Value chain · CLM-0922
In plain terms
In 2001 a National Research Council committee found that the basic trade study for the solar array had never been done, and that the mass and cost of getting the array to orbit dominates whatever the array itself costs. Their summary is that making the array free would not fix it.
The claim as recorded
The 2001 NRC committee assessing NASA's SERT programme found that "To date, there has been no comprehensive PV array trade study for SSP", that no studies were conducted to determine the support structure and electrical cabling that would be needed, and that no consideration was given to the added support structure and attitude-control mass the Sun-pointing requirement implies. It then puts the array-mass argument numerically and reaches a conclusion that does not depend on array technology at all: for a 3 GW array at the 500 W/kg ceiling it derives a mass of 6e6 kg, "approximately 241 times that of the space shuttle's maximum cargo capability", and at SERT's own $800/kg launch-to-GEO goal a cost of "$4.8 billion" to launch the array alone - concluding "Even if the solar array were free, the overriding factor is the cost of placing it in orbit."
Evidence behind this: National Research Council committee assessment of NASA's SERT programme, read directly in the held file. SRC-054 is a digitally typeset PDF, not a scan, so six of the seven SRC-111 reading hazards do not apply and only A77 hyphen-space does - and it applies hard, half of the usable-length quotations in the document being unfindable raw.
Scope and limits
2001, AND IT ASSESSES NASA'S SERT PROGRAMME RATHER THAN SBSP GENERALLY. The $4.8 billion rests on SERT's own $800/kg goal, which was a target and not a price; a reader wanting today's number must substitute today's launch cost and the arithmetic is linear in it. The 6e6 kg follows from a 3 GW array at a 500 W/kg ceiling the committee attributes to crystalline cells, and the same page notes thin-film at 1,200 W/kg would still require roughly 100 launches of the then-current shuttle. This record does not establish that the conclusion holds at any later launch price - only that it held at the programme's own stated goal. The trade-study finding is an absence as of 2001 and says nothing about work done since.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
Read first-hand from the held PDF on registration; all quotations below are present after de-hyphenation, which this document requires. Verbatim: "To date, there has been no comprehensive PV array trade study for SSP." Verbatim: "no studies were conducted to determine the support structure and electrical cabling that would be needed". Verbatim: "no consideration was given to the added support structure and guidance, navigation, and control system that would be needed to enable the Sun-pointing requirement of approximately 2" (the page follows the 2 with a degree sign). Verbatim, in sequence on p.36: "the mass of a 500-W/kg solar array alone will be 6 x 106 kg, approximately 241 times that of the space shuttle's maximum cargo capability - clearly a formidable challenge. Even assuming the SERT program's launch-to-GEO goal of $800/kg, the cost of launching the array alone would be $4.8 billion." Verbatim, later in the same paragraph on p.36: "Even if the solar array were free, the overriding factor is the cost of placing it in orbit." Contemporaneous state of the art from the same section, verbatim: "resulting in specific powers of 70-100 W/kg", "the International Space Station 260-kW array at 30 W/kg", and the SERT baseline "Measured performance for SLA at the module level is 378 W/kg" - a figure the document immediately qualifies as excluding support structure.
Basis: kg (array mass); USD (launch cost); W/kg (specific power)
Related records
- Answers question
- QST-002 not published in this release
Cite this
energyaperture.com/c/clm-0922
CLM-0922, Energy Aperture, as of 2001.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-054
- CLM-0923The 2001 committee says a solar power satellite several square kilometres across would need tens to hundreds of kilometres of cable in...CLM-0924In four parts of NASA's programme the 2001 committee found an analysis missing or a goal without a stated basis: for solar arrays, for how...CLM-0925In 2001 the whole of American space solar-cell research - NASA, the Air Force and industry together - ran at about eight million dollars a...