(Bloomberg) -- Virgin Galactic Holdings Inc., the space-tourism company founded by billionaire Richard Branson, sent a crewed flight to the edge of space for the first time in almost two years, a crucial milestone in its plans to begin commercial service next month.

The flight, called Unity 25, took off at about 9:15 a.m. local time Thursday from New Mexico with two seasoned pilots and four passengers — all Virgin Galactic employees. The VSS Unity spacecraft detached from the carrier plane about an hour later and reached space before returning to Earth.

“Successful boost, WE HAVE REACHED SPACE!,” the company said in a tweet. Virgin Galactic provided updates on social media of the mission, which the company did not live-stream.

There’s a lot riding on the mission. Virgin Galactic had only been to space four times before Thursday, and has suffered technical issues during flights and a high-profile crash in 2014 that left one pilot dead. The company, which previously expected to start commercial service at the end of 2022, is also working to overcome doubts about its financial viability and is fending off a shareholder lawsuit.

Branson’s space empire faced a setback last month when a spinoff company, Virgin Orbit Holdings Inc., filed for bankruptcy after burning through cash and suffering a high-profile launch failure in January. It said this week that it would liquidate its assets through several deals.

Virgin Galactic’s shares were down 4.8% to $4.20 at 12:44 p.m. in New York. The stock was up about 27% this year through Wednesday, but remains well below the highs of more than $55 in mid-2021. It was publicly listed through a reverse merger with a special purpose acquisition company, or SPAC, in 2019.

Virgin Galactic hadn’t seen space since July 2021, when the company famously flew its billionaire founder and five other company employees to the edge of space. The flight took place a week and a half before rival company Blue Origin LLC flew its billionaire founder Jeff Bezos to space and back.

While Thursday’s flight landed safely, it may not be immediately clear whether everything went according to plan. Branson’s 2021 mission received plenty of fanfare, but it emerged in the weeks afterward that the trip had deviated from its intended flight path. The US Federal Aviation Administration ultimately grounded Virgin Galactic’s flights as it oversaw an investigation into the mishap.

Regulators soon after gave Virgin Galactic launch clearance, but the company subsequently said it would stand down from new flights while making design improvements and other enhancements to its vehicles. The company repeatedly pushed back the targeted start date for commercial service, eventually settling on late June 2023.

Virgin Galactic’s first commercial mission will be a research flight for the Italian Air Force, which will include two Italian military officers, as well as an aerospace engineer with the Italian National Research Council. 

Members of the general public have also bought tickets, paying as much as $450,000 a seat during a sale last year. The price is much higher than in the company’s earlier days, when customers were asked to shell out $250,000.

Thursday’s mission was led by two of Virgin Galactic’s experienced test pilots – Mike Masucci and CJ Sturckow. The flight was billed by Virgin Galactic as a “final assessment of the full spaceflight system and astronaut experience” before beginning commercial flights with paying customers.

The passengers included first-time flyers Luke Mays, Jamila Gilbert and Christopher Huie, along with veteran flyer Beth Moses, who became the first woman to fly on a commercial space mission on a previous Virgin Galactic flight in 2019.

(Updates with flight’s return in second paragraph)

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