Subject Matter Expert:
Joseph Trevathan, Dan Woodard, and Victoria Friedensen
Since early times, people have looked into space and wondered
about its mysteries. The vastness of space has opened our
minds, but its size has limited our search. We want to explore
distant worlds, but how can we travel faster so we can go
farther into space?
Jet speed certainly isn’t the answer. Imagine traveling
by jet to the moon from Earth, about 386,000 km (240,000
miles). A jet traveling at 1,600 km/h (1,000 mph) would take
about 240 hours or about 40 days to reach the moon.
Scientists and engineers clearly knew from the start that
the only way to get into space is to use rockets and rocket
propulsion. The vehicles and propulsion systems developed
for the Apollo program were designed to reach the moon. Using
a chemical propulsion system, it took the Apollo astronauts
about 2.5 days to get to the moon, traveling at speeds faster
than 39,000 km/h (more than 24,000 mph).
The space shuttle uses a chemical propulsion system based
upon both liquid and solid propellants. It combines the features
of a rocket, aircraft, and glider and is designed to carry
astronauts, satellites, and other cargo into Earths’ orbit.
Traveling at approximately 29,000 km/h (18,000 mph) the shuttle
orbits Earth every 90 minutes.
By using current technology and a spacecraft powered by chemical
rocket engines, a trip to Mars could take between six to nine
months. Because of the alignment of Mars and Earth, our best
chance to launch occurs every 26 months.
We need to find other ways to travel to Mars and beyond, and
we are currently considering alternative propulsion systems.
Nuclear thermal propulsion allows a spacecraft to travel faster
by providing a more efficient, and light weight system. We
would not use nuclear propulsion systems until the spacecraft
was far from Earth. Spacecraft would still be launched from
Earth with chemical rocket engines or be built and launched
in space. A nuclear thermal propulsion system could potentially
be over 100 times more powerful than chemical systems of comparable
weight. A system like this could easily cut down the time needed
to travel to Mars and other places in our solar system.
NASA is studying a plasma-based propulsion system called project
VASIMR (Variable-Specific-Impulse Magnetoplasma Rocket). Franklin
R. Chang-Diaz, the first Hispanic astronaut, is studying this
system. VASIMR works by using a large electric power source
(such as nuclear power) to then utilize hydrogen as a rocket
propellant. Hydrogen is plentiful in the solar system, possibly
allowing a VASIMR-powered spacecraft to be launched with only
enough propellant to reach its destination. When it arrives,
it could pick up more hydrogen to use as propellant for the
return trip. According to NASA, a VASIMR flight to Mars could
take a little over three months, compared to the six to nine
months required by a conventional chemical rocket. Shorter
flight times lessen an astronaut’s time in reduced gravity
and decreases the time an astronaut is exposure to space radiation.
There is much that we want to see and explore in our Solar
System and beyond. New propulsion systems will help us get