Evidence of liquid water on saturn's moon

Beneath the central Antarctic ice sheet lies Lake Vostok -- a frozen freshwater lake about the size of Lake Ontario, with depths up to 650 feet. Now, scientists believe that Saturn's icy moon Enceladus may harbor a similar underground reservoir.
In 2005, high-resolution images from the Cassini-Huygens mission to Saturn and Titan revealed icy jets and plumes ejecting particles into space above the southern polar region of Enceladus. After examining several models, researchers working on the Cassini mission theorized that the source of the plumes could be pockets of liquid water close to the surface of Enceladus -- like icy versions of Yellowstone's Old Faithful geyser. In 2008, Cassini completed several "flybys" of Enceladus, including one on October 9 that brought the spacecraft to within just 16 miles of the moon's surface -- the closest flyby yet of any Saturn moon. Thanks to Cassini's cameras and instruments, these flybys gave researchers a closer look at the plumes. Scientists from NASA's Jet Propulsion Laboratory, the University of Colorado, and the University of Central Florida teamed up to analyze both the water vapor plumes and the ice particles being ejected from the moon. Their conclusion? That the plumes may come from a liquid water source beneath the surface of Enceladus. According to the scientists, the geysers' behavior supports a mathematical model that treats the vents as nozzles that channel water vapor from a liquid reservoir to the moon's surface at supersonic speeds. The team's findings were reported in the November 27 issue of the journal Nature.
Because water is a fundamental requirement of life, the presence of liquid water on Enceladus would have major implications for the possibility of life within icy bodies of the outer solar system. Currently, liquid water is only known to exist in two places in the solar system: Earth and Jupiter's moon Europa.
Further studies of Enceladus are a prime goal of Cassini's "Equinox Mission," which is now underway and will continue through September 2010.

If You Dropped A Corn Kernel From Space, Would It Pop During Re-Entry?

There’s a little bit of water inside each kernel of popcorn, and if you can heat the kernel above 212°F, that water should boil, turn into high-pressure steam, and pop the kernel. But in orbit, things aren’t so simple. First off, the cold vacuum of space would suck all the water out of the kernel before it could pop the corn. So any ordinary kernels would drop, not pop. But let’s say we figured out a way to keep the kernel watertight. In that case, it all depends. Anything falling through the atmosphere has what’s called a terminal velocity. This is the speed at which the upward force, or drag, from air resistance equals the downward force of gravity. Typically, a falling object, like a skydiver, speeds up until it reaches terminal velocity. If something like the space shuttle starts out in the airless vacuum of space, it can reach a speed higher than its terminal velocity. But as soon as it starts passing through the atmosphere, friction will slow it down. This friction generates heat—about 3,000° for the space shuttle. Just how much heat depends on how fast the object is going, as well as its size, shape and mass. If an astronaut were to throw a watertight kernel out of that space shuttle moving at 17,000 mph, would the kernel reach hot enough temperatures to pop as it flew through the atmosphere? It’s possible, says Kenneth Libbrecht, a physics professor at the California Institute of Technology, but he can’t run the numbers to say for sure, because no one has measured how much friction a kernel generates when it moves through the air. “Of course, the other possibility is that it will heat too quickly and the outer husk will burn off before the kernel has a chance to pop,” Libbrecht says. And so, for now at least, there’s no way to know. Note to the guys on the ISS: Let loose a pan of Jiffy Pop.

Solar Airplane Test Flights

Solar Impulse, the first plane to be powered by solar energy and to take off under its own power, will undergo test flights. It can travel up to 28 mph and cruise at an elevation of 27,900 feet because its cabin is not pressurized.

Hubble Repair....?

Astronauts will install two new instruments and repair two inactive ones in five six-and-a-half-hour spacewalks during the Hubble Space Telescope’s final servicing mission. Afterward, it should be able to study galaxies even farther away and in three different spectra: near-ultraviolet, visible and near-infrared. NASA expects at least another five years of stunning images from the Hubble.