artist Giotto di Bondone, who in 1301 witnessed what probably was Halley's Comet. The Florentine painter was so impressed by the comet that he made it the "Star of Bethlehem" in a fresco he called the "Adoration of the Magi." It still decorates the interior of the Scrovegni chapel in Padua, Italy.
The Soviet Union has sent into deep space two Vega spacecraft that will also rendezvous with the comet, but at the "safe" distance of 6,200 miles. Another spacecraft named Planet A will be launched in August by Japan, but it will come no closer than 160,000 miles. Its primary task will be to photograph the comet's tail and the huge cloud of hydrogen gas that surrounds all comets as they circle the sun on their way back towards the deep freeze of space.
The United States plans at least two space shuttle flights to observe Halley's Comet. One will take place in January, the second in March.
During the January flight, the shuttle's crew will deploy a Spartan satellite that will observe the comet from about 100 miles from the shuttle and about 50 million miles from the comet. The crew will later retrieve Spartan and return it to Earth so scientists can examine its videotaped observations.
In March, the shuttle will carry three ultraviolet telescopes that will observe the comet from orbit for an entire week. Though almost 50 million miles from the comet, the three telescopes in the shuttle's cargo bay are so large and precise that they may return with the best and most continuous images of the comet at the time it exhibits its brightest head and longest tail to viewers on Earth.
Of the more than 900 comets known to appear near Earth, Halley's Comet is clearly the best known and easily the most spectacular. Named for British Astronomer Sir Edmund Halley, who predicted its return every 76 years, the comet will be seen late this year for the 30th time in recorded history. It was first seen and documented in 240 B.C. by Chinese astronomers and last seen in 1910 by most of the world.
The comet is now behind the sun and out of sight. It will reappear to Earth's telescopes in mid-August when it begins its final approach toward the sun. It first becomes visible to the naked eye in December, then disappears again in January when it flies behind the sun. It will be most visible from Earth next March and April, when its head will swell to almost 50 million miles across and its tail will grow to almost 100 million miles.