Dan Minette wrote:
> 
>> Also, to get to the Sun it's cheaper to go to Jupiter and
>> then get back.
>> 
> 
> IIRC, there was a near sun probe that did use Jupiter.
>
Yes, but in this case it was even more critical to
get to Jupiter, because the purpose was to get 
near the North [or South] pole of the Sun. And 
this implies in a change in the orbital inclination,
which is *much* harder than a change in the 
semi-major axis.

For example, if you want to play with numbers, look
at my "Hard SF Tools" page, at...
http://www.geocities.com/albmont/hard-sf.htm

Or, in page...
http://www.geocities.com/albmont/dvorbit.htm
... by inputing Mass = 1 Sun, Inicial orbit =
circular, r = 1 Astronomical Unit, Final orbit
with perihelium at 695000 km [just touching
the Sun's surface], we need a Delta-V of 27 km/s.

By going first to Jupiter [R = 5.2 AU], we use
a Delta-V of 11 km/s, and then we spend another
3 km/s [it's even less, because we may use J's
flyby to save fuel] to get down to the Sun. 

Alberto Monteiro

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