Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!usenet.ins.cwru.edu!eagle!news
From: spgreg@earth.lerc.nasa.gov (Greg Macrae)
Newsgroups: sci.space.shuttle
Subject: Re: ion engines.
Message-ID: <1990Oct16.142841.26225@eagle.lerc.nasa.gov>
Date: 16 Oct 90 14:28:41 GMT
References: <1952.2715c044@waikato.ac.nz>
Reply-To: spgreg@earth.lerc.nasa.gov
Organization: NASA Lewis Research Center/Low Thrust Propulsion
Lines: 39
News-Software: VAX/VMS VNEWS 1.3-4

In article <1952.2715c044@waikato.ac.nz>, hamish@waikato.ac.nz writes...
> 
>Just a quick question. What ever happened to the ion rocket research programs?

Ion engine research continued to recieve funding at a low level in the US.  
Much progress has been made since the SERT and SERT II flights your book
was refering to.  (SERT II by the way is still operational as a satellite,
but it is out of fuel, so the ion thrusters cannot be used.)  Research 
also continues in Germany, Great Britain, and Japan.  All three of those
countries have plans to fly ion thrusters.  The only near term US flights 
of electric propulsion systems currently plan to use arcjets, not ion 
thrusters.  The worlds only flight qualified thrusters are available from 
Hughes.  The Japanese thrusters are still in the engineering model stage 
of development.  

For more information on the SERT projects, look for a book by Kerslake and 
Mirtich to be published soon.  

>After that it is said that the ion rocket research was dropped. Why? It's a
>cheap way (especially in payload) to get a fast engine into space. 

True, studies with real payloads suggest that it may even be possible to 
reduce the launch vehicle class by using ion engines.  

>I have faith that if the research was continued that the amount of thrust
>generated would be much higher as well as the reliability. After all it was
>about 25 years ago.

Thrusts are up to the newton range (about 1/4 pound).  The fuel has been 
changed from mercury to xenon or krypton.  Projected lifetimes are greater
than 5000 hours.  (Greater than 10,000 hours life was demonstrated with a
mercury system in 1977.)

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     MacRae                  |       Too curious flower
   NASA LeRC                 |   Watching us pass, met death...
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                             |                      -Basho
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