John C. Mankins

A fresh look at space solar power: New architectures, concepts and technologies☆

Abstract The concept of generating solar power in space for wireless transmission to receivers on the ground has been discussed at some length during the past three decades. During the first decades of the new century, global demand for electrical power is projected to growth dramatically — perhaps doubling from 12 terawatts to more than 24 terawatts. Achieving this power growth while managing environmental impacts effectively is a crucial international challenge. During 1995–1996, the National Aeronautics and Space Administration (NASA) conducted a far-reaching reexamination of the technologies, systems concepts and terrestrial markets that might be involved in future space solar power (SSP) systems. The principal objective of this “fresh look” study was to determine whether a solar power satellite (SPS) and associated systems could be defined that could deliver energy into terrestrial electrical power grids at prices equal to or below ground alternatives in a variety of markets, do so without major environmental drawbacks, and which could be developed at a fraction of the initial investment projected for the SPS Reference System of the late 1970s. Working with a major focus on emerging nations — the study examined 5 different markets and about 30 different SPS concepts, ranging from the 1979 SPS Reference Concept defined by the US Department of Energy and NASA to very advanced concepts involving technologies which have not yet been validated in the laboratory. Following a preliminary assessment of technical and economic risks and projected costs, 7 SSP system architectures and 4 specific SPS concepts were chosen for examination in greater depth using a comprehensive, end-to-end systems analysis employing a desk-top computer modeling tool that was developed for the study. Several innovative concepts were defined and a variety of new technology applications considered. A key ground rule to achieve initial cost goals was to avoid wherever possible the design, development, test and evaluation costs associated with SSP-unique infrastructure. Three architectures in particular were identified as promising: a sunsynchronous low Earth orbit (LEO) constellation, a middle Earth orbit (MEO) multiple-inclination constellation, and one or more stand-alone geostationary Earth orbit (GEO) SPS serving single, dedicated ground sites. This paper presents a summary of the results of the “Fresh Look” Study, including architectures, systems concepts and technologies.

Highly reusable space transportation: Advanced concepts and the opening of the space frontier☆

Abstract Revolutionary changes in how cargo and people are transported into space are needed to enable the affordable development and exploration of space in the 21st century. Diverse efforts to achieve major, but incremental Earth-to-orbit (ETO) improvements in the relatively near term have been undertaken in recent years in the US, including the Department of Defense evolved expendable launch vehicle system development project. The NASA-industry reusable launch vehicle (RLV) program is addressing this challenge for the mid-term. The RLV program will validate the technology to enable industry to develop all-rocket reusable launch systems that can deliver payloads from the current Civil Needs Data Base in the 20,000–40,000 pounds class and smaller to low Earth orbit (LEO) at costs of approximately

A TECHNICAL OVERVIEW OF THE "SUNTOWER" SOLAR POWER SATELLITE CONCEPT†

1000–

Thermal Wadis in Support of Lunar Science & Exploration

2000 per pound. This represents a factor of 5 (or more) reduction below existing launch services. This “next generation” improvement in launch capability is a vital element of the US National Space Transportation policy for current and planned government and commercial payloads. The longer-term challenge is also being addressed. During 1995–1997, NASA conducted the highly reusable space transportation (HRST) study project to address the longer-term challenge: how to achieve an additional factor of 10 reduction in launch costs—to approximately

Thermal Energy Reservoirs from Processed Lunar Regolith

100–

Solar Thermochemical Production of Fuels

200 per payload pound to LEO—thus enabling a revolutionary expansion of space activity and enterprise. The HRST study has identified a “grand strategy” for achieving these cost goals, based on pursuing a revolutionary advance in main propulsion architectures and technology for ETO systems to enable a dramatic improvements in subsystem operability. The HRST study has examined diverse approaches, including combination propulsion systems, combined cycle propulsion, launch assist systems, and revolutionary rocket propulsion. An integrated assessment has been conducted, including both the concepts defined as part of the study as well as past concepts. This assessment suggests that the cost goals of HRST are achievable within the next 10–20 years if appropriate technology investments are pursued. This paper provides a summary report on the results and findings of the HRST study project.

Hybrid Solar/Natural Gas Power System

Abstract During 1995–1996, the National Aeronautics and Space Administration (NASA) conducted a far-reaching reexamination of the technologies, systems concepts and terrestrial markets that might be involved in future space solar power (SSP) systems. The principal objective of this “fresh look” study was to determine whether a solar power satellite (SPS) and associated systems could be defined that could deliver energy into terrestrial electrical power grids at prices equal to or below ground alternatives in a variety of markets, do so without major environmental drawbacks, and which could be developed at a fraction of the initial investment projected for the SPS Reference System of the late 1970s. One of the key concepts emerging from the “fresh look” SSP study is the “SunTower” SPS system. This concept exploits a variety of innovative technologies and design approaches to achieve a potential breakthrough in establishing the technical and programmatic feasibility on initial commercial SSP operations. Capable of being deployed to either low Earth orbit or middle Earth orbit altitudes and various inclinations, the SunTower concept involves essentially no in-space infrastructure and requires no unique heavy lift launch vehicle. The concept, which can provide power to global market places appears to allow up to a factor of 30:1 reduction in initial investment requirements, compared to the 1979 SPS Reference Concept. This paper presents a technical overview of the SunTower SPS concept, including key technologies, sensitivity trades, operational scenarios. Potential non-SPS space program uses of the SunTower concept and related technologies are identified, including human exploration, space science and commercial space applications.

Microchannel Receiver for Solar Thermochemical Processing

Challenges associated with the exploration of the Moon include both the high cost of bringing hardware from Earth (perhaps at costs of

At the threshold: emerging opportunities for expanding commercial and governmental space operations in the new century: The 1997 KRAFT EHRICKE Lecture for the 27th Symposium on Economics in Space Operations of the IAA

50,000 to

Technology readiness assessments: A retrospective

100,000 per kilogram), which therefore places a high economic burden on bringing consumables and technologies from Earth, and providing power and heat for outposts and other systems that must survive the extreme cold of the two-week lunar night. However, it should be possible to develop thermal energy reservoirs using in-situ lunar materials, as systems that can store energy for use during periods of darkness on the Moon. In this paper, we discuss the potential to emplace one or more thermal wadis – engineered sources of heat and power – on the lunar surface in support of lunar science and exploration. These systems can provide a substantial architectural advantage to robotic systems, teleoperated from Earth and/or from a manned lunar outpost.