(Today's SpaceX flight was scrubbed due to rocket trouble. Musk said they'll try again Friday at 5 a.m. ET.)
Here's what we learned:
Food and Drink
When inviting the billionaire futurist to a party, be sure to offer him whiskey, his drink of choice. The South African-born Musk also likes French food and BBQ.
"The timeframe is not immediate, but we should be concerned," he wrote. "There needs to be a lot more work on AI safety."
Mission to Mars
Expect to learn more toward the end of 2015 about SpaceX's Mars transport system and plans for a spacesuit to be worn by astronauts traveling to Mars.
"The Mars transport system will be a completely new architecture. Am hoping to present that towards the end of this year," Musk wrote.
As for the spacesuit, "We are putting a lot of effort into design esthetics, not just utility. It needs to both look like a 21st century spacesuit and work well. Really difficult to achieve both," he said.
His Most Important Daily Habit
When asked what daily habit had the largest positive impact on his life, Musk had a one-word answer: "Showering."