[TriLUG] OT -- NASA Shuttle Launch Today
bitmage at pobox.com
Fri Jul 8 12:56:29 EDT 2011
On 07/08/2011 12:40 PM, Joseph Mack NA3T wrote:
> On Fri, 8 Jul 2011, William Chandler wrote:
>> Just a friendly reminder that the Shuttle launch is today at 11:25am.
> Thanks, watching it on the internet is better than being there.
> Anyone know why it takes 2days for the shuttle to reach the ISS? Why
> can't they launch the shuttle to arrive right at the ISS?
More details on the orbital tradeoff from the NASA question archive at
Why is the space station in a 51.6-degree inclined orbit instead of
something less or something more?
The short answer is that 51.6 degrees is the lowest inclination orbit
into which the Russians can directly launch their Soyuz and Progress
spacecraft. Both of these vehicles serve an important role in ISS
operations. The Soyuz -- there is always one attached to ISS -- serves
as an escape vehicle in the event the ISS would need to be abandoned in
an emergency. The Progress spacecraft is basically a cargo version of
the Soyuz and is used to bring up fresh food and supplies to the ISS.
Ideally, one would want to launch due east from a launch site to
maximize the cargo-to-orbit capability for a given launch vehicle. This
is because the Earth, rotating from west to east, gives rockets a "free"
head start in the right direction. Launching due east from Kennedy Space
Center would place the shuttle in a 28.5-degree inclination orbit.
Notice that the inclination is the same as the latitude of KSC.
Launching due east from Russia's main launch site, Baikonur, would place
spacecraft in a 45.6-degree inclination orbit -- the launch site
latitude. However, doing so would also drop the lower stages of the
boosters on China. To avoid this, the Russians crank up the minimum
inclination to 51.6 degrees. Although the shuttle does trade some
payload capacity for propellant needed to make up the difference between
launching at 28.5 degrees vs. 51.6 degrees, doing so allows the Russians
to participate in the ISS program. It also has the added benefit to
Earth Sciences since ISS flies over more of the Earth's surface -- about
75 percent, which covers about 95 about of the inhabited lands -- at the
higher inclination orbit.
And yet less thanks have we than you. Users scowl at us, and reporters
give us scornful names. "Geek" I am to one fat man who lives a firewall
away from foes that would steal his identity or lay his little computer
in ruin, if it was not guarded ceaselessly. Yet we would not have it
Brian Daniels bitmage at pobox.com
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