From the inside out, the “Cassini division” in faint red at left is followed by the A ring in its entirety. The A ring begins with a “dirty” interior of red followed by a general pattern of more turquoise further away from the planet, which indicates material made with more ice. The red band roughly three-fourths of the way outward in the A ring is known as the Encke gap.
The Nanosail D2 satellite unexpectedly ejected from its host satellite on January 19th at 11:30 a.m. EST. The spacecraft had not ejected as planned on December 6th 2010, and was presumed lost. A 3 day timer has started that will deploy a 10 square meter solar sail on January 23rd. This arrangement of atoms now exists in orbit around the Earth.
It’s pretty hard to travel around in space because there are very few convenient ways of providing propulsion to a space ship. The most common method used in moving a ship in space are rockets, but they require that astronauts bring their fuel with them into space. As a result, rockets are heavy and expensive. The solution that many physicists propose is a solar sail, which would catch the light of the sun much like a canvas sail does with the wind, propelling a ship forward.
Conventional solar sails provide thrust by reflecting light off of their surfaces. This reflection generates a pressure on the sail which moves the ship forward. The trouble is that this makes it impossible to steer the sail. You are forced to move wherever the light takes you.
Scientists at my old alma mater: Rochester Institute of Technology (www.rit.edu) have a solution to this problem. A refractive sail could, conceivably, be used to steer a space craft. As the light passes through the refractive material, it is deflected at an angle due to Snell’s Law, precisely like the light bouncing off the bottom of a swimming pool.
Because of this angled flight, the light provides directional thrust when it impacts the other edge of the sail. By forming a sail from super-light refractive lenses, the astronauts of tomorrow could sail between the planets on a wind of light.
IN DECEMBER, a pair calling themselves “The Benevolent Fisted Rulers” offered up 4-hectare plots of Gliese 581 g, the most habitable exoplanet yet discovered, for sale on eBay.
Setting aside the ethics of exoplanetary land grabs, the move seems a touch premature. The alien world is 20 light years away and its very existence is not confirmed. Still, if the planet does exist, it is possible that it has some good exo-real estate.
Raymond Pierrehumbert at the University of Chicago examined the range of climates that Gliese 581 g might have and found one that would have a pool of water on one side, making it look like an eyeball. Even if further observations disprove the existence of Gliese 581 g, the work could help determine the habitability of exo-Earths still to be discovered.