Mars rover is a motor vehicle that was designed and built by NASA scientists. It was operated by robots and launched into Mars. Till now five Mars rovers have been launched:
1. In 1971, the first one named Mars 2, Prop M rover was launched into Mars but it failed.
2. After that Mars 3, Prop M rover was launched but that device also failed.
3. On 4th July 1997, the third Mars rover- Sojourner rover landed successfully on Mars and until 27th September 1997 it was able to maintain communications with NASA.
4. On 4th January 2004, Spirit (MER-A), Mars Exploration Rover was launched successfully. There has been no communication from the rover since 22nd March 2010.
5. On 25th January 2004, the fifth rover named Opportunity (MER-B), Mars Exploration Rover, made it to Mars successfully and is still operating.