Space Station to Mars?

Just an out of interest question. If the space station is the biggest best
thing built in space instead why dont they send that to mars but take a few
years going there.
I read that it goes at approximate 390 km already.
Cant they add engine to that and do that??
What are the implications of doing that realisticly.

"Micky Fin" wrote in
:

Just an out of interest question. If the space station is the biggest
best thing built in space instead why dont they send that to mars but
take a few years going there.
I read that it goes at approximate 390 km already.
Cant they add engine to that and do that??
What are the implications of doing that realisticly.

It's not realistic at all.

Boosting a spacecraft to escape velocity requires a lot of delta-V. There
are two ways to obtain that delta-V: with conventional high-thrust
propulsion, or with low-thrust propulsion.

High-thrust propulsion requires a lot of propellant. The Apollo CSM/LM
stack had a mass of about 50 tons, and required a nearly fully-fueled S-IVB
stage to boost it from low Earth orbit to the moon. ISS has a mass almost
four times that of the CSM/LM, so it will require a rocket stage almost
four times the size of an S-IVB to boost it to Mars. There is no rocket in
the world that can launch a stage that large. You could do it with existing
rockets, but it will require many. many launches and in-orbit refueling of
the stage. That is problematic because the most efficient fuel, liquid
hydrogen, boils off over time, so the launches would have to be
accomplished quickly. Either that or use a less efficient fuel, which
requires more fuel mass. ISS was also not designed for high structural
loading - a thrust comparable to the J-2 engine that powered the S-IVB
stage would almost certainly rip the truss and solar arrays right off, and
would probably overstress the interfaces between the modules as well,
especially those normal to the thrust vector.

Low-thrust propulsion requires the booster to follow a trajectory that
slowly spirals out of low Earth orbit until it reaches escape velocity.
That subjects the station to a very prolonged exposure to the radiation in
the Van Allen belts, which the station was not designed to take. The
station would have to be unmanned for this, since no human could tolerate
the radiation doses involved (the Apollo astronauts had no trouble with
this because their high-thrust S-IVB boosted them through the Van Allen
belts quickly). This is bad news for the station, since it requires
frequent human maintenance and probably would suffer a breakdown during
passage through the Van Allen belts. With no crew aboard to fix it, the
station systems would die.

Either way, once the station has been boosted out of low Earth orbit, it is
well outside its design environment. Its thermal control system has been
designed to take advantage of the night side of Earth orbit to cool off,
something it could no longer do once it leaves Earth orbit. The US segment
relies on GPS for navigation, and would not operate for long once the
station is boosted above the GPS constellation. The Russian segment won't
fare much better; it uses infrared horizon sensors that would be rendered
useless once far from Earth.

And I'm not even going to get into the whole messy problem of how to
decelerate ISS once it arrives at Mars.

Bottom line is that it is not a smart idea to try to take ISS beyond low
Earth orbit.


--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

On Thu, 8 Apr 2004 22:49:52 +0100, "Micky Fin"
wrote:

Just an out of interest question. If the space station is the biggest best
thing built in space instead why dont they send that to mars but take a few
years going there.
I read that it goes at approximate 390 km already.
Cant they add engine to that and do that??
What are the implications of doing that realisticly.

The Space Station wasn't designed for interplanetary travel. You are
asking the equivalent of taking the Staten Island Ferry across the
ocean to Europe. Sure, if you work hard enough you could probably do
it, but you'll be far better off building a new ship for that job.


Brian

on 08 Apr 2004 23:42:35 GMT, Jorge R. Frank sez:
` "Micky Fin" wrote in
` :

` Just an out of interest question. If the space station is the biggest
` best thing built in space instead why dont they send that to mars but
` take a few years going there.
` I read that it goes at approximate 390 km already.
` Cant they add engine to that and do that??
` What are the implications of doing that realisticly.

` It's not realistic at all.

` Boosting a spacecraft to escape velocity requires a lot of delta-V. There
` are two ways to obtain that delta-V: with conventional high-thrust
` propulsion, or with low-thrust propulsion.

` High-thrust propulsion requires a lot of propellant. The Apollo CSM/LM
` stack had a mass of about 50 tons, and required a nearly fully-fueled S-IVB
` stage to boost it from low Earth orbit to the moon. ISS has a mass almost
` four times that of the CSM/LM, so it will require a rocket stage almost
` four times the size of an S-IVB to boost it to Mars. There is no rocket in
` the world that can launch a stage that large. You could do it with existing
` rockets, but it will require many. many launches and in-orbit refueling of
` the stage. That is problematic because the most efficient fuel, liquid
` hydrogen, boils off over time, so the launches would have to be
` accomplished quickly. Either that or use a less efficient fuel, which
` requires more fuel mass. ISS was also not designed for high structural
` loading - a thrust comparable to the J-2 engine that powered the S-IVB
` stage would almost certainly rip the truss and solar arrays right off, and
` would probably overstress the interfaces between the modules as well,
` especially those normal to the thrust vector.

` Low-thrust propulsion requires the booster to follow a trajectory that
` slowly spirals out of low Earth orbit until it reaches escape velocity.
` That subjects the station to a very prolonged exposure to the radiation in
` the Van Allen belts, which the station was not designed to take. The
` station would have to be unmanned for this, since no human could tolerate
` the radiation doses involved (the Apollo astronauts had no trouble with
` this because their high-thrust S-IVB boosted them through the Van Allen
` belts quickly). This is bad news for the station, since it requires
` frequent human maintenance and probably would suffer a breakdown during
` passage through the Van Allen belts. With no crew aboard to fix it, the
` station systems would die.

` Either way, once the station has been boosted out of low Earth orbit, it is
` well outside its design environment. Its thermal control system has been
` designed to take advantage of the night side of Earth orbit to cool off,
` something it could no longer do once it leaves Earth orbit. The US segment
` relies on GPS for navigation, and would not operate for long once the
` station is boosted above the GPS constellation. The Russian segment won't
` fare much better; it uses infrared horizon sensors that would be rendered
` useless once far from Earth.

` And I'm not even going to get into the whole messy problem of how to
` decelerate ISS once it arrives at Mars.

` Bottom line is that it is not a smart idea to try to take ISS beyond low
` Earth orbit.


` --
` JRF

Boy, I hope the original poster appreciates the quality of this
thorough and lucid (and civil!) reply. Well done Jorge.


--
================================================== ========================
Pete Vincent
Disclaimer: all I know I learned from reading Usenet.

Jorge R. Frank wrote:
|Either way, once the station has been boosted out of low Earth orbit,
|it is well outside its design environment.

Okay.

|Its thermal control system has been designed to take advantage of the
|night side of Earth orbit to cool off, something it could no longer do
|once it leaves Earth orbit.

For a large 'interplanetary' ship, how DOES one go about cooling it
off? Can't a continuous rotational spin do the same job? If the
walls are too thin, the rapid heating and cooling will cause cracks?

|The US segment relies on GPS for navigation, and would not operate
|for long once the station is boosted above the GPS constellation. The
|Russian segment won't fare much better; it uses infrared horizon
|sensors that would be rendered useless once far from Earth.

Well, what two or three brightest objects are in the night sky, once
the ship leaves Earth orbit? I would assume that a spinning ship
will maintain its spin at a very constant rate, and that the apparent
rising and setting of the Sun, the Moon, and Mars - combined with
some trigonometric figures arrived at by bringing Jupiter, Saturn,
and Venus into the equation will produce a fairly good three axis
locus for the Interplanetary Ship.

|And I'm not even going to get into the whole messy problem of how to
|decelerate ISS once it arrives at Mars.

That's why the Interplanetary Space Ship should not be manned until
much later - perhaps well after arriving at a high orbit over Mars.

|Bottom line is that it is not a smart idea to try to take ISS beyond low
|Earth orbit.

Can you suggest a link that lists the architectural specifics of a
ship that *is* capable of going to Mars? Even if it is unmanned?
The advantage of deploying an unmanned Mars Orbital Station first
is that the broadcasting of a navigational beacon from that point
will facilitate future trips to Mars.

The very first Mars Orbital Station should be unmanned, but that
said, it should also have some kind of habitation for the purpose
of maintaining it.

||Its thermal control system has been designed to take advantage of the
||night side of Earth orbit to cool off, something it could no longer do
||once it leaves Earth orbit.
|
|For a large 'interplanetary' ship, how DOES one go about cooling it
|off? Can't a continuous rotational spin do the same job? If the
|walls are too thin, the rapid heating and cooling will cause cracks?

If it is caused to spin at a particular rate, the "poles" that are
more constantly exposed to heat, will probably be the danger areas,
right? So pumping a coolant (such as water) into the area and back
out of it, should be enough to cool it. Or am I looking at this
too simplistically?

Thankyou for your explanation... It was interesting. You raised stuff Id not
thought of. Couple of points I should have perhaps clarified though. When I
posted that question I was thinking more along the lines that you would have
to reshuffle the stations pods and general layout to get there for sure...
etc, ie take down the solor panels and have some addtional storage pods, and
some more secure chambers for the people. In my thinking I thought it might
of been posible if instead of trying to go to mars on super duper thrust
they just did it taking slightly more time etc.
And used all the current pods that exsisit for storage etc. They would have
to then add admitdly something to get down to the surface of mars...

I must admit looking at the shape of the station I really cant understand
why it has been designed like that. It looks a mess. I know the solar panels
need to span a mass of area but I cant see why they didnt built it so it
could be sent places one day....
Why was this...???



"Micky Fin" wrote in message
...
Just an out of interest question. If the space station is the biggest best
thing built in space instead why dont they send that to mars but take a
few
years going there.
I read that it goes at approximate 390 km already.
Cant they add engine to that and do that??
What are the implications of doing that realisticly.

I enjoyed yours reply.
Thank you, Jorge R. Frank

The question reminded me are a
Star Trek: Deep Space Nine plot.
The fictional space station more
robust.

On Fri, 9 Apr 2004 05:54:30 -0700, "William A. Noyes"
wrote:


I enjoyed yours reply.
Thank you, Jorge R. Frank

The question reminded me are a
Star Trek: Deep Space Nine plot.
The fictional space station more
robust.

The fictional DS9 also had force fields, matter/antimatter reactors
and "inertial dampeners" to allow it to be moved from orbit above
Bajor to the Denorius Belt, where the wormhole was discovered.

Brian

On Fri, 9 Apr 2004 10:45:03 +0100, in a place far, far away, "Micky
Fin" made the phosphor on my monitor glow in
such a way as to indicate that:

I must admit looking at the shape of the station I really cant understand
why it has been designed like that. It looks a mess. I know the solar panels
need to span a mass of area but I cant see why they didnt built it so it
could be sent places one day....
Why was this...???

Because there were never any plans to do so, and trying to make it
serve such a purpose would have been much more expensive, and made it
less effective as a space station.