On 12/19/2012 2:05 AM, eles wrote:
Consider the US space shuttle design. It's probably the most wrong-headed
engineering design ever, and it persisted because too many billions of dollars
and careers were invested into it. Nobody could admit that it was an extremely
inefficient and rather crazy design.
Hey, this is really OT, but I'm interested in. Why do you consider it is such a
bad design? Because the shuttle is intended to be reentrant and this is costly?
Some other issue?
Is about the design or about the entire idea?
It boils down to the overriding expense in spaceflight is weight. There's the
notion of "payload", which is the weight of whatever does something useful in
space - the whole point of the mission.
Every bit of weight adds a great deal of more weight in terms of cost to push it
all into orbit.
To make the shuttle return and land, you've got wings, rudder, landing gear,
flight control system, basically a huge amount of weight devoted to that. That
weight subtracts from what you can push up as payload. All of the lifting
capability for that also must be insanely reliable.
(And never mind needing things like a custom 747 to transport it around because
it's too big to go on the roads, all that money spent trying to make a reusable
heat shield, etc.)
Now consider the only thing that actually has to return are the astronauts. And
all they actually need to return is a heatshield and a parachute - i.e. an
Apollo capsule.
Thinking about it from basic principles, you need:
1. astronauts
2. payload
3. a way to get the astronauts back
So the idea then is to have two launches.
1. an insanely reliable rocket to push the astronauts up, and nothing else
2. a less reliable (and hence cheap) heavy lift rocket to push the payload up
The two launches dock in space, astronauts do their job, astronauts return via
their Apollo-style capsule.
Mission accomplished at far, far less cost.