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February 26, 2009

Small and Expensive Versus Big and Possibly Infrequent Space Launch

Hobby space and and Transterrestrial (Rand Simberg) are indicating that

A. because the current market for space payloads is small then no big dumb rockets should be built.

B. Some commenters say we can just leverage in space resources (ISRU - in space resource utilization) and make do with small payloads.

C. Another commenter said, if we could have built these systems back in the sixties, then we would have.

This relates back to the article on this site on big rockets that we are technically able to make.

1. I think the volume could be there if there was a good plan and objectives to seriously develop space (industrialize, colonize and develop energy). Go for 500 (simple chemical, space dragon) then 1000 ton heavy lift (gaseous core). Try to take some near earth asteroids and use them for material. Put up 500 or 1000 ton versions of bigelow inflated structures. For people in space, send up heavier structures with better radiation shielding and more supplies.

2. Bootstrapping with In space resources and small payloads makes all of the problems more complicated and takes longer. The systems have to be more clever to make the small and life stuff work. There has not actually been any leveraging of in space resources yet.

I see and blog about paper studies about in space resource utilization and making concrete on the moon, but I do not see actual hardware being put out there.






3. Orion stopped getting funding after the air force partnered with NASA and NASA would not step up for the budget for the next phase. There was probably also the political overlay but I will be getting hold of the 2002 book and looking at the historical record as to what killed what first.

Space Dragon had a NASA study which said that it would work, could be built and would provide the lower costs for payload. Space Dragon would be cheaper to develop than Ares or Direct 2.0. Why do we need another small lift system ?

Also, how long would take and how many launches to recover the costs of tens of billions for Ares and/or Direct 2.0 ?

How much would it cost to develop a dirt simple Big Dumb Booster ? Go big and go simple and develop the rocket for say $4 billion plus $500 million/yaer to maintain the operations and then each unit costs say $500 million or $1 billion and you can still have 5-10 big launches over how many years before you get up to the Ares development costs where it has not launched anything.

The Sea Dragon rocket would have been able to carry a payload of up to 550 metric tons into low earth orbit. Payload costs were estimated to be between $59 to $600 per kg, which is much less than today's launch costs. TRW conducted a program review and validated the design and its expected costs, apparently a surprise to NASA. However, budget pressures led to the closing of the Future Projects Branch, ending work on the super-heavy launchers they had proposed for a manned mission to Mars.


4. Where are the small lift systems that are getting all these "frequent launches" and getting the economic benefit of frequent launches ?

How often are 20 ton payloads launched ?
I am seeing about 30 scheduled launches, with about 1-6 for different launch systems. No one launch system is getting more than about 3 launches in a year.

What are the payloads that will be launched with Ares or Direct 2.0 ?
The payloads and projects for the Moon and Mars seemed to be predicated on the designed capabilities of Area or Direct 2.0. They are thinking small and designing small projects.

Many of the space based power projects hang up on the fact that $/kg costs are too high. Nothing gets started because the business case has no chicken or egg to get going. We can then say that there is no demand for low 4/kg.

We can go big, if we plan big and design big.

5. I understand that the reality is that there is no real over-arching primary goal to the space program. The proposals (Ares/Direct 2.0) are variations how do we keep the current people at NASA or at the companies that make the Delta, Atlas and Space Shuttle employed. The purpose of that is keep the senators and congressman that have the jobs and business in their space and district able to say see voters I am keeping NASA/Space jobs going. The satellites and exploration are in general just enough to show that this is all not completely pointless and the honest lower-level people are trying to achieve something (as much as they can) with their piece of the overall system.

ISS - dozens of launches. What was the real point ? How does it lead to any grand larger goal in space ?

Even if the current vision for the moon were funded and came off. What would be the final result ? Maybe a peak of a dozen people on the moon. How much in space resource utilization ? What would the next phase be able to build upon ? How it get to the next step up to more capability ?

FURTHER READING
Sea Dragon - Why it would be Cheap
Remember - TRW validated the program and the costs
Also, the design and material is simple and should not have a large development cost.

To lower the cost of operation, the rocket itself was launched from the ocean, requiring little in the way of support systems. A large ballast tank system attached to the bottom of the first-stage engine bell was used to "hoist" the rocket vertical for launch. In this orientation the cargo at the top of the second stage was just above the waterline, making it easy to access. Truax had already experimented with this basic system in the Sea Bee and Sea Horse designs. To lower the cost of the rocket itself, he intended it to be build of inexpensive materials, specifically 8 mm steel sheeting. The rocket would be built at a sea-side shipbuilder and towed to sea for launch.

The first stage was to be powered by a single enormous 36 million kgf thrust engine burning RP-1 and liquid oxygen. The fuels were pushed into the engine by an external source of nitrogen gas, which provided a pressure of 32 atm for the RP-1 and 17 atm for the LOX, providing a total pressure in the engine of 20 atm (~300 psi) at takeoff. As the vehicle climbed the pressures dropped off, eventually burning out after 81 seconds. By this point the vehicle was 25 miles up and 20 miles downrange (40 km x 33 km), traveling at a speed of 4,000 mph (1.8 km/s). The normal mission profile expended the stage in a high-speed splashdown some 180 miles (290 km) downrange. Plans for stage recovery were studied as well.

The second stage was also equipped with a single very large engine, in this case a 6 million kgf thrust engine burning liquid hydrogen and LOX. Although also pressure-fed, in this case the nitrogen kept the system running at a constant lower pressure of 7 atm throughout the entire 260 second burn, at which point it was 230 km up and 940 km downrange. To improve performance, the engine featured an expanding engine bell, changing from 7:1 to 27:1 expansion as it climbed. The overall height of the rocket was shortened somewhat by making the "nose" of the first stage pointed, lying inside the second stage engine bell.

A typical launch sequence would start with the rocket being refurbished and mated to its cargo and ballast tanks on shore. The RP-1 and nitrogen would also be loaded at this point. The rocket would then be towed to a launch site, where the LOX and LH2 would be generated on-site using electrolysis, Truax suggested using a nuclear-powered aircraft carrier as a power supply during this phase. The ballast tanks, which also served as a cap and protection for the first stage engine bell, would then be filled with water, raising the rocket to vertical. Last minute checks could then be carried out, and the rocket launched.


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