NASA’s space shuttle Atlantis lifted-off today at 2:28 p.m. ET on an 11-day mission to service the the International Space Station (ISS). On-board the shuttle is the Canadian APEX-Cambium (Advanced Plant EXperiments on Orbit) experiment. The experiment will help determine the role gravity plays in trees forming different kinds of wood.
Rodney Savidge of the University of New Brunswick is a tree physiologist and is the principal investigator of the experiment. He will be working with Canadian astronaut Bob Thirsk who is on a long duration stay on the ISS. Thirsk’s task will include bending willow tree stems into loops. The goal of the research is to improve knowledge of fundamental biological processes in trees. Despite all the money spent on forestry research, relatively little focuses on basic physiology, according to Savidge. “We don’t understand how trees make wood.”
Savidge explains that parts of a tree that are not vertical typically grow one kind of wood on one side and another kind on the other. This is known as “reaction wood” and the mix of different kinds of this wood in trees influences their suitability for different uses, such as construction or paper. Scientists believe reaction wood is a response to gravity, but they have not been able to prove it.
Savidge’s experiment will reveal whether this reaction wood will grow on the upper sides of the tops and bottoms of willow stem loops in the weightless environment of space, as they do on Earth. He explains, “If we do not get reaction wood in the loops in the expected places in space, it will be an indication that weight on Earth, caused by gravity, is involved.” Cambium is the plant tissue that actually grows to form wood in trees; this remarkable tissue allows tree trunks and branches to increase in girth as the tree grows, so that the tree has the strength to remain standing as it becomes more massive.
– Advanced Plant Experiments on orbit (APEX-Cambium), Canadian Space Agency