Re: Flight Test Vasimr?


Henry Spencer wrote:
> In article <Xns9746B25CFD0Clkajehoriuasldfjknak@xxxxxxxxxxxxxx>,
> John Schutkeker <jschutkeker@xxxxxxxxxxxxxxxxxxxx> wrote:
> >What's the current status of Vasimr, and what problems need to be solved
> >before Nasa can flight test a unit?
>
> Well, building a *ground*-test unit would be a good start. (There is no
> VASIMR engine, to date -- some experimental work has been done on major
> components, but the engine as a whole remains a paper concept.)

On the contrary, Henry, they are testing a laboratory model of the
engine.
http://spaceflight.nasa.gov/shuttle/support/researching/aspl/reference/g_aiaaass2004.pdf
http://www.nasa.gov/audience/foreducators/k-4/features/F_Engine_That_Does_More.html

"After VASIMR completes some additional Earthbound testing, its
designers hope for it to be tested in orbit on board the International
Space Station (ISS). A prototype engine would be mounted on the ISS's
truss to demonstrate how it works. The prototype would draw its
electrical power from the solar panels on the ISS. If the test were
successful, the VASIMR prototype could be moved to a different part of
the ISS and used to help keep it in orbit. While ISS orbits the Earth,
atmospheric drag gradually pulls it closer to the Earth. Every so
often, the ISS has to be boosted back into a higher orbit. This is done
by a variety of means, but all of them require fuel launched into orbit
from Earth. The VASIMR engine, however, could change that, since it
would use hydrogen, which is already generated as a waste product on
the ISS. By using waste hydrogen and electricity from the solar panels
of the ISS, VASIMR could maintain the ISS's orbit without requiring any
additional fuel. "This is very exciting for us, because NASA would be
able to solve a very serious problem," he said.

Although VASIMR is still years away from being used in space,
Chang-Diaz said that it has already shown great promise during tests on
Earth. "

>
> Showing a reason why it's better than assorted competitors -- aside from
> the fact that its would-be developers issue more press releases -- would
> also be good.

There is a good argument to be made that its low end performance isn't
much better than other electric propulsion concepts. It requires much
larger power sources to operate in the full range of its performance,
but it is fully throttlable from a few dozen lbs thrust at max thrust
with Isp typical of plasma engines, to over 30,000 secs Isp at its most
lean, when it is using all three stages of its engine. What this means
is that it can take less time to get out of earth orbit than any other
electric propulsion system (less than 30 days) and accelerate to
significant velocity on an interplanetary trajectory that is rather
direct, then lean to a low acceleration level at extremely high Isp to
use almost no fuel for the duration of the voyage until orbital
insertion. This is an advantage that a fission propulsion system does
not have, being limited to Isps of 600-1000, and while Mars is at the
inner limit of the range at which VASIMR is more advantageous to use
over nuclear or chemical, the propulsion systems advantages over longer
voyages to the jovians, kuiper belt, etc are quite clear, especially if
we ever plan on going anywhere other than sending tiny robot probes. If
we ever voyage to Xena, Santa, or the other KBOs, this propulsion
system will be necessary.

In addition, it is broadly believed that the technology of VASIMR is
the best stepping stone to controlled fusion propulsion and power
generation, and for this reason should be considered the primary
propulsion technology to focus next generation R&D resources on. Could
this be why the oil industry-beholden Bush administration is apparently
trying to kill the technology? Perhaps.

.

Relevant Pages

  • Re: Flight Test Vasimr?
    ... > What's the current status of Vasimr, and what problems need to be ... > electrical power from the solar panels on the ISS. ... > the ISS and used to help keep it in orbit. ... > much better than other electric propulsion concepts. ...
    (sci.space.policy)
  • Re: Flight Test Vasimr?
    ... > What's the current status of Vasimr, and what problems need to be ... > electrical power from the solar panels on the ISS. ... > the ISS and used to help keep it in orbit. ... > much better than other electric propulsion concepts. ...
    (sci.space.policy)