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Space Elevator Teams Compete for NASA Prizes
Hugh Pickens writes "The University of Saskatchewan's has the first place climb in the Second Annual Space Elevator Games being held this weekend at the Davis County Event Center in Salt Lake City. Teams are competing for $1,000,000 in NASA prize money. Although the idea of a space elevator has been around for decades, the space technologies needed to support it have yet to be created. The non-profit Spaceward Foundation has hosted an annual competition since 2005 to build a super-strong tether, or get a robot to climb a suspended ribbon. In the robot climber competition, teams have to get their device to hurtle up a 100-metre-long ribbon, suspended from a crane, at an average speed of two metres per second. The climber must be powered from the ground: strategies include reflecting sunlight from huge mirrors on the ground to solar panels on the climber; shining lasers from the ground up to similar panels on the robot; or firing microwaves up at the climber. Qualifying rounds have been taking place all week, and although high winds and rain have caused delays, four out of eight teams have made it into the finals. There are no outdoor climbs today because of bad weather but some of the tether competitions will happen indoors later this afternoon."
For a blue-sky vision of a future with a functional space elevator, I'd recommend reading Arthur C Clarke's Foundations of Paradise novel.
"I bless every day that I continue to live, for every day is pure profit."
As silly as that is, these robots are in fact accelerating upwards at 1 gee with an 'initial' speed of 2m/s. So if you managed to get 1.01 gees for four months their end velocity would be over 1000 kilometers per second.
The fact that the robot can climb constantly from ground-based energy sources is the goal. Acceleration at 2 gees (double the force) would get you from ground to geosync in 48 minutes.
I can stand elevator music for 48 minutes if it means I get to go to space.
Getting into orbit isn't about altitude, it's about velocity. Run the numbers for a massive lifter. You might gain 5-6 miles worth of altitude, and less than Mach 1 velocity. That still leaves you needing a lot of acceleration to make orbit. It's nice for Spaceship 1, which is only suborbital. It's even the chosen approach for Pegasus, which puts some small stuff into orbit. Ultimately, for small craft it is marginally useful for avoiding a few troublesome parts of lifting off from the ground, but such an approach is useless for large launches.
Flat out wrong.
http://www.richard-seaman.com/Aircraft/AirShows/SpaceShipOne2004/
From the article:
The White Knight drops SpaceShipOne when they reached an altitude of about 50,000 feet (15 kilometers), and it takes 30 or 40 minutes for them to reach this altitude. Along the way they levelled out for some time while they checked all of the onboard systems.
PHOTOS
As they spiralled higher above the desert, it became harder to even see where they were; eventually, though, they got high enough for contrails to start forming. Finally, around 7:50AM and 47,000 feet (14,250 meters) the White Knight released SpaceShipOne, which glided for about 10 seconds then lit its rocket engine.
So yes, they use a rocket in the second stage, but describing it as a "mobile launch platform" makes it sound like an aircraft carrier. They used conventional lift to reach almost to the top of the stratosphere before firing off the rocket.
-1 Uncomfortable Truth
The highest altitude an airplane can sanely go to is say 20km, a hot air balloon can go higher but they have a very limited payload capacity. Spaceship one got detached at 15km for comparison so I'm being quite kind here, in your favor. Now let's look at some actual numbers, something I assume you're incapable of doing on your own due to lack of intelligence despite the trivial difficulty of it.
The most fuel is consumed attempting to overcome the higher gravity at earths surface, which is 9.78 meters per second per second down near the equator and drops in a non-linear fashion with distance,
Apparently you cannot comprehend the massive distances involved. At 20km, see above for why I use this, the acceleration due to gravity is 9.76. At sea level it is 9.82. Non-linear means jack shit when you start at 6371km and only go up a few dozen km. 0.7%, yeah bloody helpful.
and ploughing through the earths atmosphere, which generates drag and heat.
The amount of energy lost to drag is quite small, a quick calculation puts it at below 0.1% (of the thrust of the rocket) between 0km and 20km (velocity and atmospheric density cancel out more or less I think as you go up). Also at 20km, the highest you'll realistically get a plane to go, is still well within the atmosphere.
So you will need to send a rocket up anyway, specifically one that detaches from your lift vehicle. No spaceship can "pick up" your rocket because any such spaceship would no longer be even close to in orbit (to be at such low altitude/velocity). If you want me to explain the absurdity of it more then I will but hopefully I won't need to.
So let's look at the savings of launching at 20km instead of 0km altitude, the starting velocity in both cases will essentially be 0 (even 500km/hr is nothing).
The Soyuz launch vehicle, for example, drops it's first stage at 50km and has a velocity of ~2km/s or so I think. That stage is 30% of the whole things mass/fuel, the remaining mass is still ~120 TONS. Let's ignore the absurdity of trying to list 100+ TONS to 20km by airplane (needed for sizable payload), it's more than a 767 can lift which can't even go close to that high. Now you'd get a savings of maybe 10-15% of total at 20km once you take away those 0.5km/s of velocity it no longer has. The cost and complexity of dragging it that far up, by airplane, would more than counter any savings. Also even 20% savings is small as the cost is still absurd, a space elevator gives you maybe 95%+ savings over current rockets.
Which also causes the explosions that plague rockets.
And trying to ignite at high altitude, separate from a plane and so on will cause it's own problems. Modern rockets are decently safe.
Are you saying that the fuel you save utilizing conventional lift to reach the top of the atmosphere instead of using rockets is irrelevant?
Of course it is, fuel is amazingly cheap compared to all the other costs involved. The space shuttle for example is not absurdly expensive because of fuel but because of how complex it is to deal with (billions a year just to keep the launch facilities in working order). Your ideas are complex, compared to rockets, and so would incur massive costs of this sort.
It's so obvious that everyone in the private sector who is attempting to enter the arena of space flight has chosen this approach, including SpaceShipOne, which is functionally demonstrating the concept.
You picked the perfect example to discredit your own point. They could do it BECAUSE they didn't need to generate high velocities. They were orders of magnitude off from what any traditional rocket needs in terms of velo
Doctor Bradley C. Edwards did a study for NIAC who funded his research (when it was still around). This is a summary of his work.
My ism, it's full of beliefs.