MILITARY SPACEPLANE TECHNOLOGY PROGRAM
SPACE TECHNOLOGY DIRECTORATE
IN SUPPORT OF
AFSPC AND AFMC
Maj Ken Verderame
Maj Andrew Dobrot
DATE: 24 April 1997
Comments and questions on this draft SRD should be forwarded to Maj Ken Verderame, PL/VT-X, DSN 246-8927 ext. 150 or (505) 846-8927 ext. 150, or Maj Andy Dobrot, HQ AFSPC/DRSV, DSN 692-2567 or (719)554-2567.
1. INTRODUCTION 11.1 BACKGROUND 11.2 SCOPE 11.3 REQUIREMENTS RATIONALE 11.4 USE OF THIS SRD 21.5 CONTROL OF THIS SRD 21.6 BASIS OF THIS SRD 21.7 TERMS 22.0 MILITARY SPACEPLANE SYSTEM REQUIREMENTS 32.1 MILITARY SPACEPLANE SYSTEM 32.1.1 GENERAL MISSION CAPABILITIES 22.214.171.124 DESIGN REFERENCE MISSIONS AND MISSION SETS 126.96.36.199 DESIGN REFERENCE MISSIONS AND MISSION SETS 42.1.2 SYSTEM DEFINITION 42.1.3 OPERATIONAL SITES 42.1.4 FERRY CAPABILITY 52.1.5 SYSTEM OPERATIONS 188.8.131.52 OPERATIONS AT THE MOB 184.108.40.206 OPERATIONS AT DOLs 220.127.116.11 SORTIE RATES 18.104.22.168 HOLD AND ALERT GENERATION 62.1.6 OPERATIONAL ENVIRONMENTS 22.214.171.124 FLIGHT ENVIRONMENTS 126.96.36.199 SPACE ENVIRONMENTS 72.1.7 FLIGHT SAFETY 72.1.8 SYSTEM OPERABILITY 72.1.9 SYSTEM SUPPORTABILITY AND MAINTAINABILITY 72.1.10 SYSTEM AFFORDABILITY 82.1.11 SYSTEM INSPECTABILITY AND TESTABILITY 82.1.12 FLIGHT APPROVAL AND TESTING 82.1.13 TRAINING 82.1.14 HUMAN SYSTEMS 92.1.15 ENGINEERING PRINCIPLES AND PRACTICES 92.1.16 ENVIRONMENTAL CONSIDERATIONS 92.2 FLIGHT SEGMENT 92.2.1 REUSABILITY 92.2.2 CONFIGURATION 92.2.3 FLIGHT SEGMENT OPERATIONAL REQUIREMENTS 188.8.131.52 STANDARD MISSION PERFORMANCE REQUIREMENTS 184.108.40.206 STANDARD MISSION PROFILES 220.127.116.11.1 SUB-ORBITAL "POP-UP" PROFILES 18.104.22.168.2 ORBITAL 22.214.171.124.2 FERRY 126.96.36.199 MISSION CAPABILITIES 188.8.131.52.1 CROSS RANGE 184.108.40.206.2 "POP-UP" RANGE 220.127.116.11.3 ON-ORBIT MANEUVERING 18.104.22.168.4 POINTING ACCURACY 22.214.171.124.5 RENDEZVOUS, CO-ORBIT AND DOCKING 126.96.36.199.6 MISSION DURATION 188.8.131.52.7 ORBITAL IMPACT 122.2.4 FLIGHT SEGMENT DESIGN REQUIREMENTS 184.108.40.206 FLIGHT SEGMENT INTEGRITY 220.127.116.11 DESIGN LIFE 18.104.22.168 CRITICAL FAILURE CONDITION RATE 22.214.171.124 MASS AND BALANCE 126.96.36.199 FLIGHT PERFORMANCE RESERVE 188.8.131.52 FAILURE TOLERANCE AND DETECTION 184.108.40.206 FLIGHT ABORT 220.127.116.11 TAKEOFF AND LANDING 18.104.22.168 PROPULSION SYSTEM 22.214.171.124.1 ENGINE FAIL/OPERATIONAL CAPABILITY 126.96.36.199.2 PROPELLANTS 188.8.131.52 PAYLOAD SYSTEMS 184.108.40.206.1 PAYLOAD OPERATIONS CONCEPT 220.127.116.11.2 PAYLOAD CONTAINER 18.104.22.168.3 PAYLOAD CONTAINER CHANGE-OUT DURATION 22.214.171.124.4 PAYLOAD BAY 126.96.36.199.5 PAYLOAD BAY AND PAYLOAD CONTAINER ACCESS 188.8.131.52 CREW SYSTEMS 184.108.40.206.1 CREW COMPLEMENT 220.127.116.11.2 CREW STATION 18.104.22.168.2.1 CREW STATION ENVIRONMENT 22.214.171.124.2.2 CREW VISIBILITY 126.96.36.199.2.3 EMERGENCY INGRESS AND EGRESS 188.8.131.52.3 CREW ESCAPE DURING ASCENT AND DESCENT 184.108.40.206 TOWING 220.127.116.11 INTEROPERABILITY 18.104.22.168.1 COMMUNICATION SYSTEMS 22.214.171.124.2 NAVIGATION SYSTEMS 126.96.36.199 AUTOMATED TEST AND CHECKOUT 192.2.5 FLIGHT SEGMENT MISSION CAPABLE RATE 192.3 COMMAND AND CONTROL SEGMENT REQUIREMENTS 192.3.1 HUMAN-IN-THE-LOOP CONTROL 192.3.2 AUTONOMOUS CONTROL 192.4 SUPPORT SEGMENT REQUIREMENTS 202.4.1 MAINTENANCE, SUPPORT, AND UPGRADES 202.4.2 FERRY 20APPENDIX A: DESIGN REFERENCE MISSIONS 21APPENDIX B: MAXIMUM PERFORMANCE MISSION SETS 22APPENDIX C: REQUIREMENTS MATRIX 24
The Air Force Space Command and the Air Force Materiel Command are evaluating the potential benefits of military spaceplanes for conducting a variety of on-orbit and transatmospheric military missions. This evaluation is being undertaken by the AFSPC-AFMC Military Spaceplane Integrated Concept Team (ICT) directed by the AFSPC and AFMC commanders.
Air Force interest in military spaceplanes stretches back nearly 40 years. This has taken the form of science and technology development, design and mission studies, and engineering development programs. Examples of these activities include: the first Aerospaceplane program and Dyna-Soar/X-20 program (late 1950s-early 1960s); X-15 hypersonic and X-24 lifting body flight test programs (late 1950s through early 1970s); Advanced Military Space Flight Capability (AMSC), Transatmospheric Vehicle (TAV), and Military Aerospace Vehicle (MAV) concept and mission studies (early 1980s); the Copper Canyon airbreathing single-stage-to-orbit (SSTO) feasibility assessment and the National Aerospace Plane (NASP) program (1984-1992); SCIENCE DAWN, SCIENCE REALM, and HAVE REGION rocket-powered SSTO feasibility assessments and technology demonstration programs (late 1980s); and, most recently, the Ballistic Missile Defense Organization's Single-Stage Rocket Technology program that built the Delta Clipper-Experimental (DC-X) experimental reusable spaceplane.
With the increasing importance and criticality of military space operations to Global Engagement capabilities of the Air Force, it is recognized that achieving safe, reliable, affordable, and routine access to, through, and from space will increasingly be important to national security. Current military space launch capabilities, largely based upon upgraded ballistic missiles, are not able to support the increased military operations in space to be necessary in the near future. What is desired is to rebuild space access with new forms of transportation that embody the "aircraft-like" characteristics of safety, reliability, operability, supportability, producibility, testability, and affordability. Many of the studies previously undertaken, and highlighted above, indicate that reusable military spaceplanes are expected to achieve these objectives.
This System Requirements Document (SRD) establishes system requirements for a Military Spaceplane. These requirements represent top-level performance and functional goals or objectives that have been defined by the AFSPC-AFMC Military Spaceplane ICT to assist in the definition of military spaceplane concepts and to evaluate technology development needs.
Rationale for selected requirements are stated herein to assist in understanding why the requirement has been instituted.
This SRD shall be used:
a. To support the conceptual design of military spaceplanes for use in mission solution analyses undertaken in support of the Military Spaceplane ICT;
b. To define key performance and functional requirements to support the evaluation of Technology Needs and to define appropriate science and technology (S&T) programs;
c. To provide a starting point for the evolutionary development of the Military Spaceplane requirements and associated system verification methods;
d. To support the definition of a military spaceplane acquisition strategy;
e. To baseline Air Force requirements for use in comparisons with existing and future commercial launch capabilities;
f. To provide a starting point for the conduct of trade studies, analyses, tests, and demonstrations of the proposed Military Spaceplane System that will establish and refine performance requirements acceptable to the user organizations;
g. To provide potential users with an improved understanding of the performance and functional capabilities of this new flight system; and
h. To support the development of Mission Need Statements and Operational Requirements Documents.
This SRD and any changes to it shall be approved by the AFSPC-AFMC Military Spaceplane ICT. Minor changes between revisions shall be identified by change bars in the left margin.
This SRD is based upon the Technical Requirements Document for a military TAV developed as part of the BMDO SSRT program and the subsequent S&T programs executed through the Air Force Phillips Lab PL/VT-X organization.
a. Herein the term "including" shall be interpreted as "including but not limited to."
b. Herein the term "TBD" refers to design parameters or information to be completed by the contractor.
The Military Spaceplane System shall provide a safe, reliable, operable, supportable, producible, testable, and affordable suborbital and Earth-to-Orbit-and-Return flight system. The Military Spaceplane System may be configured as a single-stage-to-orbit (SSTO) Spaceplane or a configuration incorporating multiple flight vehicles, stages and/ or take-off assist systems. Initial Mark I Demonstrator efforts will concentrate on developing SSTO technologies and operational concepts using a suborbital configuration. Technology maturity during Mark I testing will help make the SSTO versus TSTO or multi-stage decision at a later time.
a. The Military Spaceplane System shall be capable of supporting a wide range of military air and space superiority, global attack, precision engagement, and information superiority missions requiring flight operations in, through, and from space and the transatmosphere.
b. The Military Spaceplane System shall be capable of ascending to, operating in, and descending from designated orbits. The Military Spaceplane System shall be capable of suborbital flight including exoatmospheric flight.
c. The Military Spaceplane System shall be capable of carrying a payload and deploying or otherwise utilizing the payload to execute the military missions in orbit, while ascending to orbit, while descending from orbit, or during suborbital flight.
d. The Military Spaceplane System shall be capable of executing these missions alone or in conjunction with other Military Spaceplane Systems, other civil or commercial space transportation systems, or other orbiting, endoatmospheric, marine, and/ or ground military, civil, or commercial systems.
e. The Military Spaceplane System shall be capable of supporting four levels of employment: peacetime, military operations other than war (MOOTW), major regional conflict (MRC), and global conflict.
f. The Military Spaceplane System shall be capable of executing the following missions assigned to the Air Force Space Command: Force Support, Force Enhancement, Force Application, and Space Control.
g. The Military Spaceplane System shall be capable of crewed, virtually-commanded, or autonomous operations as required by specific mission needs and system requirements.
a. Military Spaceplane System Design Reference Missions (DRMs) are defined in Appendix A. The requirements of these DRMs augment the performance and functional requirements stated herein.
b. Maximum Performance Mission Sets are defined in Appendix B. These mission sets identify specific performance capabilities or trade studies to be assessed during concept formulation. The four point solutions derived from these trade studies will assist the Air Force in understanding the military spaceplane performance trade space and utility.
To the extent practical, the incorporation of commercial requirements is highly encouraged but shall not interfere with military requirements. The Military Spaceplane system shall be designed to support deployment of small military satellites and if possible, commercial payloads (i.e., Iridium, Teledesic, etc.). The contractor is encouraged to work with the commercial sector and/or potential operating companies to develop and market a commercial spin-off capability. To augment military capabilities in crisis, consideration shall be given to operating these commercial systems as part of a dual-use Civil Reserve Air Fleet (CRAF).
The Military Spaceplane System shall be comprised of three major elements-the Flight Segment, the Command and Control Segment, and the Support Segment.
a. The Flight Segment consists of the spaceplane (a flight vehicle capable of achieving orbit), flight hardware, payloads carried by the spaceplane, and any non-orbital flight vehicles, such as a carrier aircraft first stage.
b. The Command and Control Segment consists of the flight control and ground control necessary for operators to control the total Military Spaceplane System.
c. The Support Segment supports the execution of the spaceplane missions. This includes meteorological control, planning and scheduling, maintenance, logistical support, training, and payload processing. The Support Segment may include ground systems, transportable systems, and other aircraft.
a. For the purpose of undertaking performance, safety, operability, and supportability analyses, a Main Operating Base (MOB) at Holloman AFB NM is designated. (This designation does not represent a selection of a MOB by the Air Force but is needed to provide for consistent performance estimates.)
b. For the purpose of undertaking performance, safety, operability, and supportability analyses, designated Dispersed Operating Locations (DOLs) are located at (in alphabetical order) Edwards AFB CA, Falcon AFB CO, Patrick AFB (Cape Canaveral) FL, Vandenberg AFB CA, White Sands NM, and (TBD).
The Military Spaceplane System shall be capable of ferrying the Spaceplane with its maximum payload between the production and depot facilities, MOB, DOLs, commercial airports, and military bases worldwide.
a. For peacetime operations from the MOB, the Military Spaceplane System shall be capable of fully preparing the Flight Segment for mission execution within two (2) days, with an objective of one (1) calendar day, of its landing from a previous mission. This may exclude scheduled inspections and maintenance and major repairs. The Military Spaceplane System shall be capable of maintaining this peacetime rate of flight operations indefinitely. The stated times include the time required to ferry the elements of the Flight Segment to the MOB.
b. For other than peacetime operations from the MOB, the Military Spaceplane System shall be capable of the following:
(1) For a minimum of 30 days, fully preparing a Flight Segment for flight within 18 hours, with an objective of 12 hours of its landing. This may exclude all but safety-of-flight and mission-critical system inspections and maintenance. The stated times include, as an objective, the time required to ferry the elements of the Flight Segment to the MOB.
(2) For a minimum of seven (7) days, fully preparing a Flight Segment for flight within 12 hours, with an objective of 8 hours of its landing. This may exclude all but safety-of-flight and mission-critical system inspections and maintenance. The stated times include, as an objective, the time required to ferry the elements of the Flight Segment to the MOB.
(3) Under emergency war or peace conditions, fully preparing the Flight Segment for flight within eight (8) hours, with an objective of two (2) hours of its landing at the MOB. This may exclude all but safety-of-flight and mission-critical system inspections and maintenance.
a. For peacetime operations at a DOL, the Military Spaceplane System shall be capable of fully preparing the Flight Segment for mission execution within three (3) days, with an objective of one (1) calendar days, of its landing at the DOL from a previous mission. This may exclude scheduled inspections, maintenance, and major repairs.
b. For other than peacetime operations at a DOL, the Military Spaceplane System shall be capable of fully of the following:
(1) For a minimum of 30 days, preparing a Flight Segment for flight within 24 hours, with an objective of 12 hours of its landing at the DOL. This may exclude all but safety-of-flight and mission-critical system inspections and maintenance.
(2) For a minimum of seven (7) days, preparing a Flight Segment for flight within 18 hours, with an objective of 8 hours of its landing at the DOL. This may exclude all but safety-of-flight and mission-critical system inspections and maintenance.
a. The Flight Segment shall be capable of an average peacetime sortie rate per Spaceplane of at least one (1) sortie every ten (10) days, with an objective of one (1) sortie every five (5) days.
b. The Flight Segment shall be capable of an average war and exercise sustained sortie rate per Spaceplane of at least one (1) sortie every three (3) days, with an objective of one (1) sortie every two (2) days.
c. The Flight Segment shall be capable of an average war and exercise surge sortie rate per Spaceplane of at least one (1) sortie every two (2) days, with an objective of one (1) sortie every day.
a. A mission-capable Flight Segment (no outstanding maintenance actions) shall remain mission capable without further maintenance action for 15 days (threshold), 30 days (objective).
b. A mission-capable Flight Segment shall be capable of generating to an Alert two (2) hour (launch within two (2) hours of notification) status within four (4) hours (threshold), with an objective of two (2) hours. The Flight Segment shall be able to maintain Alert two (2) hour status for three (3) days (threshold), seven (7) days (objective).
c. A Flight Segment shall be capable of generating from Alert two (2) hour status to Alert 15 minute (launch within 15 minutes of notification) status within one (1) hour 45 minutes (threshold), 30 minutes (objective). The Flight Segment shall be capable of maintaining Alert 15 Minute status for 12 hours (threshold), 24 hours (objective). A Flight Segment on Alert 15 Minutes shall be capable of launching within 15 minutes (threshold), five (5) minutes (objective).
The Military Spaceplane System shall, as an objective, have an all weather capability.
188.8.131.52 GROUND ENVIRONMENTS
The Military Spaceplane System shall be capable of conducting
ground operations in the following conditions:
CONDITION THRESHOLD OBJECTIVE
Outside Temperature -20 to 100F -45 to 120F
Wind 40 knots 50 knots
Absolute Humidity 30 gms/m3 45 gms/m3
Precipitation Light Moderate
The Military Spaceplane System shall be capable of conducting atmospheric flight operations (including take-off, landing and ferry operations) in the following conditions:
CONDITION THRESHOLD OBJECTIVE
Visibility 0 ft 0 ft
Ceiling 0 ft 0 ft
Crosswind component 25 knots 35 knots
Total wind 40 knots 50 knots
Upper level winds 95th percentile shear all shear conditions
Icing light rime icing moderate rime icing
Absolute humidity 30 gms/m3 45 gms/m3
Outside Temperature -20 to 100F -45 to 120F
Precipitation Light Moderate
The Military Spaceplane System shall be capable of conducting space operations in the following conditions:
CONDITION THRESHOLD OBJECTIVE
Radiation level TBD TBD
a. The Military Spaceplane System shall be able to operate from the MOB and DOLs with a risk of loss of the flight vehicles due to system failure of less than once per 2000 sorties (0.9995), with an objective of less than once per 5000 sorties (0.9998).
b. Risk to friendly populations shall be less than 1 x 10-6 (threshold), 1 x 10-7 (objective), per sortie.
The Military Spaceplane System shall be designed such that the processes used to operate the system are analogous to the processes used to operate military aircraft.
The Military Spaceplane System shall be designed such that the processes used to support and maintain the system are analogous to the processes used to support and maintain military aircraft. This includes standard aircraft support and maintenance processes of procuring and storing war ready reserves.
a. The Military Spaceplane System shall be designed to be produced and sustained such that the cost of ownership throughout the total life cycle of the system is minimized while complying with the performance and functional requirements herein.
b. Demonstrated advanced industrial practices shall be incorporated into the management of the total system program to minimize the cost of doing business with the government. This shall include a comprehensive review of all business and policy stipulations for the elimination of unnecessary requirements.
c. Commercial business and validated commercial engineering and production practices shall be used where consistent with achieving the performance and functional requirements herein.
The Military Spaceplane System shall be designed such that compliance with the performance and functional requirements herein can be validated through appropriate inspections, tests, and demonstrations in a manner similar to that undertaken for military or commercial aircraft. (For example, an envelope expansion flight test program is used to verify the proper functioning of the flight hardware and software and is used measure actual loads, for comparison with predicted loads, prior to approval for unlimited flight release.)
The Military Spaceplane System shall be approved for flight and tested in a manner analogous to Air Force aircraft. The goal shall be to field military spaceplanes able to routinely and reliably over-fly populated areas in a manner analogous to aircraft today. The design, development, operation, testing, and support of the Military Spaceplane System shall be undertaken such that this approval may be achieved.
An integral part of this approval and testing process shall be the ability to perform gradual flight envelope expansion tests. Military Spaceplanes, including demonstrators, shall support extensive subsonic to supersonic flight testing over a government range followed by hypersonic flight testing between government ranges. This gradual flight envelope expansion will be part of a robust risk reduction program.
The training of flight and ground support crews for the Military Spaceplane System shall be undertaken in a manner similar to that undertaken for the training of Air Force flight and ground crews for military aircraft. The design, development, operation, and support of the Military Spaceplane System shall be undertaken in a manner that supports this training.
a. The design of the Military Spaceplane System shall ensure full integration of the human into the system. Consideration shall be given to Human Systems Integration elements in the design, mission concepts, and maintenance activities associated with the Military Spaceplane System. The Military Spaceplane System should accommodate male and female crew members of no less than 100 pounds and no more than 240 pounds and a height of no less than 60 inches and no more than 76 inches.
b. Human Systems Integration shall consider the burden the design imposes on: manpower, personnel, and training; human factors engineering; survivability; and health hazards.
c. Human factors engineering requirements shall be established to: develop effective human-machine interfaces and to minimize or eliminate system characteristics that require extensive cognitive, physical, or sensory skills; require excessive training or workload for intensive tasks; or result in frequent or critical errors or safety/health hazards. MIL-STD-1776, Aircrew Systems, provides guidance.
The design, analysis, development, testing, demonstration, fabrication, operation, maintenance, and support of the Military Spaceplane System shall be based upon engineering principles and practices defined specifically for this system. These principles and practices shall be based upon the concept of engineering precedence and validation of change through test. These principles and practices shall be derived from appropriate military and commercial principles and practices. Modifications to existing precedence required to accommodate unique aspects of the Military Spaceplane System shall be validated through appropriate testing and demonstration undertaken in each stage of the system design and development.
The Military Spaceplane System shall comply with all federal, state, and local environmental laws and regulations appropriate to the intended use of this system.
The Flight Segment shall, as an objective, be fully reusable. As used in this context, fully reusable allows for the replacement of items subject to normal wear and tear, such as tires and brakes, provided such replacement can be undertaken while meeting the requirements defined herein.
The portion of the Flight Segment that achieves orbit shall be referred to as a Spaceplane.
a. The Military Spaceplane System shall be capable of achieving design reference missions I through IV contained in Appendix A with capabilities as defined in Appendix B.
b. The payload mass includes the standard payload container/interface (see paragraph 184.108.40.206.2).
c. The payload mass includes the mass of the crew and all crew accommodations that would be removed for autonomous and/or uncrewed operations.
The Flight Segment shall capable of the following mission profiles:
a. The Military Spaceplane System shall be capable of executing an "unrestricted" sub-orbital "pop up" (i.e. ballistic) exoatmospheric trajectory. The Spaceplane shall be capable of deploying the payload during the exoatmospheric portion of the ballistic flight trajectory and, then, reentering and landing downrange. The deployed payload is boosted by an upper stage to its intended target or orbit.
b. The Military Spaceplane System shall be capable of executing a "restricted" suborbital "pop up" exoatmospheric tajectory with the take-off and landing sites located within CONUS. The spaceplane shall be capable of deploying the payload during the exoatmosphrc portion of the ballistic flight trajectory. The deployed payload is then boosted by an upper stage to its intended target or orbit.
c. The maximum "pop-up" payload mass shall be as defined in Appendices A and B.
d. The Flight Segment shall be capable of safely landing in the event that the "pop-up" payload is retained.
a. The Spaceplane flies directly into an orbital trajectory. The payload is then used onboard, deployed directly into orbit or is boosted to mission destination via an upper stage.
b. The Spaceplane shall be capable of a "once-around" orbit and landing at its takeoff base.
The Miliary Spaceplane System shall be able to ferry the Flight Segment from one location to another, with or without payload onboard the Spaceplane (the payload is not deployed or used). The minimum ferry range shall be 2000 NM without landing and with a global range as an objective. All ferry profiles include carrying maximum payload.
a. The Spaceplane shall have a minimum cross range for an unrestricted "pop-up" profile of 600 NM (threshold), 1200 NM (objective).
b. The Spaceplane shall have a minimum cross range for a CONUS "pop-up" profile of 400 NM (threshold), 600 NM (objective).
c. The Spaceplane shall have a minimum cross range for an orbital profile of is 1200 NM (threshold), 2400 NM (objective).
For a CONUS only, restricted profile, the Spaceplane shall be able to take-off and land within 1600 NM (threshold), 1200 NM (objective).
a. The Spaceplane shall be capable of on-orbit maneuvering with full six degree-of-freedom (DOF) translation and rotation.
b. The Spaceplane propellant tankage shall be sized to carry sufficient on-board propellant to provide an excess (over that required to orbit and deorbit the spaceplane) on-orbit maneuvering velocity change (V) of 300 feet per second (fps), with an objective of 600 fps.. This maneuvering capability shall be accomplished with the maximum easterly payload installed. Propellant mass required to achieve the maneuvering capability shall be chargeable to the payload.
a. The Spaceplane shall be able to control the on-orbit payload bay attitude (pointing requirement) to within 15 milliradians, with an objective of 10 milliradians, simultaneously in all three axes. This pointing requirement shall be with or without the payload bay doors being open and with or without the payload extended from the bay.
b. The Spaceplane shall be capable of maintaining this pointing requirement in support of appropriate DRMs.
a. The Spaceplane shall be able to rendezvous and co-orbit (station keep) with orbital systems including other spaceplanes and satellites. This capability shall be achieved with standard mission equipment.
b. The Spaceplane, with an appropriately configured payload container/payload, shall be able to dock with orbital systems including other spaceplanes and satellites.
a. The Spaceplane shall be capable of powered on-orbit operations for a minimum of 24 hours, with an objective of 72 hours.
b. Under emergency conditions, the Spaceplane shall be capable of extending the period of on-orbit operations by 12 hours, with an objective of 24 hours.
c. For all missions, the Spaceplane shall possess sufficient reserves to support a maximum duration descent from orbit, landing, and post-landing operations following a maximum duration on-orbit stay.
The Flight Segment shall be able to safely reenter and land after an impact from debris of 1-cm diameter (mass and velocity TBD) threshold, 1-cm diameter (mass and velocity TBD) objective.
a. The Flight Segment shall incorporate the essential characteristics in subsystems and equipment that allow the specified performance, safety, reliability, operability, supportability, inspections, and testing to be achieved under the specified operational conditions over the defined service lifetime. These subsystems and equipment shall include, but not be limited to, the structure, propulsion subsystems, mechanical subsystems, avionics/electronics, and software. These essential characteristics may be achieved by evaluating and prudently applying standards from Air Force aircraft integrity programs and from test requirements for space vehicles. The following may be used for general guidance: MIL-STD-1530, Aircraft Structural Integrity Program (ASIP); MIL-STD-1783, Engine Structural Integrity Program (ENSIP); MIL-STD-1798, Mechanical Equipment and Subsystem Integrity Program (MECSIP); MIL-STD-1796, Avionics/Electronics Integrity Program (AVIP); MIL-STD-1803, Software Development Integrity Program (SDIP); and MIL- STD-1540, Test Requirements for Space Vehicle. (The guidance contained in these military standards represent the systems engineering processes that enable the achievement of the "aircraft-like" characteristics required herein. Many of these system engineering processes begin during the conceptual design phase and, as such, are appropriate for consideration at this time.
b. The Flight Segment shall be designed, analyzed, produced, operated, supported, inspected, demonstrated, and tested using engineering principles and practices that are specifically selected for this application. These unique engineering principles and practices shall be incorporated throughout the life-cycle of the system beginning with conceptual design. The concept of engineering precedence and validation of change through test shall be applied.
c. The Flight Segment shall have sufficient strength, stiffness, durability, and damage tolerance to achieve the performance and functional requirements defined herein.
d. The Flight Segment shall be designed to minimize damage and the risk of loss of the flight vehicles due to battle damage, foreign object damage, and atmospheric and space natural environments.
a. For the Spaceplane, the primary structure, including the thermal protection subsystem and the propellant tanks, shall be designed for a minimum life of 250 sorties, with an objective of 500 sorties, over a design life of 20 years.
b. For the Spaceplane, the primary structure, including the thermal protection subsystem and the propellant tanks, shall be capable of a minimum of 100 sorties with an objective of 250 sorties between major inspections and overhauls.
c. For the Spaceplane, the main engines shall be designed for a minimum life of 100 sorties with an objective of 250 sorties. The main engines shall be designed to be removed and replaced within eight (8) hours with an objective of less than four (4) hours.
d. For the Spaceplane, the propulsion subsystem and propellant transfer subsystem shall be capable of a minimum of 50 sorties with an objective of 100 sorties between major inspections and overhauls.
e. For the Spaceplane, all other subsystems and components shall be capable of a minimum life of 100 sorties with an objective of 250 sorties.
f. For the Spaceplane, all other subsystems and components shall be capable of a minimum of 100 sorties with an objective of 250 sorties between major inspections and overhauls.
g. For other aircraft or flight vehicles, the design life and inspection and overhaul intervals shall be comparable to military or commercial cargo and transport aircraft.
a. For the purposes of allocating Spaceplane subsystem and component reliability's while conducting failure modes and effects analysis (FMEA), the probability of loss of the Spaceplane shall be less than once per 2000 sorties, with an objective of less than once per 5000 sorties.
b. For other aircraft or flight vehicles, critical failure rates shall be consistent with those for large commercial aircraft.
a. Starting with the conceptual design, the Flight Segment's performance shall be based upon the empty and fueled system mass estimates, including center of gravity and mass moments of inertia, derived from estimated, calculated, and/ or measured masses of the subsystems, components, and parts.
b. Estimated and calculated masses shall specifically incorporate mass allocations to accommodate the requirements for safety, reliability, supportability, operability, producibility, inspectability, affordability, and test capabilities.
c. Estimated and calculated masses shall account for margins and uncertainties specified elsewhere in this SRD.
d. Estimated and calculated masses shall be for a complete configuration as best known at the time the estimate is made.
e. Estimated and calculated masses shall be consistently used in related analyses including performance, cost, structural analyses, etc. The accuracy (number of significant figures) of the estimated and calculated masses shall be consistent with the accuracy of related analyses.
a. The flight performance reserve of the Military Spaceplane System shall be based on 3 sigma stochastic combination of uncontrollable variables (e.g., weather, atmosphere density, propellant temperatures, propellant loading accuracy, residual unusable propellants, prediction uncertainties and hardware uncertainties) which affect this performance estimate.
b. Analytical predictions of system performance shall include performance margins commensurate with the uncertainties in the predictive methods used.
a. Flight-critical and mission-critical subsystems shall be designed to be fail-safe, as a minimum, and shall, as an objective, be fail-operational/fail-safe. Fail-operational means that the Flight Segment shall be capable of continuing with the mission following the failure of a critical system. Fail-safe means that the Flight Segment shall be capable of achieving a safe mode of operation following the failure of a critical subsystem. During ascent and under fail-safe conditions, the Flight Segment shall be capable of either landing or continuing with insertion of the Spaceplane into a safe orbit. During descent and under fail-safe conditions, the Spaceplane shall be capable of safely landing. On-orbit and under fail-safe conditions, the Spaceplane shall be capable of remaining in a safe orbit and conducting a safe emergency entry and landing.
b. Flight-critical subsystems required for a safe return from orbit shall be fail-safe, as a minimum, at the beginning of the descent. The proper functioning of these subsystems shall be determined prior to the commitment to de-orbit, re-enter, and land.
c. Combined failure rates of flight-critical subsystems shall be determined stochastically.
d. Flight-critical subsystem failure shall be detectable to allow reconfiguration of the flight system and to prevent loss of control of the flight vehicles or subsequent catastrophic failure.
a. The Flight Segment shall be capable of a safe shut down following engine start, but prior to takeoff, without damage to the Flight Segment or support system, or risk to personnel.
b. At any time after takeoff and under emergency conditions, the Flight Segment shall be capable of either returning to a safe landing or continuing the ascent of the Spaceplane to an emergency orbit. Specially prepared and supported down range abort sites shall not be necessary. Emergency conditions involve the failure of any flight-critical subsystem that does not lead to immediate catastrophic loss and is not fail-operational.
c. The flight vehicles shall be capable of landing at alternate bases during abort.
d. Flight under fail-safe emergency conditions shall not exceed the design limits of the flight vehicles.
a. For horizontal take-off and/or landing vehicles, they shall be capable of using conventional runways designed for large military and commercial transports, of less than 10,000 ft x 150 ft, and, as an objective, less than 8,000 ft x 150 ft.
b. For vertical landing vehicles, they shall be able to land within a 50 ft radius on conventional concrete runway surfaces, and as a goal within a 25 ft radius.
c.. The Flight Segment shall be able to operate from runways with an equivalent load bearing capacity of 65,000 lbs (threshold) for single wheel type landing gear (S65) with an objective of S45.
d. For vertical takeoff Flight Segments, a maximum ground area of (TBD) shall be required.
e. Takeoff and landing from a conventional runway shall not cause damage to the runway such that the runway would be put out of commission until repairs are made.
f. For vehicles that utilize runways, the Runway Condition Reading is defined in (TBD).
The Flight Segment shall be capable of safely continuing controlled flight, either to orbit or a landing after failure of a critical propulsion component.
The flight vehicle shall not use hypergolic or toxic propellants.
a. To facilitate ground processing and minimize turnaround times, an off-line payload processing and containerization system shall be required.
b. The Flight Segment shall have a standard interface to a stand-alone payload container that can be installed in and removed from the payload bay of the Spaceplane without modification to or reconfiguration of the Spaceplane.
c. Special non-standard services or requirements needed to support specific mission assets shall be accommodated by the installation of appropriate Airborne Support Equipment (ASE) in the Payload Container. Integration of the payload container, ASE, and payload shall be controlled by the payload program office.
d. The Support System shall be capable of easily and quickly removing or installing a payload container from the flight vehicle when landing at the MOB or DOL.
a. The payload container shall provide standardized structural, mechanical, electrical, communications, and other interfaces between the payload and the Spaceplane.
b. The standardized payload container shall have the internal dimensions indicated in Appendix B, or similarly functional dimensions with adequate volume able to support the DRMs. The loaded payload container shall be air, truck and rail transportable.
c. The payload deployment and safety status shall be capable of being monitored by the Military Spaceplane System.
d. The payload container shall be able to carry additional on-orbit propellant for the Spaceplane.
The maximum time required for payload container/change-out (removal of one payload container and the replacement of it with another) shall be less than one (1) hour, with an objective of less than 30 minutes.
a. The Spaceplane shall have a payload bay capable of housing a standardized payload container as defined above.
b. The payload bay and container mounting provisions shall be capable of structurally supporting the loads associated with the design payloads, including the payload container mass, during all phases of flight including emergency flight.
c. The Spaceplane shall provide the environmental and physical interfaces to the container as defined in (TBD).
d. The payload bay shall include the equipment and mechanisms necessary to safely jettison the payload and payload container while in exoatmospheric flight.
e. The Spaceplane shall be designed to fly through all nominal and abort conditions with or without the container/payload installed.
If required to perform a DRM, access between the payload bay/container and the crew station during crewed missions shall be provided.
Crew systems, as defined in the following requirements, shall be incorporated into the Spaceplane only when the need for human presence is required to meet the requirements stated herein.
a. The crew station shall accommodate two crew members.
b. The design of the Spaceplane crew station shall, as an objective, allow for the addition of one more crew member.
a. Each Spaceplane shall be capable of accommodating a crew if it is determined that crewed operations are required. The crew station may be removable and located in the payload bay provided this does not unacceptable diminish the performance of the DRMs or affect crew health, safety, and comfort.
b. The crew station shall be designed to accommodate flight crews wearing pressurized suits. Avionics and controls shall be fully integrated with the human and be anthropometrically designed. Display symbology will be standardized with current Air Force systems.
a. The crew station shall be operable during and following exposure to space.
b. The crew station shall contain a life support system capable of supporting two crew members for a minimum of 24 hours, with an objective of 72 hours.
c. The crew station shall contain an emergency life support system capable of minimally supporting two crew members for an additional 12 hours, with an objective of 24 hours.
d. The operating pressures and gas combinations of the cabin pressurization systems and the crew pressure suits shall be designed to permit rapid crew egress with little or no preoxygenation.
a. The crew station shall have a window(s) or suitable alternatives for direct outside visibility as required for the execution of the DRMs.
b. The crew shall have sufficient visibility (either directly or via video) of the payload container and payload during payload operations to verify the status of the payload and payload container as required for mission execution and vehicle safety.
a. While on the ground, the Flight Segment shall have provisions for unassisted emergency crew egress.
b. While on-orbit, the Spaceplane shall have provision for ingress and egress to enable crew rescue.
c. Spaceplane emergency access hatches, doors, or airlocks shall be capable of being manually opened, closed, and secured so as to not hinder safe reentry and landing. These hatches, doors, or airlocks shall be accessible and usable by crew members in pressure suits or by external rescue crews.
An endoatmospheric, subsonic crew escape capability shall be provided. A crew escape capability throughout the flight envelope is an objective. An on-orbit crew escape and survival capability is an objective.
The unfueled Flight Segment shall be capable of being towed intact (i.e., without vehicle disassembly or Spaceplane demating) on prepared surfaces with the maximum payload onboard.
Each Flight Segment shall be capable of interfacing with the United States C4ISRT (Command, control, communications, computers, intelligence, surveillance, recconisense and targeting) systems required to accomplish the DRMs and maintain safe, controlled flight.
Each Flight Vehicle shall be capable of utilizing the NAVSTAR/GPS (Global Positioning System) navigation aid in addition to a normal complement of aircraft navigation capabilities.
Each Flight Segment shall be capable of automated test and checkout of the flight- and mission-critical subsystems and the payload. Such test and checkout shall be capable of being performed while on the ground and during all phases of mission execution.
An individual Flight Segment shall have a mission capable rate of 80 percent, with an objective of 95 percent. System availability shall be determined in the same manner as is done for Air Force aircraft.
The Command and Control Segment shall plan, supervise, and execute all aspects of the command and control of the Military Spaceplane System. The Command and Control Segment shall interface with the command, control, communications, and computer systems utilized by the Air Force and Department of Defense necessary for execution of the military missions assigned to the Military Spaceplane System.
The flight crew shall be able to direct the Spaceplane either from onboard the Spaceplane or from the ground or support vehicles via a virtual crew interface. This capability shall be provided with or without a crew onboard.
The Spaceplane portion of the Flight Segment shall be capable of autonomous execution of preprogrammed missions with or without a crew onboard. Autonomous operation shall not degrade flight safety or mission execution.
The Support Segment shall maintain, support, operate, and train the Military Spaceplane System. The Support Segment shall maintain, support, and operate the payload container off-line ground processing. The Support Segment shall provide for operations at the MOB as well as at DOLs. The Support Segment shall provide for its own maintenance and support.
a. The Support Segment shall be able to turn a Flight Segment around for flight with no more than 100 work-hours, with an objective of 50 work-hours, of on-vehicle maintenance and servicing.
b. The main engines shall be designed to be removed and replaced within eight (8) hours, with an objective of less than four (4) hours.
c. "Aircraft like" depot or factory maintenance at regularly scheduled intervals shall be utilized as a basis for the Military Spaceplane Support Segment.
d. Modifications and system upgrades shall be undertaken in the same manner as accomplished for military aircraft.
a. The Support Segment shall be capable of undertaking the required ferry of the Flight Segment as well as the transportation of any Support Segment elements required to support this ferry capability.
b. All on-board subsystems required to ferry the Spaceplane shall be field repairable/ replaceable to the extent necessary to perform a ferry mission.
c. All ground equipment required to repair and ferry the Spaceplane shall be transportable to unprepared landing sites via existing transport aircraft.
d. If specialized support air vehicles are required, they must carry all necessary equipment.
Possible Future Design Reference Missions
Maximum Performance Missions Sets are system defining and encompass the four missions and the Design Reference Missions. Instead of giving a threshold and objective for each mission requirement, missions sets are defined. Each mission set will define a point solution and provide visibility into the sensitivities of the requirements from the thresholds (Mark I) to the objective (Mark IV). If takeoff and landing bases are constrained to the U.S. (including Alaska and Hawaii), this will reduce stated pop-up payloads by at least half.
Mark I (Demonstrator or ACTD non-orbital vehicle that can only pop up)
Mark II (Orbit capable vehicle)
REFERENCE MISSIONS TO MISSION SETS MATRIX
Ref Mission Mark I Mark II Mark III Mark IV Payload Bay Data 10' x 5' x 25' x 12' x 25' x 12' x 45' x 15' x 5' 12' 12' 15' 10 klbs 20 klbs 40 klbs 60 klbs DRM 1 (Pop up and 1-3 klb 7 to 9 klb 14 to 18 klb 20 to 30 klb deliver mission assets) DRM 2 (Pop up and 3-5 klb 15 klb 25 klb 45 klb deliver orbit assets due east 100 x 100 NM) DRM 3 (Co-Orbit) N/A 4 klb due 6 klb due east 20 klb due east 100 x 100 x 100 NM east 100 x 100 100 NM NM DRM 4 (Recover) N/A TBD TBD TBD DRM 5 (Polar Once N/A N/A 1 klb 5 klb Around)
Mission asset weight is a core weight and does not include a boost stage, aeroshell, guidance or propellant.
Orbital asset weight does not include an upperstage.
Requirements Matrix for Mark II, III and IV (Desired for Mark I) Requirement Threshold Objective Sortie Utilization Rates Peacetime sustained 0.10 sortie/day 0.20 sortie/day War/exercise sustained (30 days) 0.33 sortie/day 0.50 sortie/day War/exercise surge (7 days) 0.50 sortie/day 1.00 sortie/day Turn Times Emergency war or peace 8 hours 2 hours MOB peacetime sustained 2 days 1 day MOB war/exercise sustained (30 days) 18 hours 12 hours MOB war/exercise surge (7 days) 12 hours 8 hours DOL peacetime sustained 3 days 1 day DOL war/exercise sustained (30 days) 24 hours 12 hours DOL war/exercise surge (7 days) 18 hours 8 hours System Availability Mission capable rate 80 percent 95 percent Flight and Ground Environments Visibility 0 ft 0 ft Ceiling 0 ft 0 ft Crosswind component 25 knots 35 knots Total wind 40 knots 50 knots Icing light rime icing moderate rime icing Absolute humidity 30 gms/m3 45 gms/m3 Upper level winds 95th percentile all shear conditions shear Outside temperature -20 to 100F -45 to 120F Precipitation light moderate Space Environment Radiation level TBD TBD Flight Safety Risk to friendly population < 1 x 10-6 < 1 x 10-7 Flight Segment loss < 1 loss /2000 < 1 loss/5000 sorties sorties Reliability 0.9995 0.9998 Cross Range Unrestricted pop-up cross range 600 NM 1200 NM CONUS pop-up cross range 400 NM 600 NM Orbital cross range 1200 NM 2400 NM "Pop-up" Range CONUS pop-up range 1600 NM 1200 NM Ferry range minimum 2000 NM worldwide On-orbit Maneuver Excess V (at expense of payload) 300 fps 600 fps Pointing accuracy 15 milliradians 10 milliradians Mission Duration On-orbit time 24 hours 72 hours Emergency extension on-orbit 12 hours 24 hours Orbital Impact Survival impact object size 0.1-cm diameter 1-cm diameter Survival impact object mass TBD TBD Survival impact velocity TBD TBD Alert Hold Hold Mission Capable 15 days 30 days Mission Capable to Alert 2-hour 4 hours 2 hours Status Hold Alert 2-hour Status 3 days 7 days Alert 2-hour to Alert 15-minute 1 hour 45 minutes 30 minutes Status Hold Alert 15-minute Status 12 hours 24 hours Alert 15 Minute to Launch 15 minutes 5 minutes Design Life Primary Structure 250 sorties 500 sorties Time between major overhauls 100 sorties 250 sorties Engine life 100 sorties 250 sorties Time between engine overhauls 50 sorties 100 sorties Subsystem life 100 sorties 250 sorties Take-off and Landing Runway size 10,000 ft x 150 ft 8000 ft x 150 ft Runway load bearing S65 S45 Vertical landing accuracy 50 ft 25 ft Payload Container Container change-out 1 hour 30 minutes Crew Station Environment (if rqd) Life support duration 24 hours 72 hours Emergency extension on-orbit 12 hours 24 hours Crew Escape (if rqd) Escape capability subsonic full envelope Maintenance and Support Maintenance work hours/sortie 100 hours 50 hours R&R engine 8 hours 4 hours