Re: It's In-Line (Shuttle Derived)

On 24 Jun 2005 16:24:31 -0700, in a place far, far away, "Tom Cuddihy"
<tom.cuddihy@xxxxxxxxx> made the phosphor on my monitor glow in such a
way as to indicate that:

>Len wrote:
>> Rand Simberg wrote:
>> >
>> > The vast majority of which is propellant,
>
>is it? I think you actually have to factor in the cost of building and
>maintaining an orbital fuel depot as well.

Of course. There's no reason that it would be that big an expense,
given cheap transport to LEO.

>That includes construction costs, ground operation costs, and launch
>scheduling costs due to being in a particular orbit plane. Put it on
>the ISS and you lose the aid of the earth's rotational velocity.

Few would be foolish enough to do that.

Well, maybe NASA.

>Put it
>on the equator and you restrict launch sites or further reduce payload
>due to plane change requirements.

Only for people dumb enough to design vehicles that are inflexible
with regard to "launch sites."

>You also have to factor in complexites on the mars tranfer vehicle
>stemming from the need for the ability to refuel in LEO. You can't just
>send up an empty Centaur and say git'er done!

Of course not.

>perhaps it can be. However, since this has never yet been attempted,
>you'll also have to develop the hardware, procedures, and successful
>timeline for doing it. A delay in launching enough fuel means a delay
>in launch to Mars, so factor in a big margin.

All of these things are necessary to develop if we want to be
considered a truly spacefaring civilization. Why continue to put off
that day by falling back on failed (in terms of affordability and
sustatainability) methods?

>
>> > We need cheap lift, not heavy lift, if we're to
>> > afford to go to Mars.
>
>Ever seen a comparison of cost per pound to orbit vs. lift capacity?
>Funny, the bigger the overall lift capacity, the cheaper the cost per
>pound to orbit.

Only for a reasonable flight rate. You won't get one out of a heavy
lifter. Why do you continue to flaunt your ignorance of space
transportation economics in a knowledgable newsgroup?
.

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