7th International Energy Conversion Engineering Conference, 2009
The availability of safe, reliable, low-mass electrical power is critical to the success of NASA'... more The availability of safe, reliable, low-mass electrical power is critical to the success of NASA's Vision for Space Exploration (VSE). Accordingly, NASA has two projects within its Exploration Technology Development Program (ETDP) devoted to developing technologies for advanced space electrical power: energy storage and fission surface power (FSP). In 2007, at the request of NASA, the National Research Council formed a committee to review ETDP, including the two projects devoted to space power. The review committee found that both power projects along with the other 20 projects then comprising the ETDP were operating under serious fiscal constraints. This paper provides an overview of the report with specific emphasis on energy storage and fission surface power.
Proceedings of the 23rd Intersociety Energy Conversion Engineering Conference, 1988
Mission requirements for planned NASA and DoD spacecraft often include designing for survivabilit... more Mission requirements for planned NASA and DoD spacecraft often include designing for survivability. The threats to the survivability of a spacecraft can be either manmade (e.g., ASATs, space debris) or natural (e.g., radiation belts, micrometeoroids). An overview of the principal kinds of manmade threats and implications on the design of space power systems are discussed. In general, it is concluded that for survivability space power systems should be compact with high thermodynamic conversion efficiencies and appropriate intrinsic hardness.
The development of the Radioisotope Thermoelectric Generator (RTG) to be used on the Ulysses and ... more The development of the Radioisotope Thermoelectric Generator (RTG) to be used on the Ulysses and Galileo missions is described. This RTG, designed to provide a minimum of 285 We at the beginning of the mission, builds upon the successful thermoelectric technology developed for the RTGs now in operation on the Voyager 1 and 2 spacecraft. A total of four flight RTGs, one ground qualification RTG, and one engineering unit have been built and tested for the Galileo and Ulysses missions. The tests have included measurements of functional performance, vibration response, magnetic signature, mass properties, nuclear radiation, and vacuum performance. The RTGs are fully flight qualified for both missions and are ready for launch.
Position Paper - American Institute of Aeronautics and Astronautics (AIAA), 1995
The U.S. space nuclear power program is at a critical juncture.
The Department ofEnergy (Do) is ... more The U.S. space nuclear power program is at a critical juncture.
The Department ofEnergy (Do) is not planning to fund any work after NASA's Cassini mission to Saturn. This planned termina-
tion of support by D o jeopardizes all future NASA outer-planet missions, particularly those that will require a light, efficient power source.
If the United States is going to continue exploration of outer space beyond the Cassini mission, space nuclear power is a criti- cally importanttechnology. Yet the current Administration is with- drawing funding for the required infrastructure and for develop- ment of improved space nuclear power technologies. AIAA believes that this is unwise because space nuclear power enables outer planet missions that enrich worldculture, stimulate students, and help us understand the origins of humanity.
Nuclear power is the enabling technology for outer-planet mis- sions where there is very little sunlight (see Figure I). The basic nuclear power source consists of a nuclear source of heat (either radioisotope or reactor) and a means ofconverting that heat into useful electrical power (the thermal-to-electric conversion system, sometimes referred to as the "conversion system" or "converter"). The DoE support for the nuclear infrastructure has been critical to the development and production of nuclear power sources, most particularly the nuclear heat sources, which require the special facilities and expertise of the D o laboratories and contractors. Advanced thermal-to-electric conversion technologies being in- vestigated by NASA, D o , and DoD are essential to producing lighter, more efficient nuclear power sources. There are also op-
portunities to exploit advanced technology developed ni other countries such as Russia.
To meet future mission requirements there must be a continu- ing interactive program that blends thermal-to-electric conversion technology with nuclear heat source development. The program must maintain the essential nuclear laboratory and production ca- pabilities to produce the n u c l e a rpower sources. We cannot afford to let pressures to reduce overall government expenditures erase the nation's ability to carry out missions requiring space nuclear power, including exploration of the outer planets andbevond. Because the AIAA recognizes that maintenance of nuclear power source technology is the key to the nation's capability to conduct outer-planet missions, the Institute recommends that the government agencies, Congress, and industry strongly support the national space nuclear power technology effort.
Voyager 2 left Earth on 20 August 1977 at an initial speed of more than 10 kilometers per second.... more Voyager 2 left Earth on 20 August 1977 at an initial speed of more than 10 kilometers per second. Using a rare alignment of the outer planets to hasten its journey, Voyager 2 has been flung by gravity from Jupiter to Saturn and from Saturn toward Uranus -- the third largest planet in the Solar System.
This paper provides (1) an overview of NASA's nuclear thermal propulsion (NTP) interests in terms... more This paper provides (1) an overview of NASA's nuclear thermal propulsion (NTP) interests in terms of systems engineering from a mission u s e viewpoint; (2) a summa- ry of recent NASA NTP efforts; and (3) a re- view of the mission benefits of NTP in a wide variety of candidate or potential NASA missions involving lunar, Mars, asteroid, and planetary science a n d exploration applications. Recent NASA NTP studies and activities will be summarized to provide a starting point for future follow-on work. These studies and activities have included workshops, joint planning, analyses, and the current close-out activities.
Nuclear propulsion has been identified as a key technology by several groups that have studied ho... more Nuclear propulsion has been identified as a key technology by several groups that have studied how to implement the Space Exploration Initiative to go back to the Moon, Propulsion Office at the NASA Lewis Research Center (LeRC) is leading the project team w~th participation by NASA Marshall Space Flight Center (MSFC), the Jet Propulsion Laboratory (JPL), and several Department of Energy (DOE) laboratories for reactor establish human presences on Mars and system technology. The lead explore space beyond Mars. This laboratories for DOE are the Idaho paper will describe the results of National Engineering Laboratory some of the recent studies of the application of both nuclear electric and nuclear thermal propulsion systems in space exploration. This paper will also identify some of the issues that require further study and that have a significant effect on the propulsion system design and selection.
Introduction 1 Radioisotope thermoelectric generators (RTGs) 1 Radioisotope heater units 5 Benefi... more Introduction 1 Radioisotope thermoelectric generators (RTGs) 1 Radioisotope heater units 5 Benefits of radioisotope power 5 Challenges of radioisotope power 6 References 6 Abbreviations RHU Radioisotope heater unit RTG Radioisotope thermoelectric generator USAEC U.S. Atomic Energy Commission (1947-74) USDOE U.S. Department of Energy (1977-present) Ã NASA retired.
Description/Abstract The two current types of nuclear power sources used in US spacecraft are des... more Description/Abstract The two current types of nuclear power sources used in US spacecraft are described along with the flight safety philosophies governing their use. In the case of radioisotope thermoelectric generators, the design philosophy consists of containment, immobilization, and recovery of the nuclear materials. For reactors, the emphasis is on maintaining a subcritical configuration in all credible accident environments. To document the safety activities, a safety analysis report is prepared for each mission. These reports, which are based on the probabilistic risk assessment methodology pioneered by the space nuclear safety community, are subjected to an interagency safety review before a recommendation is made to approve the launch of a nuclear-powered spacecraft.
How real is "warp drive" or "star drive" as an earlier television generation knew it? Can we rea... more How real is "warp drive" or "star drive" as an earlier television generation knew it? Can we really get to the stars within the lifetime of the travelers and, more importantly, within the lifetimes of those who stay behind?
7th International Energy Conversion Engineering Conference, 2009
The availability of safe, reliable, low-mass electrical power is critical to the success of NASA'... more The availability of safe, reliable, low-mass electrical power is critical to the success of NASA's Vision for Space Exploration (VSE). Accordingly, NASA has two projects within its Exploration Technology Development Program (ETDP) devoted to developing technologies for advanced space electrical power: energy storage and fission surface power (FSP). In 2007, at the request of NASA, the National Research Council formed a committee to review ETDP, including the two projects devoted to space power. The review committee found that both power projects along with the other 20 projects then comprising the ETDP were operating under serious fiscal constraints. This paper provides an overview of the report with specific emphasis on energy storage and fission surface power.
Proceedings of the 23rd Intersociety Energy Conversion Engineering Conference, 1988
Mission requirements for planned NASA and DoD spacecraft often include designing for survivabilit... more Mission requirements for planned NASA and DoD spacecraft often include designing for survivability. The threats to the survivability of a spacecraft can be either manmade (e.g., ASATs, space debris) or natural (e.g., radiation belts, micrometeoroids). An overview of the principal kinds of manmade threats and implications on the design of space power systems are discussed. In general, it is concluded that for survivability space power systems should be compact with high thermodynamic conversion efficiencies and appropriate intrinsic hardness.
The development of the Radioisotope Thermoelectric Generator (RTG) to be used on the Ulysses and ... more The development of the Radioisotope Thermoelectric Generator (RTG) to be used on the Ulysses and Galileo missions is described. This RTG, designed to provide a minimum of 285 We at the beginning of the mission, builds upon the successful thermoelectric technology developed for the RTGs now in operation on the Voyager 1 and 2 spacecraft. A total of four flight RTGs, one ground qualification RTG, and one engineering unit have been built and tested for the Galileo and Ulysses missions. The tests have included measurements of functional performance, vibration response, magnetic signature, mass properties, nuclear radiation, and vacuum performance. The RTGs are fully flight qualified for both missions and are ready for launch.
Position Paper - American Institute of Aeronautics and Astronautics (AIAA), 1995
The U.S. space nuclear power program is at a critical juncture.
The Department ofEnergy (Do) is ... more The U.S. space nuclear power program is at a critical juncture.
The Department ofEnergy (Do) is not planning to fund any work after NASA's Cassini mission to Saturn. This planned termina-
tion of support by D o jeopardizes all future NASA outer-planet missions, particularly those that will require a light, efficient power source.
If the United States is going to continue exploration of outer space beyond the Cassini mission, space nuclear power is a criti- cally importanttechnology. Yet the current Administration is with- drawing funding for the required infrastructure and for develop- ment of improved space nuclear power technologies. AIAA believes that this is unwise because space nuclear power enables outer planet missions that enrich worldculture, stimulate students, and help us understand the origins of humanity.
Nuclear power is the enabling technology for outer-planet mis- sions where there is very little sunlight (see Figure I). The basic nuclear power source consists of a nuclear source of heat (either radioisotope or reactor) and a means ofconverting that heat into useful electrical power (the thermal-to-electric conversion system, sometimes referred to as the "conversion system" or "converter"). The DoE support for the nuclear infrastructure has been critical to the development and production of nuclear power sources, most particularly the nuclear heat sources, which require the special facilities and expertise of the D o laboratories and contractors. Advanced thermal-to-electric conversion technologies being in- vestigated by NASA, D o , and DoD are essential to producing lighter, more efficient nuclear power sources. There are also op-
portunities to exploit advanced technology developed ni other countries such as Russia.
To meet future mission requirements there must be a continu- ing interactive program that blends thermal-to-electric conversion technology with nuclear heat source development. The program must maintain the essential nuclear laboratory and production ca- pabilities to produce the n u c l e a rpower sources. We cannot afford to let pressures to reduce overall government expenditures erase the nation's ability to carry out missions requiring space nuclear power, including exploration of the outer planets andbevond. Because the AIAA recognizes that maintenance of nuclear power source technology is the key to the nation's capability to conduct outer-planet missions, the Institute recommends that the government agencies, Congress, and industry strongly support the national space nuclear power technology effort.
Voyager 2 left Earth on 20 August 1977 at an initial speed of more than 10 kilometers per second.... more Voyager 2 left Earth on 20 August 1977 at an initial speed of more than 10 kilometers per second. Using a rare alignment of the outer planets to hasten its journey, Voyager 2 has been flung by gravity from Jupiter to Saturn and from Saturn toward Uranus -- the third largest planet in the Solar System.
This paper provides (1) an overview of NASA's nuclear thermal propulsion (NTP) interests in terms... more This paper provides (1) an overview of NASA's nuclear thermal propulsion (NTP) interests in terms of systems engineering from a mission u s e viewpoint; (2) a summa- ry of recent NASA NTP efforts; and (3) a re- view of the mission benefits of NTP in a wide variety of candidate or potential NASA missions involving lunar, Mars, asteroid, and planetary science a n d exploration applications. Recent NASA NTP studies and activities will be summarized to provide a starting point for future follow-on work. These studies and activities have included workshops, joint planning, analyses, and the current close-out activities.
Nuclear propulsion has been identified as a key technology by several groups that have studied ho... more Nuclear propulsion has been identified as a key technology by several groups that have studied how to implement the Space Exploration Initiative to go back to the Moon, Propulsion Office at the NASA Lewis Research Center (LeRC) is leading the project team w~th participation by NASA Marshall Space Flight Center (MSFC), the Jet Propulsion Laboratory (JPL), and several Department of Energy (DOE) laboratories for reactor establish human presences on Mars and system technology. The lead explore space beyond Mars. This laboratories for DOE are the Idaho paper will describe the results of National Engineering Laboratory some of the recent studies of the application of both nuclear electric and nuclear thermal propulsion systems in space exploration. This paper will also identify some of the issues that require further study and that have a significant effect on the propulsion system design and selection.
Introduction 1 Radioisotope thermoelectric generators (RTGs) 1 Radioisotope heater units 5 Benefi... more Introduction 1 Radioisotope thermoelectric generators (RTGs) 1 Radioisotope heater units 5 Benefits of radioisotope power 5 Challenges of radioisotope power 6 References 6 Abbreviations RHU Radioisotope heater unit RTG Radioisotope thermoelectric generator USAEC U.S. Atomic Energy Commission (1947-74) USDOE U.S. Department of Energy (1977-present) Ã NASA retired.
Description/Abstract The two current types of nuclear power sources used in US spacecraft are des... more Description/Abstract The two current types of nuclear power sources used in US spacecraft are described along with the flight safety philosophies governing their use. In the case of radioisotope thermoelectric generators, the design philosophy consists of containment, immobilization, and recovery of the nuclear materials. For reactors, the emphasis is on maintaining a subcritical configuration in all credible accident environments. To document the safety activities, a safety analysis report is prepared for each mission. These reports, which are based on the probabilistic risk assessment methodology pioneered by the space nuclear safety community, are subjected to an interagency safety review before a recommendation is made to approve the launch of a nuclear-powered spacecraft.
How real is "warp drive" or "star drive" as an earlier television generation knew it? Can we rea... more How real is "warp drive" or "star drive" as an earlier television generation knew it? Can we really get to the stars within the lifetime of the travelers and, more importantly, within the lifetimes of those who stay behind?
If humans are to travel to the stars within the lifetimes of the crew, humanity will have to deve... more If humans are to travel to the stars within the lifetimes of the crew, humanity will have to develop some means of faster-than-light (FTL) travel. This chapter discusses three of the principal concepts that have been considered: (1) tachyons, (2) wormholes, and (3) warp drives. Other concepts will be described in general terms.
Radioisotope power sources/systems (RPSs) have been enabling for some of the most challenging sp... more Radioisotope power sources/systems (RPSs) have been enabling for some of the most challenging space missions such as the Pioneer 10/11 flights to Jupiter, Saturn and beyond; the Viking Mars Landers 1/2; the Voyager 1/2 flights to Jupiter, Saturn, Uranus, Neptune and beyond; the Galileo Jovian orbiter, the Ulysses solar polar orbiter; the Cassini Saturn orbiter; the New Horizons flight to Pluto and beyond; and the Curiosity and Perseverance Marsrovers. All of these missions have been powered by radioisotope thermoelectric generators (RTGs), that is, radioisotope power sources that produce electrical power by means of the thermoelectric effect. A number of these missions also employed radioisotope heater units (RHUs) to provide thermal power (“heat”) to sensitive components on the spacecraft. Fig. 1 provides a visual summary of these U.S. RPS missions. Table 1 summarizes the RTGs flown by the U.S (Bennett et al., 1984, 2006). The former Soviet Union reportedly has flown RTGs on two Earth-orbiting spacecraft (Cosmos 84 and Cosmos 90) and on two lunar rovers (Lunokhod-1 and Lunokhod-2), mostly using polonium-210 as the radioisotope. For the aborted Mars 96 mission, the lander stations carried RTGs and RHUs fueled with plutonium-238. European researchers have studied the use of RTGs, notably powered by americium-241. Chinese researchers have developed RTGs fueled with plutonium-238 as demonstrated with their Chang’e 4 lunar mission.
Outer Space - Future for Mankind, Issues of Law and Policy, 2021
As a literary genre, science fiction is a natural fit with the human exploration of outer
space. ... more As a literary genre, science fiction is a natural fit with the human exploration of outer space. Science fiction allows us to imagine other planets, other universes, other life forms and other futures. In a way, it can be thought of as allowing us to envision where current trends might take us thereby allowing us to make corrections as necessary. (st is the classic science fiction question: "Ifthis keeps going on ....")
Electrical power is essential for the operation of a spacecraft. When that spacecraft must trave... more Electrical power is essential for the operation of a spacecraft. When that spacecraft must travel far from the Sun or operate for longer periods in hostile environments (such as the long lunar night or the dust storms of Mars) then nuclear power becomes enabling. In response to the need for long-lived, Sun-independent power, the US Atomic Energy Commission (AEC) initiated studies in the 1950s of both space nuclear reactors and space radioisotope power sources. These early concepts were designated by a SNAP number where SNAP stands for Systems for Nuclear Auxiliary Power. Even-numbered SNAP power sources were reactors and odd-numbered SNAP power sources were radioisotope power sources.
Power and propulsion are enabling technologies for any space mission. Nuclear power and nuclear ... more Power and propulsion are enabling technologies for any space mission. Nuclear power and nuclear propulsion offer high-energy, compact technologies that will allow and enable human and robotic missions to the Moon, Mars and beyond.
Outer Space - Future for Humankind, Issues of Law and Policy, 2021
In his 2014 paper on saving the human species, Dr. George S. Robinson wrote that “Space migratio... more In his 2014 paper on saving the human species, Dr. George S. Robinson wrote that “Space migration and off-Earth settlement are increasingly recognized as critical to survival of Homo sapiens sapiens and its evolving transhuman and post-human descendants”.1 Space migration and off-Earth settlement will require all the necessities for human life, including power for the various space systems and propulsion to reach the destination (and possibly return to Earth). Using its nuclear-powered robotic explorers, the human race has already entered interstellar space (see Figure 1). And with nuclear power and propulsion we humans will follow.
Encyclopedia of Physical Science and Technology, Third Edition, 2002
Space nuclear power sources provide electrical power and sometimes thermal power (steady producti... more Space nuclear power sources provide electrical power and sometimes thermal power (steady production of heat) to space systems such as spacecraft and scientific stations on planetary surfaces. These nuclear power sources function by converting the heat generated by nuclear reactions into usable electrical power for space systems. There are two principal types of nuclear power source, radioisotope and reactor, as defined by whether the heat is produced from the radioactive decay of a radioisotope or from the fission process. Nuclear power sources have enabled or enhanced some of the most challenging and exciting space missions yet conducted, including missions such as the Pioneer flights to Jupiter, Saturn, and beyond; the Voyager flights to Jupiter, Saturn, Uranus, Neptune, and beyond; the Apollo lunar surface experiments; the Viking Lander studies of Mars; the Ulysses mission to study the polar regions of the Sun; the Galileo mission to orbit Jupiter and the Cassini mission to orbit Saturn. While most spacecraft have used non-nuclear power sources (typically arrays of solar cells and batteries), nuclear power is particularly attractive for long-duration missions involving very little sunlight or operating in hostile environments. Since 1961 [written in 2002], the United States has successfully flown 40 radioisotope thermoelectric generators and one reactor t
o provide power for 23 space systems. The former Soviet Union has reportedly flown at least 35 nuclear reactors and at least two RTGs to power 37 space systems.
In order to realize interstellar civilizations in which the vast distances between star systems m... more In order to realize interstellar civilizations in which the vast distances between star systems must be spanned in times much less than the lifetimes of the crew and the people remaining on the planets there must be a revolution in transportation technology. This paper surveys the general field of interstellar flight including concepts based on nuclear energy (both fission and fusion), antimatter, interstellar ramjets, beamed power, vacuum energy fluctuations and various forms of faster-than-light (FTL) travel.
Faster-than-light (FTL) travel is a staple of science fiction and it has been seriously investiga... more Faster-than-light (FTL) travel is a staple of science fiction and it has been seriously investigated by a number of physicists. Despite the challenges both theoretical and practical, the idea of FTL travel is intriguing because if it can be achieved it offers the human race the chance to travel to the stars within the lifetimes of the crew. Three of the principal FTL concepts are discussed in this paper: (1) tachyons which are hypothetical FTL particles with properties consistent with the special theory of relativity; (2) wormholes which offer a window to distant star systems using general relativity; and (3) warp drives which employ general relativity to modify spacetime to get around the velocity of light speed limit. Issues facing hypothetical FTL travelers are discussed. In space there are countless constellations, suns and planets; we see only the suns because they give light; the planets remain invisible, for they are small and dark. There are also numberless earths circling around their suns, no worse and no less than this globe of ours. For no reasonable mind can assume that heavenly bodies that may be far more magnificent than ours would not bear upon them creatures similar or even superior to those upon our human earth.-Giordano Bruno (1548-1600) Burned at the stake for heresy (
In order to realize interstellar civilizations in which the vast distances between star systems m... more In order to realize interstellar civilizations in which the vast distances between star systems must be spanned in times much less than the lifetimes of the crew and the people remaining on the planets there must be a revolution in transportation technology. This paper surveys the general field of interstellar flight including concepts based on nuclear energy (both fission and fusion), antimatter, interstellar ramjets, beamed power, vacuum energy fluctuations and various forms of faster-than-light (FTL) travel.
In May 1994, NASA and JPL sponsored a workshop on advanced quantum/relativity theory propulsion c... more In May 1994, NASA and JPL sponsored a workshop on advanced quantum/relativity theory propulsion concepts to establish and use new frames of reference for thinking about the faster-than-light (FTL) question. Using the horizon mission methodology, the participants reviewed wormholes; a hypothetical physics where the speed of light (c) is a lower bound; and the physics of additional space dimensions. While the participants did not identify any obvious method to achieve FTL travel they did identify enough open issues in physics that FTL travel could not be ruled out. Moreover, several experiments were identified that could elucidate some possible FTL-related phenomena.
Faster-than-light (FTL) transportation systems have been invoked in science fiction and in physic... more Faster-than-light (FTL) transportation systems have been invoked in science fiction and in physics journals as a method of exploring beyond the Solar System in a time interval commensurate with that of an average human's life span. This paper considers the two more serious of these theoretical FTL proposals: tachyons and wormholes in the context of known relativity and quantum physics and identifies the boundary conditions and consequences of such FTL proposals. The authors make no claims about the possibility of achieving FTL travel.
Proceedings of the 4th International Energy Conversion Engineering Conference and Exhibit (IECEC), 2006
Nuclear power sources have enabled or enhanced some of the most challenging and exciting space mi... more Nuclear power sources have enabled or enhanced some of the most challenging and exciting space missions yet conducted, including missions such as the Pioneer flights to Jupiter, Saturn, and beyond; the Voyager flights to Jupiter, Saturn, Uranus, Neptune, and beyond; the Apollo lunar surface experiments; the Viking Lander studies of Mars; the Ulysses mission to study the polar regions of the Sun; the Galileo mission that orbited Jupiter; the Cassini mission orbiting Saturn and the recently launched New Horizons mission to Pluto. In addition, radioisotope heater units have enhanced or enabled the Mars exploration rover missions (Sojourner, Spirit and Opportunity). Since 1961, the United States has successfully flown 41 radioisotope thermoelectric generators (RTGs) and one reactor to provide power for 24 space systems. The former Soviet Union has reportedly flown at least 35 nuclear reactors and at least two RTGs to power 37 space systems.
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Papers by Gary Bennett
The Department ofEnergy (Do) is not planning to fund any work after NASA's Cassini mission to Saturn. This planned termina-
tion of support by D o jeopardizes all future NASA outer-planet missions, particularly those that will require a light, efficient power source.
If the United States is going to continue exploration of outer space beyond the Cassini mission, space nuclear power is a criti- cally importanttechnology. Yet the current Administration is with- drawing funding for the required infrastructure and for develop- ment of improved space nuclear power technologies. AIAA believes that this is unwise because space nuclear power enables outer planet missions that enrich worldculture, stimulate students, and help us understand the origins of humanity.
Nuclear power is the enabling technology for outer-planet mis- sions where there is very little sunlight (see Figure I). The basic nuclear power source consists of a nuclear source of heat (either radioisotope or reactor) and a means ofconverting that heat into useful electrical power (the thermal-to-electric conversion system, sometimes referred to as the "conversion system" or "converter"). The DoE support for the nuclear infrastructure has been critical to the development and production of nuclear power sources, most particularly the nuclear heat sources, which require the special facilities and expertise of the D o laboratories and contractors. Advanced thermal-to-electric conversion technologies being in- vestigated by NASA, D o , and DoD are essential to producing lighter, more efficient nuclear power sources. There are also op-
portunities to exploit advanced technology developed ni other countries such as Russia.
To meet future mission requirements there must be a continu- ing interactive program that blends thermal-to-electric conversion technology with nuclear heat source development. The program must maintain the essential nuclear laboratory and production ca- pabilities to produce the n u c l e a rpower sources. We cannot afford to let pressures to reduce overall government expenditures erase the nation's ability to carry out missions requiring space nuclear power, including exploration of the outer planets andbevond. Because the AIAA recognizes that maintenance of nuclear power source technology is the key to the nation's capability to conduct outer-planet missions, the Institute recommends that the government agencies, Congress, and industry strongly support the national space nuclear power technology effort.
planetary science a n d exploration applications. Recent NASA NTP studies and activities will be summarized to provide a starting point for future follow-on work. These studies and activities have included
workshops, joint planning, analyses, and the current close-out activities.
The Department ofEnergy (Do) is not planning to fund any work after NASA's Cassini mission to Saturn. This planned termina-
tion of support by D o jeopardizes all future NASA outer-planet missions, particularly those that will require a light, efficient power source.
If the United States is going to continue exploration of outer space beyond the Cassini mission, space nuclear power is a criti- cally importanttechnology. Yet the current Administration is with- drawing funding for the required infrastructure and for develop- ment of improved space nuclear power technologies. AIAA believes that this is unwise because space nuclear power enables outer planet missions that enrich worldculture, stimulate students, and help us understand the origins of humanity.
Nuclear power is the enabling technology for outer-planet mis- sions where there is very little sunlight (see Figure I). The basic nuclear power source consists of a nuclear source of heat (either radioisotope or reactor) and a means ofconverting that heat into useful electrical power (the thermal-to-electric conversion system, sometimes referred to as the "conversion system" or "converter"). The DoE support for the nuclear infrastructure has been critical to the development and production of nuclear power sources, most particularly the nuclear heat sources, which require the special facilities and expertise of the D o laboratories and contractors. Advanced thermal-to-electric conversion technologies being in- vestigated by NASA, D o , and DoD are essential to producing lighter, more efficient nuclear power sources. There are also op-
portunities to exploit advanced technology developed ni other countries such as Russia.
To meet future mission requirements there must be a continu- ing interactive program that blends thermal-to-electric conversion technology with nuclear heat source development. The program must maintain the essential nuclear laboratory and production ca- pabilities to produce the n u c l e a rpower sources. We cannot afford to let pressures to reduce overall government expenditures erase the nation's ability to carry out missions requiring space nuclear power, including exploration of the outer planets andbevond. Because the AIAA recognizes that maintenance of nuclear power source technology is the key to the nation's capability to conduct outer-planet missions, the Institute recommends that the government agencies, Congress, and industry strongly support the national space nuclear power technology effort.
planetary science a n d exploration applications. Recent NASA NTP studies and activities will be summarized to provide a starting point for future follow-on work. These studies and activities have included
workshops, joint planning, analyses, and the current close-out activities.
The former Soviet Union reportedly has flown RTGs on two Earth-orbiting spacecraft (Cosmos 84 and Cosmos 90) and on two lunar rovers (Lunokhod-1 and Lunokhod-2), mostly using polonium-210 as the radioisotope. For the aborted Mars 96 mission, the lander stations carried RTGs and RHUs fueled with plutonium-238. European researchers have studied the use of RTGs, notably powered by americium-241. Chinese researchers have developed RTGs fueled with plutonium-238 as demonstrated with their Chang’e 4 lunar mission.
space. Science fiction allows us to imagine other planets, other universes, other life forms
and other futures. In a way, it can be thought of as allowing us to envision where current
trends might take us thereby allowing us to make corrections as necessary. (st is the
classic science fiction question: "Ifthis keeps going on ....")
o provide power for 23 space systems. The former Soviet Union has reportedly flown at least 35 nuclear reactors and at least two RTGs to power 37 space systems.