STARSHIPS is?
tablish a permanent, manned moon base. A manned mission may be
launched to Mars after that.
Obviously a new kind of rocket design must be found if we are ever
to reach the stars. Either we must radically increase the thrust of our
rockets, or we need to increase the time over which our rockets operate. A large chemical rocket, for example, may have the thrust of several million pounds, but it burns for only a few minutes. By contrast,
other rocket designs, such as the ion engine (described in the following paragraphs), may have a feeble thrust but can operate for years in
outer space. When it comes to rocketry, the tortoise wins over the hare.
ION AND PLASMA ENGINES
Unlike chemical rockets, ion engines do not produce the sudden, dramatic blast of superhot gases that propel conventional rockets. In fact,
their thrust is often measured in ounces. Placed on a tabletop on Earth,
they are too feeble to move. But what they lack in thrust they more
than make up for in duration, because they can operate for years in the
vacuum of outer space.
A typical ion engine looks like the inside of a TV tube. A hot filament is heated by an electric current, which creates a beam of ionized
atoms, such as xenon, that is shot out the end of the rocket. Instead of
riding on a blast of hot, explosive gas, ion engines ride on a thin but
steady flow of ions.
NASA's NSTAR ion thruster was tested in outer space aboard the
successful Deep Space 1 probe, launched in 1998. The ion engine fired
for a total of 678 days, setting a new record for ion engines. The European Space Agency has also tested an ion engine on its Smart 1 probe.
The Japanese Hayabusa space probe, which flew past an asteroid, was
powered by four xenon ion engines. Although unglamorous, the ion
engine will be able to make long-haul missions (that are not urgent)
between the planets. In fact, ion engines may one day become the
workhorse for interplanetary transport.
A more powerful version of the ion engine is the plasma engine,
tablish a permanent, manned moon base. A manned mission may be
launched to Mars after that.
Obviously a new kind of rocket design must be found if we are ever
to reach the stars. Either we must radically increase the thrust of our
rockets, or we need to increase the time over which our rockets operate. A large chemical rocket, for example, may have the thrust of several million pounds, but it burns for only a few minutes. By contrast,
other rocket designs, such as the ion engine (described in the following paragraphs), may have a feeble thrust but can operate for years in
outer space. When it comes to rocketry, the tortoise wins over the hare.
ION AND PLASMA ENGINES
Unlike chemical rockets, ion engines do not produce the sudden, dramatic blast of superhot gases that propel conventional rockets. In fact,
their thrust is often measured in ounces. Placed on a tabletop on Earth,
they are too feeble to move. But what they lack in thrust they more
than make up for in duration, because they can operate for years in the
vacuum of outer space.
A typical ion engine looks like the inside of a TV tube. A hot filament is heated by an electric current, which creates a beam of ionized
atoms, such as xenon, that is shot out the end of the rocket. Instead of
riding on a blast of hot, explosive gas, ion engines ride on a thin but
steady flow of ions.
NASA's NSTAR ion thruster was tested in outer space aboard the
successful Deep Space 1 probe, launched in 1998. The ion engine fired
for a total of 678 days, setting a new record for ion engines. The European Space Agency has also tested an ion engine on its Smart 1 probe.
The Japanese Hayabusa space probe, which flew past an asteroid, was
powered by four xenon ion engines. Although unglamorous, the ion
engine will be able to make long-haul missions (that are not urgent)
between the planets. In fact, ion engines may one day become the
workhorse for interplanetary transport.
A more powerful version of the ion engine is the plasma engine,