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Japan starts space elevator experiments

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Re: Japan starts space elevator experiments

#181

Post by WtfRuSerious »

ridgeguy wrote: post #179

I'm curious about space elevator phenomena related to lateral ∆V. At Earth's equator (zero altitude - i.e., on the ground), an object moves spinward at about 0.46 km/sec. In geosynchronous orbit, an object has to move at about 3.07 km/sec. A space elevator car ascending from stationary on the equator to a terminal at geo altitude would require a tangential (lateral) ∆V of 2.61 km/sec. This is in addition to the energ…

What about at the poles?

Seems like that would negate the lateral problems, but maybe I'm just introducing a twisting one instead...?

Re: Japan starts space elevator experiments

#184

Post by zepearl »

jaggederest wrote: post #102
zepearl wrote: post #91

Earlier quoted context omitted.

Yes, but probably only in general (meaning only from a theoretical point of view without considering external forces)? E.g. as soon as the cable has headwind (in the opposite way of the planet's rotation) the cable would slack off, the thing in orbit would slow down & lower its altitude (how much? Would it anyway have to always skim the upper atmosphere?) => then as soon as the cable gets tailwind the opposite would…

For practical purposes the atmosphere ends at 500km altitude. The cable is going to have to be 36,000 kilometers long. Atmospheric effects are pretty much rounding error at that point - imagine trying to swing a 10 foot long pole by blowing on the first inch.

Ok, you're right from that perspective :)

Re: Japan starts space elevator experiments

#185

Post by thoughtstheseus »

titanomachy wrote: post #175
dmurray wrote: post #173

Earlier quoted context omitted.

We're only 1 to 1.5 orders of magnitude away from having a material strong enough? Maybe I've been working with computers for too long, but that sounds excitingly achievable.

Yeah, just wait 6-7 years and Moore's law should take care of it.

Material science is tough. Check out engine/turbine material science developments. It can take >decade to get new materials into planes.

Re: Japan starts space elevator experiments

#186

Post by yters »

dang wrote: post #183
yters wrote: post #167

So many dumb major tech projects. Don't take your ideas from sci fi authors.

Maybe so, but can you please not post unsubstantive comments to HN?

It's substantive, pointing out there are many major tech projects these days based on pipe dreams born of sci fi books. The fact there are so many means either our tech leaders are not very smart, are scamming the government funds, and/or are out of good ideas. Which leads to the bigger question, what has happened to our vision for the future?

Re: Japan starts space elevator experiments

#187

Post by [deleted] »

skissane wrote: post #132
worldsayshi wrote: post #96

Earlier quoted context omitted.

Yeah, I wonder if anyone has patented human teleportation...

Don't patents only have a 20 year lifespan? If you patent human teleportation, and nobody actually develops it in the 20 year life of your patent (a prediction which is highly likely to be true), then you've simply wasted your filing fees, made a charitable donation to the patent office (and your patent attorney).

[deleted]

Re: Japan starts space elevator experiments

#188

Post by zepearl »

skissane wrote: post #132
worldsayshi wrote: post #96

Earlier quoted context omitted.

Yeah, I wonder if anyone has patented human teleportation...

Don't patents only have a 20 year lifespan? If you patent human teleportation, and nobody actually develops it in the 20 year life of your patent (a prediction which is highly likely to be true), then you've simply wasted your filing fees, made a charitable donation to the patent office (and your patent attorney).

Again, "teleportation" would be a "speculative" patent (you have thought about the concept but didn't present anything that works). If you would/could take ownership of only its "concept" then I would reply "screw you - I would take ownership of [humanity]" and you would become nothing. Yo :)

Re: Japan starts space elevator experiments

#189

Post by zamadatix »

WtfRuSerious wrote: post #181
ridgeguy wrote: post #179

I'm curious about space elevator phenomena related to lateral ∆V. At Earth's equator (zero altitude - i.e., on the ground), an object moves spinward at about 0.46 km/sec. In geosynchronous orbit, an object has to move at about 3.07 km/sec. A space elevator car ascending from stationary on the equator to a terminal at geo altitude would require a tangential (lateral) ∆V of 2.61 km/sec. This is in addition to the energ…

What about at the poles? Seems like that would negate the lateral problems, but maybe I'm just introducing a twisting one instead...?

Then you have an enormously large tower held up by nothing but its own strength instead of being naturally pulled into space. Also takes additional delta-v to get satteliges into common orbits post release.

Re: Japan starts space elevator experiments

#190

Post by bacon_waffle »

blahedo wrote: post #29

> "...six oval-shaped cars, each measuring 18m x 7.2m holding 30 people, ... eight days ...." Whooooa. Let's think about this for a second. Eight days means people need to sleep (and not just sitting up in a chair, no matter how comfy). At 1m x 2m per bed that would be a 15m x 4m space even without aisles to walk between the beds or down the middle or any sort of privacy separators. Also, a bathroom and actual washin…

Seems doable, to pick a random example: https://en.wikipedia.org/wiki/HMS_Endeavour 30m long, 8.9m beam, complement of 94.
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