The Columbus laboratory, in which a number of Swiss firms and the government have a stake, was shipped from Germany to the Kennedy Space Center on Sunday.
The multi-purpose science laboratory, which has taken a decade to build and cost around SFr1.55 billion ($1.26 billion), is due to dock with the International Space Station (ISS) in 2007.
The 13-ton Columbus, which has been built by the European Space Agency (ESA), was originally planned to be sent into orbit in October 2004, but the explosion of the Columbia space shuttle three years ago postponed the mission.
André Balogh, a director at the Bern-based International Space Science Institute, says Columbus's fate now hangs on the health of the shuttle programme.
"At the moment Columbus is due to be launched in 18 months' time but it really depends on how the next shuttle flights go," he told swissinfo. "There is real concern that if there are further problems, Columbus may never reach the International Space Station."
This would represent a disaster for scientists who have invested years in the 4.5-metre diameter cylindrical module, which will enable researchers, together with the help of astronauts, to conduct experiments in the weightlessness of orbit.
The lab is expected to perform hundreds of experiments in a number of disciplines during its ten-year operational lifetime, according to the ESA.
It carries ten "racks" each the size of a telephone booth and able to host its own autonomous and independent laboratory, complete with power and cooling systems, and video and data links back to researchers on Earth.
One of these, Biolab – the biological experiment module on Columbus – is of particular interest for Switzerland in that its data wil be processed in Cologne and in Zurich by the Federal Institute of Technology's Biostec Space Biology Group.
Balogh, who was a member of an ESA panel back in the 1980s when Columbus was first discussed, said scientists had faced a long and anxious wait to see the lab launched.
"These experiments can't be done anywhere else at the moment because they need a long exposure to weightlessness," he said.
He added that much hope was being pinned on certain biological experiments, including the growing of protein crystals, as well as tests on fluids.
The Columbus project was led by the space transportations unit of aerospace and defence contractor EADS and involved some 40 firms from ten European countries, including Switzerland.
Columbus will carry a "dew point" sensor for measuring humidity designed by Meteolabor, based in Wetzikon near Zurich. The system is based on the company's Thygan thermohygrometer used by Swiss meteorologists.
Zurich-based Alcatel Switzerland has provided a Payload Power Switching Box for controlling and feeding different power supplies.
Mecanex, based in Nyon, was picked by EADS to perfect and produce high precision joints for the European Robotic Arm on the ISS.
swissinfo, Adam Beaumont
Columbus left Bremen in Germany on Sunday with one day's delay for the Kennedy Space Center in the United States.
The European Space Agency says the almost complete absence of gravity will provide a unique environment for many aspects of medical research, as well as the development of high-performance industrial materials.
As a member of the European Space Agency (ESA), Switzerland contributed SFr138 million in 2003. Around 50 Swiss companies are active in the space industry.
The ESA's budget this year is estimated at more than SFr4.5 billion.
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