The Space Reviewin association with SpaceNews

Delta 4 Heavy rollout
Existing vehicles like the Delta 4 Heavy could provide much of the lift requirements of the exploration vision. (credit: Boeing)

The myth of heavy lift

<< page 1: the high cost of heavy lift

Various alternatives

If a new heavy-lift launch vehicle is so unattractive, what are the alternatives? There are, in fact, several options NASA could explore to provide launch services for the exploration initiative that are, in the long run, more affordable and sustainable. Indeed, some or all of these options could be pursued to provide a long-term solution.

One alternative is to take advantage of the existing overcapacity in the launch market today. Many of the new vehicles that have entered service in recent years were developed when companies and governments anticipated much higher launch rates than what has materialized, primarily because of a weak commercial market. This means that many vehicles are operating at a fraction of their launch and manufacturing capacity. This excess capacity could be utilized by the exploration program without the need to spend a dime on development.

A good example is the Delta 4. When Boeing built its manufacturing facility in Alabama in the 1990s for the Delta 4, it was designed to produce as many as 40 “common booster cores” (CBCs) a year. Currently, though, the Delta 4 is used only by US government customers, primarily the Defense Department. For the foreseeable future, the Delta 4 might be called upon for, on average, perhaps two Delta 4 Heavy launches a year and four Delta 4 Medium/Medium-Plus launches. At three CBCs per Heavy launch and one CBC for each “single-stick” Medium vehicle, that amounts to only ten CBCs a year. That offers—theoretically, at least—an excess capacity of up to 30 CBCs a year, enough for ten Heavy launches. The same approach can be used for the Atlas vehicle.

Given that international cooperation has been said to be a major aspect of the exploration program, creating international partnerships with Europe, Japan, and Russia would allow the use of excess capacity on the Ariane 5, H 2A, Proton, and Zenit launch vehicles, as well as Russia’s Angara booster under development. Higher launch rates of existing domestic and international vehicles could reduce per-launch costs by allowing operators to amortize costs over a larger number of launches. Moreover, the additional launches would reduce, if not eliminate, the need for government subsidies for these vehicles: the additional government-purchased launches for the exploration program would in effect become the subsidies, albeit for a more constructive purpose.

Additional launches of EELVs and other vehicles for the exploration program would effectively replace existing subsidies, and for a more constructive purpose.

At the same time new vehicles will be under development. While many of these will be smaller launch vehicles, a few larger vehicles may enter service in the next decade. In his testimony before the Senate Commerce Committee’s space subcommittee earlier this month, Elon Musk, CEO of SpaceX, noted that his company’s long-term plans include “development of a heavy lift product and even a super-heavy, if there is customer demand.” Given that Musk is offering the Falcon 5, a medium-class vehicle that competes with the Delta 2, for only $12 million, it’s possible he could offer ever-larger vehicles for a fraction of the cost of incumbent launchers.

There is also a role RLVs could play in the exploration vision. While most parties, including NASA, have all but given up on developing large orbital RLVs for the indefinite future, there is still plenty of commercial development of suborbital RLVs. Over the next 10-15 years, assuming the success of several of these ventures, one could plausibly assume that small orbital RLVs will enter service, designed most likely to serve space tourism ventures. Such vehicles could also ferry crews for lunar and other exploration missions to low Earth orbit, where they would transfer to variants of the Crew Exploration Vehicle (CEV) to carry out their missions. If such RLVs don’t materialize, the CEV could still carry out this task, but the RLVs hold the promise of doing this for the fraction of the cost of a CEV and EELV launch.

Cheap cargo, cheap launches

Lower-cost alternatives to heavy-lift vehicles may also require taking vehicle development in an entirely different direction for some cargoes. Vehicles today, be they expendable or reusable, are designed to be as reliable as possible. This makes sense given that their payloads are often very precious (humans) or very expensive (state-of-the-art satellites). This explains in large part why, in the commercial sector, customers are often very insensitive to launch price changes and very wary about flying on the first launch of a new vehicle, regardless of the price. Given that a commercial communications satellite can cost up to a few hundred million dollars—much more than the price of a launch—a customer’s primary interest is in reliability, not saving a few million dollars on the launch.

However, much of the mass required for missions in the exploration vision will be in the form of what essentially are bulk commodities: propellants, water, foodstuffs, and the like. In these cases, the cost of the launch will dominate the cost of the payload, and the payload can be cheaply and quickly replaced in the event of a launch accident. For bulk commodities, then, an emphasis of reliability over price makes little sense. A whole different vehicle concept may be in order.

Aquarius would trade off reliability for reduced cost: as many as a third of Aquarius launches would be expected to fail, yet the vehicle would still be more economical to launch bulk payloads.

At last month’s Space Access ’04 conference in Phoenix, George Herbert of Retro Aerospace made the case for just such an alternative launch system. He envisioned vehicles that could carry bulk cargoes, which he defined as costing an order of magnitude less than the vehicle itself. Such payloads—cheap enough where “you don’t care if you lose a load,” as he put it—allow for tradeoffs between cost and reliability in vehicle development. This includes single-string reliability in vehicle systems, lower margins, and simpler designs overall.

Herbert is not the only one to look at these tradeoffs. A few years ago a team at Space Systems/Loral studied a vehicle concept called Aquarius. Aquarius would be a low-cost launcher designed to carry consumables like water and propellant to the ISS or other destinations in low Earth orbit. Aquarius would trade off reliability for reduced cost: according to one study, a fifth to as many as a third of Aquarius launches would be expected to fail, yet the vehicle would still be more economical to launch bulk payloads than existing vehicles. To demonstrate this point, one illustration showed three Aquarius vehicles launching, with one exploding in flight: a picture that might give some aerospace engineers nightmares. Yet, as the study noted, terrestrial systems like aqueducts and electrical grids routinely lose a third of their payload en route and are still considered successful.

A sustainable solution?

A mix of launch alternatives like these—existing ELVs, new expendable and reusable vehicles, and even very-low-cost cargo launchers—don’t offer quite the integrated solution as a heavy-lift vehicle that could send crews to the Moon in one or two launches. Instead, the various components of such a mission would be launched on different vehicles: major spacecraft components on ELVs, crews on ELVs or perhaps small RLVs, and consumables on cargo launchers. This would require infrastructure in space to put all the components together: propellant depots and staging areas, in Earth orbit and perhaps lunar orbit or the Earth-Moon L1 point, as well as tugs to maneuver and integrate spacecraft and payloads.

This alternative sounds far more complex, and in many respects it is. However, this same infrastructure can be used for far more than just human missions to the Moon: it can serve as the basis for journeys to Mars and other destinations in the solar system. The same infrastructure could conceivably support commercial and other government applications. This architecture could end up being far more affordable and sustainable in the long run than any system that relies on a new heavy-lift launch vehicle.

The Saturn 5 proved that heavy-lift vehicles can enable human exploration of the Moon. It’s tempting to go back to what worked, but different times require different solutions. In the 1960s, the Saturn 5 was the best option in an era where the goal was less to explore than Moon than to beat the Soviets. Today, with no real race against another superpower, the goal should be to blaze new trails into the solar system in such a way that others can follow. The Saturn 5 didn’t do that, and their modern equivalents may be similarly ill-suited to that task. If the long-term goal is, in the words of one advocacy organization, to “create a spacefaring civilization”, perhaps it’s time to leave the Saturn 5 and their ilk in the past, and seek a new approach.