UF Researchers Build Mars Simulator To Put Interplanetary Greenhouses To The Test

In the years after the Viking probes landed on the surface of Mars, many scientists spent their spare time building bottle-like devices that replicated the thin air or the surface of the Red Planet — and using them to see whether plants could survive under Martian conditions.

"It was a hobby thing, something you'd have on the back bench in your lab," said Bucklin, a professor of agricultural and biological engineering at the University of Florida. "Most of these experiments didn't produce any published research, but they showed how easy it is for Mars to capture the imagination."

Now Bucklin and his graduate students at the UF's Institute of Food and Agricultural Science (UF/IFAS) have put together a Mars jar to beat them all — a room-sized chamber in which the researchers can test models of greenhouses that could one day be built on the Red Planet.

"Our goal is to address some of the basic engineering questions associated with these greenhouses, and to do that, we need to test them in the conditions one would find on Mars," said Inka Hublitz, an agricultural and biological engineering graduate student and one of the creators of the UF/IFAS "Mars simulation chamber."

The chamber, housed in a basement laboratory in Frazier Rogers Hall, consists of an industrial sized freezer with a custom-built vacuum chamber inside. When it's in operation, the chamber is filled with the same mixture of gases found in the Martian atmosphere, and at the same pressure — about one percent of the pressure found on Earth at sea level. And the temperature can be brought down to 30 degrees below zero — a balmy temperature in Martian terms, but within the ranges found on the Red Planet.

The chamber is just one element of an ongoing UF program that explores ways astronauts might grow plants on long trips into space. If humans venture to Mars or establish a permanent base on the Moon, the researchers say, it's likely they'll take a garden with them. Spaceborne gardens could be used to recycle waste generated by astronauts on a Mars mission or Moon base, turn carbon dioxide into oxygen, and provide more food than astronauts would be able to carry with them, UF researchers say.

"Growing food on a long mission might be a complicated process, but its certainly going to be cheaper than shipping tons of packaged food into space," Bucklin said.

The prospect of Martian agriculture has sparked a number of visions in the minds of researchers — from plants growing under artificial light in chambers beneath the Martian surface to crops growing in transparent domes under air that is thinner, colder and drier than anything found on earth.

Before any design can leave Earth, however, it will have to undergo rigorous testing under conditions true to the Martian climate. That's why simulation chambers like the one at UF may become much more common in coming years.

"There's a lot of engineering that's going to have to be done before we can establish a presence on Mars," Bucklin said. "We're going to have to test every component of the mission against every condition that component is likely to face. We're at the very beginning of that process."

Hublitz plans to use the chamber to test her own prototype greenhouse, a transparent plastic dome in which plants would grow at a fraction of the temperature, pressure and humidity found on earth. Some plants have shown an ability to grow in very thin, dry air, she said, and pressurizing a greenhouse to one earth atmosphere would make for a much bulkier structure.

"It's very expensive to lift things into space, and on a mission to Mars, and it's important to make things as small and light as possible," said Hublitz. "We can save quite a bit of weight by taking advantage of a plant's ability to grow in what may seem like harsh conditions."

There are still variables in her design that need to be worked out. For one thing, Hublitz isn't sure what will happen to the water vapor that collects on the dome of her greenhouse in the sub-zero temperatures of Mars. Condensation could conceivably freeze, locking up precious water and creating a sheet of ice that keeps plants from getting enough light. Or a dozen other unforeseen problems could lurk in the design.

"The only way to find and eliminate these problems is to test the device in actual Mars-like conditions," Hublitz said. "Without a simulation chamber like this one, that couldn't be done."

Hublitz said greenhouses similar to hers could one day dot the landscape around a base on Mars, allowing astronauts to grow rice or wheat that has been bred or genetically engineered to thrive in the greenhouse's climate. Future experiments in the simulation chamber will test how various crops grow in the greenhouse under Mars-like conditions.

The chamber may also have a much closer-to-home application: finding better ways to ship tropical fruit and other food products by air.

The air inside the cargo hold of a jet airplane is typically maintained at a lower pressure than one would find at sea level, and temperatures in an aircraft can fluctuate significantly as it climbs to a high altitude. That can create problems when food or other moisture-laden products are in a cargo hold, said Jean-Pierre Emond, an associate professor in UF’s agricultural and biological engineering department.

"When you have these rapid changes in temperature and pressure, sometimes a mist will form in the cargo compartment," Emond said. "Often that mist will falsely trigger the fire-detection system in the cargo compartment."

Roughly 85 percent of all emergency landings are done in response to in-flight fire alarms, Emond said. And many, if not most, of those incidents turn out to be false alarms, he said.

Emond is working with UF/IFAS agricultural engineering professor Khe V. Chau and graduate student William Pelletier to solve that problem. They hope to design fire-detection systems that aren't fooled by mist, and they plan to use the Mars simulation chamber — which can easily duplicate the low temperatures and pressures of flight — to test their designs.

"With the chamber, we can recreate the conditions of flight repeatedly without having to actually send a device up in an aircraft," he said. "It will give us a chance to take a more detailed look at the way a design behaves at altitude."