A lack of vitamin C was all it took to
give sailors scurvy, and vitamin deficiencies can cause a number of
other health problems. Simply packing some multi-vitamins will not be
enough to keep astronauts healthy as they explore deep space. They will
need fresh produce.

Right now on the space station, astronauts
receive regular shipments of a wide variety of freeze-dried and
prepackaged meals to cover their dietary needs – resupply missions keep
them freshly stocked. When crews venture further into space, traveling
for months or years without resupply shipments, the vitamins in
prepackaged form break down over time, which presents a problem for
astronaut health. 

NASA is looking at ways to provide astronauts
with nutrients in a long-lasting, easily absorbed form—freshly grown
fresh fruits and vegetables. The challenge is how to do that in a closed
environment without sunlight or Earth’s gravity.

Veggie

The
Vegetable Production System, known as Veggie, is a space garden
residing on the space station. Veggie’s purpose is to help NASA study
plant growth in microgravity, while adding fresh food to the astronauts’
diet and enhancing happiness and well-being on the orbiting laboratory.
The Veggie garden is about the size of a carry-on piece of luggage and
typically holds six plants. Each plant grows in a “pillow” filled with a
clay-based growth media and fertilizer. The pillows are important to
help distribute water, nutrients and air in a healthy balance around the
roots. Otherwise, the roots would either drown in water or be engulfed
by air because of the way fluids in space tend to form bubbles.

In
the absence of gravity, plants use other environmental factors, such as
light, to orient and guide growth. A bank of light emitting diodes
(LEDs) above the plants produces a spectrum of light suited for the
plants’ growth. Since plants reflect a lot of green light and use more
red and blue wavelengths, the Veggie chamber typically glows magenta
pink.

To date, Veggie has successfully grown a variety of plants,
including three types of lettuce, Chinese cabbage, mizuna mustard, red
Russian kale and zinnia flowers. The flowers were especially popular
with astronaut Scott Kelly, who picked a bouquet and photographed it
floating in the cupola against the backdrop of Earth. Some of the plants
were harvested and eaten by the crew members, with remaining samples
returned to Earth to be analyzed. One concern was harmful microbes
growing on the produce. So far, no harmful contamination has been
detected, and the food has been safe (and enjoyable) for the crew to
eat.
Our team at Kennedy Space Center envisions planting more produce
in the future, such as tomatoes and peppers. Foods like berries,
certain beans and other antioxidant-rich foods would have the added
benefit of providing some space radiation protection for crew members
who eat them.

Veggie Fact Sheet
 

Advanced Plant Habitat

The
Advanced Plant Habitat (APH), like Veggie, is a growth chamber on
station for plant research. It uses LED lights and a porous clay
substrate with controlled release fertilizer to deliver water, nutrients
and oxygen to the plant roots.

But unlike Veggie, it is enclosed
and automated with cameras and more than 180 sensors that are in
constant interactive contact with a team on the ground at Kennedy, so it
doesn’t need much day-to-day care from the crew. Its water recovery and
distribution, atmosphere content, moisture levels and temperature are
all automated. It has more colors of LED lights than Veggie, with red,
green, and blue lights, but also white, far red and even infrared to
allow for nighttime imaging.

When a harvest is ready for research
studies, the crew collects samples from the plants, freezes or
chemically fixes them to preserve them, and sends them back down to
Earth to be studied so scientists can better understand how space
affected their growth and development.

APH had its first test run
on the space station in Spring 2018 using Arabidopsis thaliana (the
“white mouse of the plant research world”) and dwarf wheat. The
time-lapse video of this was a popular social media release from the
space station worldwide.

Dr. Norman Lewis is the principal
investigator for the Arabidopsis Gravitational Response Omics
(Arabidopsis-GRO) consortium study, which will be the first study using
APH. He and his collaborators are especially interested in what happens
to plants in space at the gene, protein and metabolite level, and what
changes occur and why.

A key question they want to answer is the
relationship between microgravity and plant lignin content. Lignins in
plants have functions whose closest analogy is that of bones in humans.
They give structure and rigidity to plants and the means to stand
upright against gravity. We already know space causes bone and muscle
loss in humans because the physical demands are lower in space. So what
about lignins?

Lewis and his team also want to know if plants
genetically engineered to have less lignin can survive and function
normally in space. This could give space-grown plants several
advantages, including being better for nutrient absorption when humans
eat them and in making plant waste easier for composting. Lewis and his
team believe this fundamental science information will guide our
strategies for deep space exploration and colonization.

Lewis
knows space science has come a long way already — and that the
possibilities on the horizon were previously the world of fiction!

Biological Research in Canisters

The
Biological Research in Canisters (BRIC) is a facility used to study the
effects of space on organisms small enough to grow in petri dishes,
such as yeast and microbes. BRIC-LED is the latest version, which added
light-emitting diodes (LEDs) to support biology such as plants, mosses,
algae and cyanobacteria that need light to make their food.

Right
now, BRIC-LED is undergoing hardware validation tests. Scientists want
to ensure the LEDs don’t get too hot for the plants and do other system
checks. Soon, researchers such as Dr. Simon Gilroy of the University of
Wisconsin-Madison will use it to conduct studies.

Gilroy is
interested in how the Arabidopsis plant’s gene expression changes in
space. “There are literally thousands of experiments done on Earth [on
Arabidopsis],” Gilroy explains. “Cold shock. Touched them. Not watered
them. Too much water. Shouted at them,” he says with a chuckle. “Those
databases are all available to us. So we look and see if there are any
patterns anyone has found and what on the ground mimics what happens in
space.”

Some patterns that arise are expected, like when the
genes associated with gravity become altered. But two patterns that have
caught Gilroy’s attention have to do with the plants’ immune system.

The
plants seem to have increased stress from oxidation. Normal chemistry
in the cells makes a very reactive oxygen-based chemical. Uncontrolled,
this “reactive oxygen species” can react with the machinery that repairs
DNA and mess that up, or it can damage mitochondria. In a healthy
plant, the cells have ways of dealing with it. But in space, plants are
making more of it.

The other pattern is certain genes associated
with the immune system turn on and others switch off in space.
Scientists suspect this may compromise that plants’ ability to fight off
infections.

There is anecdotal evidence, too, that plants in
space may be struggling to fend off pathogens. Once, the zinnias in
Veggie got a little overwatered, and there was a lack of air flow. A
fungus started growing on the plants, and some died. Astronaut Scott
Kelly delicately cleaned off the fungus, nursed the surviving plants
back to health and got them to flower. It could have been a fluke, but
it raised the question if space was weakening the zinnia’s health.

Rather
than intentionally making Veggie plants sick to test this theory,
scientists want to run gene expression studies using BRIC-LED and trick
plants into thinking they’re being threatened. They do this by
manipulating protein receptors on the plants, which are constantly on
the lookout for signs of bacteria.

Bacteria use a whip-like
structure called a flagellum to help them swim, and flagella all share a
common set of 22 amino acids nicknamed “flag-22.” Plants are looking
for flag-22, and their defense systems kick on as soon as they pick up
on it. Scientists can squirt a harmless solution of flag-22 onto the
plants. “The plant freaks out and thinks it’s being attacked,” Gilroy
explains.

In the BRIC-LED experiment, tiny plants are grown for
10 days, and then scientists squirt them with flag-22. An hour later,
the plants are fully defending themselves, and scientists douse them
with a chemical fixative to stop all biological processes. This fixative
does a great job of preserving the plants’ response state, but as an
added step, the plants are put into a deep freeze. The plants are later
sent back down to Earth and ground up to have their RNA extracted and
analyzed.

Gilroy hopes to learn more about the effects of space
on a plant’s health this way. “The patterns will tell us whether the
plant defense system is operating correctly or not,” he says.