The team members behind the LightSail experimental solar sail spacecraft say that they've accomplished their mission and are counting down to the satellite's fiery, fatal plunge through the atmosphere this weekend.
"I am so excited because this mission is a success," Bill Nye the Science Guy, chief executive officer of the nonprofit Planetary Society, declared during a teleconference on Wednesday.
Success was measured by the nearly complete deployment of LightSail's 344-square-foot (32-square-meter) panels of ultra-thin plastic on Sunday — two and a half weeks after the 4-by-4-by-12-inch (10-by-10-by-30-centimeter) CubeSat-based spacecraft was launched on May 20.
LightSail's project manager, Doug Stetson of the Space Science and Exploration Consulting Group, said the sail was stretched out to about 90 percent of its full extent. "It is conceivable that we could run the motor a few more counts and stretch the sail out more," he said. "We're going through a process right now to decide how we'll spend our last few days on orbit."
Stetson and other mission controllers may not have much say in the matter. Just after the teleconference, the Planetary Society's Jason Davis reported a new problem. "During last two passes, LightSail was broadcasting a weird constant-transmit, nonsense signal," he reported on Twitter.
Davis said a system reboot may straighten out the problem, which is just the latest snag in a mission that's repeatedly been described as an emotional roller coaster ride.
LightSail's team, which is headed by the Planetary Society but also includes a host of academic and commercial partners, had to deal with two extended communication outages before Sunday's successful deployment. "There were some real worried nights, sleepless nights," Stetson recalled.
Low-cost space missions
Stetson said LightSail's resilience demonstrated that the team had "a very robust and reliable solar sail system that, coupled with small spacecraft like CubeSats, can really open the door to an entirely new class of low-cost exploration missions."
Solar sails take advantage of the pressure of sunlight for propulsion and steering. The technology already has been put to the test by Japan's Ikaros mission and NASA's NanoSail-D mission — but LightSail marks the first successful solar sail mission funded by private contributions. (An earlier effort by the Planetary Society ended in failure 10 years ago due to a malfunctioning Russian booster.)
Nye said solar sailing "has the potential to democratize space," because the technology could send small, low-cost spacecraft to virtually any destination in the solar system.
"You can get there because you never run out of fuel," he explained. "The sun shines all the time."
Wait till next year
This particular spacecraft, known as LightSail-A, was placed into an orbit that was too low for actual solar sailing. The point of this mission was merely to test the sail deployment mechanism. Stetson said that the sail's interaction with the upper layers of the atmosphere was expected to drag the spacecraft down to a fiery re-entry by Sunday.
Related: LightSail Sends Solar Sail Selfie
Another spacecraft, LightSail-B, will be sent into a higher orbit next year — and the team expects to be able to steer that craft through a series of tests in Earth orbit.
LightSail-B is to be launched aboard a SpaceX Falcon Heavy rocket as a secondary payload, accompanying another experimental satellite called Prox-1. That satellite will be programmed to monitor LightSail-B before, during and after the solar sail's deployment, said Georgia Tech's Kevin Okseniuk, who is project manager for the student-led Prox-1 mission.
Total projected cost for the double-barreled LightSail project is $5.3 million, said Jennifer Vaughn, the Planetary Society's chief operating officer. She said about $400,000 remained to be raised, partly through a Kickstarter campaign that's already drawn more than $850,000 in pledges.
The Planetary Society's partners in the LightSail project include Stellar Exploration Inc., which designed the spacecraft; Ecliptic Enterprises Corp., lead contractor for integration and testing; California Polytechnic State University at San Luis Obispo; and Georgia Tech. The project is managed by Doug Stetson of the Space Science and Exploration Consulting Group. Boreal Space and Half-Band Technologies are contractors to Ecliptic. For updates on LightSail, check in with the Planetary Society.