Both Nations have just recently put satellites in orbit around the Red Planet, and are planning a joint radar satellite to study the earth in 2020. The agreement was signed at the 65th International Astronautical Congress in Toronto.
This is wonderful news and shows that it is possible for nations to come together and cooperate for the betterment of the human species. But it doesn't go far enough. The American government for years has refused to cooperate with China in space because of perceived "national security threats" (basically they don't want to give Russia access to NASA's rocket and other "sensitive" technologies). China has been interested in cooperating on the International Space Station, but fear, and lack of trust is causing problems.
These are huge obstacles that need to be overcome if humans are to venture together, united, into space. It is possible as Russia and the USA have cooperated peacefully in space which started in 1975 with the Apollo-Soyuz Test Project which was the first joint US-Soviet space flight, right in the middle of the Cold War.