LaserMotive Finds Success In Space Elevator Competition

Bucc5062 writes "LaserMotive has achieved the first step towards the creation of a working space elevator by qualifying for the $900,000 prize in a contest sponsored by NASA. To achieve this first level, LaserMotive needed to propel a platform up a cable dangling from a helicopter at over 2 m/s. They hit a top speed of 4.13 m/s. The next level of qualification will be to achieve a climb speed greater then 5 m/s. LaserMotive beamed roughly 400 watts of laser power to a moving target at a distance of 1 kilometer, as part of the vertical laser alignment procedure. The target was a retro-reflective board a little larger than 1 meter on a side. The contest will continue for another two days with at least two other teams challenging for the prize. To win the Power Beaming competition, the LaserMotive system uses a high-power laser array to shine ultra-intense infrared light onto high-efficiency solar cells, converting the light into electric power which then drives a motor. 'Our system will track the vehicle as it climbs, compensating for motion due to wind and other changes. Building on our experience from last year’s competition, we are designing an improved system able to capture the full $2,000,000 prize.'"

Comments

Professor Myrabo at RPI

[Gothmolly]

Leik Myrabo at RPI has been working on this stuff for years. In his words, if we can hit an enemy ICBM travelling at many times the speed of sound with a laser, surely we can keep one focused on a friendly target with a known/desired trajectory. These projects will NOT become accidental Death Stars. Given the absurdly high percentage that fuel makes up of a vehicles launch weight, anything you can do to power the craft externally gives you huge savings.

Uh-oh

[Pete Venkman]

What if someone farts in the space elevator? You'll be stuck for way more than a few floors.

Are we serious?

[Kupfernigk]

The key word that's part of ICBM is "ballistic", from the Greek ballein, I throw. It's travelling through extremely thin gas, and its trajectory is therefore practically simple Newtonian dynamics. Its position from moment to moment should be extremely predictable. Now consider an object attached to a rope in the atmosphere. It's subject to constantly changing wind forces in three dimensions. Even when it's out of the atmosphere, the beam is subject to deviation caused by atmospheric effects, which is why stars twinkle and big telescopes need clever adaptive control systems. Its path is many times less predictable. In a nutshell, it's the difference between catching a lofted cricket ball or baseball, and catching a fly. It is not an object with a "known/desired" trajectory.

The problem is, I'm sure, soluble, but the technical difficulty should not be underestimated.

Re:Are we serious?

[IndustrialComplex]

Soluble, sure, but only in aqua fortis.

Or did you mean solvable?

Well Archimedes did say, "Give me a powerful enough solvent, and a large enough bathtub, and I'll dissolve the Earth."

They could but there is a problem,

[Kupfernigk]

The sun is effectively at infinity, so the reflection from the parabolic mirror will come to a focus at some distance from the mirror and thereafter diverge. This won't work. You would need, in fact, a large array of flat mirrors which were steerable so they all converged on the target, and continued to do so as it rose. This could be technically very difficult indeed. It makes a lot more sense to use electricity to power one laser which then only requires steering. You can generate the electricity with solar panels if you like.

(A C Clarke had a story in which large numbers of flat mirrors were used to vaporise a football referee. Obviously, everybody holding a mirror had to steer it. In reality, the target would have been so bright they would probably not have been able to aim effectively.)

Re:shouldn't they be able to design the cable also

[CopaceticOpus]

Nobody is able to design the cable. We simply don't have the technology, which is why they're focusing on the climber instead.

This is a bit like having a contest to design a cool hat to be worn while using an anti-gravity belt. If someone wins the contest, then we are one step closer to being able to float while wearing a cool hat - all that's left is the bit with the belt.

Re:Mod parent up.

[IndustrialComplex]

Let's say that at our current progress it would take us 30 years to develop a way to manufacture the cable. Then let's assume that it will take 15 years to develop a machine capable of climbing that cable.

Since the two technologies are completely distinct from each other (i.e. the solution will come from different industries) Doesn't it make sense to develop them in parallel rather than wait for the cable to be developed and then have to wait an additional 15 years for the climber technology to mature?

I've certainly polished my shoes while waiting for the limo to arrive. If the limo didn't arrive, it would have made the shoe polishing pointless, but I wouldn't want to pay for a limo to wait while I got ready.

Re:Good to hear.

[FiloEleven]

making the issue of getting out of our atmosphere a relatively dull process

...until someone creates space elevator music. Then it will become a dull, agonizing process.