An astronaut practises installing the support boom on the Special Purpose Dexterous Manipulator, a double-armed robotic tool created for the maintenance and servicing of the International Space Station by Brampton, Ont.-based MD Robotics, which also developed the Canadarm. (CP PHOTO/HO-MD Robotics)

While the Canadarm may have opened the door to Canadian participation in the shuttle program, good science and first-rate astronauts are keeping the country involved.

Canadian astronaut Steve MacLean will be the next to fly into space, on the space shuttle Atlantis, scheduled for launch in August 27, 2006. As part of the space station construction mission, MacLean is scheduled to perform a spacewalk and to be the first Canadian to operate the Canadarm 2 in space.

MacLean was to have been part of a shuttle mission in April 2003, but the entire fleet was grounded after the loss of Columbia.

When Columbia disintegrated a few minutes before it was scheduled to land on Feb. 1, 2003, it looked as though the shuttle program might not have much of a future. But NASA determined that it should get back into the business of space flight as soon as it safely could.

The investigation into the disaster that killed seven astronauts concluded that a piece of foam came off the shuttle's external fuel tank and hit the wing. That left a hole, which led to the wing overheating as the shuttle re-entered the atmosphere.

The report identified 44 safety issues that it recommended be addressed before the shuttle program got back off the ground. Among them were:

• Redesigning the external tank.
• Removing foam "ramps" that cover struts attaching the tank to the shuttle's nose.
• Installing an electric heater on the liquid oxygen feed-line to prevent ice from building up.
• Installing 66 sensors on each wing to measure acceleration and impact data.
• Installing 22 sensors to measure temperature during the climb to orbit.

Another key change involved the development of a remote-sensing system that could inspect hard-to-see parts of the shuttle while the craft was in orbit. It would work with the Canadian-built remote manipulator arm.

Part of the system is an extension to the Canadarm – the 15-metre-long Orbiter Boom Sensor System (OBSS). It works like a dentist's mirror.

The OBSS was developed by Brampton, Ont.-based MacDonald, Dettwiler and Associates Ltd., the same company that has been providing the Canadarm for a generation.

At the end of the OBSS will be two laser cameras and laser ranging sensors that can inspect every shuttle tile for cracks and holes while in orbit. It was designed by Ottawa-based Neptec.

When Columbia went down, so did several Canadian experiments. The Canadian Space Agency paid for three experiments on the flight, which was to be the last mission dedicated to science on NASA's current schedule. Subsequent flights were to deal exclusively with the International Space Station.

The experiments were to look at the accelerated rate of bone loss in space.

The microgravity of space allows researchers to study, more quickly than they could on Earth, what happens during bone loss, and possible ways to treat it.

Scientific experiments have been central to the participation of Canadian astronauts in the shuttle program. Since Marc Garneau's first flight in 1984, most Canadian astronauts have been payload specialists – people who are selected and trained by commercial or research organizations for flights of a specific payload.

Among the experiments Garneau conducted during his first flight was one aimed at determining why 40 per cent of all astronauts suffer from motion sickness in space. Another looked at whether food really does taste sweeter and less spicy in space.

When Roberta Bondar blasted off a little over five years later, she conducted 43 experiments for 13 countries.

Garneau's second space flight was one of the busiest for Canadian experiments. They included the Commercial Float Zone Furnace (CFZF), the Aquatic Research Facility (ARF), the Nanocrystal Get Away Special (NANO-GAS) and the Atlantic Canada Thin Organic Semiconductors (ACTORS).

The Canadarm may be the most visible Canadian content in the shuttle program. Its successor – Canadarm 2 – is the workhorse of the International Space Station. It weighs 1,640 kg, is 17.6 metres long when fully extended, and has seven motorized joints. It's capable of handling large payloads and helping dock the space shuttle.

It was installed on the space station in April 2001, when Chris Hadfield became the first Canadian to take a walk in space.

Canadarm 2 differs in another major way. The original Canadarm is mounted outside a shuttle's payload bay. Each end of Canadarm 2 has a hand that can grasp an anchor on the space station. By flipping end-over-end between anchor points, Canadarm 2 can move around the ISS like an inchworm.