Dropped rockets may take astronauts into orbit

 作者:爱田     |      日期:2019-02-27 01:16:03
By Jeff Hecht (Image: t/Space) Rockets that drop in a vertical orientation from carrier aircraft could carry astronauts into space safely and cheaply, suggest drop tests of the new approach. Development of the technique is being spearheaded by a consortium of small aerospace companies called t/Space that includes Scaled Composites, the firm that in 2004 won the $10 million Ansari X Prize for private spaceflight. With $3 million in seed money from NASA, t/Space is developing a rocket that would first be carried by aeroplane to an altitude of between 10 and 13 kilometres. The rocket would launch from that height before carrying four astronauts to low-Earth orbit. There, the crew could board the planned replacement for the space shuttle, called the Crew Exploration Vehicle (CEV). Using an aircraft means the rocket uses less fuel than starting from the ground. “The advantage is that you get the first 10 to 13 kilometres very cheaply,” says Michael Mendenhall, vice president of Nielsen Engineering and Research in Mountain View, California, US, who has done consulting work for t/Space. At that height, the aircraft would drop the horizontal rocket’s tail first, holding onto its nose for a fraction of a second longer. Gravity would pull the tail downwards, with a parachute ballooning out behind it to slow its rotation. The rocket would thus fall into a vertical position so it could fire its engines a safe distance behind its carrier aircraft. Other rockets, such as the winged Pegasus, already launch from high-flying planes, but they take off horizontally. The Pegasus zooms under and in front of its carrier, rising at an increasing rate until it reaches an elevation such that it can drop its then redundant wings. Such winged, horizontal flight benefits from lift in the atmosphere. But t/Space says its wingless design saves on weight, allowing it to carry a heavier payload. And it asserts its system could be ready faster than launching astronauts directly in the CEV, using an existing heavy-lift rocket that has not yet been rated for human payloads. To test the concept, t/Space built models 6.35 metres long – about one-quarter of the size of the full scale 27.5-metre rockets. Each of the mock-ups consisted of two steel tanks welded together with a nose and tail made of fibreglass. During one drop test in May and two in June over California’s Mojave desert, the launchers behaved as predicted by computer simulations. The test rockets were dropped from a Proteus aircraft built by Scaled Composites, but the real rockets will be carried by a larger aircraft. David Gump, president of t/Space, is proud of how fast the company developed the booster rockets. “We went from brainstorm to booster drop in just 135 days,” he says. Mendenhall, who has worked on the Pegasus rockets, is also impressed at the quick turnaround. “t/Space can just jump up and start something and do it,