October 4 marked the 40th anniversary of the launch of Sputnik, the satellite that opened the Space Age and started the Space Race between the United States and the Soviet Union. The NASA History Office has compiled an impressive online resource with information about Sputnik, placed in a historical background from the years leading up to Sputnik to the launch of Explorer 1, America's first satellite. This site includes a detailed chronology, pictures of Sputnik and American satellites, and much more.

http://www.hq.nasa.gov/office/pao/History/sputnik/

The Archimedes Institute is "devoted to the efficient and equitable development of the solar system" by studying the current legal structure which makes commercial use of space, including claims of other bodies in the solar system, difficult to impossible. The institute's Web site features a large collection of legal and other documents related to space, including federal legislation and international treaties. There's also a private registry which is designed to handle claims on extraterrestrial bodies.

http://www.permanent.com/archimedes/

While Mars has captured our interest in the last year, from the discovery of possible evidence of past life on the planet to the successful Mars Pathfinder and Mars Global Surveyor missions, the planet has been the subject of hundreds of books, articles, and other writings for centuries. Mars in the Mind of Earth is a bibliography of those works, from science fiction to serious scientific articles to movies and Web sites about the Red Planet. This site is a great starting point in your search for information about Mars.

http://www-personal.engin.umich.edu/~cerebus/mars

Most people associate SETI (Search for Extraterrestrial Intelligence) with radio observatories and searches at microwave wavelengths. However, as Dr. Stuart Kingsley explains at this Web site, searches at optical wavelengths -- from the ultraviolet through the visible to the infrared -- can also be used to turn up evidence of extraterrestrial intelligence. This largely overlooked technique is discussed in detail at this Web site, along with other information about SETI.

http://www.coseti.org