By Bob McDonald, host of the CBC Radio One science program Quirks & Quarks.

While Space Shuttle Discovery prepared for its final mission to the International Space Station, it had to wait for an unmanned European spacecraft called Johannes Kepler to get there first.  It was an interesting comparison between a modern, low-cost robotic approach to delivering supplies to the Space Station, and the aging, human-driven space shuttle that does the same task at much greater cost.

This is the second time the European Space Agency has sent up an Automated Transfer Vehicle (ATV). It's a 10 metre long, 4m wide cylinder, carrying tonnes of equipment, food, oxygen and fuel that flies up to the Space Station and then docks with it completely automatically.

Once attached, the module becomes an extra room used to store supplies until next summer, when it will become a garbage truck delivering Space Station trash to a fiery incineration in the upper atmosphere over the Pacific Ocean. 

This driverless delivery truck is a far simpler and much cheaper way to reach the Space Station than the space shuttle, and follows in the decades-long tradition of Russian Progress supply ships, and joins the Japanese KOUNOTORI2 as the next generation of unmanned supply missions.

Space Shuttle Discovery, meanwhile, four months behind its launch date because of fuel leak problems, also carries supplies and spare parts for the Station - but it also carries six people and will cost more than $1 billion US to make this flight. It's about time the shuttles are retired.

The space shuttles have been remarkable in their ability to carry people and cargo into space. They have been the heavy lifters, delivering most of the large components of the Space Station. But it is their dual purpose that has made them the most complex machines to ever fly and therefore prohibitively expensive.

The future, and cheaper way to reach space is to separate the people from the cargo and fly them in two different, simpler vehicles. That means rocket launches, at least in the short term, will be smaller, missile-style missions, which are not nearly as spectacular as a shuttle liftoff.

The good news about the next era of space flight is that the International Space Station can finally begin to operate as a fulltime scientific laboratory, rather than a construction site. That includes Canadian science.

Before taking off, on this current mission, the shuttle astronauts has their feet tickled, and they will be tickled again in space, not just for laughs, but as part of a study from the University of Guelph and Wilfred Laurier University, looking at how the sense of touch changes in space. Spruce seedlings from the Canadian Wood Fibre Centre in Quebec City, which have been growing on the Space Station for the past month, will be brought back to Earth by Discovery to see how the plant world deals with micro-gravity. And blood samples from the astronauts will be delivered to the University of Waterloo to look at how space flight seems to mimic the effect of aging on blood cells.

And of course, the next commander of the Space Station will be Canadian Astronaut Chris Hadfield.

So, there is a lot of science still to come.  But if you want to see the last of the old- fashioned, big, expensive, noisy ways of reaching space, there are only two opportunities left. Endeavour is scheduled to fly in April and the final flight of Atlantis is slated for June.

Believe me, the experience of a live shuttle launch is worth the effort. It will be a bit like watching the last steam-driven train go by: big, noisy, and majestic - but their day has come and gone.