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Fast Plasma Rocket Test

Ad Astra Rocket Company of Webster, Texas is nearly ready to test its Variable Specific Impulse Magnetoplasma Rocket (VASIMR) in space. A scale model of the plasma rocket will be put through its paces at the International Space Station (ISS) in the near future. If successful, this technology could cut the travel time between Earth and Mars from the 6-9 months required for traditional propulsion engines to less than 3 months with VASIMR.




VASIMRTM) system encompasses three linked magnetic cells. The
VASIMR system encompasses three linked
magnetic cells. The “Plasma Source” cell
involvesthe main injection of neutral gas
(typically hydrogen, or other light gases)
to be turned into plasma and the
ionization subsystem. The “RF Booster” cell
acts as an amplifier to further energize the plasma
to the desired temperature using electromagnetic
waves. The “Magnetic Nozzle” cell converts the
energy of the plasma into directed
motion and ultimately useful thrust
(Credit: Ad Astra Rocket Company)

Consisting of three linked magnetic cells, the VASIMR engine ionizes a light neutral gas (typically hydrogen), heats it, and then directs it to create thrust in the desired direction. The first cell, called the Plasma Source Antenna, converts the gas into plasma. The plasma is directed through superconducting magnets into the second cell, called the RF Booster Antenna, which uses electromagnetic waves to heat the plasma to the desired temperature. The heated plasma is then directed through a third cell called the Magnetic Nozzle which directs the flow and created the thrust needed to move the rocket payload in the desired direction.

This process is more efficient than traditional propulsion rockets and can provide significantly more thrust, resulting in faster travel with larger payloads. In addition, the thrust is adjustable, allowing slower trips with higher payloads or faster trips with lower payloads with the same power output. The design is also more reliable than chemical rockets and parts should last longer before requiring replacement.

Chemical vs. Plasma - The exhaust velocity of modern chemical rockets is at least one order of magnitude too small for the needs of fast interplanetary travel. The amount of propellant that must be carried along today constitutes most of the ship's mass and hence leaves little room for useful payload. Its flow rate is so high, that the rocket ship spends it all in a few short bursts. That does not lend itself well for human missions. High exhaust velocity can be achieved by the use of plasma. The temperature of a plasma starts at about 10,000° C. But present day laboratory plasmas can be a thousand times hotter. These temperatures are comparable to those in the interior of our Sun. No known material could survive direct contact with such plasma. Fortunately, plasma responds well to the presence of electric and magnetic fields. A magnetic channel can be constructed to both heat and guide plasma, without ever touching material walls. Magnetized plasmas are envisioned to some day generate abundant energy on Earth by controlled thermonuclear fusion. (Credit: Ad Astra Rocket Company)
Chemical vs. Plasma – The exhaust velocity
of modern chemical rockets is at least
one order of magnitude too small for
the needs of fast interplanetary travel.
The temperature of a plasma starts at
about 10,000° C. But present day laboratory
plasmas can be a thousand times hotter.
These temperatures are comparable to
those in the interior of our Sun.
(Credit: Ad Astra Rocket Company)

Ad Astra founder and former astronaut Dr. Franklin Chang Diaz first began working on plasma rockets at MIT’s Draper Laboratory in 1979 and continued his research at Johnson Space Center from 1994 through 2005 when he left to start Ad Astra. Diaz and his company still have close ties to NASA, expediting a recent agreement to test the VASIMR at ISS. Specific plans for the tests have not been revealed at this time.

While VASIMR would be an invaluable tool for making trips to Mars viable in the near future, initial plans are to use the rocket to haul cargo from low Earth orbit to low lunar orbit. VASIMR could double the current payload maximum of chemical rockets (2000 pounds versus 1000 pounds) when configured for a six month journey between the Earth and Moon.

TFOT has reported on other innovative rocket engine technologies and spacecraft including an antimatter engine using positrons for fuel, a new privately developed lunar lander, an experimental supersonic combustion ramjet, or scramjet, and tests of a methane-powered rocket engine.

Read more about VASIMR and view several videos related to the project at the Ad Astra Rocket Company website here.

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About

Janice Karin has a B.A in physics from the University of Chicago and a M.S. in physics from the University of Pennsylvania. In addition to extensive experience as a technical writer focused on development tools, databases, and APIs, Janice has worked as a freelance reporter, editor, and reviewer with contributions to a variety of technology websites. One of her primary focuses has been on PDAs and mobile devices, but she is interested in many other areas of science and technology.

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