In the 1960s, NASA sent robotic probes and landers to test the lunar environment before sending men. In the 2010s, the agency is sending plants in advance of its manned missions. A NASA experiment set to launch in late 2015 aboard the Moon Express lander, one of the contestants vying for the Google Lunar X-Prize, will see whether plants can grow and thrive on the Moon, the idea being that if plants can call the Moon home, at least temporarily and with all the necessities provided, humans will be able to as well.
Aside from the lack of breathable air and readily tillable soil, the Moon presents some challenges for life. Even with a habitat, the amount of solar radiation that hits the Moon is a challenge, as is the limited gravity. The Moon only has about one-sixth of Earth's pull.
This plant-based mission is designed as a technological demonstration aimed at gathering data on germination and plant growth in a lunar environment with a focus on the increased solar radiation and weaker gravitational environment. NASA is planning to send a 2.2 pound unit housing roughly 100 seeds of Arabidopsis, 10 basil seeds, and 10 turnip seeds. Their only light source will be direct sunlight and the light reflected off the Moon’s surface. What happens when water is added to the small experiment bay is the crux of the experiment.
Seedlings, it turns out, are a pretty good stand-in for humans. Like us, seedlings are extremely sensitive to their environmental surroundings and carry genetic material that can be damaged by radiation. Putting plants on the Moon in advance of humans is sort of like testing the survivability of a mine by putting a canary in the shaft before sending down miners.
The Moon Express lander/Steve Jurvetson
Once NASA has its seedlings watered and on the Moon, the agency will monitor their growth by gathering data by sensors as well as by taking images over five days, which is all of the air the container can hold. Results of the lunar test will then be compared against a control growth experiment done on the Earth.
The key data scientists will be looking at is leaf size and growth rate over time. This will provide information on how plants can be expected to grow on the Moon over a longer timeframe compared to plants on the Earth. Plant movement as they grow would also be studied, such as whether they change orientation as they grow and the light source shifts.
This will be the first dedicated test of life sciences on another world, the first demonstration of in situ resources being put to use for life support. and ultimately an important first step towards using plants as a life support system off the Earth. But this isn’t the first time plants will have been grown in space. Scientists have studied plant growth on space shuttle missions as well as aboard the International Space Station.
Follow-up experiments will go further, looking at the effects of the long lunar night on plants, how multiple generations of plants grow in the lunar environment, and how more diverse plants fathom in a lunar greenhouse. There are also specific time benchmarks scientists will be looking for: living for 14 days will suggest plants can sprout in the Moon’s radiation environment; 60 days will suggest sexual reproduction can occur in a lunar environment; and 180 days will demonstrate the effects of radiation on dominant and recessive gene traits. Subsequent experiments over multiple plant generations will provide even more science return.
All this is gearing towards long-duration manned mission lasting more than a few days or weeks, mission that will benefit significantly from having plants on board. Not only are they useful in term of human life support providing a source of food, water, and air, they have psychologically calming effects. If astronauts are going to be stuck on the barren Moon for months at a time, a reading nook inside a thriving greenhouse would probably help stave off space madness.