Space Solar Power Exploratory Research and Technology program

The

Space Solar Power Exploratory Research and Technology program (SERT) program, conducted by NASA, was initiated by John C. Mankins

and led by Joe Howell in March 1999 for the following purpose:

Perform design studies of selected flight demonstration concepts;

Evaluate studies of the general feasibility, design, and requirements.

Create conceptual designs of subsystems that make use of advanced SSP technologies to benefit future space or terrestrial applications.

Formulate a preliminary plan of action for the U.S. (working with international partners) to undertake an aggressive technology initiative.

Construct technology development and demonstration roadmaps for critical Space Solar Power (SSP) elements. It was to develop a
gossamer structure with concentrator lenses or solar dynamic engines to convert solar flux into electricity. The initial program looked at systems in Sun-synchronous orbit, but by the end of the program, most of the analysis looked at geosynchronous
ing unimaginably large initial investments in fixed infrastructure before the emplacement of productive power plants can begin.

Space solar power systems appear to possess many significant environmental advantages when compared to alternative approaches.

The economic viability of space solar power systems depends on many factors and the successful development of various new technologies (not least of which is the availability of exceptionally low cost access to space) however, the same can be said of many other advanced power technologies options.

Space solar power may well emerge as a serious candidate among the options for meeting the energy demands of the 21st century.

Program

Model System Categories (MSCs) were defined and ranged from relatively small-scale demonstrations to very large-scale operational SPS systems. In broad terms, each MSC represented an idea of what scale, technology, missions, etc. might be achievable in a particular future timeframe. The technology investment plan uses a time phased methodology to develop hardware and systems starting at 600 volts, followed by 10,000 V, and ending with 100,000 V to spread development and testing infrastructure costs over the life of the program rather than incur them from the beginning. The 600 V technology had immediate application for the NASA Advanced Space Transportation Program (ASTP).^{[citation needed]}

2005: ~100 kW, Free-flyer, demo-scale commercial space
2010: ~100 kW Planetary Surface System, demo-scale, space exploration
2015: ~10 MW Free-flyer, Transportation; Large demo, solar clipper
2020: 1 GW Free-flyer, Full-scale solar power satellite commercial space^{[citation needed]}

Solar power generation

Current

thin film solar cells was pursued. In the year 2000 the production of 5% efficient prototype small-area cells was followed by a 10% efficient prototype on kapton.^{[citation needed}

]

Very high efficiency photovoltaics

Two longer range investigations into high efficiency solar cells was undertaken. 1) "Rainbow" cells to be tailored to the

bandgaps throughout the solar energy emission spectrum. Theoretical efficiencies were in the range of 50–70%.^{[citation needed}

]

The arrays for an SSP platform would have to operate at 1000 volt or higher, as compared to the current International Space Station's 160 vVphotovoltaic arrays. Development of design and manufacturing techniques to prevent 1000 V self-destructive arcing continued. Several arc mitigation techniques were evaluated. Samples incorporating the most promising techniques were acquired and tested to achieve a non-arcing "rad" hard high voltage (greater than 300 V) array. Initial development was performed at 300 V to utilize existing facilities and equipment.^{[citation needed]}

Solar dynamics

Solar Dynamic (SD) power systems concentrate sunlight into a receiver where the energy is transferred to a

compressor, and rotary alternator to produce power using an inert gas working fluid. Such a system was devised for use on an SSP.^{[citation needed}

]

Cost, mass, and technical risk of various Solar Power Generation (SPG) options for a solar dynamic system were studied. For a 10MW SD system, at high power levels this technology was shown to be competitive with projected photovoltaic systems. Testing was performed to determine the characterization of high temperature secondary concentrator

refractive materials in an SD environment. A prototype refractive secondary concentrator with a concentration ratio of 10:1 was designed. This, combined with a primary concentrator of 1000:1 would result in a very high 10,000:1 ratio which permits a reasonable pointing accuracy requirement of 0.1°. The performance of the sapphire concentrator was evaluated via an on-sun calorimeter test.^{[citation needed}

]

Power management and distribution

Power Management and Distribution (PMAD) covers the entire power system between the source or power generator and the load, which in this case is the

superconductors, system voltage level vs. environmental arcing mitigation strategies, types of power converters and system protection devices, and high temperature radiation resistant circuit elements. Results were to be published by the Systems Analysis and Technology Working Group (SATWG) at the culmination of FY 98–99 SERT. Meanwhile, technologies were selected, wherever possible, to leverage other government technology investigations.^{[citation needed}

]

Superconductors

A contracted study was continued for the implementation of superconductors on the SSP. Initial studies showed that transmission voltages could be reduced to less than 300 Volts, mitigating arcing effects. Superconductor complications included

magnetic repulsion force (on the order of 3.5 MT/meter radially at 1 Megamp) could be used for deployment and to present an extremely rigid structure.^{[citation needed}

]

Silicon carbide power electronics

Silicon carbide technologies leading to power devices continued to be pursued. This leveraged work previously funded to develop defect free and thick SiC

epitaxial substrates. Although substrates could currently be manufactured with acceptably small numbers of micropipe defects, the next goal was to reduce other defects that can harm the performance of power devices. An objective was to demonstrate the high temperature operation of high-voltage SiC diodes, MOSFETs, and JFETs in a DC-DC power converter and develop models for predicting the influence of defects on device performance.^{[citation needed}

]

Milestones/products 1999: Demonstrated a 2 kW SiC thyristor operating at 300 °C; breadboarded 300 V switch and 600 V switch; completed dynamic characterization of SiC thyristors. 2000: Completed converter topology vs. device study with a breadboard converter prototype; Tested 600 V/100 A solid body fuse.^{[citation needed]}

Ion thrusters

Hall thruster technology provides overall greater benefits, including quicker trip times, good power density, a good contemporary technology base and good flight history, all translating into commercial industry acceptance. Advances such as direct power drive from the solar arrays and single and/or two-stage operation will allow payloads of 13 to 15 metric tons per 20 metric tons to LEO from launch as opposed to only 2 metric tons using chemical propulsion. Trip times from LEO to GEO are also reasonable at 120 to 230 days depending on performance setpoint. The proposed Hall thruster system consisted of four 50 kW krypton Hall thrusters directly driven from a 200 kW solar array. The propulsion system will be included on each SSP segment. Performance required from the Hall thruster units is 2000 to 3500 sec ISP with an overall system efficiency of 52% to 57%. Due to the mass of fuel required to place the entire system into geostationary orbit, propellants besides xenon (normally used), such as krypton and noble gas mixtures were proposed. Additional work on alternative fuels would eventually need to be conducted.^{[citation needed}

]

In 2000: high power Hall thruster were tested. Evaluations were made of the 1st generation domestic 50 kW breadboard engine in GRC high power Hall thruster test bed and high current cathode development.^[citation needed]

References

Space Solar Power Satellite Technology Development at the Glenn Research Center—An Overview James E. Dudenhoefer and Patrick J. George, NASA Glenn Research Center, Cleveland, Ohio
Reinventing the Solar Power Satellite", NASA 2004-212743, Geoffrey A. Landis, NASA Glenn Research Center
J. Howell and J.C. Mankins, "Preliminary results from NASA's Space Solar Power Exploratory Research and Technology Program," 51st International Astronautical Congress, Rio de Janeiro, Brazil, 2000.
H. Feingold and C. Carrington, "Evaluation and comparison of space solar power concepts," 53rd International Astronautical Federation Congress. Acta Astronautica. Vol. 53, 4–10, August–November 2003, pp. 547–559.
doi:10.1016/S0094-5765(03)80016-4

External links

Solar Dynamic Power (SDP) Overview from NASA Glenn Research Center
De La Garza, Alejandro (June 1, 2023). "Scientists Just Got A Step Closer to The Sci-Fi Reality of Building Solar Power Stations in Space". Time. Archived from the original on June 5, 2023. Retrieved June 5, 2023.