Non sequitur.The airlines do not separate crew from cargo. Nor do they use “crew” to include both flight crew and passengers — an annoying malpropism NASA has introduced into the English language.

Passengers and cargo may or may not be separated onto different flights or different types of airplanes. Cargo and crew are never, ever separated onto different airplanes. The reason why cargo flights are not unpiloted can be summed up in two words: money and reliability.

Mr Wright: I was not arguing cost and I was not suggesting building new Saturn 5’s. I was only pointing out the waste involved in relying on a single all-purpose vehicle because, at the last, you’d be sending crews up in otherwise empty vehicles. Airlines don’t fly jumbo jets on routes that only generate a handful of passengers, and they don’t buy or fly kind of all-purpose aircraft. There’s reason for that and they work for space vehicles as well.

Let’s see. Assume you fly to orbit 5 times a week, with two weeks for annual maintenance. That’s 250 trips a year. In one year, this hypothetical vehicle can carry 125 tons — the equivalent of one Skylab — plus 1250 passengers.

A fleet of four such vehicles could launch the equivalent of four Skylabs plus 6000 passengers a year.

A fleet of 40 could launch the equivalent of 40 Skylabs plus 60,000 passengers.

> Working constuction I can tell you, “Not a whole lot”.

Not a whole lot compared to terrestrial construction, perhaps, but a hell of a lot compared to anything NASA has done, is doing, or is planning to do.

> The heavy hauling is left to dump trucks, 18-wheelers, and cranes.

Yes, because the amount of material hauled on Earth is orders of magnitude more than anything we’re contemplating in space. It may be efficient to use dump trucks, 18-wheelers, and cranes to build the MGM Grand. That doesn’t mean it’s cost-effective to use them for building an outhouse at a Scout Camp. Especially if you have to develop a dump truck, and 18-wheeler, and a crane and assign all the costs to the construction of the outhouse.

> I’ve never seen one carry an integral part of the project onto the site,
> though, they are pretty much useless for that.

That means you’ve never seen a small home improvement project.

> Substitute “half-ton truck” with “Space Shuttle” and “large
> construction project” with “International Space Station”, and
> you’ll see what I am getting at.

I don’t see what you’re getting at. The Shuttle is not a half-ton truck; its cargo bed has the same capacity as an 18-wheeler. Depending on an expensive, unreliable heavy lifter did not make ISS go smoothly. If we had a dependable “half-ton truck,” we could have real space stations in orbit now — with thousands of visitors a year.

“Not a whole lot” by Las Vegas standards, but not too shabby by space standards.

Are there not two types of cargo – on Earth, as it is in heaven??? Cheap and expensive? A Hubble Space Telesope is expensive cargo, while water, food, laundry, is perishable and should be cheap? But with the shuttle all mail is first class – no way to minimize cargo class cost, and I am not saying to do so.

There is some cargo I would not want to lose, but there is a lot of junk mail in my mail box I could live without. We need to learn how to make cargo cheaper to begin with – mass production.

Regarding launch escape, without data it is all just hype. We gave up LES after November ’63 or so with Apollo, thinking failure no longer an option. I don’t watch batman. Automakers crash test vehicles in various failure modes to collect data. There is no data collection with rockets LES’s for low or high altitude or fast or slow or failure mode, so no need for you or I to speculate. We can hypothesize… a version of the LES did save a couple Cosmonauts, but that is just one datapoint. I’ve seen too many space shuttle is this or that reliabilities based upon many good and one bad datapoints … now 2 bad datapoints.

I’d like to see more testing. I’d like to see a developmental space agency.

How do you propose to make unmanned flights as reliable as manned flights? Even in aviation, unmanned vehicles are orders of magnitude less reliable. Why would you expect unmanned space to be different in that regard?

> The point about higher margins of safety for manned flights is well taken
> though. I just think that our expectations as far as overall reliability of
> launch vehicles have been set far too low for the past few decades. By now,
> we should be able to design a launch vehicle that does not inadvertently
> shed large pieces of itself under normal operating conditions.

We can, but first we have to design not to *advertently* shed larges of themselves in normal operations.

If you had a reliable low-cost vehicle, why would you continue flying cargo on the Saturn V at 100 times the cost? That’s not an argument for separating crew from cargo, it’s an argument against the Saturn V.

> If you separate crew from cargo to low Earth orbit, you can concentrate
> on a gemini sized vehicle with launch escape system, and continuous
> improvement of reliability, bail-out, and minimize size and cost.

Don’t mistake bail-out for what you see on TV, where a gentle puff of air tosses Batman out of his Batmobile. In real life, “successful” ejections often leave pilots with longterm disabilities. The aviation term is “attempted suicide to avoid certain death.” It’s a last resort, not a first resort. When people talk as if they can make an ELV safe just by adding an ejection system, it shows how unsafe ELVs really are. No one in aviation ever says (for example) “we can leave out the engine restart system because we have an ejection seat.”

> There are many fewer crit 1 components. This technology and reliability
> imrpovement will be needed someday to and from the Mars surface, and same
> philosophy

What makes you think it’s not needed for cargo? Federal Express worries about reliability and cost just as much as any airline does. What’s the advantage of delivering cargo on an unreliable (and therefore high cost) vehicle?

Hopefully this would make cargo launches cheaper and constraints fewer.

Once in orbit, you can combine cargo and crew again – Apollo 13 demonstrated that two vehicles in one redundancy was a lifesaver – and make interplanetary travel very safe compared to the planetary ups and downs. (Slow boat to China .. perhaps even with China).

The same transport module to and from planetary bodies can be used to build space stations and planet habitats at first. One 5 year then it craters recreational vehicle module two person building block, with several variations, does it all.

In any case, as Rand said, vehicles need to be reliable, regardless of how many different kinds of vehicles we fly. That, though, is a different issue, unless a desire to build a particular kind of vehicle causes you to fall prey to political and budgetary constraints and compels you to build a fundamentally bad design.

Griffin is no fan of the Shuttle. If projected costs and downtime for this round of tank fixes puts his VSE schedule at risk, or if he believes there is no fix, I would not be surprised to see him end crewed Shuttle flights now. If a Shuttle-derived cargo vehicle could be made to accommodate the unlaunched payloads of the ISS partners, he might soothe their angst by offering to do just that after 2010. If not, it sure doesn’t look like the Shuttle or the ISS are on Griffin’s critical path.

Also making the cargo compartment of a vehicle permanently attached to the crew compartment, as in the shuttle, makes it difficult to impossible for the crew to safely abort in many emergency scenarios. This should be avoided in future designs, at least until vehicle reliability and durability is several magnitudes greater.

Launching crews and cargo together in the Apollo mode where the cargo is behind and separate from the crew is perfectly acceptable, IMHO.