[en] Solar cells of all space objects are damaged by radiation in orbit. This damage, however, can be removed by laser annealing. A new in-orbit laser regeneration system for both body- and spin-stabilized space objects is proposed. For successful annealing of solar cells damaged by 10 years' radiation dose in orbit it is necessary for the temperature rise in the incidence point of the laser beam to reach about 400⁰C. By continuous regeneration, however, between two annealing cycles the solar cells are hit by about two orders of magnitude lower radiation dose. This makes it possible to carry out the regeneration at a temperature rise well under 1⁰C! If an optimal laser regeneration system is used, such low temperature rise laser annealing of radiation-damaged solar cells is possible. A semiconductor GaAlAs diode laser with output power up to 10 mW CW was used for annealing. Some results of the very low temperature rise annealing experiment are given in this paper. (author)

[en] The Galileo spacecraft will explore the Jupiter system and Ulysses will fly by Jupiter en route to a polar orbit of the sun. Both spacecraft are powered by general purpose heat source radioisotope thermoelectric generators (RTGs). As a result of the Challenger accident and subsequent mission reprogramming, the Galileo and Ulysses missions' safety analysis had to be repeated. In addition to presenting an overview of the safety analysis status for the missions, this paper presents a brief review of the missions' objectives and design approaches, RTG design characteristics and development history, and a description of the safety analysis process. (author)

[en] Four isotope power system concepts are presented and compared on a common basis for application to on-board electrical prime power for an autonomous planetary rover vehicle. A representative design point corresponding to the Mars Rover Sample Return (MRSR) preliminary mission requirements (500 watts) was selected for comparison purposes. All system concepts utilize the GPHS isotope heat source developed by DoE. Two of the concepts employ thermoelectric (TE) conversion: one using the GPHS RTG used as a reference case, the other using an advanced RTG with improved thermoelectric materials. The other two concepts employed are dynamic isotope power systems (DIPS): one using a closed Brayton cycle (CBC) turboalternator, and the other using a free piston Stirling cycle engine/linear alternator (FPSE) with integrated heat source/heater head. (author)

[en] In space activity, the energy remotely transmitted by means of a laser beam is valuable for many purposes. This energy can be used as electric power through an energy converter. In this paper, a new energy converter is proposed, in which a relativistic electron beam is used. In this method, the operation of high power density is possible while maintaining a high efficiency, since the unconverted laser beam is transmitted rather than absorbed in the converter. (author)

[en] Since 1961, the United States has successfully flown 35 space nuclear power sources on 20 space systems. These systems have included the Apollo, Pioneer, Viking and Voyager spacecraft launched by the National Aeronautics and Space Administration and navigation and communications satellites launched by the Department of Defense. These power sources performed as planned and in many cases exceeded their power requirements and/or lifetimes. All of the power sources met their safety requirements. This paper surveys past uses of space nuclear power in the US and thus serves as a historical framework for other papers in this Conference dealing with future US applications of space nuclear power. (author)

[en] This paper summarizes the current status of proposed NASA Human Exploration Missions (HEMs), presenting detail with respect to schedule and system features. Using the Lunar exploration and Mars exploration missions as design drivers, new vehicle elements have been configured and optimized to meet proposed mission requirements. Both conventional chemical propulsion and alternative vehicle designs incorporating advanced nuclear propulsion systems are included, and the total mass required in Low Earth Orbit (LEO) is compared for each propulsion system. (author)

[en] A method of power transmisssion over a very long distance using a laser beam has been proposed. The characteristics of direct energy conversion from laser energy to electricity by means of a laser-produced plasma are reported. It is found that the efficiency η₁.η_3max (where η₁ and η₃ are the conversion efficiency from laser energy to ion energy and from plasma ion energy to electricity respectively) increases with laser output using a carbon target. (author)

[en] The restrictions on spacecraft power supply systems in terms of compactness, reliability, cost and wide range of usage are discussed. The advantages of ultrahigh temperature vapor core reactors in overcoming these constraints are outlined and the results of an on-going research program are presented. Technical features discussed include reactor outlet temperature, energy conversion, radiators, fuel and washing fluid and magneto energy conversion. (U.K.)

[en] Central-station electric power for spacecraft has been explored conceptually for over two decades as a solution to the economic delivery of high power levels over long periods of time. However, all spacecraft designs to date have been based on the use of onboard supplies-solar, nuclear, and chemical-because the total space power demand has not yet reached the levels at which dedicated space power depots would be economically viable. Nevertheless, the growth in projected power demand for the next several decades could warrant the use of such dedicated space-based powerplants. This paper examines and assesses the various technological options for space power generation and transmission and the system considerations associated with the space-based central-power-station concept. (author)

[en] After discussing the system reliability of a nuclear reactor powered spacecraft in mathematical terms with respect to the individual reliability of its subsystems, two types of redundancy are discussed. The power supply consists of a nuclear reactor subsystem and thermionic diodes. It is concluded that the necessary reliability goals for the space industry are very challenging and require a modular approach. (U.K.)