Washington (AFP) – A prototype of a SpaceX rocket the company hopes will one day journey to Mars crashed in a fiery explosion as it tried to land upright after a test flight Tuesday. It was the second such explosion after the last prototype of Starship met a similar fate in December. “We had again another great flight,” said a SpaceX announcer on live footage that was broadcast online. “We’ve just got to work on that landing a little bit,” he added. The company’s founder Elon Musk was uncharacteristically quiet on social media, having announced the night before he was “Off Twitter for a while….