The Spaceline: a space elevator alternative achievable with current technology

Re:The Spaceline: a space elevator alternative achievable wi... by wbhart on Friday September 06, 2019 @03:01PM (#20898721)

So they found a material which won't degrade in 24 hours due to radiation from the sun, or a way to shield it? And what about the mismatch between the rotation of the moon around the earth and geostationary orbit? And they figured out how to go around the van Allen belts to prevent frying sensitive electronics in the payload? And when the payload gets close to the moon, they have a way to stop it plunging to the surface of the moon for unscheduled disassembly?

Of course the cheapest part of getting to the moon is the bit between the edge of space and moon orbit. Approximate current cost: $0. Approximate cost after placing 40,000kg fishing line in the way....

I'm also pretty sure crawling along a fishing line will be prohibitively slow compared to letting a rocket coast with its engines off.

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Re:The Spaceline: a space elevator alternative achievable wi... by jimrandomh on Friday September 06, 2019 @04:03PM (#20899380)

> Of course the cheapest part of getting to the moon is the bit between the edge of space and moon orbit. Approximate current cost: $0.

No, it costs 4.1km/s of delta-v. https://en.wikipedia.org/wiki/Delta-v

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Re:The Spaceline: a space elevator alternative achievable wi... by wbhart on Friday September 06, 2019 @05:18PM (#20899993)

I meant to compare getting to GEO (as proposed in the paper) as opposed to Lunar orbit.

Of course the way I worded this is a bit lose, and it's not completely free, but according to the figure in that Wikipedia article, the difference between getting into geosynchronous orbit and getting to lunar orbit from earth seems to be only about 0.1km/s, which is negligible compared to the total cost. So my basic point still stands.

It's actually really expensive to get to GEO.

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Re:The Spaceline: a space elevator alternative achievable wi... by civilian on Friday September 06, 2019 @06:32PM (#20900463)

"letting a rocket coast with it's engines off"

you should play some Kerbal Space Program to get an intuition for delta-Vs and the cost of getting to the Mun.

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