• The Inspiration4 mission, dubbed "the world's first all-civilian mission" and launching with SpaceX to orbit in September, unveiled the final two crew members after a month-long online competition.
• Joining commander and benefactor Jared Isaacman and medical officer Hayley Arceneaux are Dr. Sian Proctor and Christopher Sembroski.
• Proctor, a geoscientist and communications specialist, will serve as the mission's pilot, while Sembroski, a Lockheed Martin employee, will serve as a mission specialist.

The Inspiration4 mission, dubbed "the world's first all-civilian mission," on Tuesday unveiled the final two crew members after a month-long online competition.

Joining the mission are Dr. Sian Proctor, a geoscientist and communications specialist, and Christopher Sembroski, a Lockheed Martin employee and U.S. Air Force veteran. Inspiration will launch with SpaceX to orbit in September,

SpaceX's Crew Dragon spacecraft will be commanded by Jared Isaacman, the billionaire founder and CEO of Shift4 Payments and the mission's benefactor.

Last month, St. Jude cancer survivor and physician assistant Hayley Arceneaux was announced as the flight's first crew member. Arceneaux will serve as Inspiration4's medical officer.

The mission is raising support for St. Jude Children's hospital, with about $113 million raised so far. Previously scheduled for the fourth quarter of 2021, Inspiration4 announced that launch is targeted for no earlier than Sept. 15.

Proctor, who will serve as the mission's pilot, was the top entrant of an online business competition through Isaacman's Shift4Shop company.

"This opportunity is proof that hard work and perseverance can pay off in unimaginable ways," Proctor said in a statement. "I have always believed that I was preparing for something special, and that moment has arrived with Inspiration4."

Sembroski donated to the St. Jude fundraising campaign and was selected among nearly 72,000 entries. He will serve as a mission specialist, helping to manage payloads and science experiments during the flight.

"Although I've been fortunate to have spent years in the aerospace industry, I never imagined having the opportunity to reach the stars, especially through something as simple as supporting St. Jude," Sembroski said in a statement.

The crew of four will launch on a SpaceX Falcon 9 rocket in the company's Crew Dragon capsule into orbit around the Earth. The trip is expected to last three days, with the mission planned for an orbit of about 540 kilometers altitude – which Inspiration4 noted is "further than any human" since NASA's Hubble space telescope missions.