The rocket鈥檚 power was increased by strapping on extra boosters
The first in a new generation of US heavy-lift rockets, the Boeing Delta 4 Heavy, made its maiden flight on Tuesday, from Cape Canaveral in Florida. However, the launch was only a partial success.
The rocket got off the ground safely after several days of delays. But a problem with the first stage engine burn meant the two small satellites the rocket was carrying did not reach geosynchronous orbit.
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鈥淲e had a shorter than expected first stage burn. That was compensated for by longer first and second burns in the second stage,鈥� said Dan Collins, Boeing vice president for Expendable Launch Systems, speaking to SpaceflightNow.com. But the longer burns meant the rocket ran out of fuel during its final burn, leaving the satellites stranded.
Nonetheless, Boeing says the test met 鈥渁ll its major objectives鈥�. Collins said 鈥渨e got a huge amount of data that allows us to move forward with high confidence鈥� and that the customer 鈥� the US Air Force 鈥� was 鈥渧ery, very happy鈥�.
Shuttle replacement
The launch marked an important milestone both for the military and for NASA鈥檚 search for a shuttle replacement.
The Delta 4 Heavy is 鈥渢he most capable US launch vehicle, able to launch the largest weight, other than the space shuttle鈥�, says Phil McAllister of Futron, a defence consulting firm in Bethesda, Maryland, US. With the shuttle no longer launching satellites and due to be grounded in 2010, a heavy-lift capability is critical to both NASA and the Pentagon.
The Delta 4 Heavy towers 70 metres high and is designed to lift up to 23 tonnes to low-earth orbit. Unlike the shuttle it can also reach higher orbits. By adding six solid-fuel boosters, Boeing hopes to double the payload so the rocket can carry 50 tonnes to low-earth orbit.
A version of the Delta 4 Heavy designed to launch crewed spacecraft is in the running to launch NASA鈥檚 future Crew Exploration Vehicle. Other craft competing for this task are a completely new rocket, a reconfigured version of the shuttle, and Lockheed Martin鈥檚 design for a heavy version of its Atlas 5 rocket. With a selection due in 2005, a successful test launch was crucial for Boeing.
Spy satellites
It was also vital for the Pentagon, which is flying its last Titan 4B rocket in summer 2005. It will not entrust its heavy satellites to the other existing heavy rockets, the European Ariane 5 and the Russian Proton.
At least two big US defence satellites are already in the queue, one to detect missile launches and a classified spy satellite. Both those satellites were too costly to risk on the untried Delta 4 Heavy, so the Air Force instead paid to launch a dummy payload and a pair of small research satellites.
Boeing launched a smaller, liquid-fuelled version of the Delta 4 in 2002, able to carry 8 tonnes to low earth orbit. To build the Heavy version, Boeing strapped two more liquid boosters to the first stage.
Lockheed Martin鈥檚 Atlas 5 was developed under the same military program, and can carry 10 tonnes to low earth orbit. The aerospace giant has designed a heavy version of the Atlas 5, which it believes could match the Delta 4 Heavy鈥檚 launch capacity, but none have been built yet.
