I was appalled by the article “Space Tourism is a Hoax” [Nov. 16, page 15]. The practicality of space tourism obviously depends on the cost of space transportation, but the authors have no idea why space transportation is so expensive. They say it’s because launch vehicles are “very big, complicated machines.” Well, 747s are also “very big, complicated machines,” but cost about three orders of magnitude less to fly than something like the shuttle. In fact, excepting the shuttle’s thermal protection system, a 747 is more complex than a shuttle orbiter.
Is the high cost due to the “basic laws of physics”? Is the amount of energy involved in spaceflight so different from terrestrial experience? No. In a maximum-range flight, the engines of a 747 generate more energy than the plane and its payload would have if they were in low Earth orbit.
The only remaining claim that the authors make that is based on the laws of physics is that we cannot place a significant payload into orbit with a single-stage-to-orbit (SSTO) launch vehicle. There is some disagreement over whether SSTO rockets are feasible with existing technology, but they undoubtedly will be feasible eventually. Two-stage, fully reusable launch vehicles, however, are well within the state of the art today. There is no reason to believe that SSTOs are necessary for the tourism market — two-stage vehicles will work just fine. There also is no reason to believe that both stages cannot be reusable.
The authors, however, assume that the shuttle has proved that reusable launch vehicles are “horrendously expensive” and therefore not usable for the tourism market. Nothing could be further from the truth.
The shuttle is not a “reusable” launch vehicle; it is a “partly reusable” launch vehicle. The cost of the expendable external tank alone puts the shuttle into the expendable launch vehicle cost range. Add up the cost of the external tank, refueling the solid rocket boosters, refurbishing the thermal protection system, etc., and the recurring cost of a flight is over $100 million.
The authors’ $1.5 billion estimate of the cost of a shuttle flight is highly inflated, but it is true that the biggest part of the cost of a shuttle flight is the large fixed cost of maintaining the shuttle system spread over a relatively small number of flights. The $1.5 billion estimate is based on the assumption that the shuttle can be flown only twice a year. It can fly many more times than that, but has been restricted to flying only those missions that require human presence, such as international space station logistics.
The tourism market, by definition, requires human presence, and the vehicles will be operated by the private sector, so there will be no artificial limits on flight rate. Give us a relatively simple two-stage, vertical-takeoff-and-landing reusable launch vehicle, which is designed for reliability and maintainability to keep recurring costs to a minimum, and the private sector will be able to bootstrap to hundreds of flights per year, which will minimize fixed cost per flight. It’s easier to operate a properly designed reusable launch vehicle than an expendable launch vehicle because you don’t have to give the vehicle a complete functional test before every flight.
The authors compare the ticket prices and revenues appropriate for a small reusable launch vehicle with the cost of a “big” expendable launch vehicle. Surprise, surprise, it doesn’t work. A reusable launch vehicle able to carry 50 passengers could easily be operated for less, eventually much less, than $50 million per flight, for a ticket price of less than $1 million, or 5 percent of what the Russians charge for a ride on a Soyuz. That’s enough to get us going. The path to low-cost space transportation is quite clear, and has nothing to do with anti-gravity.
Dick Morris, Seattle