Video of Engine Test
Posted on 10/08/2009 3:02:57 AM PDT by Dallas59
The tests on the ISS would provide periodic boosts to the space station, which gradually drops in altitude due to atmospheric drag. ISS boosts are currently provided by spacecraft with conventional thrusters, which consume about 7.5 tons of propellant per year. By cutting this amount down to 0.3 tons, Chang-Diaz estimates that VASIMR could save NASA millions of dollars per year.
The test last week was the first time that a small-scale prototype of the company's VASIMR (Variable Specific Impulse Magnetoplasma Rocket) rocket engine has been demonstrated at full power.
Plasma, or ion engines uses radio waves to heat gases such as hydrogen, argon, and neon, creating hot plasma. Magnetic fields force the charged plasma out the back of the engine, producing thrust in the opposite direction.
They provide much less thrust at a given moment than do chemical rockets, which means they can't break free of the Earth's gravity on their own. Plus, ion engines only work in a vacuum. But once in space, they can give a continuous push for years, like wind pushing a sailboat, accelerating gradually until the vehicle is moving faster than chemical rockets. They only produce a pound of thrust, but in space that's enough to move 2 tons of cargo.
Due to the high velocity that is possible, less fuel is required than in conventional engines.
Currently, the Dawn spacecraft, on its way to the asteroids Ceres and Vesta, uses ion propulsion, which will enable it to orbit Vesta, then leave and head to Ceres. This isn't possible with conventional rockets. Additionally, in space ion engines have a velocity ten times that of chemical rockets.
Rocket thrust is measured in Newtons (1 Newton is about 1/4 pound). Specific impulse is a way to describe the efficiency of rocket engines, and is measured in time (seconds). It represents the impulse (change in momentum) per unit of propellant. The higher the specific impulse, the less propellant is needed to gain a given amount of momentum.
Dawn's engines have a specific impulse of 3100 seconds and a thrust of 90 mNewtons. A chemical rocket on a spacecraft might have a thrust of up to 500 Newtons, and a specific impulse of less than 1000 seconds.
The VASIMR has 4 Newtons of thrust (0.9 pounds) with a specific impulse of about 6,000 seconds.
The VASIMR has two additional important features that distinguish it from other plasma propulsion systems. It has the ability to vary the exhaust parameters (thrust and specific impulse) in order to optimally match mission requirements. This results in the lowest trip time with the highest payload for a given fuel load.
In addition, VASIMR has no physical electrodes in contact with the plasma, prolonging the engine's lifetime and enabling a higher power density than in other designs.
To make a trip to Mars in 39 days, a 10- to 20-megawatt VASIMR engine ion engine would need to be coupled with nuclear power to dramatically shorten human transit times between planets. The shorter the trip, the less time astronauts would be exposed to space radiation, and a microgravity environment, both of which are significant hurdles for Mars missions.The engine would work by firing continuously during the first half of the flight to accelerate, then turning to deaccelerate the spacecraft for the second half. In addition, VASIMR could permit an abort to Earth if problems developed during the early phases of the mission, a capability not available to conventional engines.
VASIMR could also be adapted to handle the high payloads of robotic missions, and propel cargo missions with a very large payload mass fraction. Trip times and payload mass are major limitations of conventional and nuclear thermal rockets because of their inherently low specific impulse.
Chang-Diaz has been working on the development of the VASIMR concept since 1979, before founding Ad Astra in 2005 to further develop the project.
Cool
To Mars and back in 78 days, neat.
Too bad Mars does not have much atmosphere. It’s kind of wasteful to have to spend half the voyage braking if there were some other way to achieve the deceleration needed at the end.
The very high speed could spell trouble for the craft if encountering a bit of asteroid or comet dust. I’d want to send the first few to Mars unmanned to make sure it could be safely done.
Yes too bad that NASA has determined that Mars consists of rocks and dirt. You would think that looking at rocks and dirt could be accomplished by going to any number of places on this planet, and yet taxpayer money keeps getting squandered on sending stuff to mars.
Here’s another thing to chew over.
Suppose one of these gets built. Now we have a guided, ultra high speed interplanetary missile, weighing a ton or so, which... could quite well be steered in a U-turn and back onto any site on earth after having achieved some ungodly velocity. Tunguska wherever you want it! Now some of these craft get into the hands of the bad guys. Book of Revelation disasters anybody???
Sounds like another reason for the Anglophone nations to get the high ground first.
Using a Space Hammer could quite possibly be a global suicide scenario because of all the debris it would kick into the atmosphere.
There was a thread yesterday on HAARP which mentioned plasma, magnetic fields and charged ions..........Wonder if there's a connection between the two?
In that test, a large directional antenna emitting a very high power beam of microwaves into the sky excited a humanly visible aurora-like display in the upper atmosphere.
Somehow I don’t think we’re going to beat St Helens on the debris/atmosphere front.
This theory was tested on the big centrifuge at Johnsville PA in the late 1950s. Dr. Clark a researcher there believed man could reach Mars in 46 hours if he were under constant acceleration for half the trip and deceleration for half. This would subject an astronaut to 2 Gs for the entire trip. Dr. Clark brought his recliner in from home and rode the machine for 24 straight hours and proved it could be tolerated. By the way the building is now under conversion to a museum. If anyone should want to see the monster machine they can check the website www.nadcmuseum.org for details.
...of course, it’ll shred a human body to bits moving that fast, but we’re working the bugs out...
There is a pretty lengthy list of planetary probes that never made it to Mars.
A cursory look shows that the Rooskies had a lot of computer chip problems.
The US lost it’s share of probes after the initial Mariner mission. It was getting pretty spooky.
The Earth gets hit with about 400 tons of meteors/day. The space rocks we drop on our enemies don’t have to be megaton range. A guided reentry vehicle with 50 tons of rock would wipe out an underground Iranian nuke facility with minimal damage on the surface.
Dropping a few rocks on the bad guys will not cause “nuclear winter”.
That’s not the same as 400 1-ton meteors!
So you read that Niven book, too?
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