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Concept art, shows the VASIMR engine powering a moon mission.  (Source: Ad Astra)

The VASIMR engine is of an electric rocket design. This type of rocket is trickier to perfect, but performs better than a chemical rocket, with increased speed, lower costs, and better safety.  (Source: Ad Astra)

A VASIMR engine is shown here in action, generating plasma thrust.  (Source: Ad Astra)

Ad Astra envisions a rich market of spaceflight applications.  (Source: Ad Astra)
Former NASA astronaut turns heads with his innovative engine

Commercial space flight is very expensive.  As a result of its reliance on chemical boosters, the cost of flying a single pound into space aboard the space Shuttle to approximately $5,000 to $6,000.  The cost of launching space missions to far-away bodies such as the Moon or Mars grows exponentially higher -- it is estimated that the cost of sending one pound sent to the Moon is around $200,000.  These extreme costs have put longer manned commercials spaceflight out of reach, with the commercial space industry instead turning to a few luxury tourism startups.

While much of this fuel is expended on launch, some is also expended in the vacuum.  And as longer missions are attempted, the need for more efficient rockets operating in the vacuum increases.

A new engine, named VASIMR, could provide exactly the solution needed.  Developed by former astronaut Franklin Chang Diaz, the engine could change a lot about how we interact with space.  The new rocket, driven by plasma, is able to use cheaper fuels like neon, argon, or hydrogen, while providing finer control over thrust and specific impulse -- two key parameters that determine a rocket's movement and speed.  The new rocket is also much safer and more reliable than traditional chemical rockets, reducing the risks associated with space flight.

The engine exhausts plasma, a fourth state of matter along with solids, liquids, and gases.  Plasma is essentially ionized gas.  It is typically created via either low pressure or extremely high heat (10,000° C or more).  Plasma consists of a mix of electrons and positively charged gas ions.

No known material can contain plasma, so VASIMR instead uses magnetic fields for containment.  It uses radio frequency waves to ignite and throttle the rocket precisely.  The rocket is capable of long burns, with its long term goal being to produce enough sustained thrust and impulse to reach Mars in under three months.

The new engine is the flagship technology of Mr. Diaz's startup, Ad Astra Rocket Company.  After three decades of development at NASA, MIT, and elsewhere, the rocket engine is finally approaching commercial readiness.  The rocket recently passed a momentous milestone -- 200 kilowatts of power, the amount necessary for the company to start developing its flight version.

According to Mr. Diaz, "[Ad Astra is] getting ready to fly the VASIMR engine on the International Space Station (ISS). It is a 200-kilowatt plasma rocket, the most powerful rocket ever built to fly in space, and the prototype is being tested on the ground in our facilities in Houston. We have been gradually ramping up the power over many months, and our goal is to reach 200 kilowatts, which is the power level the rocket will run at on the ISS, and we achieved that today. We actually reached 201 kilowatts. It was a very exciting moment because it happened right when we were in the meeting, and I kept getting text messages."

The rocket will be first tested in space in October 2013, aboard the International Space Station.  Describes Mr. Diaz, "We will install it on the ISS and test it there. After the test is finished, we will use it commercially to reboost the space station [to a higher altitude] to provide the drag compensation. [Currently the ISS requires periodic boosts to get it to the right orbit for space shuttle or Progress dockings.]"

Ad Astra is trying to convince NASA to enter a greater contractual relationship with it to lower costs manned and unmanned space missions, via use of the VASIMR engine.  Given the shaky state of NASA's Shuttle-successor, Orion, that certainly seems possible.  Founder Diaz believes that using commercial bidding and innovation are key to NASA and other international space organizations lowering their costs, as well as the key to getting other commercial entities involved in the space industry.

Mr. Diaz explains, "The agency really transformed the world in space with the achievements of the moon landings, but the whole world changed, and NASA didn't change. NASA remained in the glory days of the past, and 40 years have gone by, and NASA is still the same NASA as the 1960s. And I don't mean it in a bad way. It was so wonderful what was done, and people were completely fascinated by it. But a new opportunity has been created because NASA's fascination with its own past in the present has created a gap, a hole, which is perfect for the private sector to move into.

"The private sector is going to fill the void in rapid access to low earth orbit, allowing NASA to be NASA, to do what NASA was really meant to do, which is look forward to the frontier. Let the private enterprise build the base camp now that we know how to do it, and NASA can go conquer the summit."

The startup is in talks with two space tourism companies -- SpaceX and Orbital Sciences -- to create the body to house the VASIMR engine and finish a contract-ready rocket, which would incorporate efficient chemical boosters to reach orbit and then fire the VASIMR to continue its spaceflight.  Both of these organizations have the advantage of access contracts to the ISS -- Ad Astra is currently trying to figure out which best meets its needs.



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RE: Power =/= Thrust
By stromgald30 on 10/12/2009 1:15:08 PM , Rating: 2
Plasma contains a mix of ions. When you heat almost any gas to the temperatures of plasma, it ionizes. However, unlike ion drives, both positive and negative ions are exhausted together, so there's no need for neutralizing the charge at the exhaust with a cathode.

One of the biggest issues with the VASIMR is the fact that there is a tendency for the plasma ions to follow the magnetic field lines around to the front of the engine (you can't have a magnetic monopole). This would charge up the ship if the ions are cool enough or damage it, if they're still in plasma form. It never comes up in laboratory tests because the way the test cells are set up prevents this problem. It's not an insurmountable engineering problem, just one that requires space trials and careful usage of the engine.

Holding plasma in the chamber is possible, but I'd be more concerned with damage to the engine rather than power (since this thing is supposed to used 24/7). Think of shooting water through a pipe. If the water's fast enough, it won't go into any 90 degree branches off the straight pipe. However, if you try to just hold the water in the pipe or slow the flow, it will expand/fill areas you don't want it to get to. The magnetic field to contain and accelerate the plasma isn't perfect. There will be weak spots. Holding plasma for long periods would be asking for trouble in stray plasma molecules contacting the inside of the chamber.

I don't mean to come off as bashing the new technology, I just know of some limitations and think that it will not completely replace the current chemical engines.


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