Growing Plants in Space
As NASA plans missions to the Moon and Mars, a key factor is figuring out how to feed crew members during their weeks, months, and even years in space.
Astronauts on the International Space Station primarily eat prepackaged food, which requires regular resupply and can degrade in quality and
nutrition. Researchers are exploring the idea of crews growing some of their food during a mission,
testing various crops and equipment to figure out how to do this without a lot of extra hardware or power.
NASA also has tested facilities to host future microgravity gardens. One is the Vegetable Production System, or Veggie, a simple, low-power chamber that can hold six plants. Seeds are grown in small fabric “pillows” that crew members look after and water by hand, similar to caring for a window garden on Earth.
Another system, the Passive Orbital Nutrient Delivery System, or Veggie PONDS, works with the Veggie
platform but replaces seed pillows with a holder that automatically feeds and waters the plants.
The Advanced Plant Habitat is a fully automated device designed to study growing plants in ways that require only minimal crew attention.
A series of experiments aboard the space station known as Veg-04A, Veg-04B, and Veg-05 grew Mizuna mustard, a leafy green crop, under different light conditions and compared plant yield, nutritional composition, and microbial levels. The investigation also compared the space-grown plants to ones grown on Earth,
and had crew members rate the flavor, texture, and other characteristics of the produce.
Plant Habitat-04 analyzed plant-microbe interactions and assessed the flavor and
texture of chile peppers. The first crop, harvested on Oct. 29, 2021, was eaten by the crew and 12 peppers
from the second harvest were returned to Earth for analysis. This experiment demonstrated that research about
space crop production is on the right path and researchers plan to apply lessons learned to testing other plants.
An early experiment, PESTO, found that microgravity alters leaf development, plant cells, and the chloroplasts used in photosynthesis, but did not harm the plants overall. In fact, wheat plants grew 10% taller compared to those on Earth.
The Seedling Growth investigations showed that seedlings can acclimate to microgravity by modulating expression of some genes related to the stressors of space, a discovery that adds to knowledge about how microgravity affects plant physiology [1].
One way that plants sense gravity is via changes to calcium within their cells. Plant Gravity Sensing, a JAXA (Japan Aerospace Exploration Agency) investigation, measured how microgravity affects calcium levels, which could help scientists design better ways to grow food in space.
ADVASC, an investigation that grew two generations of mustard plants using the Advanced Astroculture chamber, showed that seeds were smaller but germination rates near normal in microgravity [2]
One significant challenge for growing plants in microgravity is providing enough water to keep them healthy without drowning them in too much water. Plant Water Management demonstrated a hydroponic (water-based) method for providing water and air to plant roots. The XROOTS study tested using both hydroponic and aeroponic (air-based) techniques to grow plants rather than traditional soil. These techniques could enable large-scale crop production for future space exploration.
( https://www.nasa.gov/missions/station/ways-the-international-space-station-helps-us-study-plant-growth-in-space/ 10/25/23.)
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