Space Probes
	Some space probes, such as Pioneer 10, fly out of our solar system and never come back. Other space probes, like the Hubble Space Telescope, stay in orbit around the same planet their whole life.

Space probes are made to conduct science experiments. They do not have people on them. Space probes have helped scientists get information about our solar system. Most probes are not designed to return to Earth. Some have landed on other planets! Others have flown past the planets and taken pictures of them for scientists to see. There are even some space probes that go into orbit around other planets and study them for a long time. The information they gather is used to help us understand the weather and other changes which happen on planets other than the Earth. This information is important in helping to plan other space missions such as ones to Mars and to Saturn. During the summer of 2003, NASA launched twin robotic rovers named Spirit and Opportunity. The rovers were launched approximately 3 weeks apart, but they had the same destination. Spirit and Opportunity were headed to Mars. The rovers landed in January of 2004 on different parts of the planet. They were sent to Mars to look for evidence of water. Each rover carried scientific instruments to help scientists explore the planet from Earth. The Earth-bound scientists tell the rovers where to go and what to examine. As the rovers move across the surface, they examine soil and rocks. This information is sent back to Earth. The rovers were built to last approximately 90 days. However, as of January 1, 2009 the rovers were still working! And they have found lots of evidence that water was once all over the surface of Mars! The Cassini probe to Saturn was launched on October 15, 1997. It is the biggest and most expensive probe to ever visit another planet. The Cassini spacecraft went into orbit around Saturn in July 2004. It will study the planet, its ring system, and many of its moons for at least 4 years. Two missions have been launched and are now making the long trips to their target solar system objects. The Messenger spacecraft was launched in 2004 and will arrive at Mercury in 2011. It will be only the second probe sent to that small, rocky planet. The New Horizons spacecraft was launched in 2006, and will arrive at Pluto in 2015. It will be the first spacecraft to visit that very distant dwarf planet.

A Question True or False Most space probes safely return to Earth and are picked up in the Pacific Ocean.