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From: earle@smeagol.UUCP (Greg Earle)
Newsgroups: net.space
Subject: Re: Mt Shasta on Uranian moon!!
Message-ID: <578@smeagol.UUCP>
Date: Thu, 30-Jan-86 22:44:45 EST
Article-I.D.: smeagol.578
Posted: Thu Jan 30 22:44:45 1986
Date-Received: Sat, 1-Feb-86 21:40:40 EST
References: <8601261231.AA04077@s1-b.arpa>
Organization: Spacecraft Data Systems, JPL, Pasadena, CA
Lines: 21

> When are we gonna get that damn ion rocket developed so we can send
> Mariner/Viking/Galileo-class spacecraft (orbiter/lander) to all the outer
> planets without having to wait ten years to get the craft to the very outer
> ones via gravity-assist from the nearer ones? 

(a) They're working on it.

(b) You (and everyone in net.spaceland) should be grateful for what you got,
because it so happens that the relative positioning of Jupiter-Saturn-Uranus,
that allowed Voyager to make it to Uranus in 'only' 8.5 years, only happens
once in *175* years, and it's happening *now*.  Without a major-league 
improvement in propulsion systems (and they have to operate with low mass
fuel supplies, so as to not make the thing a huge fat blimpo when it takes 
off), you and I are not likely to see *any* outer planet missions within our
remaining lifetime.  It would normally (given random relative positions)
take up to *30* years to get to Uranus, much less get to Neptune at all.

	Greg Earle
	JPL
	sdcrdcf!smeagol!earle (UUCP)
	ia-sun2!smeagol!earle!csvax.caltech.edu (ARPA)