Wednesday, October 16, 2013

NASA "will be Back in the Meantime" - Ion

First a look at where no man has gone before, that would be Voyager 1.  In April 2013 a blast wave from a massive 2012 Solar eruption reached the Voyager 1 spacecraft in interstellar space.  It caused the plasma around the spacecraft to oscillate in a particular tone and was recorded.

This is huge for mankind we have been able to travel 11 billion miles into deep space and pass through our own Solar System bubble of this year and it's NASA's 55 birthday, nice present.



New NASA Ion Thruster 

We're getting closer to deep space travel, one glitch that's holding us off is fuel the other is radiation but let's have a look at fuel and the engine that might get us there.

NASA's Evolutionary Xenon Thruster (NEXT) project has completed the longest duration test for a Space propulsion system (48,000 hours/5 1/2 years).  This look inside the thruster's discharge chamber shows how it works.



Ion Propulsion

The efficiency of a rocket engine can be described by its specific impulse, which is the change of momentum gained from a 1-kilogram weight of propellant.  The Space Shuttle main engines have a specific impulse of 453 seconds which is typical of a liquid fueled rocket engine.

An Ion thruster has a specific impulse of more than 3000 seconds and so requires less than a sixth of the fuel of a liquid fueled engine.   Gridded electrostatic ion thrusters commonly utilize Xenon gas.  The gas is first ionized by bombarding it with electrons.  The positively charged ions then diffuse through the positive grid and enter a potential difference between the positive and negative grids.  The potential difference accelerates the ions to high velocities, which then leave the engine to create thrust.  An electron emitter, on the exterior of the engine, neutralizes the ion beam to prevent charge build-up.

The typical thrust of an Ion engine is equivalent to a weight of 10 grams - about the weight of a sheet of paper.  This means ion thrusters need to provide continuous thrust for a very long time in order to achieve a reasonable change in velocity. This would be like your car coming off the ramp entering the highway at full throttle, would take four days to reach 60 mph but acceleration would continue on up to 90,000 mph, welcome to the fast lane!

Electrostatic ion engines have been tested for 3.5 years of continuous thrust at full power.  The collision of ions with the charged grids causes their erosion and will lead to eventual failure.  Ion engines consume more than 2 kilowatts of electrical power, which may be generated by solar arrays or nuclear generator.   NASA has developed a Xenon ion thruster called NSTAR for use in their inter-planetary missions. This thruster was tested in the space probe Deep Space 1, launched in 1998. The Dawn mission was launched in September 2007 to explore the dwarf planet Ceres and the asteroid Vesta. To cruise from Earth to its targets it will use three Deep Space 1, heritage, NSTAR thrusters firing only one at a time to take it in a long outward spiral.  The three thrusters are required to meet the lifespan requirement of the engine.

 Joe Montana


The Dinosaur

So like many things on the planet that come to be extinct, the piston engine along with the Banksters and Government shutdown will go the way of the Dinosaur and future generation will be talking of.  Remember the country was on a monetary diet, how the hell did they get anything done?

May the force be with the US, the people.

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