[ExI] Inflatable tower could climb to the edge of space

spike spike66 at att.net
Mon Jun 15 14:05:07 UTC 2009


> -----Original Message-----
> From: extropy-chat-bounces at lists.extropy.org 
> [mailto:extropy-chat-bounces at lists.extropy.org] On Behalf Of 
> dan_ust at yahoo.com
> Sent: Monday, June 15, 2009 5:52 AM
> To: ExI chat list
> Subject: Re: [ExI] Inflatable tower could climb to the edge of space
> --- On Fri, 6/12/09, spike <spike66 at att.net> wrote:
> > ...If so, then this project will require 
> Chinese money 
> > and a nearly equatorial latitude... Keith do you 
> recall where 
> > that is?
> The powersats themselves should be on an GEO orbit, no?  By 
> launching from low latitude is not required.
> Regards,
> Dan

Dan there is a big advantage to launching near the equator, especially if we
have a lot of payload going up.  Consider, there are atmospheric losses
during launch, so we need to punch thru it as quickly as possible (Keith's
pop up and push notion launches almost vertically).  

Upon achieving orbit, the inclination of the orbit is the latitude of
launch.  So if an equatorial orbit is needed, a good rule to know is that it
requires as much delta vee to change an orbit pi/2 as it has velocity to
start with.

For instance, if a satellite is orbiting at 7 km per second, and it is at a
Florida latitude of 27 degrees, then the delta vee needed to get to an
equatorial orbit is 7*27/90 or 2.1 km per second of delta vee, which
represents about half of your intial payload, assuming chemical propulsion.
What I mean by that last sentence is this: if you are in a 27 degree orbit
with a payload, and you need to get to 0 degrees, so you need 2.1 km/sec,
then half of your payload mass must be propellant.  Actually it is over
half.  Orbit inclination changes are costly.  So low latitude launch sites
are your friends.


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