Value chain · CLM-0701
In plain terms
The 1980 study assumes each kilogram being moved has 75 watts of electrical power pushing it. One real electric satellite manages between about 2 and 9 watts per kilogram of its whole launch weight. The study's figure is 8 to 33 times that, but it counts only the cargo, so on a like-for-like count the gap would be smaller. That assumption, more than the thruster type, is why its travel times look so short for such a huge payload.
The claim as recorded
JPL's 1980 SBSP-scale transfer case assumes a specific transfer power of 75 W per kilogram of payload (150 MW for 2 x 10^6 kg). One flown all-electric comsat, ABS-3A on a Boeing 702SP, gives roughly 2.3 to 9.1 W per kilogram of launch mass in our arithmetic (an XIPS-25 thruster draws 4.5 kW, against a launch mass of 1,975 kg, depending on how many thrusters fire at once). JPL's figure is between about 8 and 33 times that, but on a different mass basis: per kilogram of payload rather than of launch mass, so the multiple on a common basis would be lower by an amount the paper does not give for this case, and that assumption, not the thruster technology, is what keeps its trip times near those of a 2-tonne comsat.
Scope and limits
The comsat comparison is a range, not a figure, because how many XIPS-25 thrusters fire simultaneously during orbit raising is not established in any source in the register. The 8-33x band is wide for that reason and should not be quoted as a single number. This is a comparison of a 1980 assumption against 2015 practice, not a demonstration that either is right. The two figures are on different mass bases: JPL's per kilogram of payload, the comsat's per kilogram of launch mass including propellant and bus. JPL gives no initial vehicle mass for this solar-array case; for its separate microwave-powered case it gives an initial mass of 1.39 times the payload, which on our arithmetic would give about 54 W/kg and a band of about 6-24x, but that ratio belongs to a different concept and is not carried into the claim.
What it assumes
that JPL's 150 MW is electrical power delivered to the thrusters, and that the comparison comsat fires between one and four thrusters simultaneously - the exact duty is not stated in the sources held.
Where it comes from
This is the project's own working, shown in full:
150e6 W / 2e6 kg = 75 W/kg. Boeing 702SP: XIPS-25 at 4.5 kW per thruster; ABS-3A launch mass 1,975 kg. One thruster firing gives 2.28 W/kg, two give 4.56, four give 9.11. Ratios 32.9x, 16.5x and 8.2x respectively.
Basis: W per kg; JPL per kg of payload, comsat per kg of launch mass
Related records
- Answers question
- QST-040 not published in this release
Cite this
energyaperture.com/c/clm-0701
CLM-0701, Energy Aperture, as of 2026-09-03.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-190
- CLM-0700A 1980 JPL paper already worked out how to move a two-thousand-tonne payload from low orbit to high orbit using electric thrusters. It...CLM-0702Electric trips from a low orbit to a high one took four to seven months on real flights and in most models held here, and NASA's four-month...