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.

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.