Sedna will apparently become closest to the sun in about 70 years.
Doesn't this mean that that this therefore becomes an ideal time to
send an
unmanned mission to Sedna ?

With the current techonolgy, when should a mission be launced so that
it reaches Sedna in the shortest possible time and how long would it
take to
get there ? I guess the probe may have to sling-shot around planets a
couple of times ... ?