SpaceShipTwo

The Scaled Composites Model 339 SpaceShipTwo (SS2) is a suborbital, air-launched spaceplane, designed for space tourism. It is under development by The Spaceship Company, a California-based joint venture between Scaled Composites and the Virgin Group, as part of the Tier 1b program.

SpaceShipTwo is carried to its launch altitude by a mothership, the Scaled Composites White Knight Two, before being launched to fly on into the upper atmosphere, powered by a rocket motor. It then glides back to Earth and performs a conventional runway landing.^[1] The spaceship was officially unveiled to the public on Monday, 7 December 2009, at the Mojave Air and Space Port in California.^[2] The aircraft is currently undergoing flight-testing, having conducted 16 successful gliding flight tests as of October 2011.^[3]

The Virgin Galactic spaceline plans to operate a fleet of five SpaceShipTwo spaceplanes in a private passenger-carrying service, starting in 2013,^[4][5] and are already taking bookings, with a suborbital flight carrying a ticket price of US$200,000.^[6]

Design overview

The SpaceShipTwo project is based in part on technology developed for the first-generation SpaceShipOne, which was part of the Scaled Composites Tier One program, funded by Paul Allen. The Spaceship Company licenses this technology from Mojave Aerospace Ventures, a joint venture of Paul Allen and Burt Rutan, the designer of the predecessor technology.

SpaceShipTwo is a low-aspect-ratio spaceplane that will carry passengers to space; the capacity will be eight people: six passengers and two pilots. The apogee of the new craft will be approximately 110 km (68 miles) and in the thermosphere, 10 km (6 miles) higher than both the SpaceShipOne target (though the last flight of the SpaceShipOne reached 112 km), and the Kármán line. SpaceShipTwo will reach 4,200 km/h (2,600 mph), using a single hybrid rocket motor – the RocketMotorTwo.^[7] It launches from its mothership, White Knight Two, at an altitude of 15,200 m (50,000 ft), and goes supersonic within 8 seconds. After 70 seconds, the rocket motor cuts out and the spacecraft will coast to its peak altitude. SpaceShipTwo's crew cabin is 3.66 m (12 ft) long and 2.28 m (7.5 ft) in diameter.^[8] The wing span is 8.23 m (27 ft), the length is 18.29 m (60 ft) and the tail height is 4.57 m (15 ft).^[9]

SpaceShipTwo uses a feathered reentry system, feasible due to the low speed of reentry – by contrast, the Space Shuttle and other orbital spacecraft re-enter at orbital speeds, closer to 25,000 km/h (16,000 mph), using heat shields. SpaceShipTwo is furthermore designed to re-enter the atmosphere at any angle.^[10]

SpaceShipTwo will decelerate through the atmosphere, switching to a gliding position at 80,000 ft and will take 25 minutes to glide back to the spaceport. Once the passengers return, their passports will receive a spaceflight stamp and they will be awarded their astronaut wings at an awards ceremony. They will also be able to relive their flight from footage filmed during the spaceflight.

SpaceShipTwo and White Knight Two are, respectively, roughly twice the size of the first-generation SpaceShipOne and mothership White Knight, which won the Ansari X Prize in 2004. SpaceShipTwo will have 43 cm and 33 cm (17 and 13 in) diameter windows for the passengers' viewing pleasure,^[9] and all seats will recline back during landing to decrease the discomfort of G-forces.^[11] Reportedly, the craft can land safely even if a catastrophic failure occurs during flight.^[12] In 2008, Burt Rutan remarked on the safety of the vehicle:

This vehicle is designed to go into the atmosphere in the worst case straight in or upside down and it'll correct. This is designed to be at least as safe as the early airliners in the 1920s...Don’t believe anyone that tells you that the safety will be the same as a modern airliner, which has been around for 70 years.^[13]

In September 2011, the safety of SpaceShipTwo's feathered reentry system was tested when the crew briefly lost control of the craft during a gliding test flight. Control was reestablished after the spaceplane entered its feathered configuration, and it landed safely after a 7-minute flight.^[3]

Fleet and launch site

The launch customer of SpaceShipTwo is Virgin Galactic, who have ordered five vehicles.^[14][15] As of October 2007^[update], only the first two have been named, the VSS (Virgin Space Ship) Enterprise,^[16] and the VSS Voyager.^[17] Both are in development.^[18] As of May 2011, only VSS Enterprise^[19] has made glide flights; VSS Voyager^[17] has yet to begin flight tests.

The SpaceShipTwo craft will take off from the Mojave Air and Space Port in California during testing. Spaceport America – formerly Southwest Regional Spaceport, a US$212 million spaceport in New Mexico partly funded by the state government^[20] – will become the permanent launch site when commercial launches begin.^[8]

Development

On 28 September 2006, Sir Richard Branson unveiled a mock-up of the SpaceShipTwo passenger cabin at the NextFest exposition, in the Javits Convention Center, New York.^[21] The design of the vehicle was revealed to the press in January 2008, with the statement that the vehicle itself was around 60% complete.^[8] On 7 December 2009, the official unveiling and rollout of SpaceShipTwo took place. The event involved the first SpaceShipTwo being christened by then-Governor of California Arnold Schwarzenegger as the VSS Enterprise.^[22]

2007 test explosion

On 26 July 2007, an explosion occurred during an oxidizer flow test at the Mojave Air and Space Port, where early-stage tests were being conducted on SpaceShipTwo's systems. The oxidizer test included filling the oxidizer tank with 4,500 kg (10,000 pounds) of nitrous oxide, followed by a 15-second cold-flow injector test. Although the tests did not ignite the gas, three employees were killed and three injured, two critically and one seriously, by flying shrapnel.^[23]

Flight test program

In October 2009, Virgin Galactic CEO Will Whitehorn outlined the flight test program for SpaceShipTwo. The test program includes seven phases:

1. Vehicle ground testing.
2. Captive carry under White Knight Two.
3. Unpowered glide testing.
4. Subsonic testing with only a brief firing of the rocket.
5. Supersonic atmospheric testing.
6. Full flight into suborbital space.
7. Execute a detailed and lengthy appraisal process with the FAA/AST to demonstrate the system's robustness and eventually obtain a commercial launch license to begin commercial operations.^[24]

On 22 March 2010, the SpaceShipTwo vehicle VSS Enterprise underwent a captive carry test flight, with the parent White Knight Two aircraft, VMS Eve, performing a short flight while carrying the Enterprise.^[25] A second test flight was made on 16 May 2010,^[26] reaching SS2's launch altitude (51,000 feet) and lasting nearly five hours, in order to facilitate "cold soak" testing of SS2's avionics and pressurization system. Thereafter, "a simulated spaceship descent/glide mission was made from [launch] altitude."^[27] Between these two flights, the SpaceShipTwo airframe was modified by the addition of two interior fins, with one fin being added to the inside (rocket-side) of each of the craft's twin vertical stabilizers.^[28]

On 15 July 2010, VSS Enterprise made its first crewed flight. The craft remained attached to VMS Eve as planned, and underwent a series of combined vehicle systems tests. The flight lasted a total of 6 hours and 21 minutes. A second, similar crewed flight of VSS Enterprise and VMS Eve was carried out on 30 September 2010, lasting approximately 5 hours. Among the objectives of these flights was the improvement of pilot proficiency, and the results of the flights were deemed to show that the systems were capable of supporting future glide missions.^[26]

On 10 October 2010, VSS Enterprise made its first manned gliding test flight. It was released from VMS Eve at 45,000 feet and glided to a safe landing at the Mojave Air and Spaceport.^[29][30][31] A second gliding test flight took place on 28 October 2010^[32] and a third on 17 November 2010.^[33] As of December 2010^[update], Scaled reported that the flight test program is exceeding expectations.^[34] The fourth test flight took place on 13 January 2011,^[35] with the fifth and six glide flights were on the 22 and 27 of April 2011, respectively.^[36] Following this, the feathered reentry configuration was tested in flight on 4 May 2011,^[36] with weekly test flights continuing through the end of May.^[36] On the 9th of June 2011, the release of the SS2 failed during its 11th planned glide flight due to a technical problem.^[37] Testing resumed with five successful glide flights in June 2011.^[36]

In July 2011, after 15 successful glide flights, flight testing of SS2 was halted for two months while planned revisions to the spaceplane were made.^[38] Flight tests resumed in late September 2011, although the 16th glide flight – on 29 September – was marred by a brief loss of control aboard SS2, forcing the crew to utilise the feathered wing configuration to land safely.^[39][3]

SpaceShipTwo test flights

Source: ^[36]

Commercial operation

The duration of the flights will be approximately 2.5 hours, though only a few minutes of that will be in space. The price will initially be $200,000.^[40] More than 65,000 would-be space tourists applied for the first batch of 100 tickets. In December 2007 Virgin Galactic had 200 paid-up customers on its books for the early flights, and 95% were passing the 6-8 g centrifuge tests.^[41] By the start of 2011, that number had increased to over 400 paid customers.^[42]

Following 50–100 test flights, the first paying customers are expected to fly aboard the craft in 2013.^[4] Refining the projected schedule in late 2009, Virgin Galactic declined to announce a firm timetable for commercial flights, but did reiterate that initial flights would take place from Spaceport America. Operational roll-out will be based on a "safety-driven schedule".^[24] In addition to making suborbital passenger launches, Virgin Galactic will market SpaceShipTwo for suborbital space science missions.^[24]

NASA sRLV program

As of March 2011^[update], Virgin Galactic has submitted SpaceShipTwo as a reusable launch vehicle for carrying research payloads in response to NASA's suborbital reusable launch vehicle (sRLV) solicitation, which is a part of NASA's Flight Operations Program. Virgin projects 110 km (68 mi) altitude in flights of approximately 90 minutes duration, while carrying a research payload. Flights will provide approximately four minutes of microgravity. Payload mass and microgravity levels have not yet been specified.^[1] The NASA research flights could begin during the test flight certification program for SpaceShipTwo.

Future spacecraft

In August 2005, the president of space tourism company Virgin Galactic stated that if the suborbital service with SpaceShipTwo is successful, the follow-up SpaceShipThree will be an orbital craft. In 2008, Virgin Galactic changed their plans and decided to make it a point-to-point vehicle. This vehicle will offer transportation through point-to-point suborbital spaceflight.^[43]

Specifications

General characteristics

• Crew: 2
• Capacity: 6 passengers
• Length: 18.29 m (60 ft)
• Wingspan: 8.23 m (27 ft)
• Height: 4.57 m (15 ft)
• Powerplant: 1 × RocketMotorTwo liquid/solid hybrid rocket engine

Performance

Source: ^[44]

See also

• SpaceShipOne
• White Knight Two
• Virgin Galactic
• Scaled Composites
• Burt Rutan
• Spaceport America
• Ansari X Prize
• Spaceplane
• Space Shuttle program
• SpaceX
• Commercial spaceflight

References

External links

• Virgin Galactic
• Scaled Composites
• Information on SpaceshipTwo and Virgin – spaceshiptwo.net
• Formation of The Spaceship Company – space.com
• The Birth of SpaceShipTwo – SpaceDaily
• Space or Bust: Feature article on space tourism – Cosmos Magazine
• Space Law in Paris – Space Law Probe
• Videoblog of Wired NEXTFEST – People With Ideas
• CNET Images of SS2 mockups – CNET News
• Epic Enterprise Information Documentary about SpaceShip Two
• SpaceShipTwo at AerospaceGuide.net