Two additional teams have entered the $10 million X Prize competition to demonstrate a privately financed reusable spacecraft. The 21 teams registered have been given until January 2005 to fly a three-seat vehicle to 100km (60miles) altitude, return safely and fly again within two weeks.

The latest entrants are Dallas, Texas-based Armadillo Aerospace and ARCA of Romania, joining teams from Argentina, Canada, Russia and the UK, as well as the USA. While there has been little progress since the X Prize was established six years ago, several key tests are scheduled for next year as the teams race to meet the new deadline.

Leading the field is Burt Rutan's Scaled Composites, which plans to release a rocket-powered vehicle from a turbofan-powered mother ship at 37,000ft (11,300m). An unusual twin-boom aircraft, the Model 318, has been undergoing flight testing at Rutan's Mojave, California, base since September and is believed to be the mother ship.

Argentina's Pablo de Leon and the UK's Starchaser Industries are also ranked among the leaders. De Leon plans to launch a half-scale version of his Gauchito vehicle next year. This features a recoverable booster and capsule. Starchaser's Thunderbird is intended to take off vertically under turbofan power, switching to a liquid-fuel rocket engine.

ARCA is building a half-scale version of its Orizont vehicle, which also uses a recoverable booster and capsule. The Canadian Arrow team has begun engine testing for its vehicle, which combines a liquid-rocket first stage with solid-rocket second stage, both recoverable.

Russia's Cosmopolis XXI team is working with Myasishchev on a rocket-powered mini-shuttle that would be launched from the design bureau's M-55 high-altitude research aircraft at 56,000ft. Canada's da Vinci team plans to release its recoverable rocket-powered vehicle from a hot air balloon at 40,000ft. The USA's Kelly Space and Technology plans to tow its Eclipse Astroliner reusable spaceplane to release altitude behind a Boeing 747.

Source: Flight International