Since the beginning of the space age, the idea of colonizing other planets has often brought to mind visions of steely eyed rocket men (and women) boarding sleek reusable vehicles to head off into the unknown. And in the era before the internet and social media, these images were often presented on the covers of golden age science fiction books or in periodicals such as Life or Colliers. Reality is often quite a bit grittier than fiction however, and for every intrepid explorer who blasts off for adventure and discovery, there may be many times their number sweating the details of the crop yield. This was obviously a major plot point of the The Martian, but it also forms background of the Heinlein adolescent novel, Farmer in the Sky, which was published in 1950.
Much like our understanding, or complete lack thereof, of the effects of the partial gravity found on the Moon or Mars on the human organism, we are still often woefully ignorant of the effects of different gravitational environments on plant growth.
After 15 years of continuously occupying the International Space Station, much of which was devoted to its construction, NASA is finally beginning to make inroads in understanding what it will take to grow crops in zero-G through the plant growth or experiment, or “Veggie System” which shipped to the station aboard the SpaceX CRS-3 flight in April of 2014. Based on the initial results, Orbital Technologies Corp of Madison, Wisconsin, which build the system, made a number of improvements in procedures which hydrate an nourish the plants. Unfortunately, the next round of seed and nutrient pods were lost aboard the CRS-7 flight in June of last year.
That accident did not stop astronauts aboard the station from continuing to press on with the original experiments however, and just in time for Valentines Day, Scott Kelly harvested Zinnia plants which were activated back in November.
The saga of the Zinnia plants, which were nearly lost to mold, is covered in this NASA.gov story from last month, and despite the obligatory references to Mark Watney, it is serves as a clear example of just how limited our understanding of the space environment is in many respects. It also tends to re-reinforce the observation that an immediate human presence is indispensable for many forms of on-orbit experimentation.
As for why the Zinnias were chosen in the first place, from the story:
“The zinnia plant is very different from lettuce, said Trent Smith, Veggie project manager. “It is more sensitive to environmental parameters and light characteristics. It has a longer growth duration between 60 and 80 days. Thus, it is a more difficult plant to grow, and allowing it to flower, along with the longer growth duration, makes it a good precursor to a tomato plant.”
Interestingly, one of the more relevant aspects of the Valentines Day harvest is that in addition to the leaves, stems and even the mold being preserved for shipment back to Earth when the SpaceX Dragon resumes return flights, a sample of the seeds are being preserved as well for eventual planting, thereby establishing one of the very first actual examples of the sort of “cycle of life” undertakings which must necessarily underpin a permanent human presence off Earth. We clearly have a long way to go.