UW astrobotanist launches seed experiment in space
If humans eventually travel to Mars and beyond, scientists must figure out how to feed them.
It will take a couple of years to reach Mars, followed by time spent on the Red Planet and a trip home. That's several years of three square meals per person each day. And astronauts can't count on supply rockets filled with sandwiches,Tang and Mars bars for Mars.
Which means they'll have to grow their own food.
A University of Wisconsin-Madison astrobotanist is among the scientists trying to figure out how to successfully grow plants in zero gravity, which is as difficult as it sounds.
Last week one of the astronauts on the International Space Station opened a shoebox-sized container filled with mustard seeds packed by UW botany professor Simon Gilroy and his team. The seeds were part of a SpaceX cargo ship that lifted off Dec. 15 and arrived at the space station two days later.
American astronaut Scott Tingle, who trained for the mustard seed experiment under Gilroy's direction, unwrapped 26 Petri dishes, each filled with 10 mustard seeds, and placed them under grow lights. As the plants grow Tingle is snapping photos under a microscope.
After one week under the grow lights, Tingle will use tweezers to pull out all the plants, place them in test tubes and use a syringe to squirt a growth-stopping chemical. The samples will be placed in a freezer on board the space station, return to Earth on a supply ship next month and finish their journey in Madison.
Just as astronauts float weightlessly in space, other things do, too. Like water.
And that makes watering plants very tricky. On Earth, gravity draws water down to roots buried in soil, but that doesn't happen in space. Also, water molecules naturally want to stick to each other, but on terra firma, gravity pulls those molecules apart. In space, water molecules continue to stick together, which is why it's common to see liquid globules floating away from astronauts as they eat.
So even if astronauts inject water into the soil, the water will stick to the plant and the roots, creating a low-oxygen environment.
Another problem: The natural way plants grow on Earth, using light from the sun to create oxygen, doesn't happen in space. Gases such as nitrogen, carbon dioxide and oxygen are continuously mixing in Earth's air, but they don't in space, which means plants can quickly run out of oxygen.
"Space is a weird place. If you think about biology — humans or plants — it's only ever existed on the planet Earth. That's what it's used to," Gilroy said in a phone interview Tuesday.
"Floating around weightless, astronauts lose bone mass and muscle mass because they're not fighting against gravity anymore. The same thing happens to plants. Biology just gets lazy in space," said Gilroy, a native of England who has taught at UW for 10 years.
Last week Gilroy and his team planted identical mustard seeds in a lab in Madison, mimicking the environment in space except with gravity to compare the difference in the growing cycles for the plants in space and Earth. The seeds are Arabidopsis, a small, fast-growing mustard plant common in botany research.
Eventually, nucleic acid will be extracted from the mustard plants and the roughly 30,000 genes will be measured.
"We'll find out which genes switched on and off and compare them to those on Earth," Gilroy said. "Then ask, did space switch on or off the genes."
Gilroy has now sent four botany experiments into space, and this is the first time he'll be able to grow his plants under lights. His previous experiments were in darkness.
In 2015 the International Space Station crew tasted space-grown lettuce. Hardware was developed with an eye toward supporting future deep space missions beyond Earth orbit, to provide those crew members with a way to grow some of their own food.
In addition to some day creating plants that will grow well in zero gravity and feed space travelers, Gilroy is hopeful the research could spawn applications on our planet. Scientists may discover genes that pinpoint stress for plants from low oxygen, extreme temperatures and low light.
"We want to use that knowledge to make plants OK to live in that environment," said Gilroy. "With an engineering approach we could build a machine or tinker with the biology and get the plants to be able to adapt to the environment."