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Going Up?
jmiyaku writes "The National Post is reporting that NASA has given a Seattle company a $570,000 grant to continue its investigation into constructing a space elevator. Coupled with some production-grade technology from a Japanese car company (carbon nanotube composites), this elevator could be a reality within 15 years..." The Highlift website has some more information.
http://www.highliftsystems.com/faq.html
This talks about what will happen if it falls, what terrorists can do to it, etc. It actually seems fairly honestly done, not all marketing-speak.
The energy required to actually launch something 'into the Sun' from Earth is enormous. The Earth's orbital velocity is around 30 km/s, or 108000 km/h (~64800 mph). That's a LOT of delta-V to get rid of! I'll leave the details to the science geeks, but even with a gravitational slingshot (say off Venus), you're not gonna kill all that speed without entering atmosphere. The alternative would be to haul shit up to the graviational midpoint then let it slide along the shaft, accellerating and getting whipped off at 1G at the end of it, aiming it to smack into Jupiter or something, instead. ;-)
e ar thfact.html
That whole 'spiraling into the sun' thing bugs me.
http://nssdc.gsfc.nasa.gov/planetary/factsheet/
.f00Dave
Beware of Programmers who carry screwdrivers. -- Leonard Brandwein
Why don't you all just read the FAQ ? Let me quote:
For the portion that doesn't burn up in a fall- what effect will it have on the environment?
Honestly, it will make a little bit of a mess. But New York City tickertape parades have made bigger messes. Comparatively it will put much less dust, dirt, debris and chemicals into the environment than wildfires of the American west, any one of the large expendable rockets, or a month of natural meteors hitting Earth. The ribbon is light (7.5 kg/km) so, any pieces that fall to earth will slow down, in the air, to about the same terminal velocity as that of an open newspaper page falling. It will not have enough momentum to cause mechanical damage when it comes down. We have considered other health risks such as inhalation of very small fragments and believe this will not be a problem but we are conducting studies to make sure this isn't a problem. Since we are aware of the possible problems now we can design the elevator to avoid these problems.
They covered this on the web site. It will carry a current, but it's in the range of milliwatts because of the size and makeup of the ribbon. The comment was based on using a cable (like an Earthbound elevator) and so doesn't really apply here.
Virg
Charles Sheffield's novel _The Web Between Worlds_ is a fictional account of the construction of such a "beanstalk." It's strong on the science and is a pretty good read.
The energy gained by the falling cable will be at most its gravitational potential energy, which is within a factor of two of conventional high explosives (per unit weight).
There is also rotational energy to deal with, but I don't think this will elevate the total energy out of the range you're discussing.
As an aside, in terms of force on impact, the F=dP/dt, or the change in momentum when the cable strikes the surface. This is why the dorce imparted is so much worse than merely the weight of the cable.
"We reject as false the choice between our safety and our ideals." --The American President (20.1.2009)
Actually, if you break the cable then it flutters down like a newspaper dropped from the... damn, start over. ...like a newspaper dropped from the Sears Tower. In the site's FAQ list they address the problem and the biggest unknown seems to be whether it's going to disintigrate into powder and cause some people to have a breathing problem. It's ~23.5 lbs per mile of cable so it isn't going to cause a tidal wave or anything. It's light, it's chemically very stable, it's unlikely to cause problems and has a projected space lifetime of about a thousand years.
Highlift Systems is sponsoring a two-day conference (Space Elevator Conference 2002) at the Seattle Sheraton, ending today. See http://www.confcon.com/sp_elev_02/sp_elev_02.html . I Googled to get the location details, here.
:-)
And yes, ny the way, they had a dinner last night at the Space Needle
Cable safety is really a bugbear. The only part of the cable that will fall towards earth is the part below the point of breakage. In a worst case scenario, this is at Geosynch orbit. But what most people fail to realize is that as the cable falls it speeds up just like any other falling object. 60 or so Km up the cable is falling fast enough to burn up completely on reentry. So only 60 km or less of cable reaches the ground even in a worst case breakage scenario. The plan that highlift talks about puts it in the middle of the pacific ocean, convieniently 60 km or more from anything that might be damaged by a falling cable.
I don't understand these people who think you can build an elevator into space. Can't anybody understand that you cannot just "tie" a cable from Earth to something in orbit in space?
I really hope you're deliberately trolling, but just in case...
The only possibility of maintaining an actual elevator cable is if it is hooked onto something in geosyncronous orbit with the Earth. The only problem there is that the object would have to be 40,000 miles away from the Earth to maintain constant orbit with a fixed position on Earth. Good luck.
Err, yes? Thats exactly what people are proposing, in fact people have been proposing this for many years. See this NASA Summary for details for the current ideas. You'll notice that they specifically say that the elevator will be to geo-stationary Earth orbit (GEO) in the first sentence.
Al.The Daily ACK - Eclectic posts by yet another hacker
Several times they dodge the questions of weather by saying that they'll simply put it in a place where there are no hurricanes and no thunderstorms. While I don't doubt there are places where these are infrequent, I don't believe for a second that there is anywhere on Earth around the equator where it's impossible to run into bad weather.
If I remember correctly, the reason they don't want to deal with the lightning question is because running a huge electrical charge through a carbon nanotube will make it explode into a cloud of graphite, severing the connection.
So, the question becomes, what do they plan on doing when (not if) bad weather comes for the orbital elevator. Can it be moved?
Another unanswered question is what they plan to do about space debris.
If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
If you notice anything else in the project that doesn't quite make sense, rest assured that a wizard will take care of it.
Come on, you great big putz!
How much of an IQ does it take to figure out that there are plenty of people out there who have not read Red Mars and that maybe a spolier warning might have been warranted before posting the above?
I've just started reading the god-damned book and you've already ruined what must surely be a major plot point.
Crap.
HighLift Systems' real provider lives at http://highlift.1000planets.com/.
Got time? Spend some of it coding or testing