 |
SMART-1's Ion Drive Not Science Fiction
SMART-1, the European Space Agency craft currently in orbit around the moon, makes use of a technology that was pure science fiction until almost 1960 - the ion drive. An ion drive is a method of propulsion that uses electricity to create charged ions and then accelerate them with a magnetic field, pushing them out the rear of a spacecraft.
The ion drive was first described in science fiction in 1947 by Jack Williamson in a short story published in Astounding Science Fiction called "The Equalizer." In the story, the spacecraft achieves a significant fraction of the speed of light, returning decades later due to time dilation.
George Lucas makes use of ion drives in Star Wars: the old Empire makes use of T.I.E. Fighters as small, manuverable spacecraft. T.I.E. is an acronym for Twin Ion Engines:
US astronaut Edward Gibson published Reach in 1989; this novel features a spacecraft with an ion drive that accelerates atoms of mercury to one percent of the speed of light before sending them out the rear of the craft.
SMART-1 has a stationary plasma thruster using xenon gas with 1190 watts of power available, giving a nominal thrust of 68 mN. The spacecraft contains 48 liters of xenon gas at 150 bar. The lifetime of the thruster is 7,000 hours at maximum power. The thrust is equivalent to two pennies resting in the palm of your hand.
The hexagonal solar panels supply power to a unique propulsion system. Microparticle accelerators propel Ionized gasses at a substantial fraction of lightspeed...
(Read more about T.I.E. Fighters)
(From SMART-1 Ion Drive)
If this seems like a propulsion system that is a bit short of "warp speed," you're right. However, in the frictionless environment of space, even a gentle acceleration like this can produce real velocity if applied constantly over a long enough period of time. Take a look at the path of SMART-1 as it gradually increased its speed, spiralling further and further from Earth before breaking free of Earth's gravity and heading toward the moon. Since a solar panel-equipped ion drive craft only carries the weight of the propellant, and can eject the propellant at significantly greater velocity, such a craft will outperform a spacecraft that uses conventional chemical propulsion over the long run. (Chemical propulsion depends on carrying the weight of the reactant chemical; the exhaust velocity is also significantly less.)
(From SMART-1 Orbital Path)
The US probe Deep Space 1 also used an ion drive, succeeding in its dual missions of flybys of asteroid Braille and Comet Borrelly in 1999. Ion drives have been used in satellites as a way of gently nudging them into higer orbits; the Irridium satellite network made use of ion drive propulsion for positioning and to prevent orbit decay.
SMART 1 has traveled a total of 80 million kilometers in 13 months to reach the moon (due to its spiraling path); Apollo 11 traveled 400,000 kilometers in four days during the first Moon landing mission. On the other hand, the washing machine-sized SMART 1 cost just $85 million.
The early history of the idea of accelerating particles electrically as a means of propulsion goes back as early as 1906, when American scientist Dr. Robert Goddard mentioned the possiblity in his research into rocketry. Dr. Hermann Oberth, a German engineer, introduced Dr. Wernher von Braun to the possibility in the 1930's, and published Possibilities of Space Flight in 1939, devoting a chapter to electric propulsion methods. It was Dr. von Braun who eventually talked NASA into working on a prototype, saying "I wouldn't be a bit surprised if we flew to Mars electrically." The basic principles of the ion drive were tested as early as 1959 at NASA's Glen Research Center; the first working drive was created in 1970. Deep Space 1, launched in 1998, was the first ion drive craft sent into space (read the final technical evaluation of its propulsion system).
The European Space Agency has a very nice website about SMART-1; along with mission objectives and updates, it includes a set of articles about electric spacecraft propulsion. You'll also find some information about ion drives and other science-fictional technologies in the short book Innovative Technologies from Science Fiction. Thanks to David Raitt for pointing these out. See also the comprehensive article Ion propulsion - over 50 years in the making.
Scroll down for more stories in the same category. (Story submitted 11/18/2004)
Follow this kind of news @Technovelgy.| Email | RSS | Blog It | Stumble | del.icio.us | Digg | Reddit |
Would
you like to contribute a story tip?
It's easy:
Get the URL of the story, and the related sf author, and add
it here.
Comment/Join discussion (Back On) ( 3 )
Related News Stories - (" Space Tech ")
The Interplanetary Internet, Vint Cerf Speaking
'This was the center of Interplanetary Communications.'- George O. Smith, 1942.
30-Day Trip To Mars?
'The Federation Ship Champion... made the crossing under Lyle Drive in only nineteen days.'- Robert Heinlein, 1961.
The Atacama Large Millimeter Array - And Fred Hoyle
'Scientifically it would all make a lot more sense in Chile.'- Sir Fred Hoyle, 1973.
Students! NASA's Space Radiation Challenge Is On
'The rocket-water tanks - all around us... that saved us?'- John W. Campbell, 1936.
Technovelgy (that's tech-novel-gee!) is devoted to the creative science inventions and ideas of sf authors. Look for the Invention Category that interests you, the Glossary, the Invention Timeline, or see what's New.
Current News
MIT Robot Cheetah Video Shows Gait Transition
'The legs are long, curled way up to deliver power, like a cheetah's.'
TrackingPoint Smart Rifle
Not your typical 'smart bullet' approach.
'Hello, Computer!' Google Now Highlighted at IO13
'Hello, computer!'
Sky City's 220 Stories Are Go
'It rested among green parklands and... stood in total isolation, a glittering block of whites and flashing windows dotted with colors.'
CARMAT Bioprosthetic Total Human Heart Replacement
'George Walt's corporate existence proved the workability of wholly mechanical organs...'
Personal Sniffer Robots
'...The ticking combinations of the olfactory system of the hound.'
Physical Exam? We've Got Apps
See the future of handheld, personal medical devices.
The Interplanetary Internet, Vint Cerf Speaking
'This was the center of Interplanetary Communications.'
Drosophila Robotica, The Mechanical Fly
'... the Scarab [flying robot] buzzed into the great workroom as any intruding insect might...'
Robo-Raven Flapping Wing Robot Bird
'When he had first built them, they had been crude indeed, flying mechanisms with little more than a reflex-response unit.'
Japan's Nursing Home Robot Plan
Let's make the Roujin Z-0001 Robotic Bed!
Samsung Smart TVs With Gesture Control
'He waved his hand and the circuit switched abruptly.'
Swiss HCPVT Giant Photovoltaic 'Flower'
'...leaning against one of the slender stalks of a sunshade-photocell collector.'
Mini-Livers Made By 3D Printer
Organleggers may experience an employment downturn.
Smartphone Sensor System Tracks Gunfire
'Sound trackers on the roof could zero in on weapons action...'
Bacteria Now Make Biofuel Like Oil
'They have ... germs that eat pretty near anything, and produce oil as a waste product.'
