Saturday, July 31, 2010
A clip that should be on Youtube :P
Matt asks Neil if it is worth spending $3bn on the Cassini probe. Neil responds by pointing out that the money spent on lip balm exceeds the money spent on the mission.
Calacademy: WISE Surveys the Skies. NASA's WISE mission has just completed its first survey of the entire sky.
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WISE is a NASA-funded Explorer mission that will provide a vast storehouse of knowledge about the solar system, the Milky Way, and the Universe. Among the objects WISE will study are asteroids, the coolest and dimmest stars, and the most luminous galaxies.
WISE is an unmanned satellite carrying an infrared-sensitive telescope that will image the entire sky. Since objects around room temperature emit infrared radiation, the WISE telescope and detectors are kept very cold (below -430° F /15 Kelvins, which is only 15° Centigrade above absolute zero) by a cryostat -- like an ice chest but filled with solid hydrogen instead of ice.
Solar panels will provide WISE with the electricity it needs to operate, and will always point toward the Sun. Orbiting several hundred miles above the dividing line between night and day on Earth, the telescope will look out at right angles to the Sun and will always point away from Earth. As WISE orbits from the North pole to the equator to the South pole and then back up to the North pole, the telescope will sweep out a circle in the sky. As the Earth moves around the Sun, this circle will move around the sky, and after six months WISE will have observed the whole sky.
As WISE sweeps along the circle a small mirror scans in the opposite direction, capturing an image of the sky onto an infrared sensitive digital camera which will take a picture every 11 seconds. Each picture will cover an area of the sky 3 times larger than the full Moon. After 6 months WISE will have taken nearly 1,500,000 pictures covering the entire sky.
Each picture will have one megapixel at each of four different wavelengths that range from 5 to 35 times longer than the longest waves the human eye can see. Data taken by WISE will be downloaded by radio transmission 4 times per day to computers on the ground which will combine the many images taken by WISE into an atlas covering the entire celestial sphere and a list of all the detected objects.
Saturday, July 10, 2010
From the fires of a sun's birth... twin planets emerged. Venus... and Earth. Two roads diverged in our young solar system. Nature draped one world in the greens and blues of life.
While enveloping the other in acid clouds... high heat... and volcanic flows. Why did Venus take such a disastrous turn?
For as long as we have gazed upon the stars, they have offered few signs... that somewhere out there... are worlds as rich and diverse as our own.
Recently, though, astronomers have found ways to see into the bright lights of nearby stars.
They've been discovering planets at a rapid clip... using observatories like NASA's Kepler space telescope... A French observatory known as Corot ... .And an array of ground-based instruments. The count is approaching 500... and rising.
These alien worlds run the gamut... from great gas giants many times the size of our Jupiter... to rocky, charred remnants that burned when their parent star exploded.
Some have wild elliptical orbits... swinging far out into space... then diving into scorching stellar winds. Still others orbit so close to their parent stars that their surfaces are likely bathed in molten rock.
Amid these hostile realms, a few bear tantalizing hints of water or ice... ingredients needed to nurture life as we know it.
The race to find other Earths has raised anew the ancient question... whether, out in the folds of our galaxy, planets like our own are abundant... and life commonplace?
Or whether Earth is a rare Garden of Eden in a barren universe?
With so little direct evidence of these other worlds to go on, we have only the stories of planets within our own solar system to gauge the chances of finding another Earth.
Consider, for example, a world that has long had the look and feel of a life-bearing planet.
Except for the moon, there's no brighter light in our night skies than the planet Venus... known as both the morning and the evening star.
The ancient Romans named it for their goddess of beauty and love. In time, the master painters transformed this classical symbol into an erotic figure.
It was a scientist, Galileo Galilei, who demystified planet Venus... charting its phases as it moved around the sun, drawing it into the ranks of the other planets.
With a similar size and weight, Venus became known as Earth's sister planet. But how Earth-like is it?
The Russian scientist Mikkhail Lomonosov caught a tantalizing hint in 1761. As Venus passed in front of the Sun, he witnessed a hair thin luminescence on its edge.
Venus, he found, has an atmosphere. Later observations revealed a thick layer of clouds. Astronomers imagined they were made of water vapor, like those on Earth. Did they obscure stormy, wet conditions below?
And did anyone, or anything, live there? The answer came aboard an unlikely messenger.... an asteroid that crashed into Earth.
That is... according to the classic sci-fi adventure, The First Spaceship on Venus. A mysterious computer disk is found among the rubble.
With anticipation rising on Earth, an international crew sets off to find out who sent it... and why. Approaching Venus, the astronauts translate the contents of the disk. The news is not good.
In a desperate attempt to prevent an interplanetary war... and save their home planet... the crew embarks on a dangerous mission.
They descend to the planet's dark surface to confront the adversaries.