Make It So: science fiction to reality

Many of us grew up watching the starship Enterprise sail among the stars in adventure after adventure. Star Trek has endured the decades and is the most successful science fiction show in the world. It has entertained people all over the world for over 30 years. More than that, however, the show has also inspired some engineers to turn science fiction into science reality with NASA s Deep Space One.

On October 24 of this year Deep Space One was launched. The spacecraft is the first in a series of deep space and Earth-orbiting missions which are part of the New Millennium Program. Among Deep Space One s objectives are close fly by of both an asteroid and a comet. But what is really amazing about DS1 is i t engines, the first ion propulsion to be used and the idea for them came straight out of star trek!

Up until now our spacecraft have been powered by burning various chemical propellants. Ion propulsion involves ionizing a gas and using the energy generated to propel the spacecraft. DS1 uses the gas Xenon (similar to neon but heavier.) The xenon is given an electrical charge (from the solar arrays on the spacecraft) and then electrically accelerated to about 30 km/sec. When xenon ions are emitted at such high speed as exhaust from a spacecraft, they push the spacecraft in the opposite direction.

If ion propulsion is proven to work on DS1, it will be used on future missions in the program. Deep Space four is designed to use four ion engines to fly alongside a comet in 2004 so that it can actually land on the comet!

Ion propulsion produces a lot of energy, however it does not produce fast acceleration like conventional chemical engines. Instead, ion propulsion has a gentle, steady acceleration which can eventually produce velocities 10 times as fast as chemical propulsion. Ion propulsion will be very useful for missions to comets and asteroids, missions to the inner solar system and for some trips to the outer solar system. Ion propulsion is also much cheaper to produce than chemical engines.

The idea of ion propulsion has been around since the 1960's, however it had been considered too risky to try. In the spirit of NASA s new philosophy of  smaller, cheaper, better  it was decided to give ion propulsion a try. The main purpose of the New Millennium program is to try new technologies.

One of the most exciting tasks to be carried out by the Deep Space 1 spacecraft will fly by the near-Earth asteroid Asteroid 1992 KD on July 29, 1999. DS1 will pass a mere 10 km from the asteroid! This is closer to the asteroid than a jet airplane is above Earth when it is cruising at an altitude of 33,000 feet. During this close fly-by the spacecraft will take images of the asteroid and determine its composition, size, shape and brightness. DS1 will also look for changes in the solar wind as it interacts with the asteroid to try to determine if the asteroid has a magnetic field. The Solar wind is a field of high energy particles that emanates from the Sun.

The mission is scheduled to end in September of 1999, however there is a chance it could be extended. If Deep Space 1's mission is extended, it could fly by two comets, Wilson-Harrington and Borrelly, where it will take close-up pictures, determine the size and shape of their nuclei, and study their comas (the cloud of water and gases that surrounds a comet's nucleus). The spacecraft will also examine the relationship of the surface features of the comet's nucleus to its dust  jets ,and the interaction of the comet with solar wind.

Currently the spacecraft is normal cruise configuration and NASA engineers say it is in excellent condition. The flight  team is testing the many new technologies on DS1. For more information on the net, check out the Deep Space One home page at: http://nmp.jpl.nasa.gov/ds1/