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The Incredible Ions of Space TransportationAfter a successful test during NASA's Deep Space 1 mission, scientists say ion propulsion is here to stay. |
After a development history spanning nearly 40 years and following
the successful flight of Deep
Space 1 in 1998-1999, ion propulsion has now entered the
mainstream of propulsion options available for deep-space missions,
according to an abstract written by Brophy.
But there was a catch that scientists soon discovered. "While it was easy to make the engines perform well, it was very hard to make them last." CONTINUES AFTER SIDEBAR
However, no one was ready to give up on these engines. NASA
scientists continued to work on solutions to the longevity problem.
Then, in 1992, NASA started the NSTAR (NASA Solar Electric Propulsion
Technology Application Readiness) program, which had at its core
the removal of the barriers to using ion propulsion on deep space
missions. There were two main problems that stood in the way
of successfully demonstrating the ion propulsion systems.
After several more years of work, the NSTAR ion propulsion system was ready to be tested on Deep Space 1. However, as with many long term projects, there were issues to be resolved before the system could actually fly. "We were told that the Deep Space 1 project could not afford to build the solar array that would be required to fly the ion propulsion system, but that NASA would fly it if we could find a free solar array to use," said Brophy. "Fortunately, we found one. The Ballistic Missile Defense Organization (BMDO) had an advanced solar array that they wanted tested, so they provided it to NASA." Deep Space 1, outfitted with BMDO's solar array and the NSTAR ion propulsion system was a success, with both working exactly as planned. New demands have followed for ion systems with increased capabilities. ![]() "The NSTAR system was conservative on purpose," said Brophy. "We wanted to see if it would work first. Now it is a legitimate option that is being considered for many new missions." Brophy explained that many of the deep-space missions that are relatively easy to perform from a propulsion standpoint, such as planetary flybys, have already been accomplished. However, future high priority mission classes, which include sample returns and outer planet orbiters, place substantially greater demands on the onboard propulsion systems. Ion propulsion systems make missions more affordable and scientifically more attractive by enabling the use of much smaller, lower cost launch vehicles, and by reducing flight times, according to Brophy. Some proposed mission concepts considering ion propulsion include the Comet Nucleus Sampler Return (CNSR), the Saturn Ring Observer, the Titan Explorer, the Neptune Orbiter, and the Europa Lander. ![]() Left: This artist's rendering shows the Rosetta Lander sitting on the nucleus of comet Wirtanen after the Rosetta spacecraft arrives in 2011. Propulsion experts think that improved ion engines could eventually propel space probes to nearby comets and asteroids faster than conventional engines. Image Credit: ESA. Despite the great possibilities presented by the successful flight of Deep Space 1, scientists are still working on improvements to the current ion propulsion technology needed for future planetary missions. "At the moment, we are mostly working on improving how long the thrusters last," said Brophy. "We are hoping to double the engines' designed operating time, which is approximately 1 year at full power." |
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Propulsion Concepts -- from the Jet Propulsion Laboratory Ion Propulsion on DS1 -- JPL June 9, 2000: A Little Physics and a Lot of String - Using space tethers for propulsion. May 31, 2000: Advanced Space Propulsion Conference - Scientists meet to discuss the latest in space transportation. May 29, 2000: What's the Matter with
Antimatter?-
It may be the ultimate fuel
for space travel, but right now antimatter is fleeting, difficult
to work with, and measured in atoms not pounds! Stories from the
1999 Space Propulsion Workshop: |
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