Reusable boosters in moon missions

[Paul Colby]

TL;DR Summary

Wonder how the system trade to use single use launch systems works out?

I’m with everyone else cheering the Artemis launch and the whole return to the moon bit, but I can’t quite see why reusable booster technology wasn’t used. I realize trade studies are just that, studies. So an answer might be complex. The standard answer is reusable boosters can’t lift as much. Fine, divide and conquer.

Let’s say the cost of a single use rocket to lift a payload of weight X is C. If I take out my chainsaw and hack X into say N chunks and use one reusable rocket to orbit the N chunks which I assemble on orbit, then the launch costs is ND where D is the cost of one reusable flight. All I need is that ND << C. So, Artemis launch costs are in the tens of billions while reusable systems are in the tens of millions. I assume this argument hold no water and I would like to know why.

 

[FactChecker]

This may be a case where the marginal cost savings is not worth the added complexity. The initial test of a new unmanned flight to the moon is incredibly expensive and already very complicated. It might not be the right time to save (relatively) pennies at the cost of adding more complexity and risk. Eventually, that might change.

 

[Paul Colby]

What I have trouble with is the enormous nonrecurring engineering cost of developing a special purpose single use rocket. I suspect the current fleet of reusable boosters didn’t exist when the trades were made Is the simple answer.

 

[anorlunda]

SpaceX works on a trial and error basis. SpaceX tolerates many (even dozens) of failures before success. They learn from each failure.

NASA tolerates no failures. They attempt to design, test and launch with zero failures after launch. As a result, their design and test cycles are must longer and more expensive than SpaceX's. This culture goes all the way back to the 60s. The Saturn V series used for the Apollo Project never experienced a failure at or after launch. Zero.

Many people in the traditional space industries were stunned at how fast SpaceX could innovate.

 

[FactChecker]

SpaceX works on a trial and error basis. SpaceX tolerates many (even dozens) of failures before success. They learn from each failure.

NASA tolerates no failures. They attempt to design, test and launch with zero failures after launch. As a result, their design and test cycles are must longer and more expensive than SpaceX's. This culture goes all the way back to the 60s. The Saturn V series used for the Apollo Project never experienced a failure at or after launch. Zero.

Many people in the traditional space industries were stunned at how fast SpaceX could innovate.

Even after the development, I am skeptical that the business culture can support space travel without unacceptable failure rates. For instance, the tendency to cut corners in nuclear energy has never been fully conquered. Occasional disasters result. I don't know if any commercial business can do much better for space travel.

 

[Paul Colby]

SpaceX failure rate at launching satellites is quite low. Also, they have gotten people to and from the ISS. In addition, NASA need not use SpaceX as the only contractor on a project. It’s typical for them to use many.

For the cost of Artemis I would have been tempted to switch approaches as SpaceX technologies matured rather than just slogging on through. Oddly enough, they never contacted me :)