669 P.S.

Just comparing Hohmann transfer trajectories, I compute that it takes just
over 1 km/sec delta-V to reach NEO 2000 SG344. By contrast, to get to
Jupiter requires almost 14.5 km/sec delta-V along the same type
trajectory. Not that Hohmann transfer is particularly probable as the
means by which one would get to these places, but it is a way to compare
energies.

Of course, like you said, you can alternatively spend years getting
propellant-free boosts by flybys of Venus and Earth before you head on out
to Jupiter.

If a person in a modern space suit were to stand on the surface of Europa
for 10 minutes, then he or she would look a lot like those guys in K-19
after they came out of the reactor...

Ron
******

Ian Woollard
07/10/03 11:14 AM
Please respond to spacesettlers

To: spacesettlers@yahoogroups.com
cc:
Subject: Re: [spacesettlers] Re: Re 669 P.S.

rmenich@... wrote:

>Jupiter and Europa are way, way, way, way out of bounds as far as energy
>expenditure goes with respect to space settlement activities.
>
Actually, no. The delta-v isn't ridiculous; it's pretty high, but if
you're building large space settlements then it's not out of the question.

The main problem is just that it can take years to get there and come
back, so any ROI is a long time coming. You can play lots of tricks with
gravitational slingshots, and that can speed things up considerably, but
the launch windows have to line up just right for that.

> Everything
>we need for the next 200 years resides within 2.5 AU of the Sun. If we
>go to Jupiter or Europa, it is only with probes for scientific reasons,
>not for space settlement reasons.
>
They're possibly pretty good places to live though; better than most
places I suspect. There's plenty of mass floating around in high
potential energy states in close proximity. That's the problem with
space- it's deficient in mass; so it pays to hang around near to mass
concentrations. All those moons are bound to give you a fantastic mix of
materials to choose from and then there's all the games you can play
with gravitational assists to minimise costs to move around.

>Ron
>******
>
--

-Ian

"If you want to build a ship, don't drum up the workers to gather wood,
divide the work, and give orders. Instead, teach them to yearn for the
vast and endless sea." -Antoine de Saint-Exupery