This morning, space tourism venture Virgin Galactic successfully flew its spaceplane during another powered flight test over the Mojave desert — sending the vehicle to its highest altitude yet. It marks the third time the vehicle, the VSS Unity, has ignited its engine during flight. It’s another successful test among the many that Virgin Galactic plans to do before people start flying for the first time.

The last time the VSS Unity took the skies was in May, when it performed its second powered flight from Virgin Galactic’s base at the Mojave Air and Space Port. After a 31-second burn, that trip sent the spaceplane to an altitude of 22 miles above the surface, at a speed of Mach 1.9, or twice the speed of sound. But today’s test flight pushed the vehicle even further. The two test pilots on VSS Unity, Mike Masucci and Dave Mackay, ignited the engine for a total of 42 seconds, pushing the vehicle to Mach 2.47 and a height of around 32.3 miles. That’s still not high enough to be considered space, which most argue begins at around 62 miles up. But Virgin Galactic is more than half of the way there now.

It’s still unclear how many tests Virgin Galactic plans to do before passengers begin to fly. “We’re making good progress,” George Whitesides, Virgin Galactic CEO, tells The Verge. “I think we have to look at the data from today. We still have some more tests to go in our test flight program.” However, Whitesides adds that things are “getting very real.”

Whitesides says that ultimately the company plans to do three phases of testing. The first phase, which is currently underway, is to see that the vehicle is structurally sound and can get to space. During these flights, Virgin Galactic has been flying a mannequin on board called Annie as a stand-in passenger. The second phase will be what Whitesides calls “cabin testing,” during which the company will test out the procedures that will happen inside the ship during passenger flights. “Because we’re going to let people get out of their seats, we want to make sure they’re properly trained,” says Whitesides. “That we can properly train them to make sure to get out of their seat and back in their seat. That they can move around the cabin. It’s just to make sure that the procedures we’ve designed on the ground work well in space.”

After that testing is complete, the team will move to Virgin Galactic’s future home, Spaceport America in New Mexico, where the company plans to conduct its first commercial flights. Whitesides says the plan is to do a few more test flights there to get the pilots acclimatized to the new facility and airspace. And when that is complete, VSS Unity will carry its first paying customers.

The VSS Unity is Virgin Galactic’s premiere vehicle that the company will use to take paying customers to the edge of space and back. It doesn’t take off vertically, as most other vertical rockets do, but instead gets an initial boost by riding to a high altitude underneath the wing of a giant carrier aircraft, called WhiteKnightTwo. Once the pair reach a height of around 45,600 feet, VSS Unity is released and falls free for a few seconds. That’s when the spaceplane ignites its rocket engine, which propels the vehicle upward through the atmosphere.

Eventually, the goal is for VSS Unity to reach an altitude between 50 and 62 miles after a 60-second engine burn. At that height, any passengers on board will experience a few minutes of weightlessness before heading back to Earth. VSS Unity uses a “feathering” system, in which its wings shift upward, slowing the vehicle and allowing the spaceplane to safely reenter Earth’s atmosphere. The spacecraft is then meant to glide and land on a runway, just like a typical airplane.

It was the feathering system, though, that was partly responsible for a fatal crash of one of Virgin Galactic’s previous spaceplanes in 2014. During a powered test, the wings shifted too early after one of the test pilots unlocked the system earlier than planned. The vehicle broke apart, leading to the death of one of the pilots and injuring the other.

Nearly four years later, the new VSS Unity, which debuted in 2016, has flown on its own a total of 10 times, including seven glide flights. Though, Virgin Galactic says it lost a few customers after the 2014 crash, the company has managed to sell around 700 tickets to future passengers at a price of $250,000 a seat. In May, Virgin Galactic founder Richard Branson said he was “months away, not years away” from riding into space on his company’s spacecraft, according to an interview with BBC Radio.