Delta Sprint Library Report
1 Mission and Description

All elements of this report are tentative and may be subject to change.

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1. Mission and Description

  

1.1 Delta Sprint Standard

 

The Delta Sprint is a three person crew transfer vehicle designed for use from a commercial Delta II launch vehicle modified to accept piloted spacecraft, the Fregat upper stage, abort system, and partial fairing.  The launch facility has a Rapid Egress Tower (RET) added to it.  It is put on a mobility track that does not interfere with the existing Mobile Service Tower (MST) or Fixed Umbilical Tower (FUT), although both the MST and RET cannot be in place at the same time.  The RET is used for flight crew ingress and egress during normal operations as well as providing a quick escape in case of a pad fire prior to the last four minutes of the countdown.

 

The Delta Sprints primary mission is crew transfer to the International Space Station (ISS), but in doing so, provides a bailout role.  The Delta Sprint has two extended missions:

 

1.1.1 Bailout for the International Space Station

 

The same variant of Delta Sprint is used as for crew transfer, but due to improvements in on-orbit serviceability, with an eye on reducing upmass logistics required to maintain a safe bailout capability.  This bailout mission is considered an extended mission because using Shuttle replacement (i.e. ISTS or NGLT) in this role ties up reusable launch assets.  It also improves upon Soyuz in this role.  The Delta Sprint most likely is hauled as cargo to the International Space Station or its successors by ISTS (International Space Transportation System) or another fully reusable launch system.

 

1.1.2 Planetary Crew Return and Bailout

 

In this mode, it is assumed that the first piloted planetary mission requiring Delta Sprint will be Mars Direct (pending report(s)).  A version designed for return from Mars will have no trouble accommodating crew return from the Moon without modification to the Descent Module.

 

1.2 Launch System

 

Delta Sprint uses a modified Delta 7920 launch vehicle with a partial fairing around the Service Module and Fregat upper stage; Delta Sprint Standard exceeds the maximum mass that can be orbited by the Delta 7920, which inserts the spacecraft into an approximately 6500m/s suborbital trajectory at an altitude of between 125 and 150km using its propellant depletion shutdown mode.  The Delta Sprint uses the Fregat upper stage to insert itself into a transfer orbit to the International Space Station.   The Fregat upper stage performs several rendezvous maneuvers and is jettisoned at 500m from the International Space Station.  Using the Fregat this way simplifies the Service Module of Delta Sprint. Delta Sprint returns to the old standard of flying with an abort system capable of aborting the launch and saving the crew in the event of a problem with the launch vehicle.  Ascent details are in Chapter 3.

 

1.3 Importance of the Crew Transfer Mission

 

In the first few days and weeks after the STS-107 catastrophe, no one could be sure that the cause of the disaster could be fixed and the Shuttle could be returned to flight.  After Columbias first goal was to address this possibility.  At first the craft was called simply Sprint because it would be needed fast and on the cheap.  Sprint was expanded into a program ( aftercolumbia.tripod.com/library/id2.html ) to address all the needs of the International Space Station on the fast and cheap; Delta Sprint is one of its elements.  The spacecraft, wherever possible, uses off-the-shelf subsystems, with backups and simplicity provided where they are best suited to simplify development and enhance safety.

 

Delta Sprints simple mission profile of getting a crew to orbit and providing them with a lifeboat has proven remarkably versatile in studies, resembling the broad range of applications envisioned for Gemini, Soyuz, and Apollo in the 1960s and 1970s.

 

The concept has expanded somewhat to include the Fregat upper stage, which is intended to increase the mass that can be lifted, and assist in rendezvous maneuvers with its relatively long battery life and multiple restart capability.  Later, it may be used to reboost the International Space Station once qualified to thrust a craft thats not designed to survive its failure.  The Fregat is young enough that it may be of questionable reliability, but Starsems documentation regarding the Fregat says that its design philosophy matches Delta Sprint in using quality off-the-shelf components from other systems, most of which have been flying since the 1960s.

 

It only makes sense to use proven Shuttle thermal protection materials, and, due to the expense of the same, make the Descent Module reusable.  A ballistic design with some crossrange capability is required for pinpoint entries, and a parasol with several reefed positions like that used on X-38 is required for pinpoint landings.  Other systems, such as life support, avionics, electrical systems, motors, the docking radar, crew interface equipment, pyrotechnics, etc. will be selected from off-the-shelf systems for mass, long term reliability, simplicity, and fault tolerance.

 

After Columbia is quite certain that a competent NASA development team could bring Delta Sprint to service within 2 years of being given full authority and funding (based on Jupiter, Thor, Saturn I/IB, Mercury and Gemini experience.) This is approximately the schedule of the STS-33/26R return to flight efforts after the Challenger disaster.  It is likely that it has already cost NASAs Shuttle Program more to recover from STS-107 than it would have to develop Delta Sprint.  Because of the extremely conservative design of Delta Sprint (excepting the PES), the use of a proven existing launch system, and the dynamically stable ballistic planform, Delta Sprint is not likely to experience the mass and cost growth typical of most piloted spacecraft.  For the same reasons, After Columbia is expecting opposition to Delta Sprint from the groundbreaking technology research groups within NASA.


(c) 2004 After Columbia