The myth of heavy lift
by Jeff Foust
|Developing a new heavy-lift vehicle could be the least desirable step NASA could take if it wants a sustainable, affordable exploration program.|
Yet, fans of the Saturn 5, and large launch vehicles in general, have seen signs of hope. NASA’s new Vision for Space Exploration, the broad new space plan announced by President Bush four months ago, will require the launch of many hundreds of tons of cargo to be carried out in full. This has led to consideration of developing new launch vehicles capable of launching far heavier payloads than is possible today with the shuttle, the retiring Titan 4B, and the heavy versions of the Atlas 5 and Delta 4 EELVs. While no one is seriously considering resurrecting the Saturn 5, the plans on the drawing board now range from upgraded EELVs to shuttle-derived vehicles to “clean sheet” designs that could rival the Saturn 5 in capability. However, the debate over such designs misses one key point: developing a new heavy-lift vehicle could be the least desirable step NASA could take if it wants a sustainable, affordable exploration program.
Few will argue against the notion that heavy-lift vehicles are expensive to develop and operate. How expensive, though, is something often overlooked. According to the Encyclopedia Astronautica, the cost to develop the Saturn 5 was nearly $7.5 billion—in 1966 dollars. When adjusted for inflation, that price becomes a staggering $43 billion in 2004. The Saturn 5 was also not cheap to operate: the same source pegs the launch cost of a single Saturn 5 at $431 million in 1967, or over $2.4 billion a launch in 2004 dollars.
Just how much is included in those development and launch costs, and how accurate they are, are certainly open to debate. However, more contemporary experience also suggests that heavy-lift launches are expensive. The cost of a single shuttle mission varies widely, from under $100 million a flight to in excess of $1 billion, depending on how one does the accounting (not to mention what answer one desires). For purposes of cost accounting for the International Space Station program, NASA authorization legislation from 2000 caps the price at $380 million per shuttle flight. A single launch of a Titan 4B, with a similar payload capability to the shuttle, costs in the range of $400-500 million. Even the heavy versions of the EELV, designed to be less-expensive alternatives to the shuttle and Titan 4, are not cheap: a NASA document in late 2003 pegged the cost of an EELV Heavy launch, and assorted launch services, at $232 million.
Indeed, NASA appears to be preparing to make a significant investment in a new heavy-lift launch vehicle. Even as the agency studies various approaches for a heavy-lift vehicle, Aviation Week reported last month that the budget for the overall exploration plan through 2020 includes $13-16 billion—nearly the current annual budget of the entire agency—to develop such a vehicle. Given the agency’s mixed record of cost estimates, this price is more likely to go up than down as plans are refined. It’s not inconceivable that a new heavy-lift vehicle would cost on the order of $15 billion to develop and perhaps $1 billion per launch—more expensive than the shuttle but still heavily discounting the perhaps anomalously high Saturn 5 cost estimate.
Proponents of new heavy-lift vehicles will argue that, on a per-pound basis, such large vehicles are more economical than smaller vehicles. That’s true, in general: larger launch vehicles will usually have lower costs per unit of payload mass than smaller ones. The problem, of course, is that one cannot by a launch vehicle by the pound: you either buy the entire vehicle, at perhaps a billion dollars in this case, or nothing at all. This means NASA needs to know how much mass it will need to launch to carry out its exploration program in order to determine just how economical various heavy-lift launch options will be. Yet NASA is unlikely to have more than a rough guess at that amount for years.
|An exploration program reliant on a heavy-lift vehicle would be easy for a future Administration or Congress to terminate, leaving virtually nothing left of government manned spaceflight.|
The costs of heavy-lift vehicle development would be less of an issue if there were other uses—and other paying customers—for such a vehicle. Outside the exploration program, though, there is unlikely to be much interest for any vehicle much larger than those available today, even at fairly modest launch costs. The US military’s plans for space for the foreseeable future assume nothing larger than a heavy EELV will be available; indeed, the Defense Department has turned its attention more recently to smaller, potentially more responsive vehicles. Even if a new heavy-lift vehicle was available, it’s unclear what use the military would have for it other than possibly some missile defense applications that have yet to be fleshed out.
On the commercial side, the largest customer is the satellite communications industry. While there has been a trend towards larger satellites, that trend has tailed off in recent years, given both overcapacity among existing satellites as well as a rash of problems with a new generation of large communications satellites. Even if that trend was to continue unabated, existing vehicles are large enough to accommodate these satellites for the foreseeable future. Other commercial applications, from remote sensing to emerging markets like space tourism, can get by mostly with smaller, possibly reusable vehicles.
One advantage that heavy-lift vehicles have is that they would make it easy, from an operational standpoint, to mount human missions to the Moon: a single mission could be carried out with one or two launches, just as the Apollo missions required a single Saturn 5 launch. This advantage, though, could ultimately become a disadvantage. Heavy-lift vehicles would require little in the way of in-space infrastructure to mount a mission: no space stations, propellant depots, or other facilities, just launch and go. Given that this would be supplied by an expensive heavy-lift vehicle with no other applications, it would be easy for a future Administration or Congress to terminate the program and leave virtually nothing left of government manned spaceflight. This is hardly the hallmark of a program that is supposed to be affordable and sustainable. Instead, it would simply be Apollo redux.