In article , ff fdfd wrote:
Beyond that, you are rapidly approaching the point where you are likely to
spend more on development than you will save on launch costs.

How is this mission to mars different then then staying on the mir for a
long dururation?

The inability to do regular resupply runs to a Mars expedition in flight.

Ok the russians can ship extra's to the mir at almost
anytime but still they don't count on it.

On the contrary, they did count on regular resupply for certain things.
There was some flexibility, but if all supply shipments had stopped, Mir
would have had to be abandoned.

Moreover, the way they did certain things reflected this. Notably, there
were no laundry facilities on Mir (and if memory serves, there are none on
ISS), so they relied on regular resupply of fresh clothing rather than on
recycling of wash water. (Laundry is the biggest wash-water consumer.)

One reason why ISS is currently running on a two-man crew is that without
the shuttle, they don't have enough water supply to support three for any
length of time.

But they also have a closed enverioment. Like earth to mars would have.

No, they didn't (and ISS doesn't either).
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |