In an exclusive interview with "Mad Money" host Jim Cramer, Boeing CEO Dennis Muilenburg told CNBC that Boeing will beat Elon Musk's SpaceX to Mars.
Musk took to Twitter to clap back at Muilenburg, saying "Do it."
Boeing, Muilenburg tells CNBC, is in the final assembly stages of developing a rocket called the Space Launch System, with the help of NASA. He estimates that the Space Launch System will be ready for a test flight by 2019 and that it will bring humans to Mars for the first time, ahead of Elon Musk and SpaceX.
"We're going to take a first test flight in 2019 and we're going to do a slingshot mission around the Moon," he said. "Eventually we are going to go to Mars, and I firmly believe that the first person that sets foot on Mars will get there in a Boeing rocket."
Musk's pithy twitter response could reflect that he thinks Muilenburg is bluffing, that he is confident in SpaceX's timeline — or both.
In September, SpaceX released the plans for its new "BFR" rocket lineup, which Musk predicts will take humans to Mars in five years and would facilitate expansion on Mars by 2024.
At the International Astronautical Congress in Australia Musk presented his plans for a trip to the red planet: "I feel fairly confident we can build the ship and be ready for the launch in five years. Five years seems like a long time for me."
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