 Comet Halley is making its regular 76-year pilgrimage around our sun, as it has been doing for countless centuries. The comet is the target of study for five exploratory spacecraft from Europe, Japan, and the Soviet Union, each whizzing by the giant snowball of ice, gas, and dust from different vantage points. The European Space Agency's JOTO spacecraft will be the most daring probe by taking a flight path just 300 miles in front of the comet's head. JOTO hopes to photograph the comet's nucleus. Two other highly-instrumented Soviet spacecraft, Vega-1 and Vega-2, are scheduled to fly by the comet at a distance of 6,000 miles, hoping also to obtain images of the comet's nucleus. Lastly, two Japanese spacecraft studying Halley are Planet A, which approaches the sunward side of Halley at a distance of 120,000 miles, and Sakigaki, which will pass about 4 million miles from the comet. A list of other American spacecraft slated for study of the comet includes Astro-1 and the Spartan Halley platform. Both will be maintained by the Space Shuttle, the Solar Maximum Mission Satellite, Pioneer Venus, and the International Cometary Explorer. In order to get the best use out of all the research being done on the comet, the International Halley Watch was organized. Thousands of scientists and amateur and professional astronomers from 47 different countries have joined forces. The Halley Encounter is a once-in-a-lifetime chance to study one of the most primitive objects in our solar system. A program dedicated to visiting some of the planets in our solar system with two unmanned probes had a history of success ever since its beginning. In 1977, Voyager 1 and Voyager 2 were both launched on their way to Jupiter and Saturn. Now, having logged nearly 2 billion miles in space since 1977, Voyager 2 will point its sensors and TV cameras at a planet we have never seen up close, Uranus. Voyager project scientist Dr. Edward Stone, NASA's Jet Propulsion Laboratory in Pasadena, California. There are several unique things about Uranus. First of all, it's the most remote planet that we will have visited in the solar system. It formed in a much colder region of the solar nebula and therefore is made of different materials than either Jupiter or Saturn. So we'll be studying the different properties of Uranus and its satellites. The other interesting thing about Uranus is that it's tipped over on its side with its spin axis at this time basically pointing at the Sun. So it has a much different orientation with respect to the Sun. The questions will be answered during the encounter before the tiny one-ton spacecraft ventures even further into our solar system to visit the eighth planet from the Sun, Neptune.