Call me when they hit Warp 1.
Posted on 07/31/2003 8:55:12 AM PDT by RightWhale
NASA's Ion Engine Runs for Nearly 5 Years: No Problems
The future is here for spacecraft propulsion and the trouble-free engine performance that every vehicle operator would like to see, achieved by an ion engine running for a record 30,352 hours at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The engine is a spare of the Deep Space 1 ion engine used during a successful technology demonstration mission that featured a bonus visit to comet Borrelly. It had a design life of 8,000 hours, but researchers kept it running for almost 5 years -- from Oct. 5, 1998, to June 26, 2003 -- in a rare opportunity to fully observe its performance and wear at different power levels throughout the test. This information is vital to future missions that will use ion propulsion, as well as to current research efforts to develop improved ion thrusters.
"Finding new means to explore our solar system -- rapidly, safely and with the highest possible return on investment -- is a key NASA mission," said Colleen Hartman, head of Solar System Exploration at NASA Headquarters, Washington, D.C. "Robust in-space flight technologies such as ion propulsion are critical to this effort and will pioneer a new generation of discovery among our neighboring worlds." While the engine had not yet reached the end of its life, the decision was made to terminate the test because near-term NASA missions using ion propulsion needed analysis data that required inspection of the different engine components. In particular, the inspection of the thruster's discharge chamber, where xenon gas is ionized, is critical for mission designers of the upcoming Dawn mission. Dawn, part of NASA's Discovery Program, will be launched in 2006 to orbit Vesta and Ceres, two of the largest asteroids in the solar system.
"The chamber was in good condition," said John Brophy, JPL's project element manager for the Dawn ion propulsion system. "Most of the components showed wear, but nothing that would have caused near-term failure."
Marc Rayman, former Deep Space 1 project manager, said, "There are many exciting missions into the solar system that would be unaffordable or truly impossible without ion propulsion. This remarkable test shows that the thrusters have the staying power for long duration missions." Ion engines use xenon, the same gas used in photo flash tubes, plasma televisions and some automobile headlights. Deep Space 1 featured the first use of an ion engine as the primary method of propulsion on a NASA spacecraft. That engine was operated for 16,265 hours, the record for operating any propulsion system in space. Ion propulsion systems can be very lightweight, because they can run on just a few grams of xenon gas a day. While the thrust exerted by the engine is quite gentle, its fuel efficiency can reduce trip times and lower launch vehicle costs. This makes it an attractive propulsion system choice for future deep space missions.
"The engine remained under vacuum for the entire test, setting a new record in ion engine endurance testing, a true testament to the tremendous effort and skill of the entire team," said Anita Sengupta, staff engineer in JPL's Advanced Propulsion Technology Group. "This unique scientific opportunity benefits current and potential programs."
"The dedicated work of NASA's Solar Electric Technology Application Readiness test team, led by JPL, continues to exemplify a commitment to engineering excellence," said Les Johnson, who leads the In-Space Propulsion Program at NASA's Marshall Space Flight Center, Huntsville, Ala. "This work, along with significant contributions from NASA's Glenn Research Center in Cleveland, will take NASA's space exploration to the next level."
NASA's next-generation ion propulsion efforts are led by the In-Space Propulsion Program, managed by the Office of Space Science at NASA Headquarters and implemented by the Marshall Center. The program seeks to develop advanced propulsion technologies that will help near and mid-term NASA science missions by significantly reducing cost, mass or travel times. The Jet Propulsion Laboratory is managed for NASA by the California Institute of Technology, Pasadena, Calif.
Call me when they hit Warp 1.
When I worked on the Shuttle, we could see the effects on the orbit of a 0.02 lb "vent" force -- acting on a 230,000 lb Shuttle. If you're patient, you can get a whole lot out of a very little force.
A better engine would have a high specific impulse AND high rate mass ejection. Then instead of fractional g's acceleration, you could get a nice 1g accel for human artificial gravity. You could get to Mars in a few days. Sweet. :-)
The rocket math argues against it, though. You need a LOT of power to accelerate a lot of mass. For example, NASA recently tested a 10kW Hall Effect thruster that was rated at 500 mN of thrust. It takes a lot of mass to produce that kind of power -- wouldn't it be better to wait a little longer, and devote that extra mass to the mission payload?
Actually, the result is about as surprising as the sun rising in the east. The fact that they bothered to do it is testimony to the fact that they really don't have a clue what is worthwhile and what isn't.
There are some fantastic propulsion concepts on the drawing board, but they may never fly because they use politically incorrect technology like nuclear reactors.
Every time I hear some NASA drone talking about how it takes months or years to get to Mars it makes me want to beat my head against the wall. It is probably no harder to develop the advanced propulsion ideas than it is to work out the logistical nightmare of a two year mission.
Deep Space 1 also worked fairly well. The lab bench setup is of course easier to adjust should something get out of spec.
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