% title ISSDC: Training Fundamentals

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<H2>Fundamentals</H2>

<H3>Space Vehicles </H3>

<p>A common difficulty for Space Settlement Design Competition teams is
the business of figuring out the types of space vehicles that are needed
to support construction and operations of a space settlement.

<p>In order to get your group thinking about this topic, first think about
where they want to go, and the different kinds of vehicles that would be
required to get to each place. The Space Settlement Design Competition
description of the company Northdonning Heedwell gives some clues. First,
we can tell from that description that in the foreseeable future, nobody
will develop the Millenium Falcon, the starship Enterprise, the shuttle
Galileo, or any ability to teleport or "beam up". We will have to use
more conventional methods.

<p>The primary factor in determining the efficiency of an aerospace
vehicle is weight. The more an aircraft or spacecraft weighs, the less
paying cargo it can carry with the same engine power, or the less distance
it can go with the same amount of fuel. When carried to the extreme,
an aircraft could be so heavy that it would not be able to get off the
ground. The Space Shuttle typically carries up as much as 50,000 pounds
to a 150 mile orbit. If it needs to go farther, perhaps to 350 miles,
it can only complete the mission with 20,000 pounds or less. If it were
flown with no cargo at all, it would not be able to get more than 600
miles above the Earth.  Because so much energy is needed to get off of
the Earth's surface, most of the Space Shuttle's weight on the launch
pad is fuel. On the other hand, satellites or other vehicles that are
already in orbit can move to different orbits with relatively little fuel.

<p>We can anticipate that three basic types of transportation vehicles
will need to be considered in Space Settlement Design Competition
proposals. Although there can be different vehicle designs in each
of these major vehicle categories (to account for passenger vs. cargo
operations, or different kinds of cargo), the judges will be looking
for teams' appreciation of limits imposed by foreseeable technology on
vehicle operations:

<H3>Launch Vehicles </H3>

<p>The space vehicles we are familiar with in real life are launch
vehicles. Their job is to get cargo (satellites, experiments, crew, and
Space Station supplies) off the Earth's surface, through the atmosphere,
and into orbit. Their principal features are huge fuel tanks, engines,
and shapes with insulation that enable them to survive a high-speed boost
through air. The Space Shuttle Orbiter weighed about 200,000 pounds (empty)
at landing, and carried about 50,000 pounds of cargo. As a Space Shuttle
stood on its pad just before launch, it weighed 4.5 million pounds--almost
95% of which was fuel, the weight of the tanks that contain the fuel,
and the engines that burn the fuel. All launch vehicles have smooth
aerodynamic shapes to reduce drag through the atmosphere, and large
reusable vehicles like the Space Shuttle need wings, tail(s), landing
gear, and thermal protection systems for the mission home; after these
vehicles reach 150 miles of altitude, all of this stuff is useless weight,
which requires additional fuel to push it around to wherever the vehicle
needs to go.

<p>Studies are being conducted on space elevators to do the job now
accomplished by launch vehicles.  The concept starts construction by
deploying counter-balancing ribbons from a terminus in geosynchronous
orbit, one down to Earth's surface and the other an equal distance up.
A vehicle would climb or descend on the ribbon between the surface and
space. The Competition Co-Founders are watching this research; although
the physical principles appear sound, no material currently exists that
can be manufactured into a cable or ribbon strong enough to withstand
the forces induced by this application. On-orbit experience with space
tethers also shows that unexpected effects may delay development of this
technology.  Design Competition proposals that include space elevators
will be penalized.

<H3>On-Orbit Vehicles </H3>

<p>Unless a space settlement is located at about 250 miles of altitude
or less, it is not practical to consider routine operations of launch
vehicles directly to the settlement. Special on-orbit or orbit transfer
vehicles will not need huge fuel tanks, wings, tail(s), thermal
protection systems, and most of the other physical features (weight)
that distinguish launch vehicles. Most on-orbit vehicles will fire their
engines for only a few minutes at a time, and coast through the vacuum of
space to their next destination. Indeed, even the engines are smaller;
the engines the Space Shuttle uses for its on-orbit maneuvers generate
only 6000 pounds of thrust. These vehicles also can be boxy or oddly
shaped, since streamlining provides no advantage in the vacuum where
they live. Of course, for cargo and passengers to get from the Earth's
surface to a space settlement's location, they will need to transfer
from a launch vehicle to an on-orbit vehicle, and it can be expected
that some sort of Space Station or on-orbit Port facility would provide
services to support this operation.

<p>Space vehicles that need to go to destinations outside of Earth orbit,
however, will have somewhat different design requirements.  The huge
distances involved in getting to other destinations in the solar system
make it necessary to carry larger fuel tanks than would be needed by
Earth-orbit vehicles. Exotic propulsion systems also become interesting,
including ion engines (very low thrust engines that operate continuously
for long periods of time), solar sails, or perhaps nuclear engines.

<H3>Landers and Atmospheric Vehicles </H3>

<p>Because of huge launch costs for getting materials from Earth, it is
expected that some (perhaps most) materials employed in space settlement
construction will be acquired from extraterrestrial sources. The Moon
is an obvious materials source, and some asteroids with orbits that
bring them close to Earth could prove very useful.  Every destination
will present its own priorities for vehicle design.  Lunar landers will
need landing gear and engines for landing and ascent. Asteroid mining
vehicles will need some means for staying attached to their targets,
and for harvesting, processing, and transporting large quantities of
ore. For Space Settlement Design Competition scenarios that involve
settlements on or near other planets (e.g., Mars), atmospheric and
environmental characteristics must be considered in designs of the
vehicles that service these communities.

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