By-Pass the Moon?

> Because launch costs are so high it's impossible to replace a component that
> breaks during or just after launch. So everything has to be designed to
> extremely high standards of reliability, and have identical copies tested
> for this realiability in extreme enviroments. They also have to be extremely
> light weight.

To a large extent, the same can be said about aircraft.

>(Space is a vacuum and a vacuum cannot have
>temperature. But you wouldn't know that from NASA press briefings on the
>subject!)

Near Earth space is a near vacuum, so technically the temperature is whatever the temperature of those few remaining molecules is. For spacecraft design purposes, tho, the only temperature that matters is the temperature at which the spacecraft will reach thermal equilibrium. This is higher in near earth space than on Earth itself because, there just isn't enough air to carry that heat away through convection. Instead, radiation must be relied upon, and that only becomes sufficient to balance the heat from the sun at fairly high temperatures. This is a significant issue in spacecraft design, but is not an issue once that design has been finalized and metal is being cut. Issues like this are why I want cheaper spacecraft designed, and for assembly-line asteroid probes and the like to be used instead of NASA's current paradigm of designing a new one every flight. Spacecraft design and integration is the hard part, not hardware.

> Compare and contrast with a reliable reusable rocket. If you want to go to
> the moon, you don't design, or build or even own one of these rockets; you
> rent cargo space. Put one of these in orbit and refuel it

We have expendable launch vehicles. The closest thing we have to a reusable launch vehicle is NASA's Space Shuttle. Expendables currently fly less than 5 times per year for any given model, and in some cases only once per year (Taurus, Pegasus etc.). Everybody loves to complain about the cost of those. Space Shuttles currently fly about 5 times per year, and are much less economical per flight. And much more expensive than originally planned. What stands out to me, however is not how inefficient these vehicles are now, but how far below intended capacity they all are. EELV's were originally designed based on a flight rate of at least 8 per year. Both models are flying at well below half that rate, and nearly double the cost per launch advertised. The Shuttle was originally planned to fly 60 (!!!!!) times per year, and was supposed to cost well under $100m in todays dollars. Instead, they now cost over half-billion per launch, and fly less than 1/10 as often as
once hoped for. Sounds to me like launch rate is what is wreaking havoc with the industry. Antonio Elias, Pagasus chief designer said a little while ago RLV's only become more economical at flight rates of around 50-60 per year (Shuttle's originally planned rate, BTW).

Spacecraft cost a lot to develop. They usually fly once per model/design. Launch vehicles cost a lot to develop. Each design flies many times. If anything, I favor reusable spacecraft or multi mission spacecraft designs before RLV's.

If you're using a reusable rocket for ascent/decent to and from the lunar surface, that might work at decent economies of scale. It might even raise ELV or RLV flight rates enough to make most designs economical. But still to me, that seems to be relying on reuse of spacecraft or making cheaper ones before bringing Earth launch costs down.

Sincerely
Michael

"It is better to fail in originality than to succeed in imitation."
-Herman Melville