What red planet have humans put robots on?

What are two kinds of observation? Why did the ability of Russia to launch a satellite into space scare the U.S. so much? What is the name of the giant stars? How far is the nearest pulsar from earth? Where did Robert H Goddard work? Why is NASA sending astronauts to live on the moon? Why do the planets have an approximate spherical shape due to their gravitational forces? What year did astronauts first land on th moon? What color will the moon appear to be during the lunar eclipse on February 21 2008? What are the functions of a revolving nose piece? Has the earth always been tilted the same amount? What was Yuri Gagarin's contribution to the space industry? Why do meteors burn in the mesosphere before entering the earth even if it is the coldest layer of the atmosphere? How does the ISS orbit the earth? What is the circumference of all the planets? What inspired reflecting road lights to be invented? What was the purpose of the Gemini missions? How do scientists use the measurements they get from tornado probes? What day of the week was February 4 1956? Who invented the first mirror ever?