Two Canadian-based research projects with applications in the health sector were destroyed when the space shuttle Columbia broke up in mid-air on Saturday, killing all seven astronauts.

Marc Garneau, Canada's first astronaut and president of the Canadian Space Agency, pegged the Canadian investment in the experiments at "hundreds of thousands of dollars."

"The experiments were successful during the mission, but the analysis of the samples was to be done when the shuttle returned," said Garneau.

A team from the Canadian Space Agency was waiting Saturday at the Kennedy Space Centre in Florida to fly the retrieved materials in a Lear jet to Pearson airport in Toronto for distribution to researchers in Toronto, Kingston, Ont., Montreal and Saskatoon.

The Columbia mission was the seventh since 1993 in which the Canadian Space Agency had sponsored similar research.

The Canadian experiments were among more than 100 projects on the subject of microgravity conducted during the 16-day mission.

Microgravity is the proper term for the condition, often referred to as zero-gravity, that exists onboard an orbiting spacecraft.

The term zero-gravity is actually a popular misconception. Gravity does exist on board an orbiting spacecraft -- it is the force that keeps a craft in orbit around the earth. However, it acts on all objects equally, including astronauts, other items, even the entire spacecraft. The result is a condition that appears to have no gravity.

The first research project was part of the OSTEO-2 experiments, designed to study the degenerative effects of prolonged exposure to microgravity conditions.

Microgravity conditions lead to significant physiological changes among astronauts. According to the Canadian Space Agency, astronauts' muscles and bones deteriorate up to 10 times faster than the rate seen in patients suffering from muscular dystrophy and osteoporosis. While in space, astronauts can lose up to 2 per cent of their bone mass each month.

The experiments onboard the Columbia attempted to discover the molecular mechanism that causes this degeneration and find an effective countermeasure.

There were four Canadian experiments involved with the OSTEO-2 research project.

Dr. Leticia Rao and Dr. Tim Murray of St. Michael's Hospital in Toronto led a team investigating the use of hormones to increase bone formation in microgravity.

A second team, led by Dr. Reginald Gorczynski of the University Health Network in Toronto, investigated the effects of disturbances in sleep and and immune functions on bone metabolism.

Dennis Sindrey of Millenium Biologix and Dr. Bradford Brinton on NPS Pharmaceuticals led an experiment to characterize and identify bone gene regulation patterns.

Finally, a University of Toronto experiment studied how microgravity affected the cells involved in bone metabolism.

The second research project also involved microgravity, but studied protein crystal growth. Sedimentation and convection impede protein crystal growth on earth, but not in space, where the size and quality of crystallized proteins is much better. Scientists study the architecture of crystallized proteins to design more efficient medication with fewer side effects. Protein crystals are used to fight breast and prostate cancer, diabetes and antibiotic-resistant bacteria.

Five Canadian scientists from universities and research institutes across the country were involved in the protein crystal research project.

Ron Dittemore, shuttle program manager, told a news briefing that a few results from Columbia experiments had been routinely transmitted to NASA and would be "a legacy" of the dead astronauts. He said he could not imagine that the shuttle's problems would be traced to any of the 100 experiments on board.

Among the cargo on board for experiments were spiders, flowers, cancer cells, ants, carpenter bees, fish embryos, silkworms and rats.

With files from Canadian Press