ISS in "Moon" role?

Please read the fine print:

"each orbit allows 2 launch windows to the Moon **provided the Moon is
close to the end of the patched conic from that launch point**." So,
how often does THAT happen?





Bjørn Ove Isaksen wrote in message ...
Explorer8939 wrote:
How many times a month does that happen?

As the article stated, 2 times per orbit. A full orbit is about 90 min.
Month of 30 days assumed:
30 days * 24 hour/day * 60 min/hour / 90 min/revolution * 2 times.

=21600 times.

2 times a month.

Explorer8939 wrote:

Please read the fine print:

"each orbit allows 2 launch windows to the Moon **provided the Moon is
close to the end of the patched conic from that launch point**." So,
how often does THAT happen?

Whops. Thanx for correcting me (could'nt realy figure out why *you* would
ask this questinon). As the original poster already has said by now, its
two times. It is basicaly when the velocity vector at the orbits highest
point, points (or is paralell to) the moon-earth forming plane. It is at
the "same time" doing that at its low point. Now the moon has to be in the
dircetion of the velocity vector (forward or backward), so it's two times a
month.

Note that the same would be valid for any inclined orbit wrt. the earth-moon
plane (eg. 28 deg).

Sincerely
Bjørn Ove

John Doe wrote in message ...

If you build the mars ship at 28°, it will probably means that you'll need 2
launches for every module. The module itself, and then a manned rocket to
supervise the docking/berthing and connections, at least until the ship is big
enough to support permanent manned presence. So the argument that building
that ship at a lower inclination would save on number of launches may be moot
once the shuttle has been removed from the equation.

The other advantage of building the mars ship from the ISS is that you will
need a single supply line to keep both the ISS and mars ship running during
construction. And you get to use the Russian Progress/Soyuz as backup should
something fail either with the US launchers, or on the station.

This assumes that ISS's physical dimensions would be compatible with the
Mars ship which (as far as I know) hasn't been designed yet. Is it worth
limiting the design of the Mars ship just so it can be put together at
ISS? I doubt it since that ship design would be something we could use
for the next 20-30 years ideally and ISS isn't going to be around that
long. Makes more sense (to me) to build an assembly facility in orbit
that serves whatever the design of the Mars ship is -- assuming that
automated self-assembly isn't possible.

-McDaniel

Hobbs aka McDaniel wrote:
This assumes that ISS's physical dimensions would be compatible with the
Mars ship which (as far as I know) hasn't been designed yet. Is it worth
limiting the design of the Mars ship just so it can be put together at
ISS?


There are two issues here. First, the Mars ship need not be limited to the
size of ISS, you only need to add some sort of adaptor between the two, very
much like there is one between the russian and US segments.

Secondly, the ISS already has many re-usable designs, for instance, the CBM
hatches which contain intermodule connections for water, air, electricity data
etc, as well a the general design of the tin cans.

If the tooling is retained, then it would cost a lot less to re-use those
designs for the mars ship.

While the interior of the tin cans can probably be reused, they'll probably
have to work out totally different shielding.

Stuff such as rack design, ECLSS etc can be reused. So NASA doesn't need to
start from scratch when designing the Mars ship.

They can probably also use their experience with the ISS truss structure to
build a structural spine along the ship that would distribute the forces of
thrust from engines to each individual module to reduce stress on modules
nearer to the engines.

If they are to have one long ship, then they will have to consider the
possibility of a breach in a module in the middle. Perhaps they should be able
to use the arm to remove the faulty module and replace it with a spare
"tunnel" that would reunite the two segments.

Or, put each module on a track running along the main spine. Normally locked
into place, but if needed, they could unlock modules and move them (instead of
each module being motorized, use the arm to move them). This way, they could
remove a faulty module and push the forward segment back towards the either
segment to close the gap left by the removal of the faulty module.

Upon return to earth orbit, such a design would allow individual modules to be
removed and sent back to earth for refurbishement or replacement for the next mission.

John Doe wrote in message ...
Hobbs aka McDaniel wrote:
This assumes that ISS's physical dimensions would be compatible with the
Mars ship which (as far as I know) hasn't been designed yet. Is it worth
limiting the design of the Mars ship just so it can be put together at
ISS?


There are two issues here. First, the Mars ship need not be limited to the
size of ISS, you only need to add some sort of adaptor between the two, very
much like there is one between the russian and US segments.

Secondly, the ISS already has many re-usable designs, for instance, the CBM
hatches which contain intermodule connections for water, air, electricity data
etc, as well a the general design of the tin cans.

If the tooling is retained, then it would cost a lot less to re-use those
designs for the mars ship.

While the interior of the tin cans can probably be reused, they'll probably
have to work out totally different shielding.

How much volume is required to move the life support, food, living
and work space for a Mars mission crew? How big is the crew? Does
using ISS sized cans rule out building a ship large enough to spin
up some G fraction equivalent or the inhabitants? How big are the
engines? How big is the communications gear? Do we need to assemble
two or three vehicles simultaneously? Oh yeah, how long would it
take willing ISS partner's astronauts to put it all together -assuming
those countries want their ISS crew wearing hard hats.

Lot of unknowables but if you start with the premise that ISS
is the place to build the thing of course you will limit the
design to suit.

Stuff such as rack design, ECLSS etc can be reused. So NASA doesn't need to
start from scratch when designing the Mars ship.

Why let NASA design everything? When the DOD wants a new fighter craft
it gives contractors a list of functional design paramaters and the
best bid wins.

They can probably also use their experience with the ISS truss structure to
build a structural spine along the ship that would distribute the forces of
thrust from engines to each individual module to reduce stress on modules
nearer to the engines.

If they are to have one long ship, then they will have to consider the
possibility of a breach in a module in the middle. Perhaps they should be able
to use the arm to remove the faulty module and replace it with a spare
"tunnel" that would reunite the two segments.

Look at ISS. Removing a module is a lot more complicated than changing
the spare tire on your car because of all the electrical connections.
In fact you might end up with a bigger problem if you disrupt
communication between your command module and the engines or whatever
sensors you have wired up.

Or, put each module on a track running along the main spine. Normally locked
into place, but if needed, they could unlock modules and move them (instead of
each module being motorized, use the arm to move them). This way, they could
remove a faulty module and push the forward segment back towards the either
segment to close the gap left by the removal of the faulty module.

Or don't build the ship at ISS so you won't be limited to having a
linear chain of modules. A circle of cans surrounding a smaller
circle and joined to other similar structures would allow every
can to have up to five solid connections to five other cans.

Upon return to earth orbit, such a design would allow individual modules to be
removed and sent back to earth for refurbishement or replacement for the next mission.

Forget about ISS and you'd be able to consruct 2 or 3 of the
ships faster. One could be left in Mars orbit for years as an orbiting
space station/ management for ground ops and emergency rescue if
needed. The second ship could be run unmanned and be stocked full of
additional consumable supplies. The third ship carries a crew
for a landing. Provided enough provisions the two manned ships
could swap roles allowing for two seperate missions to the surface
of Mars within a single year.

-McDaniel