Orbital Transfer Vehicle Research Articles

Computational chemistry and aeroassisted orbital transfer vehicles

An analysis of the radiative heating phenomena encountered during a typical aeroassisted orbital transfer vehicle (AOTV) trajectory was made to determine the potential impact of computational chemistry on AOTV design technology. Both equilibrium and nonequilibrium radiation mechanisms were considered. This analysis showed that computational chemistry can be used to predict (1) radiative intensity factors and spectroscopic data; (2) the excitation rates of both atoms and molecules; (3) high-temperature reaction rate constants for metathesis and charge exchange reactions; (4) particle ionization and neutralization rates and cross sections; and (5) spectral line widths.

Radiation enhancement by nonequilibrium in earth's atmosphere

The status of knowledge of shock-layer radiation in the low-density nonequilibrium regime, as appropriate to the flight of the proposed aeroassisted orbital transfer vehicle, is surveyed. The existing laboratory data and the flight data from Apollo and Fire are scrutinized. Nonequilibrium radiation is found to be significant in the flight regime of the vehicle, but a factor-of-thre e uncertainty is found in its magnitude. The available theoretical models are reviewed, their weaknesses are pointed out, a computer code that approximately reproduces the existing data is introduced, and recommendations are made for future research.

Subsystem Impact on Space Station System Design

This article shows that space station evolutionary system designs are strongly influenced by subsystem technology. To understand this impact, the article describes an evolutionary space operations system and element interactions with mission user payloads. This description addresses what and who are involved, what are the accommodations, and when, where, and how space station facility users are accommodated. Other topics discussed include space-based orbit transfer vehicles (OTV’s), station electrical power levels, subsystem tradeoff issues and their technology development challenges, cost interactions with benefits, and payload accommodations (user-subsystem interfaces). A highlight of the discussion is the view presented of requirements for subsystem supporting technology developments.

European electronuclear OTV for the end of the 1990s

The concept of an Electronuclear Orbital Transfer Vehicle, associated with Ariane V, is currently studied at CNES and CEA. The objective is to increase European Space Transportation Competitivity after 2000 for high energy orbits. The system appears to be feasible and economically interesting; it offers impressive performance and a very large growth potential.

A Future Solar Orbital Transfer Vehicle Concept

The limiting performance of any orbital transfer vehicle (OTV) is fixed by its mass characteristics and the energy content of its propellant. The direct heating of hydrogen to high temperatures can produce practical specific impulses of 790 s which is to be compared with the liquid oxygen/liquid hydrogen limit of about 480 s in practical systems. A solar orbital transfer vehicle (SOTV) has been designed which utilizes a 100 m diameter concentrator system to provide the approximate 10 MW of thermal power needed to provide a nominal thrust level of 2780 N. The SOTV offers a compromise between typical chemical OTVs and electric propulsion OTVs. The SOTV can deliver 16 000 kg to geosynchronous orbit and 5000-10 000 kg to the inner planets. A four-week period for the assembly and payload integration for the SOTV has been found necessary. Several techniques for controlling the thrust level and thermal soak of the heat exchanger have been examined. Two of these, an expandable pupil stop reflector and concentrator surface deformation, are highly competitive. Considerable mission injection opportunity flexibility is possible with more than a 10 h launch window centered about each of local dusk and dawn.

Concepts for, and Utility of, Future Space Central-Power Stations

T rate of industrial development in space is largely dependent on the cost of transportation to, through, and from space and the cost of electrical power in space. The technological and economical impact of a large central-power station in Earth orbit on the cost and performance of future spacecraft and their orbital-transfer systems has been examined. Analysis of the cost effectiveness of meeting Earth-orbiting spacecraft electrical power demands from a central-power station indicates that this application cannot justify the investment required for the central station. However, laser-thermal and laser-electric propulsion systems powered from a central-power station promise major cost savings when compared to orbital-transfer vehicles using advanced, conventional, chemical, and solar-electric propulsion—at least within the bounds of the assumptions made.

Application of electromagnetic accelerators to space propulsion

Recent investigations of DC electric rail gun performance show that these devices are attractive for high acceleration launch to high velocity. Application of high performance electric rail guns to space propulsion is discussed in this paper. The parameters which may be used to characterize a spaceborne propulsion system are described. From a systems viewpoint, the components comprising a spaceborne propulsion system are described and the performance discussed. As an orbital transfer vehicle an electric rail gun propulsion system appears feasible and could provide attractive mission performance.

Economic and Programmatic Considerations for Advanced Transportation Propulsion Technology

Requirements for space transportation will increase after the Space Shuttle becomes operational. Shuttle derivatives and new earth-to-orbit vehicles are compared economically. The addition of both one and two new vehicle types are considered. Programmatic considerations are included in deriving a scenario which appears reasonable and includes the Space Shuttle, a heavy-lift cargo derivative of the Shuttle, a unique dual-fuel orbit transfer vehicle, and a small new earth-to-orbit vehicle in the foreseeable future. Large new orbital transfer and earth-to-orbit vehicles would be added when needed.

Preliminary Design for a Space-Based Orbital Transfer Vehicle

A space-based orbital transfer vehicle has been sized for a 50-metric-ton payload delivery from low-earth-orbit to a geosynchronous orbit. Space basing effected substantial reductions in cryogenic insulation, tank, and body structure. The tank and body structural masses are shown to be lower for space basing because of the larger difference in acceleration loads between the on-orbit case (0.2 g's) and delivery (3.0 g's), the latter applying to ground-based vehicles which are delivered to orbit fully loaded with propellants. Insulation masses are lower because of the absence of an atmosphere and the attendant heat transfer losses. Insulation systems masses are also reduced because of the elimination of the problem of liquefaction and freezing of moisture on the tanks.

Propulsion Options for Space-Based Orbital Transfer Vehicles

A concept for a lightweight space-based orbital transfer vehicle (OTV) featuring thin, spherical, pressuredesigned aluminum liquid-oxygen and liquid-hydrogen tanks and a truss structure of composite materials is used as a baseline design for a large-cargo OTV. Vehicle sizing, fleet analysis, and parametric cost analysis are used to evaluate the effects of engine technology, vehicle staging, and high-thrust vs. low-thrust transfer. Results indicate that Earth-to-orbit launch costs and OTV engine performance are strong drivers in orbital transportation cost and that there is no significant benefit in staging vehicles. At the low values of Earth-to-orbi t cost representative of advanced launch vehicles, low-thrust and high-thrust OTV's are competitive.

Aeromaneuvering orbit transfer vehicles for the space transport system

Alternatives to all-propulsive manned Orbit Transfer Vehicles (OTV) are presented that utilize aeromaneuvering in combination with propulsive maneuvering. Aeromaneuvering OTV concepts use atmospheric lift and drag forces for maneuvering (orbit plane and ΔV change) to substantially increase payload carrying capability over all-propulsive OTV capabilities. This paper includes a summary of the results of feasibility and concept definition studies and discusses the advantages and disadvantages of aeromaneuvering as compared with all-propulsive vehicles. Manned aeromaneuvering OTV concepts will be presented such as the Aeromaneurvering Orbit-to-Orbit. Shuttle (AMOOS) that can provide future orbital transportation and the Aeromaneuvering Recovery System (AMRS) that will permit emergency recovery of crewmen from high altitude orbits. The AMRS mission requires that an AMRS vehicle be placed in the mission orbit where it remains on-station attached to a manned space facility until required for emergency crew return. The main contributions of this paper are: (1) to establish the concept of the aeromaneuvering OTV for the purpose of performing manned and unmanned orbit transfer; (2) to present data regarding aeromaneuvering OTV configurations, performance, system tradeoffs and mission applications; and (3) to present data concerning major design parameters such as dynamic pressure, heating rates and guidance.