The goal of the SSTO program is to build a new spaceship that will take off straight up, fly to orbit without dropping anything off, & that will then land on its tail on a pillar of fire, not gliding but under power, much like the rocketships of 1950s science fiction movies. Because of their improved engines, high-tech lightweight materials, & airplane-like servicing, reusable SSTOs could reduce the cost of getting to space by 90% or greater. Because they will be certified for flight like an aircraft, they will be able to operate from spaceports located in any state.
Production model operational SSTOs will probably be cone-shaped, approximately 130 feet high & 40 feet across their base. They will have 8 or more rocket engines, providing a safe return if an engine fails, again just like an airliner. SSTOs will probably not have wings like Shuttle but will use small movable flaps to help maneuver. They will not require strap-on external tanks or boosters.
A 1/3rd sized experimental vehicle, the DC-X1, flew its first test launch August 18, 1993. A full sized demonstrator capable of reaching orbit, the X-33, could be ready to fly in the summer of 1999.
X-33 test flights will probably be from White Sands Missile Range, New Mexico, but once production of actual operational SSTO vehicles begins any state in the Union will be able to have its own spaceport. Unlike Shuttle, SSTOs won't need a long runway, a huge Vehicle Assembly Building, or a Mission Control building; but only a 200 foot diameter concrete pad, a maintenance hanger, & a hydrogen/oxygen propellant facility. SSTOs will navigate using satellite signals from the existing Global Positioning System.
The total cost of developing the first SSTO orbital demonstration vehicle will be about the same as the development cost of a new commercial airliner such as the Boeing 777.
An orbital tourist trip should cost roughly the same as the cost of a round the world trip on a cruise ship.
Once fully operational a reusable SSTO will be as safe as flying on a typical commercial airliner. In fact, the operational SSTO vehicles that are to be derived from the orbital demonstrator will be certified by the U.S. Department of Transportation's Office of Commercial Space Transportation.
Unlike Shuttle, SSTOs will burn only hydrogen & oxygen. Its exhaust will consist primarily of hot but pure water vapor -- the combustion product of hydrogen & oxygen.
When an airplane flies faster than sound it generates a shock wave which we experience as a sonic boom. For this reason the Concorde jet is not allowed to fly supersonically to inland airports in the U.S. But since SSTO vehicles will launch straight up, the sonic boom will be limited to the spaceport area. When landing an SSTO will slow down to subsonic speed at about 70,000 feet altitude.
Under a Defense Department contact McDonnell Douglas lead a team to build the DC-X1, a subscale experimental vehicle flown to validate & verify some elements of the technology & operations of single stage rockets for supporting orbital flights. Based on the successful tests of the DC-X1, NASA is now developing an SSTO "X" vehicle demonstrator -- the "X-33."
Two crew members & 10 tons of cargo and/or passengers into low Earth orbit, or 2 crew members & 5 tons of cargo and/or passengers into polar orbit are typical of current baseline operational designs.
An SSTO derivative vehicle, refueled in low Earth orbit, would be able to fly to the Moon, land there, & return to Earth orbit.
Anticipated turn-around will be about 1 day.
Commercial airplanes don't need all their engines to fly safely; they are designed that way. The same principle will be used to design SSTOs. If there is an engine malfunction during ascent, an SSTO would be capable of either continuing on to orbit or returning to base. If the ship needs to return from orbit sooner than expected, it will be able to maneuver to spots over 1200 miles to either side of its landing orbit trajectory. Unlike Shuttle, which requires a 3 mile long landing strip, an SSTO will be able to land on any reasonably flat spot.
The reason most rockets, including Shuttle, have parts that drop off (stages) is this: Every additional pound of vehicle that we lift all the way to orbit requires additional pounds of fuel. The additional fuel requires a larger, & heavier, fuel tank, which then requires even more fuel to carry, & so on.
There are 3 ways to address this problem: 1) Make the rocket so huge (keep in mind that size correlates to cost) that it can carry enough fuel to lift itself all the way to orbit; or 2) Toss off empty tanks as you go (the traditional multi-stage method); or 3) Make your engines so efficient & the vehicle structure so lightweight that you don't need to carry huge amounts of fuel and/or you won't need to throw away any pieces of your ship.
The underlying design principle of the SSTO program is to make a structure lightweight enough to fly single stage to orbit. Because of the National AeroSpace Plane program (NASP) & military airplane development programs of the 1980s, we now have industrially available the strong, lightweight materials that will enable the SSTO concept to work. (These materials have been demonstrated in actual use, too.)
The Shuttle's design was frozen in the early 1970s. If we had built a vehicle like the SSTO's design back then, it could have taken off from New Mexico & gotten to Greenland, but it would not have been able to reach orbit (too heavy). In the 20 years since we have learned a lot about design, lightweight materials, trajectory optimization, avionics, computers, & engine design. (The Shuttle is a multi- stage rocket.)
In addition, SSTOs are being designed with supportability & operability as priority design considerations. For example, the engines on SSTOs won't be run at 110% of their design capacity, as the Shuttle's do (only about 80% -- by design), so unlike the Shuttle's engines, the SSTO's engines won't have to be torn down & rebuilt before each flight. If on-board diagnostic instruments indicate a problem with an SSTO engine or any other component, it is designed so components (called line replaceable units) can be pulled & replaced quickly after landing.
In recent years NASA has been mostly focussed on flying the Shuttle & building the Space Station. In the meantime, the Defense Department saw an urgent need to prove the technologies required for SSTO vehicles. Because BMDO, with its streamlined management style, was an excellent agency for developing & demonstrating new technology initiatives, it was given the job of building the DC-X1. The success of the DC-X1 program convinced NASA that SSTO is the way to go. As a result, NASA has now initiated the X-33 program to build and fly an SSTO orbital demonstration "X" vehicle.
Yes. McDonnell Douglas & its SSTO teammates have already made a significant investment in the basic technologies & the skills & facilities necessary to develop an SSTO. Once the orbital demonstration vehicle has been built, these & other private companies will be able to build & operate commercial-grade SSTO vehicles so that finally you, the citizen, can buy a ticket to space.
Two things. The first is money -- lack of it. Despite the fact the proposed SSTO program will save the government & taxpayers money by making it cheaper & easier to get civil & military payloads to space, it is still in danger from a budget conscious (or unconscious!) Congress.
Most legislators have never even heard of the currently-funded DC-X1 project, let alone the benefits of a full-scale SSTO orbital demonstrator & its follow-on operational vehicles. Because the program hasn't (yet) been very visible in the media, some in Congress may feel the program has no real constituency.
The 2nd threat to SSTO is turf protection. There are many very powerful interests involved in the development of old style multi-stage vehicles, such as Shuttle & the "EELV" program ("Evolved Expendable Launch Vehicle"). While these systems do nothing to accelerate the opening of space, they do keep a lot of people employed & have friends in Congress who see those jobs as votes & money for the folks back home. It's sad that such a revolutionary & common sense idea as SSTO should be attacked (as it has) by those favoring the old & costly dinosaurs of the past.
We in the Space Frontier Foundation have already helped to save the SSTO project from such attacks, but we need your help now, for as the project grows & becomes more visible these entrenched interests will attack again. If they succeed your chance of ever entering space will remain science fiction.
The Space Frontier Foundation is committed to opening the space frontier as quickly as possible. The SSTO program is one of the best U.S. space projects to come along in a long time because it offers the possibility of dramatically lowering the cost of getting people & cargo into space. Making it possible, finally, for you, too, to go.
So: Make copies of this flyer & hand 'em out to your friends who want to go, too.
Second, get on the Foundation mailing list (send us a few bucks to help pay our costs) & be willing to write letters and/or make calls & faxes to Congress and/or your newspaper when asked.
Third, if you're a public speaker, published writer, or can help us develop materials (artwork, graphics, printing) or take on other volunteer projects, tell us & we'll help you do it.
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