ion engine was RE: [extropy-chat] Saving the Hubble

[Technotranscendence]

On Tuesday, January 20, 2004 9:11 AM Robert J. Bradbury
bradbury at aeiveos.com wrote:
>> That new SMART-1 ion engine seems to
>> be working well.  How much does one of
>> them cost.  The first was pricey naturally,
>> but now the price should go down, right?
>
> The mission cost was $110m Euros ($126M).

Which still does not tell us how much the propulsion system cost.
Hopefully, it would be much lower than 110M Euros.

>  But the launch costs were defrayed due to
> it piggy backing on an Ariane 5 with 2 large
> communications satellites.

This is true.

> The U.S. also had a ion engine in Deep Space
> 1 and I believe has 1-2 teams at NASA Glenn
> and the JPL working on versions with
> increased thrust.

NASA has done some work, I recall reading, on long-term use of ion
thrust.

> I could see 3 problems with an ion engine
> rescue --
> a) Possibly surrounding the Hubble in a
> cloud of ions    (though one presumably
> has a problem with the exhaust
>     of chemical trusters as well);

My understanding of ion thrust is that the ions are neutralized during
or after exiting as exhaust.  If not, all ion propelled craft would be
lowering their efficiency, no?

> b) the low thrust disrupting telescope
> operations for a longer period
> (remember the Hubble is *heavy*);

That's the killer with current ion engines.  I'd rather use chemical for
this job.  Reliable, well tested, and no need for a lot of fancy
new-fangled development.

> c) the need for the ion engine to take
> up its own solar  panels for power (I
> doubt the designers thought far
>    enough ahead to include a power
> outlet on the outside
>    of the Hubble itself...).

Well, there are more power sources than just solar, e.g., an RTG might
do the trick or having an external power source -- beaming power to the
system.  However, this increases complexity and mission risk.

IIRC, there already is a company out there that that is going to make a
pack to strap on existing satellites, extending their operational life
time.  This might be adopted for the Hubble and might be cheap enough to
privately fund.  (I haven't been following this thread too closely, so I
don't know if anyone else has mentioned that company or private
funding...)

Cheers!

Dan
http://uweb.superlink.net/neptune/