Value chain · CLM-0987
In plain terms
They built in high orbit not because it was cheaper - the 1978 numbers said low orbit was - but because a half-built satellite in low orbit gets pulled about by gravity gradients and drag, cools every time it passes into shadow, and cannot be flown up to high orbit in one piece without breaking.
The claim as recorded
The reference system's choice of GEO over LEO construction rests, in NASA's 1981 summary, on loads and environment: gravity-gradient loads two orders of magnitude lower, negligible drag and eclipse thermal effects, low collision hazard and a simpler sequence, with GEO's greater personnel logistics and transport cost judged "not significant" in percentage terms, and LEO construction of a complete satellite for transfer "not practical because of control requirements and loads to the structure". Boeing's 1978 cost trade of the same options had found LEO construction with recovery of the electric transportation elements to be the lowest cost.
Evidence behind this: T3, the programme summary's stated basis, with the prime contractor's earlier cost trade beside it.
Scope and limits
THE STEP FROM "LEO CHEAPER" IN 1978 TO "GEO CHOSEN" IS NOT NARRATED IN THE PAGES READ; the 1981 summary states the outcome and its basis without the intermediate trade, and the 1978 cost chart (SRC-469 PDF 84) has not been rendered. SRC-469 p.85 (printed 84) compares the options on three bases and the support quotes one: construction preparation, where LEO with recovery is lowest; placement of the first satellite, where LEO without recovery is cheapest, "nearly $3 billion cheaper than the LEO construction with recovery and approximately $5.5 billion cheaper than the GEO construction concept"; and average per satellite with all capital amortised, where LEO with recovery gives "approximately $130 million savings per satellite ... over the GEO construction case and approximately $700 million over the construction with no recovery"; the middle basis reads the other way.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
p.5, normalised: "Studies have shown that either low Earth orbit (LEO) or geosynchronous orbit (GEO) construction is feasible. The GEO construction location is used in the reference system. Construction of the satellite in GEO has several advantages." "Gravity-gradient loads are two orders of magnitude lower than in LEO, aerodynamic drag loads are not significant, thermal effects from passing through the Earth's shadow are negligible, collision hazard from other satellites is low, and the construction sequence is simpler." "Personnel logistics requirements and transportation costs for the construction base, on the other hand, are greater than in LEO, but the percentage cost impact is not significant. Building the satellite as a complete unit in LEO for transport to GEO is not practical because of control requirements and loads to the structure". SRC-469 PDF 85: "the total cost for the construction preparation period indicates that the LEO construction approach with recovery of the electric transportation system to be the lowest cost".
Basis: construction location; loads; cost
Related records
- Answers question
- QST-003 not published in this releaseQST-015 not published in this release
Cite this
energyaperture.com/c/clm-0987
CLM-0987, Energy Aperture, as of 1981.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-465
- CLM-0982The famous six months to build a satellite in orbit was decided first and the designs were fitted to it. One contractor says outright that...CLM-0984The programme's own arithmetic for the antenna frame: each beam takes its length divided by five metres a minute plus twenty minutes to...CLM-0985By 1981 the programme put about four hundred people at the orbital construction base, with roughly two-thirds of them on the actual...
- Also from SRC-469
- CLM-0986The beam-machine speeds in these studies were chosen off a curve, with the operating figure set where going faster stopped helping, and the...