Re: Ion Propulsion
Tue, 10 Jun 1997 14:28:16 -0400 (EDT)

In a message dated 6/10/97 12:13:42 AM, (Michael Lorrey)

>The Air Force's
>Phillips Labs is developing an interorbital tug that uses a thermal
>solar electric generator and an Arc-Jet propulsion system. They hope to
>have it up and operating by late 1998-99. This will allow 100 day
>transfer times between LEO and Geosynch orbits at 1/10th of the cost of
>a current chemical propelled upper stage. Each tug will have enough fuel
>to do 10 missions before needing refueling. Current transfer costs range
>from $10-20 million for a 10,000 lb payload.

I've long thought something like this might be good for cleaning up space
debris (the big stuff, obviously). LEO is getting hazardous, and some people
think that in just a few decades there will be so much stuff up there that
there will be a kind of collision chain reaction catatrophe where debris
smashes other debris into smaller bits which in turn smash other debris until
LEO is full of screws and paint chips flying about at 8 klicks per second.
If that happens, it's a couple hundred years before we can use LEO again and
even crossing LEO would involve meaningful hazard. I understand that current
philosophy for LEO is to make sure jumk and debris falls back into the
atmosphere, but there's a lot of stuff up there already and in higher orbits
this isn't too practical.