Sputnik
Sputnik number 1 was the first artificial satellite. It was 585 mm and a small metal sphere. It had a radio on it so it could control radio pulses. Sputnik was launched to a low Earth orbit on October 4, 1957. It was visible all around Earth. Sputnik was also scientifically valuable. It was valuable because the propagation of its radio signals gave information about the ionosphere. The signals continued for 22 days until the transmitter batteries ran out on October 1957. It finally burned up on January 4, 1958.
http://en.wikipedia.org/wiki/Sputnik_1
Sputnik 2
This was the second spacecraft launched into Earth's orbit space on November 3, 1997. It was also the very first one to carry a living animal named Laika. Sputnik number 2 was 13 ft cone shaped capsule with a base diameter of 2 meters. There was another little compartment for Laika! It was in space for 162 days.
http://en.wikipedia.org/wiki/Sputnik_2
Sputnik 3
Sputnik 3 was a Soviet satellite launched into space on May 15, 1958. It was a research satellite to explore the upper atmosphere and the near space. It was in space for 692 days! Sputnik 3 had succeeded into making it into orbit.
http://en.wikipedia.org/wiki/Sputnik_3