There has been a minor kerfuffle in the space community over the last few weeks about what to call the Inspiration4 mission that is set to launch this evening from Florida on SpaceX's Falcon 9 rocket.

Entrepreneur Jared Isaacman, who paid for and will lead the three-day mission, preferred that it be deemed the "world's first all-civilian spaceflight to orbit." But that's not actually accurate. According to Harvard University's Jonathan McDowell, there have previously been 15 all-civilian orbital flights, beginning with the Soyuz TMA-3 mission in 2003. The most recent civilian flight was SpaceX's Crew-2 mission. The definition of "civilian" is "a person not in the armed services."

Technically, then, Inspiration4 is the first orbital spaceflight with an "all private" crew—people who are neither in the military nor professional astronauts for a civil space agency. But regardless of semantics, this mission is different.

It is, indeed, historic.

Every other orbital human spaceflight before has been flown for or by a government agency. Yes, there may have been one or two private citizens on board, but they were strictly passengers along for the ride.

By contrast, Inspiration4 is a mission bought by a private citizen and flown by a private company, and it will serve a primary purpose of leisure. If space is truly to become a place where thousands of people live, work, and play, we will need non-government missions. And this is the start of that era.

Isaacman, founder of the payment processing company Shift4 Payments, did not want his mission to be seen as merely a rich person's joyride. So he brought a diverse crew along with him: Dr. Sian Proctor, a geoscientist, entrepreneur, and trained pilot; Hayley Arceneaux, a physician assistant at St. Jude Children’s Research Hospital; and Chris Sembroski, an aerospace data engineer.

Through awareness activities before, during, and after the flight, Isaacman has set a goal of raising $200 million for St. Jude Children’s Research Hospital to address pediatric cancer. He is also something of a marketing master, turning the mission into a film for Netflix and getting several Time magazine covers.

"We know that the four of us are about to have an experience that only about 600 or so have had before us," Isaacman said during a news conference on Tuesday. "We're very focused on making sure that we give back every bit of that time that we get on orbit for the people and the causes that matter most to us."

The mission is set to launch at 8:02 pm ET on Wednesday (00:02 UTC Thursday) from Kennedy Space Center in Florida. After taking off, the Crew Dragon spacecraft will separate from the Falcon 9 rocket and fly to an altitude of 575 km, higher above the planet since the Apollo Program than all but NASA's Hubble Spacecraft missions. Weather conditions for launch appear to be fine.

Over the course of three days, the crew of four will enjoy microgravity and be able to look upon the Earth through a new "cupola" observation dome, which replaces the mechanism used on Dragon’s previous flight to dock to the International Space Station.

One interesting aspect of the mission will be the extent to which 72 hours in a relatively confined space, among four people, affects the psychology of the crew. Is this too long for a private, free-flying orbital mission? Just enough time? We're about to find out.

SpaceX's webcast for the Inspiration4 mission should begin about four hours before launch.