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.)