SpaceX announced Monday that it would fly a crew of private citizens into orbit around the Earth, potentially by the end of the year, in a multiday mission designed to raise money for St. Jude Children’s Research Hospital.

The announcement comes after the company, founded by Elon Musk in 2002 to make space more accessible, flew two crews of NASA astronauts last year, as well as an astronaut from Japan, to the International Space Station. It also plans to fly a crew of four — all private citizens — to the International Space Station early next year.

The flight announced Monday would mark another significant milestone in the privatization of spaceflight, as private companies erode governments’ long-held monopoly on human spaceflight. It is being funded by Jared Isaacman, the 37-year-old founder and chief executive of Shift4 Payments, a payments technology company. Isaacman, an accomplished pilot who flies commercial and military aircraft, would command the mission and is donating two of the seats to St. Jude.

One is going to a yet-to-be named health-care worker at the hospital. The other seat would be raffled off, in an attempt to raise at least $200 million for St. Jude.

The flight will leave from Kennedy Space Center in Florida, but NASA, the U.S. government space agency, is not directly involved in planning the trip, in which the spacecraft will orbit the Earth every 90 minutes. “NASA has been briefed on this and has been supportive,” Musk said.

It was unclear how much Isaacson was paying for the mission, but he said he is donating $100 million to St. Jude as part of the fundraising effort. “What we aim to raise in terms of those funds and the amount of good it will do will certainly far exceed the cost of the mission itself,” he said during a call with reporters.

The mission could last between two and four days, but Musk said the flight parameters were not yet defined. “You get to go where you want to go,” he said to Isaacman on the call.

The occupant of the fourth seat will be determined by a competition starting this month among users of Isaacson’s platform. The company plans to air an ad during Sunday’s Super Bowl to raise awareness about the mission and the opportunity to fly on it.

Isaacson said that contestants would make a video about their business and why they should be sent to space and that the winner would be announced by an independent panel of judges.

The crew, called Inspiration4, will receive astronaut training from SpaceX on the Falcon 9 rocket and the Dragon spacecraft, the company said. It will train them on emergency preparedness and full mission simulations.

SpaceX said that the flight “will be carefully monitored at every step by SpaceX mission control” and will end in a splashdown off the Florida coast.

Axiom Space, a Houston-based company, has purchased a flight on SpaceX’s vehicle to fly a crew of private citizens to the International Space Station as early as January. That mission is to be commanded by Michael Lopez-Alegria, a former NASA astronaut who now serves as a vice president at Axiom Space.

The three participants on that flight — all wealthy business executives — are paying $55 million for the flight, training and costs associated with staying aboard the space station for up to eight days.

Richard Branson’s Virgin Galactic and Jeff Bezos’s Blue Origin also plan to fly space tourists out of the atmosphere, but on suborbital missions that would scratch the edge of space, giving paying customers a few minutes of weightlessness before coming back down. (Bezos owns The Washington Post.)

Musk said the private astronaut missions are a “steppingstone on the way toward providing access to space for all.” The price initially will be “real expensive,” he said, “because it’s new technology. … And so we actually need people who are willing and able to pay the high prices initially in order to make it affordable in the long term for everyone.”

As for his personal goals he said, “I will be on a flight one day, but not this one.”