NEW ROCKET TECHNOLOGY COULD CUT MARS TRAVEL TIME



June 13, 2000



Michael Braukus
Headquarters, Washington, DC
(Phone: 202/358-1979)



John Ira Petty
Johnson Space Center, Houston, TX
(Phone: 281/483-5111)



Dave Micheletti
MSE Technology Applications, Inc., Butte, MT
(Phone: 406/494-7289)

<h4>Release: H00-91</h4> <h3>New Rocket Technology Could Cut Mars 
Travel Time</h3> 

An agreement to collaborate on development of an advanced rocket 
technology that could cut in half the time required to reach Mars, 
opening the solar system to human exploration in the next decade, has 
been signed by NASA's Johnson Space Center, Houston, TX, and MSE 
Technology Applications Inc., Butte, MT.



The technology could reduce astronauts' total exposure to space 
radiation and lessen time spent in weightlessness, perhaps minimizing 
bone and muscle mass loss and circulatory changes.



Called the Variable Specific Impulse Magnetoplasma Rocket (VASIMR), 
the technology has been under development at Johnson's Advanced Space 
Propulsion Laboratory. The laboratory director is Franklin 
Chang-Diaz, a NASA astronaut who holds a doctorate in applied plasma 
physics and fusion technology from the Massachusetts Institute of 
Technology, Cambridge.



Chang-Diaz, who began working on the plasma rocket in 1979, said, "A 
precursor to fusion rockets, the VASIMR provides a power-rich, 
fast-propulsion architecture."



Plasma, sometimes called the fourth state of matter, is an ionized (or 
electrically charged) gas made up of atoms stripped of some of their 
electrons. Stars are made of plasma. It is gas heated to extreme 
temperatures, millions of degrees. No known material could withstand 
these temperatures. Fortunately, plasma is a good electrical 
conductor.



This property allows it to be held, guided and accelerated by properly 
designed magnetic fields.



The VASIMR engine consists of three linked magnetic cells. The forward 
cell handles the main injection of propellant gas and its ionization. 
The central cell acts as an amplifier to further heat the plasma. The 
aft cell is a magnetic nozzle, which converts the energy of the fluid 
into directed flow.



Neutral gas, typically hydrogen, is injected at the forward cell and 
ionized. The resulting plasma is electromagnetically energized in the 
central cell by ion cyclotron resonance heating. In this process 
radio waves give their energy to the plasma, heating it in a manner 
similar to the way a microwave oven works.



After heating, the plasma is magnetically exhausted at the aft cell to 
provide modulated thrust. The aft cell is a magnetic nozzle, which 
converts the energy of the plasma into velocity of the jet exhaust, 
while protecting any nearby structure and ensuring efficient plasma 
detachment from the magnetic field.



A key to the technology is the capability to vary, or modulate, the 
plasma exhaust to maintain optimal propulsive efficiency. This 
feature is like an automobile's transmission which best uses the 
power of the engine, either for speed when driving on a level 
highway, or for torque over hilly terrain.



On a mission to Mars, such a rocket would continuously accelerate 
through the first half of its voyage, then reverse its attitude and 
slow down during the second half. The flight could take slightly over 
three months. A conventional chemical mission would take seven to 
eight months and involve long periods of unpowered drift en route.



There are also potential applications for the technology in the 
commercial sector. A variable-exhaust plasma rocket would provide an 
important operational flexibility in the positioning of satellites in 
Earth orbit.



Several new technologies are being developed for the concept, 
Chang-Diaz said. They include magnets that are super-conducting at 
space temperatures, compact power generation equipment, and compact 
and robust radio-frequency systems for plasma generation and heating.



Coordinated by Johnson's Office of Technology Transfer and 
Commercialization, the Space Act Agreement calls for a joint 
collaborative effort to develop advanced propulsion technologies, 
with no money exchanged between the two parties. Such agreements are 
part of NASA's continuing effort to transfer benefits of public 
research and development to the private sector.

	
-end-