August 2013, 640 customers had signed up for a flight, initially at a ticket price of $200,000 per person, but raised to $250,000 in May 2013. Tickets are available from more than 140 "space agents" worldwide. SpaceShipTwo's projected performance SpaceShipTwo was designed to fly to a height of 110 km, going beyond the defined boundary of space (100 km) and lengthening the experience of weightlessness for its passengers. The spacecraft would reach a top speed of 4000 km/h (2485 mph). On 23 May 2014, Virgin Galactic announced that they had abandoned use of the Sierra Nevada Corporation (SNC) nitrous-oxide-rubber motor for SpaceShipTwo; on 24 July 2014, SNC confirmed that they had also abandoned use of this motor for its Dream Chaser space shuttle. Future testing will see SpaceShipTwo powered by a polyamide grain powered motor. As of July 2021 the maximum height reached has been 89.9 km. In honor of the science-fiction series Star Trek, the first ship was named after the fictional starship Enterprise. To reenter the atmosphere, SpaceShipTwo folds its wings up and then returns them to their original position for an unpowered descent flight back onto the runway. The craft has a very limited cross-range capability, and until other planned spaceports are built worldwide, it has to land in the area where it started. Further spaceports are planned in Abu Dhabi and elsewhere, with the intention that the spaceline will have a worldwide availability and commodity in the future. There have been a series of delays to the SS2 flight test vehicle becoming operational, amidst repeated assurances from Virgin Galactic marketing that operational flights were only a year or two out. The Wall Street Journal reported in November 2014 that there has been "tension between Mr. Branson’s upbeat projections and the persistent hurdles that challenged the company’s hundreds of technical experts." The company has responded that "the company and its contractors 'have internal milestones, such as schedule estimates and goals, but the companies are driven by safety and the completion of the flight test program before moving into commercial service.' Virgin Galactic’s schedules have always been consistent with internal schedules of its contractors and changes have 'never impacted flight safety'." SpaceShip Three SpaceShipThree is an evolved version of SpaceShipTwo. Delta-class spaceship Virgin Galactic plans to have its third generation spaceship, the Delta class, ready for 2025, along with the next generation of mothership. The Delta class is