Suborbital Passenger Trips
Much higher-altitude suborbital trips will open up new regimes for doing biomedical research, in that there is a longer period of weightlessness and much higher gravity levels on launch and entry. However, the duration of the weightless experience will still be too brief (a few minutes) for the longer-term aspects of space sickness to show up, and the experience, though much more thrilling, since one will actually go into space, is still medically more like parabolic flight than an extended visit to space.
While many ventures are seeking funds to build suborbital vehicles, particularly in pursuit of the X-Prize, for the purposes of this report, there is really only one practical funded candidate for near-term suborbital rides—the X-34. Lockheed-Martin’n while a suborbital vehicle, would be much too costly per trip to consider for tourist applications, even if it weren’t having extreme technical difficulties and program delays.
X-34
The X-34 vehicle, being built by Orbital Sciences Corporation (OSC) under contract to NASA, is the only near-term fully-funded vehicle that, in principal, could offer a suborbital trip. It is a research vehicle, designed to test out reusable launch vehicle (RLV) technologies. It masses 18,000 pounds dry, with a total propellant capacity of 30,000 pounds mass. It is fifty-eight feet long, with a wingspan of twenty-eight feet. It uses liquid oxygen and kerosene as propellants, and is air launched from OSC's Lockheed L-1011 aircraft, after which it lights its rocket engine, accelerates up to Mach 8, leaves the atmosphere, attaining altitudes up to 250,000 feet (fifty miles) and then reenters and returns for a runway landing.
The system is designed for rapid (for a space transportation vehicle) turnaround. Nominally this will be two weeks, but one of the program goals is also to demonstrate the surge capability of a 24-hour turnaround. Because it is to be a test bed for operability technologies, the vehicle should have favorable costs relative to other current launchers.
The system is not currently designed to carry people, either as crew or passengers. However, it has two separate LOX tanks, and the center one could potentially be removed to provide volume for a crew capsule. This would reduce the vehicle performance substantially, but a suborbital tourist trip would not require the full Mach 8 speed. The most desirable attribute of such an experience would be the thrill of the high-gravity acceleration, the several minutes of weightlessness between engine burnout and atmosphere entry, the view of the earth from fifty miles above it, and attainment of sufficient altitude to earn one’s astronaut wings. The flight profile would have to be tailored to minimize the g-loading, and the passenger would probably have to wear a g-suit, as well as a pressure suit.
Certainly the vehicle will not be available for such modifications and use prior to the end of its career as a test and vehicle and research platform, unless the modification and demodification for passenger trips can be made routine, because there will be many missions for which the full LOX capacity will be required. However, the fate of the two X-34 vehicles following the completion of the testing required for the NASA contract is unclear, and it is quite conceivable that ownership with full rights could eventually revert to OSC, either to use for whatever purposes that company desires, or to sell or lease to another operator for commercial use.
Should this occur, we will have a very interesting test case for passenger regulation, because we will have a true space transportation vehicle that is not certified by the AVR division of the FAA, but will rather be issued a launch license by AST. If this occurs prior to any of the X-Prize contenders, it will establish a legal and regulatory precedent.
In this case, as was previously discussed, AST may choose to impose additional requirements on the trip for passengers that it does not for cargo, and this choice may or may not be challenged in court, and such a challenge may or may not be successful. If AST decides to regulate it too strenuously, the business may simply not be formed, as it is already on the edge of economic feasibility. If, on the other hand, they stick to their current policy and simply review the trip for range safety, national security, etc., then the venture could move forward in developing the necessary passenger module, and integrating it into the vehicle.
This module will have to provide life support for the passengers. This will be relatively straightforward, because of the short duration of the excursion. Perhaps the biggest challenges in module design will be in coming up with a means of providing windows for the passenger(s). Since the view will be a major feature of the experience, inability to provide this feature will probably be a show stopper. Overall, the module, in order to meet the requirements, will probably cost on the order of several million dollars to develop amd manufacture (a more precise estimate than this ROM is far beyond the scope of this study).
If this estimate is in the ballpark, each ride on the vehicle will cost on the order of a million dollars or more (to recover all costs). This is a price that is potentially sustainable for a unique suborbital experience—there are many who would like a trip to space, and given the current state of the national and world economy, many who could afford to pay that much for one. The biggest question, and one that investors in such a venture would have to seriously consider, is whether or not this vehicle would be competitive with others that are developed specifically for that purpose, such as Vela Technology's Space Cruiser (TM) concept.
X-34 was designed for the specific purpose of testing specific technologies. It was not designed with the intent of providing space joy rides, though it is physically capable of that, given sufficient additional investment. It was burdened with its unique requirements, and it was done under a government contract. Experience has shown that, no matter how innovative and technically competent the contractor, government-contracted space transportation vehicles are not low cost, either in development or operationally. It is the author’s opinion that any system privately funded specifically for the purpose of providing a suborbital experience would have cost structures at least an order of magnitude less than the X-34, and would satisfy that market in a far superior manner, since that would be the sole intent of the investment. It will be up to the investor to make the bet that his investment in augmenting X-34 for suborbital tourism will not be either quickly or eventually (before she can earn her money back) superceded by someone else's investment in a vehicle developed specifically for that purpose.