Starship - Part 2

Alright, continuing from part 1 last week, i was talking about ion engine, solar sails and ramjet engines.

This week i'll cover the remaining alternatives of propulsion system.

The fourth alternative is nuclear electric rocket. In 1956, the U.S. Atomic Energy Commission (AEC) began to look at nuclear rockets seriously under Project Rover. In theory, a nuclear fission reactor would be used to heat up gases like hydrogen to extreme temperatures, and then these gases would be ejected out one end of the rocket, creating thrust.

Continuing from the nuclear propulsion, the fifth is nuclear pulsed rockets. This is a possibility that use a series of mini-nuclear bombs to propel a starship. In project Orion, mini-atomic bombs were to be ejected out the back of the rocket in sequence, so that the space craft would "ride" on the shock waves created by these mini-hydrogen bombs. On paper, such a design could take a spacecraft close to the speed of light. Originally conceived in 1947 by Stanislaw Ulam, who helped designed the first hydrogen bombs, the idea was further developed by Ted Taylor (one of the chief designers of nuclear warheads for the U.S. military) and physicist Freeman Dyson of the Institute for Advanced Study of Princeton.

In the late 1950ss and 1960s elaborate calculations were made for this interstellar rocket. It was estimated that such a starship could make to pluto and back within a year, with a top cruising velocity of 10 percent the speed of light. But even at that speed, it would take about forty-four years to reach the nearest star. Scientist have speculated that a space ark powered by such a rocket would have to cruise for centuries, with a multigenerational crew whose offspring would be born and spend all their lives on the space, in order that their descendants could reach nearby stars.

Another novel means of hurling an object near the speed of light is to use the "slingshot" effect. When sending space probes to the outer planets, NASA sometimes whips them around a neighboring planet, so they use a slingshot effect to boost their velocity. NASA saves on valuable rocket fuel in this way. That's how the Voyager spacecraft was able to reach Neptune, which lies near the very edge of the solar system.

Princeton physicist Freeman Dyson proposed that in the far future, we might find two neutron stars that are revolving around each other at great speed. By traveling extremely close to one of these neutron stars, we could whip around it and then be hurled into space at speeds approaching a third the speed of light. In effect, we would be using gravity to give us an additional boost to nearly the speed of light. On paper this just might work.

Others have proposed taht we whip around out own sun in order to accelerate to near the speed of light. This method, in fact, was used in Star Trek IV: The Voyage Home, when the crew of the Enterprise hijacked a Klingon Ship and then sped close to the sun in order to break the light barrier and go back in time. In the movie When Worlds Collide, when Earth is threatened by a collision with an asteroid, scientists flee the Earth by creating a gigantic roller coaster. A rocket ship descends the roller coaster, gaining velocity, and then whips around the bottom of the roller coaster to blast off into space.

Yet another ingenious method for flinging objects into space at fantastic velocities is the rail gun, which Athur C. Clarke and others have featured in their science fiction tales, and which is also being seriously examined as part of the Star Wars missile shield.

Instead of using rocket fuel or gunpowder to boost a projectile to high velocity, a rail gun uses the power of electromagnetism.

In its simplest form, a rail gun consist of two parallel wires or rails, with a projectile that straddles both wires, form a U-shaped configuration. Even Michael Faraday knew that a current of electricity will experience a force when placed in a magnetic field. (This , in fact, is the basis of all electrical motors.) By sending missions of amperes of electrical power down these wires and through and through the projectile, a huge magnetic field is created around the rails. This magnetic field then propels the projectile down the fails at enormous velocities.

Rail funs have successfully fired metal objects at enormous velocities over extremely short distances. Remarkably, in theory, a simple rail gun should be able to fire a metal projectile at 18,000 miles per hour, so that it would go into orbit around the earth. In principle, NASA's entire rocket fleet could be replaced by rail guns that could blast payloads into orbit from Earth.

Given the slow but steady advances in spaceship design, it is reasonable to assume that the first unmanned probe of some sort might be sent to nearby stars perhaps later in this century or early in the next century, making it a Class I impossibility.

But perhaps the most powerful design for a starship involved the use of antimatter. Although it sounds like scnience fiction, antimatter has already been created on Earth, and may one day provide the most promising design yet for a workable manned starship.