A SpaceX civilian astronaut who flew in orbit for 3 days joins rival company Blue Origin as an engineer

• Civilian astronaut Chris Sembroski said he's joined Blue Origin, Jeff Bezos' rocket manufacturer.
• The move comes after he launched with Elon Musk's SpaceX in September for a three-day trip in orbit.

A civilian astronaut who launched on SpaceX's rocket last year has joined rival space company Blue Origin as an avionics engineer.

Chris Sembroski, who was previously a Lockheed Martin employee and an Air Force veteran, posted on $4 on Monday that he was now working at Blue Origin, Jeff Bezos' rocket manufacturer.

Sembroski's $4 says he is now an avionics engineer based in Kent, Washington.

"I am thrilled to be a part of our expansion out to the rest of the universe – AND to announce I have joined Blue Origin! Let's go!" he wrote in his Twitter post.

Sembroski was one of the $4 on the $4 that took off on September 16, sending them$4 into orbit for three days onboard SpaceX's Crew Dragon spacecraft. They flew as high as 367 miles (590 kilometers) above the Earth.

Billionaire Jared Isaacman chartered the flight from SpaceX and gave the three other seats to Sembroski; Dr. Sian Proctor, a geoscientist; and Hayley Arceneaux, a physician assistant and childhood cancer survivor.

Sembroski's last job, which lasted from April to July, was a senior analytics engineer at DB Engineering, according to his LinkedIn profile.

Sembroski didn't disclose any details about what the new posting at Blue Origin will involve. He didn't immediately respond to Insider's request for comment about the job update.

Elon Musk's SpaceX and Bezos' Blue Origin are known for their rivalry given that the two billionaires have butted heads $4.

Last year, Blue Origin $4 over the agency's decision to award a moon-landing contract to SpaceX. This added to the tension, with Musk saying $4$4. The two billionaires have made $4 at each other and $4 over their space ambitions.