Wednesday, April 12, 2006

Planet Update
In honor of the first full moon of Spring, let's take a quick look at space exploration in our solar system. Mercury: Messenger on the way, due to arrive for a first Mercury fly-by in January 2008, easing its way into an orbit by March 2011. Why so long for the third-closest planet? Mercury orbits the sun pretty fast and it takes a bit of time to optimize the spacecraft's approach to use the least amount of fuel as possible to slow down for orbit. Why is fuel weight so important? The less fuel you use, the more weight you can dedicate to scientific instruments. Venus: Europe's Venus Express just arrived in orbit yesterday. Atmospheric studies ahead. Artist's conception on the right. Luna (aka the Moon): Nothing at present. Strange that you have such a large celestial object nearby and nobody has bothered to conduct near the study we devote to Mars, Jupiter or Saturn. Go figure. Mars: Lots of stuff going on at Mars. About a half-dozen active space probes are in the vicinity or on the surface. The latest is the Mars Reconnaissance Orbiter. It will be able to image an object the size of a chasuble on the surface of Mars. The special camera was tested a few days ago. Here's an image from it: I urge you to go to the MRO web site and take a peek at the first color images. Way cool. Jupiter: The mission's over but you can see some interesting stuff at the old Galileo web site. At present, the New Horizons probe is heading that way, due for arrival in early Lent 2007. Jupiter's gravity will be employed to speed up the probe on its way to Pluto. Saturn: Cassini, of course. Here's a recent image showing storm systems on the gas giant. Unlike Earth, Saturn's weather is generated from heat within the planet. Why is Saturn hot? Because it's been contracting since it was formed 4.6 billion years ago. The crush of planet innards produces heat, which eventually radiates through the deep layers of hydrogen and helium to the surface. Uranus and Neptune: No new missions planned as of now. Voyager site looks back at 1986 and 1989 studies of these distant planets. Pluto: By 2015, New Horizons will arrive. What an era for space information! Go avail yourself of some of it, if you wish.

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