Saturday science subject: Climbing up the space elevator

Arthur C. Clarke once famously said that the space elevator will be built about 10 years after everybody stops laughing. We're certainly getting there: as New Scientist reports, NASA has awarded a $900,000 prize to a team that developed a robotic climber capable of ascending a cable at 3.9 m/s with a wireless power supply.

Compared to conventional rockets, a space elevator—essentially a massive cable connecting the Earth's equator to a counterweight in geostationary orbit—would make it cheaper (and safer) to send payloads and people into space. However, New Scientist points out that building an elevator involves overcoming technological hurdles, such as how to power the climbing apparatus.

The winning team, Seattle-based LaserMotive, powered its climber using "solar cells to absorb energy from a ground-based infrared laser."

On Wednesday, LaserMotive fired up its laser, powering the climber to ascend 900 metres up a cable suspended from a helicopter at Edwards Air Force Base in Mojave, California.

The climber reached the top in just over 4 minutes, for an average speed of 3.7 metres per second. The team's climber repeated the feat at a slightly higher speed of 3.9 metres per second on Thursday.

On Friday, two other teams failed in their final attempted climbs. That means LaserMotive will receive the entire $900,000 NASA set aside for climbers that could make the climb faster than 2 metres per second.

The remaining $1.1 million in NASA prize money was reserved for climbs faster than 5 metres per second, which none of the competitors was able to achieve.

3.9 m/s works out to just 8.7 mph. At that speed, reaching the altitude of the International Space Station would take just over 25 hours—not exactly a short trip, but there's probably plenty of time to break new speed records before we actually send a climber up into orbit. Aside from the space elevator, other applications for the laser-based power beaming technology include "lunar rovers and space propulsion systems to airships above the Earth," NASA says.

(Oh, and happy Carl Sagan day.)

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