CAPE CANAVERAL: The US space shuttle Discovery blasted off at dawn today towards the International Space Station for a mission that will put more women in orbit than ever before. Discovery lifted off from Launch Pad 39A at the Kennedy Space Centre in Cape Canaveral, Florida at 6:21 am as scheduled. The two booster rockets, which account for 80 per cent of the shuttle’s lift during takeoff, peeled away as planned 120 seconds after the launch. They fell into the Atlantic Ocean, where they will be subsequently retrieved and reused. The shuttle reached Earth’s orbit eight-and-a-half minutes after launch, moving at five times the speed of sound to reach 26,000 km per hour. Once it goes into orbit some 225 km above Earth, Discovery will begin its race towards the ISS, itself located 343 km above Earth. Discovery’s planned arrival at the International Space Station is tentatively scheduled for Wednesday and will be one of the final missions for the shuttle programme, which will be shuttered later this year. It is the first shuttle mission with three female crew members and will also mark a first in space, with four women in orbit. During the 13-day mission, Discovery and its crew will deliver nearly eight tonnes of cargo, including spare bunks for the occupants of the space station, a large tank of ammonia coolant and seven racks filled with science experiments. Discovery is also carrying an exercise machine designed to study the effects of micro-gravity on the body’s musculoskeletal system. Muscles can atrophy during long sojourns in space so astronauts have to take care to exercise regularly. The supplies, racks and other gear are packed into a pressurized Italian-built module named Leonardo, carried in the shuttle’s bay. Until construction of the orbital outpost is completed, NASA has to ferry spare parts and gear to maintain the space station and service the scientific experiments on board. Two Discovery astronauts will conduct three space walks lasting six and a half hour each on days five, seven and nine of the mission. One of their principal and most complex tasks will be to replace an empty ammonia tank attached to the rear of the station with one that is full. Ammonia is used in the station’s cooling system. The ISS, a hundred billion dollar project begun in 1998 with the participation of 16 countries, is financed mainly by the United States.