Hey @spacenerd, thanks for joining the MARSfarm community and creating a new topic. I consider myself a #nerdfarmer - so I love the name of your account!
Great job pivoting your question based on @webbhm’s advice.
First question
If you live in the United States (and lots of other places around the center of the Earth), thousands of plants can be grown outdoors and dozens of them are produced at scale. When deciding whether to plant something outdoors, the most important thing to consider is temperature, because if it gets too cold the plants will certainly die. To help people decide which plants will thrive where they live, the United States Department of Agriculture (USDA) publishes a “Plant Hardiness Map Zone Map” based on the average annual minimum temperature. If you look at where I live (St. Louis, Missouri) you’ll see that it actually stays warmer in the city (see all the highways) than it does in the rural areas - which means I can plant tomatoes in my garden a week before they can!
Map of USDA plant hardiness zones for area surrounding St. Louis, MO.
Now, if you’re trying to grow lots of plants for food or money (agriculture) then you want to make sure that you’re maximizing the productivity of whatever plants you are growing. One way of doing that is to find out how many “Growing Degree Days (GDD)” the plant you are growing requires in order to reach harvest. Essentially, for every 10F increase, plants double their productivity. For a plant that has to produce something with a lot of calories (like a sweet potato), it requires more GDD than something with very few (lettuce). To help farmers know if there are enough GDD in their region, the USDA publishes a map showing the number of GDD over the last 30 years.
USDA GDD Map
Some plants are worth more than others. People are willing to pay more for fresh fruits and vegetables (lettuce, herbs, tomatoes, cucumbers, peppers, strawberries, etc.) because they are more nutritious and taste better when eaten fresh. These plants are worth so much that companies are investing billions of dollars to build “Controlled Environment Agriculture (CEA)” farms to grow them. CEA is a fancy term that describes high-tech greenhouses/vertical farms, which use technology like hydroponics and LEDs to control the temperature, irrigation, and lighting of the plants being grown.
Examples of companies that use CEA technology on Earth to produce food
If Mars had a “Plant Hardiness Zone” - it would be at least -10. Honestly, it’s a horrible place to try and grow plants. The temperature is way too cold, there’s no rainfall, and there’s not even enough light. That’s why we’re going to have to use CEA technology to grow plants in space. That’s why NASA picks people like Dr. Gene Giacomelli to research what technology and plants should be grown in space. Dr. Giacomelli teaches students who usually go on to work in CEA farms (on Earth), but check out this video where he talks about the Lunar Greenhouse prototype they built using funding from NASA - they learned a lot!
Second question
In an interview Dr. Giacomelli had this say about “The Martian” - where someone actually grows potatoes on Mars: “It was science fiction, of course, but it brought a lot of real science and engineering to all the people - young people particularly. It should have excited a lot of people about the ingenuity, the capabilities that we have for living on another planet 10, 20 years from now. But the real exciting part to me was that we’re working on much of what Mark Watney had to do so he could survive. We’re doing that in our laboratory,”
Let me know if you have any more questions!
If you want to learn more about what plants are best suited for growth in CEA farms, check out this forum post: