Okay, enough dancing around the issue. What is the capabilities, in terms of watts per kilogram, of solar dynamic? I want relatively hard figures, not stuff pulled out of one's nether regions.
Photovoltaic, state-of-the-art, can do around 150W/kg at 1 AU from the Sun (for Ultraflex), and can be extended in many different ways to 500W/kg. 1kW/kg is feasible for lightweight thin-film arrays. (And, with some handwavium, even higher specific powers are possible... 10kW/kg at the cell level... imagine a solar sail coated with photovoltaic materials.)
And while typical thin-film cells are less efficient than stiff triple-junction cells, there have been advancements and at least on the laboratory scale, multiple-junction thin-film cells are making performance gains to rival older triple-junction cells.
Okay, enough dancing around the issue. What is the capabilities, in terms of watts per kilogram, of solar dynamic? I want relatively hard figures, not stuff pulled out of one's nether regions.
{snip}
I have found a report on a Stirling convertor being developed for use on the Moon. A space tug would also need radiators, mirror and sun tracking hardware.
12kW * 1000 / 256kg = 46.8 W/kg
Or excluding the controller 12kW * 1000 / 188kg = 63.8 W/kg
Title "Free-Piston Stirling Power Conversion Unit for
Fission Surface Power, Phase I Final Report
NASA/CR—2010-216750"
http://gltrs.grc.nasa.gov/reports/2010/CR-2010-216750.pdfIn Phase I, we completed the design of a 12 kW dual-opposed free-piston Stirling convertor and controller. The convertor is shown in Figure 1. The convertor mass is calculated as 188 kg not including
the piping shown, and the controller is projected at 68 kg for a total of 256 kg. The machine operates at 60 Hz at an operating pressure of 6.2 MPa (absolute). The convertor is approximately 0.3 m (11.9 in.) in
diameter and 1.1 m (43 in.) long.
Okay, enough dancing around the issue. What is the capabilities, in terms of watts per kilogram, of solar dynamic? I want relatively hard figures, not stuff pulled out of one's nether regions.
{snip}
I have found a report on a Stirling convertor being developed for use on the Moon. A space tug would also need radiators, mirror and sun tracking hardware.
12kW * 1000 / 256kg = 46.8 W/kg
Or excluding the controller 12kW * 1000 / 188kg = 63.8 W/kg
Title "Free-Piston Stirling Power Conversion Unit for
Fission Surface Power, Phase I Final Report
NASA/CR—2010-216750"
http://gltrs.grc.nasa.gov/reports/2010/CR-2010-216750.pdf
In Phase I, we completed the design of a 12 kW dual-opposed free-piston Stirling convertor and controller. The convertor is shown in Figure 1. The convertor mass is calculated as 188 kg not including
the piping shown, and the controller is projected at 68 kg for a total of 256 kg. The machine operates at 60 Hz at an operating pressure of 6.2 MPa (absolute). The convertor is approximately 0.3 m (11.9 in.) in
diameter and 1.1 m (43 in.) long.
Thanks. So, it appears solar dynamic is not competitive, on a pound-for-pound basis, with photovoltaics.
Okay, enough dancing around the issue. What is the capabilities, in terms of watts per kilogram, of solar dynamic? I want relatively hard figures, not stuff pulled out of one's nether regions.
{snip}
I have found a report on a Stirling convertor being developed for use on the Moon. A space tug would also need radiators, mirror and sun tracking hardware.
12kW * 1000 / 256kg = 46.8 W/kg
Or excluding the controller 12kW * 1000 / 188kg = 63.8 W/kg
Title "Free-Piston Stirling Power Conversion Unit for
Fission Surface Power, Phase I Final Report
NASA/CR—2010-216750"
http://gltrs.grc.nasa.gov/reports/2010/CR-2010-216750.pdf
In Phase I, we completed the design of a 12 kW dual-opposed free-piston Stirling convertor and controller. The convertor is shown in Figure 1. The convertor mass is calculated as 188 kg not including
the piping shown, and the controller is projected at 68 kg for a total of 256 kg. The machine operates at 60 Hz at an operating pressure of 6.2 MPa (absolute). The convertor is approximately 0.3 m (11.9 in.) in
diameter and 1.1 m (43 in.) long.
Thanks. So, it appears solar dynamic is not competitive, on a pound-for-pound basis, with photovoltaics.
That is in cslunar; only the mirrors need increasing when going to Mars.
The mechanics are not worried by Van Allen Belt radiation.
edit: is to are
There are press reports that the inspace testing of the VASIMR at the ISS has been delayed until 2014. So a small SEP tug could be developed before the VASIMR tug. A tug has other parts including guidance system, star tracking, RCS, cargo docking adaptor and rendezvousing.
The T-220 Hall Effect Thruster produced 500 mN of thrust for 10 kW.
http://www.grc.nasa.gov/WWW/RT/RT2000/5000/5430mason.htmlThe BHT-8000 made by Busek Co. Inc produces 512 mT of thrust for 8 kW.
http://www.busek.com/halleffect.htmlA 0.5 N SEP tug could get half to three quarters of a tonne of cargo from LEO to EML1/2 or LLO in about half a year. It could use a single UltraFlex solar array or a single Stirling engine pair.
edit: add cargo size