Speed Reads
On Friday afternoon, NASA launched a two-man crew for a one-year space mission on the International Space Station. The pair includes Scott Kelly, an American astronaut, and Mikhail Kornienko, a Russain cosmonaut.
The journey will be especially notable because Kelly's identical twin brother, Mark, is staying on Earth. Mark will undergo genetic studies while his brother is in space, and scientists will use data from both twins to further explore how the body changes while in space for longer periods of time.
The mission is also a test for future trips to Mars, where astronauts could stay in orbit for 500 days or more.