The immense 381 m high zero-pressure balloon is constructed from 5,000 kg of polyethylene, using helium as the lift gas at its maximum altitude the balloon's volume will be 1.25 million m³ (40 million ft³). The two pilots will be on an open deck, relying on Zvezda manufactured spacesuits to keep themselves alive during the anticipated twelve-hour flight.
The attempt was originally planned for 2002 but adverse high altitude conditions halted attempts in that year. The launch site for the twelve-hour flight was decided to be from off the coast of Cornwall.
In 2003 the launch was initially set to take place on September 2 from the deck of RV Triton off the coast of St Ives. Early that morning, it was decided to postpone the launch for 24 hours due to cloud at high altitude. The following morning an attempt was made to inflate the balloon. At around 6.55am with the balloon inflated to a height of 15 metres, helium began to escape from the envelope. An irreparable tear was discovered along one of the seams of the balloon and all efforts for a flight in 2003 were abandoned.
The current record is held by Malcolm Ross and Vic Prather of the US Navy, who took Strato-Lab to 34,668 m (113,740 ft) on May 4, 1961 above the Gulf of Mexico. Prather was drowned when the balloon ditched in the sea at the end of the flight.