Sunjammer, World's Largest Solar Sail, Passes Key Test for 2015 Launch

                    

An early prototype of L’Garde solar sail is evaluated in a vacuum chamber at the NASA Glenn Research Center’s Plum Brook Facility in Sandusky, Ohio. This test article is a quarter the size of the sail the company plans to fly in 2015. 

A NASA plan to launch the world's largest solar sail into space and unfurl it like a giant parasol has passed a major test as the mission moves closer to a planned January 2015 launch. Sunjammer mission successfully deployed part of its huge solar sail in a test on Sept. 30, revealing the craft should be ready to function successfully following its January 2015 launch.

The giant Sunjammer solar sail, cleared a successful design test that required the deploying beam to stretch a quarter of the sail completely open. Because the Sept. 30 test took place on Earth, gravity and atmosphere made conditions more challenging than they would be in the vacuum of space, the sail's designers said.

"If this test succeeded under these stressing conditions, we certainly anticipate it will work exceedingly well in space," Nathan Barnes, President of lead contractor L'Garde Inc, said in a statement.When Sunjammer launches in 2015, it will be the largest solar sail ever flown. Covering an area of almost 13,000 square feet (1,200 square meters), the full sail will span approximately a third the length of a football field. Despite its size, the enormous sail will be only about five millionths of a meter thick, keeping its weight down to 70 pounds (31 kilograms).

The lightweight, reflective material will rely on the pressure generated by sunlight to maneuver it through space. Smaller sails at the end

Credit: NASA and L’Garde

                        Aurora in the Red

Photograph courtesy NASA

Many auroras appear green, but sometimes other colors such as red show up—as in this picture taken from the International Space Station on September 26.

An aurora's colors depend on which types of atoms cause the splash of light. In most cases, auroral lights appear when charged particles from the solar wind collide with oxygen atoms in Earth's atmosphere, according to a NASA statement.

"This produces a green photon, so most auroras appear green. However, lower-energy oxygen collisions—as well as collisions with nitrogen atoms—can produce red photons, so sometimes auroras also show a red band, as seen here."