Optimal round trip space tug trajectories for earth escape missions
Space tug optimal round trip trajectories for payload earth escape injection missions, obtaining boundary value problem solution by Newton- Raphson iteration technique
Teren, F.↗
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Space Tug - Mission and program planning
An additional propulsive stage, carried in the payload bay, will be necessary for delivery of payloads to orbits beyond those which can be reached by the Shuttle alone. The concept of a reusable third stage, or Space Tug, has been under study for several years. Aspects of space tug operations planning are discussed together with payload studies, shuttle third stage program options, expendable stage studies, growth stage studies, and engine studies. Studies concerning reusable space tugs are considered, giving attention to a minimum development cost tug, a direct developed tug for 1983 operational capability, and a phased developed tug. Payload requirements are examined along with shuttle interface requirements, ground operations, and program options.
Wild, J. W.↗
Space tug point design study. Volume 1: Summary
The design and characteristics of a space tug are discussed. The primary objective of the study is to verify the performance capability of a baseline design to deliver and retrieve payloads between 100 nautical miles, 28.5 degrees inclination, and geosynchronous. The space tug is ground based, reusable for 20 mission cycles, and is shuttled to and from low earth orbit by an earth orbital shuttle (EOS) with a 65,000 pound payload capability. It is shown that the baseline concept can meet the target performance goals. The design analysis encompassed: (1) definition of the vehicle primary structure, (2) thermal control, (3) meteoroid protection, (4) propulsion and mechanical subsystems, and (5) avionics including power generation and distribution.
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Space Tug Aerobraking Study. Volume 2: Technical
The feasibility and practicality of employing an aerobraking trajectory for return of the reusable Space Tug from geosynchronous and other high energy missions was investigated. The aerobraking return trajectory modes from high orbits employ transfer ellipses which have low perigee altitudes wherein the earth's sensible atmosphere provides drag to reduce the Tug descent delta velocity requirements and thus decrease the required return trip propulsive energy. An aerobraked Space Tug, sized to the Space Shuttle payload capability and dimensional constraints, can accomplish 95 percent of the geosynchronous missions with a single Shuttle/Tug launch per mission. Aerodynamics, aerothermodynamics, trajectory, quidance and control, configuration concepts, materials, weights and performance parameters were identified. Sensitivities to trajectory uncertainties, atmospheric anomalies and re-entry environments were determined. New technology requirements and future studies required to further enhance the aerobraking potential were identified.
Corso, C. J.↗
Space tug economic analysis study. Volume 2: Tug concepts analysis. Part 1: Overall approach and data generation
An economic analysis of space tug operations is presented. The subjects discussed are: (1) data base for orbit injection stages, (2) data base for reusable space tug, (3) performance equations, (4) data integration and interpretation, (5) tug performance and mission model accomodation, (6) total program cost, (7) payload analysis, (8) computer software, and (9) comparison of tug concepts.
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Space tug point design study. Volume 3: Design definition. Part 1: Propulsion and mechanical, avionics, thermal control and electrical power subsystems
A study was conducted to determine the configuration and performance of a space tug. Details of the space tug systems are presented to include: (1) propulsion systems, (2) avionics, (3) thermal control, and (4) electric power subsystems. The data generated include engineering drawings, schematics, subsystem operation, and component description. Various options investigated and the rational for the point design selection are analyzed.
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The Space Tug mission role and program planning.
More than half of the planned payload programs require a velocity increment beyond that nominally provided by the Space Shuttle. The reusable Space Tug system can satisfy this placement requirement and, in addition, can provide other, vital operational services for payloads in the 1980s. To realize maximum operational and economic benefits, it is desired that an orbital propulsive stage such as the Space Tug be available concurrently with Space Shuttle initial operations. Potential tug missions, significant interfaces, system characteristics, and configuration alternatives are discussed in conjunction with salient program planning factors.
Schnyer, A. D.↗
Space tug economic analysis study. Volume 2: Tug concepts analysis. Appendix: Tug design and performance data base
The tug design and performance data base for the economic analysis of space tug operation are presented. A compendium of the detailed design and performance information from the data base is developed. The design data are parametric across a range of reusable space tug sizes. The performance curves are generated for selected point designs of expendable orbit injection stages and reusable tugs. Data are presented in the form of graphs for various modes of operation.
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Space tug avionics definition study. Volume 3: Avionics baseline configuration definition
The baseline avionics systems for the space tug is comprised of a central digital computer that integrates the functions of all of the tug's subsystems by means of a redundant digital data bus. The major subsystems of the avionics system are: data management; communications; guidance, navigation, and control; rendezvous and docking; electrical power; and instrumentation. The baseline avionics system for the space tug resulting from system and subsystem trade studies is defined. Tug interfaces with the spacecraft, orbiter and the ground, and the baseline philosophy and configuration for onboard checkout of the tug are included. Baseline configurations, functional and operational features, component details and characteristics, and the supporting software are included in the subsystem descriptions.
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Pre-phase A Study for a Analysis of a Reusable Space Tug. Volume 5 - Subsystems Final Report
Reusable space tug subsystems for operational and performance requirements
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Optimal round trip space tug trajectories for earth escape missions
Reusable space tug payload injection missions, determining optimal round trip trajectories at earth escape energy levels
Teren, F.↗
Space tug thermal control
It was determined that space tug will require the capability to perform its mission within a broad range of thermal environments with currently planned mission durations of up to seven days, so an investigation was conducted to define a thermal design for the forward and intertank compartments and fuel cell heat rejection system that satisfies tug requirements for low inclination geosynchronous deploy and retrieve missions. Passive concepts were demonstrated analytically for both the forward and intertank compartments, and a worst case external heating environment was determined for use during the study. The thermal control system specifications and designs which resulted from the research are shown.
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Space Tug systems study (storable). Volume 3: Executive summary
Space tug program options that consider key issues and mission requirements are assessed, component and subsystem candidates are evaluated, and tug configurations synthesized. Three tug program options are defined and evaluated.
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Lightweight Space Tug body structure
Lightweight honeycomb sandwich construction using a wide variety of metal and fibrous composite faceskins was used in the design of a typical Space Tug skirt structure. Relatively low magnitude combined loading of axial compression and torsion resulted in designs using ultrathin faceskins, lightweight honeycomb cores, and thin faceskin/core adhesive bond layers. Two of the designs with metal faceskins (aluminum and titanium) and four with fibrous composite faceskins (using combinations of fiberglass, boron, and graphite) were evaluated through the fabrication and structural test of a series of small development panels. The two most promising concepts with aluminum and graphite/epoxy faceskins, were further evaluated through the fabrication and structural test of larger compression and shear panels. All panels tested exceeded design ultimate load levels, thereby, verifying the structural integrity of the selected designs. Projected skirt structural weights for the graphite/epoxy and aluminum concepts fall within original weight guidelines established for the Space Tug vehicle.
Lager, J. R.↗
Study of liquid oxygen/liquid hydrogen auxiliary propulsion systems for the space tug
Design concepts are considered that permit use of a liquid-liquid (as opposed to gas-gas) oxygen/hydrogen thrust chamber for attitude control and auxiliary propulsion thrusters on the space tug. The best of the auxiliary propulsion system concepts are defined and their principal characteristics, including cost as well as operational capabilities, are established. Design requirements for each of the major components of the systems, including thrusters, are developed at the conceptual level. The competitive concepts considered use both dedicated (separate tanks) and integrated (propellant from main propulsion tanks) propellant supply. The integrated concept is selected as best for the space tug after comparative evaluation against both cryogenic and storable propellant dedicated systems. A preliminary design of the selected system is established and recommendations for supporting research and technology to further the concept are presented.
Nichols, J. F.↗
Optimal round trip space tug trajectories for earth escape missions
Optimal round trip space tug trajectories for earth escape missions
Teren, F.↗
Analysis of space tug operating techniques supplemental report (study 2.4)
An analysis of space tug operating techniques is presented. The subjects discussed are: (1) sustaining engineering requirements, (2) off-site facility requirements, (3) evaluation of tug checkout alternatives, and (4) spares provisioning. Tables of data are included to clarify the written presentation.
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Analysis of space tug operating techniques. Volume 2: Study results
The design requirements for space tug systems and cost analysis of the refurbishment phases are discussed. The vehicle is an integral propulsion stage using liquid hydrogen and liquid oxygen as propellants and is capable of operating either as a fully or a partially autonomous vehicle. Structural features are an integral liquid hydrogen tank, a liquid oxygen tank, a meteoroid shield, an aft conical docking and structural support ring, and a staged combustion main engine. The vehicle is constructed of major modules for ease of maintenance. Line drawings and block diagrams are included to explain the maintenance requirements for the subsystems.
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