The Inspiration4 mission had raised another $60.2 million in donations, before Musk pledged to contribute $50 million himself – pushing the campaign's total raised to more than $210 million.

"Count me in for $50M," Musk said in a tweet on Saturday.

The historic Inspiration4 mission with a private crew spent three days in space, carrying Isaacman, pilot Sian Proctor, medical officer Hayley Arceneaux and mission specialist Chris Sembroski.