Euro was introduced as the currency of many European nations in 1999. On January 1, 2002, the Euro became the official currency of these nations, and all national currencies were removed in February of 2002.
2001 Mars Odyssey was launched on this date and reached Mars on October 24, 2001. The robotic satellite began to send back data on February 19, 2002. Now 2001 Mars Odyssey is the oldest operating spacecraft beyond earth. Children can learn more at: 2001 Mars Odyssey.