MISSIONS TO MINOR BODIES.

Comets and asteroids are enticing venues for the next big leap forward in the space investigation of the solar system. So far three exploratory missions have occurred. In March 1986, Giotto glimpsed a cometary nucleus from a distance of 605 km. At a stroke this converted our hypothetical musing about the large dirty snowball nucleus into startling reality. In 1976, Viking Orbiter 1 passed within 88 km of Phobos and Viking Orbiter 2 within 28 km of Deimos. This is the nearest we have gotten to any 'asteroids' although, unfortunately, close-ups of the moons of Mars, which might be captured asteroids, are not the same thing as images of the real asteroids that orbit in a belt around 2. 8 AU from the Sun. Still, we have seen three minor bodies and the images have shown convincingly what fascinating objects they are.