SpaceShipTwo

SpaceShipTwo is a suborbital spaceplane. Its purpose is to carry passengers in private spaceflight, commencing space tourism. The craft partly uses the technology developed for SpaceShipOne project, the hybrid rocket motor. This aircraft launches horizontally, unlike a spacecraft, but rises following an exponential curve which causes to shorten the horizontal range of takeoff. SpaceShipTwo will fly somewhere between 135 and 140 km in altitude, higher than the original SpaceShipOne vessel which reached the 100km line.

A hybrid rocket propulsion system is a combination of a solid fuel and a liquid oxidiser. The oxidiser is fed into the combustion chamber and the mixture is then ignited which causes the fuel to burn. A hybrid motor is preferred to the previous use of solid propulsion systems, especially in commercial use, since it offer four advantages. First, the motor can be restarted. This implies the motor can be turned off when suborbital space is reached and then turned back on for landing. Second, the hybrid propellant is very safe, especially compared to the other forms used in space travel. It is inert, therefore should not explode unless given extraordinary circumstances. Also, the explosive equivalent of hybrid is taken to be 0, compared to 100% for solids. Third, the force of the motor can be controlled; augmented or diminished as desired. Fourth, this new propulsion system is cleaner. Environmental concerns are growing for the general public and since such commercial flights will occur more frequently than space missions, it is a preoccupation to limit the environmental damage caused. One disadvantage however, is that one cannot predict with absolute certainty how the solid and the liquid will mix which affects the average specific impulse, the actual efficiency of the rocket.

SpaceShipTwo will offer commercial orbital flights to the public. The first flight is schedule to launch in 2009. The initial cost of a ticket will be of 200,000$, but will drop within a year to 20,000$. This new technology offers the possibility, in the future, of shortening long distance flights by reaching orbital altitude and taking advantage of free displacement. This would greatly shorten the time required to travel from one end of the world to another. As the mode of transportation becomes more popular, the ticket price will become more affordable. These new spaceplanes will revolutionize the travel industry as well as the business world due to increased speed and ease of travel.


References:
-urocketman.com, "Hybrid Rockets," available at http://www.ukrocketman.com/rocketry/hybridscience.shtml
-wikipedia.org, "Scaled Composites SpaceShipTwo," available at http://en.wikipedia.org/wiki/Scaled_Composites_SpaceShipTwo
-space.com, "First Civilian Astronaut Pilots SpaceShipOne into Suborbit," available at http://www.space.com/missionlaunches/SS1_airborne_040621.html