From: begley@l14h13.jsc.nasa.gov
Subject: SSTO Concepts FAQ
Organization: Lockheed Engineering and Sciences
Distribution: usa
Date: Thu, 17 Dec 1992 14:18:05 GMT

 THE SPACE FRONTIER FOUNDATION 
ANSWERS 20 QUESTIONS ABOUT
THE DC-X SSTO PROJECT


1. What is the Single-Stage-to-Orbit (SSTO) program?
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 its improved engines,
high-tech lightweight materials, & airplane-like servicing, a reusable SSTO
could reduce the cost of getting to space by 90% or greater.  Because it will
be certified for flight like an aircraft, it will be able to operate from
spaceports located in any state.

2. What will it look like?
The production model operational SSTO will probably be cone-shaped,
approximately 130 feet high & 40 feet across the base.  It will have 8 or more
rocket engines, providing a safe return if an engine fails, again just like an
airliner.  SSTO will not have wings like Shuttle but will use small movable
flaps to help maneuver.  It will not require strap-on external tanks or
boosters.

3. When will it be flying?
A 1/3rd sized experimental vehicle, the DC-X, is on schedule for its first test
launch in late April, 1993.  A full sized demonstrator capable of reaching
orbit could be ready to fly in the summer of 1997.

4. Where will it fly from?
Test flights will 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, SSTO 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.  SSTO will navigate using the satellite
signals from the existing Global Positioning System.

5. What will it cost to design & build a full-size SSTO?
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 or McDonnell-Douglas MD-12.

6. What will I have to pay to fly on an SSTO?
An orbital tourist trip should cost roughly the same as the cost of a round the
world trip on a cruise ship.

7. How dangerous will it be?
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.

8. What about air pollution, especially near the ozone layer?
Unlike Shuttle, SSTO will burn only hydrogen & oxygen.  Its exhaust will
consist primarily of hot but pure water vapor -- the combustion product of
hydrogen & oxygen.

9. What about sonic booms & noise when launching or landing?
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.

10. Who's building SSTO?
Under a Defense Department contact McDonnell-Douglas is leading a team to build
the DC-X, a subscale experimental vehicle which will be flown to validate &
verify some elements of the technology & operations of single stage rockets for
supporting orbital flights.  Based on successful tests of the DC-X during the
spring & summer of 1993, the designs & concept will be available to other
government agencies -- such as NASA -- to develop & demonstrate an SSTO orbital
demonstration vehicle.

11. How much will the SSTO be able to carry?
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.

12. Will an SSTO be able to fly to the Moon?
An SSTO derivative vehicle, refueled in low Earth orbit, would be able to fly
to the Moon, land there, & return to Earth orbit.

13. How often will the SSTO be able to fly?
The anticipated turn-around will be about 1 day.

14. What if something goes wrong during a flight?
Commercial airplanes don't need all their engines to fly safely; they're
designed that way.  The same principle will be used to design the SSTO.  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.
 
15. Why haven't we built a single-stage rocket before?
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.)

16. Why should I believe all these claims for SSTO when similar ones were made
for Shuttle?
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, SSTO is being designed with supportability & operability as
priority design considerations.  For example, the engines on the SSTO 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.

17. Why isn't NASA building an SSTO?
In recent years NASA has been mostly focussed on flying the Shuttle & building
Space Station Freedom.  In the meantime, the Defense Department saw an urgent
need to prove the technologies required for SSTO vehicles.  Because SDIO, with
its streamlined management style, is an excellent agency for developing &
demonstrating new technology initiatives, it was given the job of building the
DC-X.  Once the technology demonstration phase is completed, the concept will
be available for either the DoD or NASA to develop, build, & fly an SSTO
orbital demonstration vehicle.

18. Does private industry have a role?
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 into space.

19. What could threaten the success of the SSTO program?
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-X 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 National Launch System.  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.

20. OK, you've convinced me.  What can I do to help?
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 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.

 JOIN THE SPACE FRONTIER FOUNDATION'S FIGHT FOR CHEAP ACCESS TO SPACE!
Call us at 1-800-78SPACE & leave your address, or write us at the address
below.
 
SPACE FRONTIER FOUNDATION  1110 NASA Road 1, Suite 103 Houston TX 77058