2. Spacecraft General Properties
2.1 Delta Sprint Standard
Our baseline Delta Sprint we will
tentatively call Standard. This craft is launched a modified Delta 7920 launch
vehicle. On top of this a custom adapter and partial fairing have been added. The Standard version uses the Fregat as a third stage.
The Delta Sprint spacecraft itself consists of a Service Module and Descent Module, similar to piloted spacecraft that
have gone before (including Vostok/Voskhod, Gemini, Apollo, Soyuz/Zond, and Shenzhou.)
Because of the Fregat upper stage, advanced electronics, and desire to service the craft on orbit, the Descent Module
is uncharacteristically large compared to the Service Module when Delta Sprint is compared to these other spacecraft. To dock with the space station, a small radar is stored in the nose, inside the doors
which protect the docking port from the ascent airflow. This radar is intended to operate only when the doors are open. The Fregat is used for the initial docking maneuvers.
Once at the minimum distance to the station, the Fregat is jettisoned and deorbited into the Pacific
Ocean, while Delta Sprint completes docking with the space station. When it is time to return to Earth, the spacecraft undocks from the space station,
closes its docking port doors and uses an off the shelf solid fuelled motor to deorbit, allowing the craft to enter the atmosphere. The craft uses a parasol system similar to the one used on X-38 to land, and a series
of airbags to cushion the landing. It is intended that Delta Sprint land on a
grass field or similar surface, although it will also be able to land on water, swamp, and runway surfaces, all of which are
in the KSC area.
2.2 Alternative options for Delta Sprint
2.2.1 Delta Sprint Spartan
Similar to Standard but lacking the
Fregat upper stage and ascends on the heavier Delta 7920H launch vehicle. The
Service Module, required to do more maneuvers to rendezvous with the space station, will need larger propellant tanks and
weigh more as a result. On both Standard and Spartan, the deorbit motor and docking
engines back each other up to provide a redundant capability to deorbit and save the crew if one or the other should fail. The mission mass budget for Delta Sprint Spartan is 5500kg based on the Delta II Payload
Planners Guide Figure 2-22 on page 2-21. Simulation in Orbiter has shown that
the PES may improve performance slightly (by about 1/4 of its own mass, with conservative parameters for specific impulse
and burnout mass fraction.)
2.2.2 Sprint X-38
The X-38 Sprint option is to take
the X-38 spacecraft as is and fly it on a Delta IV to the space station. This
option resembles OSP (Orbital Space Plane) to a great extent, but does not require an all-new planform and structure. After Columbia dislikes this option because the Delta IV launch vehicle is quite new and prefers a more
proven system for the next piloted craft. The X-38 planform might also require
a failure free avionics system and have difficulty with backup recovery modes because of its planform. Mission mass is known to be less than 25000kg based on Shuttle payload performance.
2.2.3 Canadian Arrow Sprint
A while back, After Columbia contacted
the Canadian Arrow project (an X Prise contender) inquiring about the use of their spacecraft on an orbital launch vehicle. They were not open to the possibility and did not provide After Columbia with sufficient
information to select study launch vehicle possibilities.
2.2.4 Delta Sprint Planetary
A future model of Delta Sprint being
used as a crew entry vehicle for piloted planetary missions returning from their destinations.
These would include Mars Direct and GaiaShield, both originally conceived and analyzed by Robert Zubrin, president
of the Mars Society. Delta Sprint Planetary is expected to have a mission mass
of approximately 6200kg.
2.2.5 Delta Sprint II
Delta Sprints limited crew/passenger
capacity favors a development towards (perhaps even initial development of) a 4m diameter class four or six person crew transfer
vehicle. If initial development is undertaken, the Fregat, already designed for
4m diameter fairings onboard the Soyuz FG commercial launch vehicle, can much more easily be accomodated to serve, as on Delta
Sprint Standard, to simplthe Service Module. If developed as a follow on to the
original three person Delta Sprint, it may be possible to design variants in different weight classes to ascend on different
launch vehicles (such as Atlas family, Delta III, Delta IV-M, Delta IV-M4.2, Soyuz FG, Ariane 5G.) An example would be a four person Low Energy Orbit vehicle ascending on a Delta IV-M, heavier logistics
variant ascending on Delta IV-M4.2, and a four person Planetary variant ascending on Delta IV-M4.2 to a planetary spacecraft
such as Ares/Mars Direct or GaiaShield (both by Robert Zubrin, pending reports.)