Technology

Space exploration: Getting plant life to the red planet

NASA spent millions on a support system for plants, when a Ziploc bag did just fine.

Even failed scientific experiments can prove useful. That’s a consolation to professor Rod Savidge, who struggled for years to arrange a tree growth experiment aboard the International Space Station. It descended into farcical disaster yet delivered an unexpected lesson that might help humans reach the red planet.

Savidge, a professor at the University of New Brunswick, is an expert in tree physiology and wood anatomy. For decades, he’s been fascinated by reaction wood – a variety of wood produced in both conifers and broad-leaved trees. It’s typically found in leaning or crooked stems and in branches, areas subjected to mechanical stress. Though little is known about how it forms, “it has always been assumed to be a response to gravity,” Savidge says. It has commercially undesirable traits – in softwood lumber, for example, it has been known to fail abruptly.

The ISS’s near-weightless environment offered an ideal venue for studying the problem. For years, the Canadian Space Agency spurned Savidge’s research proposals, finally relenting in 2006. So Savidge proposed to grow willows simultaneously aboard the ISS and on Earth, and compare the results. To restrict the experimental variables to gravity, NASA developed something called the Advanced Biological Research System, or ABRS. It contains two independently controlled chambers, and is designed to fit racks aboard the space shuttle and ISS. It can regulate temperatures, light, humidity and carbon dioxide, and has three cameras for monitoring.

Despite its impressive specifications, the ABRS does have one drawback: it kills trees. In a test prior to launch at the Kennedy Space Center in Florida, Savidge’s willows died within 10 days from drought. A second batch was saved only after Savidge had NASA water the trees. But by then it was too late to turn back. “We had to go to launch,” he says. “We had no choice, it was all manifested.” So STS-129, a shuttle mission by Atlantis primarily intended to stock the ISS with spare parts, left Earth on Nov. 16, 2009, with 18 willow seedlings and an ABRS aboard.

Atlantis docked with the ISS and transferred its payload. Canadian astronaut Robert Thirsk began the experiment on Nov. 21, and considered it one of the more interesting tasks he performed during his six-month mission. “My job was to take these willow seedlings and put a 360-degree loop into their stems, and store them in an incubator for a month or so,” Thirsk says. Two days later, at Kennedy Space Center, another batch of willows was contorted in an earthbound ABRS. Thirsk’s involvement ended when he returned to Earth last December, but he hoped the experiment might eventually help improve the quality of Canada’s exported lumber.

It didn’t. The ABRS aboard the ISS failed to maintain the environmental set points, and NASA called Savidge to let him know his trees were in rough shape. “If we’d left them, they would have died,” Savidge says. Desperate to salvage his experiment, he persuaded NASA to place the trees in resealable plastic bags – similar to the kind you may have in your kitchen. The willows recovered somewhat afterward, and returned to Earth in February aboard Endeavour during mission STS-130. But since all semblance of control over variables had been lost, the experiment’s results became unintelligible.

There was one unexpected outcome, however: the trees survived in plastic bags with minimal attention. The significance of that may seem elusive, until one recalls U.S. President Barack Obama’s recent proclamations. Obama called upon NASA to dispatch a manned mission to Mars by the mid-2030s. Thirsk explains that plants would likely accompany any such mission. Through photosynthesis, plants produce much-needed oxygen. They also consume carbon dioxide and wastewater. “So they’re perfect for a life support system aboard a spacecraft that’s travelling to Mars, or a small colony that’s on Mars,” Thirsk says. “And of course, they also provide a source of food for astronauts too.”

Savidge says the unreliable, high-maintenance ABRS just won’t cut it. The humble sandwich bag, though, might just do the trick. “We’ve set the stage for getting plants to Mars in a very simple, pragmatic way,” Savidge says. “It’s too simple,” he adds, laughing. “They had to spend millions and millions of dollars engineering very sophisticated boxes…a one-dollar Ziploc does just fine.”