01:00 AM EST on Saturday, January 28, 2006

Unmanned space missions may lack a certain glamour, but dollar for dollar they have recently proved a better research investment than their manned counterparts. The latest such effort is the New Horizons spacecraft, which set out this month on a nine-year voyage to Pluto.

Though some astronomers argue that Pluto is not technically a planet, tradition ranks it as the solar system's most distant member. Small, icy Pluto was the only planet to be discovered by an American, Clyde W. Tombaugh, who located it in 1930, and died in 1997, at age 90. It is fitting that some of Mr. Tombaugh's ashes are on the spacecraft.

If all goes well, New Horizons will approach Pluto in July of 2015. For five months, without ever landing, the craft will study Pluto's composition and atmosphere, along with its large moon, Charon. A variety of cameras and spectrometers will be used to collect data. Beyond Pluto, the mission will take aim at the Kuiper Belt, a collection of icy, rocky objects that apparently includes stunted planets. Studying these may offer clues to how planets are formed.

Scientists believe that material in the Kuiper Belt may be left over from the creation of the solar system, and could therefore contain a wealth of information. Two small moons discovered last year by the relentlessly productive Hubble Space Telescope are also on New Horizons' agenda.

Waiting for this mission to bring results will take patience. Scientists who could end up attached to the project may now be working their way through school. But if taking the long view is not quite in Americans' nature, the findings from Pluto could help change that. New Horizons is the fastest spacecraft ever launched; it is able to travel at 36,000 miles an hour. Yet even so, it will be slow in arriving -- a reminder of the vastness of space, and of human history's relative brevity.