"A spacecraft approaches the lunar pole, spits out a pod from which sprout several tubular arms it uses to bury itself in the soil, where it begins growing plants in preparation for man's return to the moon"
Dan Sorenson (¶ 1).
One way to grow food to prepare for man's return to the moon, according to Dan Sorenson in the newspaper account, "Greenhouses for the moon and mars: Team project would get key plants started ahead of explorers' arrival," could be to program/manipulate a spacecraft to plant a prepared pod to plant in the moon's "soil" to begin to grow plants. Another complementary method could be to build a lunar green house, where astronauts will grow plants; fruits etc. while they reside on the Moon during space travel. The overall logistics to building a Lunar Green House, the focus for this study, explores:
The overall concept of building a lunar greenhouse, along with why it is needed;
NASA's vision on the design of a greenhouse; recent design concepts;
Mission advantages and disadvantages of a lunar greenhouse.
Significance of a lunar greenhouse for future space missions.
OVERALL LUNAR GREENHOUSE BUILDING CONCEPTS
Concepts of Building Lunar Greenhouse
The prospect of growing food on the moon, introducing this study, Sorenson (2007) asserts, does not constitute a fictional portrayal, but a contemporary scientific concept. The need to build a lunar greenhouse, the literature asserts, includes a number of, but may not be limited to the following reasons:
1. Taking astronauts' exhaled carbon dioxide and turning it into oxygen generates
oxygen astronauts need (Sorenson).
2. "Hanging out" with some vegetables will help fill some physical and psychological needs, as the sight of something naturally green appears to be something humans naturally crave and find soothing (Sorenson).
3. Plants grown in lunar greenhouses will help reduce the weight of the supplies that need to be lifted off the earth (Greenhouses for Mars).
Lunar Greenhouses Require Redundancy
One cannot merely go out and purchase a lunar greenhouse. "Space requires redundancy," Sorenson asserts, stressing redundancy to be a significant point of a bio-based air-recycling system. Grant Van Hemert explains: "The most basic form of redundancy requires the inclusion of a hand-off-auto switch for each component. In the automatic mode, the plant or system controller runs the process." A plant-based recycling system, according to Sorenson, possess built-in redundancy. If/when some of the plants die, others continuing the growing process with a limited number of tiny seeds replacing the dead ones. The results, although less drastic as a mechanical system's failure, would not mandate the utilization of the space of mechanical multiple-redundancy backup systems.
Lunar Greenhouse Inside Environment
The projected future inside environment for the lunar greenhouse would constitute a more densely packed version of the hydroponic growth system previously used. On the moon's surface, a robotic digger would bury the lunar greenhouse, which would pop out of a spacecraft module similar to a jack-in-the-box. Burying the unit in the lunar soil will shield it from meteorites and radiation. Light transported from a fiber-optic collector on the moon's surface would provide heat for the lunar greenhouse.
Gene Giacomelli, a plant-sciences and biosystems engineering professor in the department of agricultural and biosystems engineering, and director of the Controlled Environment Agriculture program, under the College of Agriculture and Life Sciences., along with Phil Sadler, president of Tempe-based Sadler Machine Company; trained as a botanist and specializing in designing and building projects for extreme environments, assert that recent research/experiments growing vegetables at the South Pole Food Chamber could be duplicated the moon. An unmanned mission would deliver the lunar greenhouse in an unmanned mission to allocate enough time for plants to grow plants prior to the astronauts' arrival to the lunar station, Sadler explains. Water, prohibitively heavy as payload, yet crucial for plant and human life, albeit, must be found somewhere off Earth, a problem NASA still has to solve.
Discovering water frozen in the lunar soil, and then utilizing solar power to thaw it may proffer one or part of a solution regarding the need for water. Some advantages to a lunar greenhouse being located on the moon rather than Earth, according to Sadler and Giacomelli, could be: With the moon's gravity equaling one-sixth of the Earth's, "the lunar greenhouse won't need as much structural support to keep the 8-foot-diameter, 18-foot-long arms from collapsing. Plans call for 8-foot-diameter aluminum support rings spaced every 3 feet to support the airtight shell" (¶ 3). Giacomelli asserts their greenhouse-based system provides mechanical answers to NASA's needs.
NASA's Vision: Lunar Greenhouse Design
In "Lunar Gardening," Taber MacCallum, CEO of Paragon Space Development Corporation predicts that by 2014, the vision of the first moon flower may become a reality. Currently, Paragon and Odyssey Moon, Google Lunar X-PRIZE contender, work together, with the aim to deliver a biological greenhouse to the lunar surface. MacCallum purports: "We've grown plants in space before, but this will be the first time we'll attempt to grow a plant on another world" (Lunar Gardening ¶ 10).
MacCallum notes a number of technical requirements still need to be worked out for the lunar greenhouse, such as oxygen -- carbon dioxide exchange and the right materials that will let in sunlight but block the sun's harmful rays. "It's going to be a small growth chamber, but even that is pretty complicated," MacCallum (Lunar Gardening ¶ 10) stated. Figure 1 depicts one recent design concept, a prototype space greenhouse by Paragon Space Development Corporation.
Figure 1: A Prototype Space Greenhouse (Lunar Gardening 2009).
Figure 2 portrays one artist's concept of greenhouses that could be utilized on the moon and/or Mars.
Figure 2: One Artist's Concept of Lunar Greenhouses (Miller).
In "Of a Garden on the Moon, part I," Ken Murphy counters one frequent objection that plants can't grow in Moon-dirt; that growing plants on the moon would require tons of Earth dirt shipped up for the plants. Murphy poses the question: Can plants can grow in Moon dirt? Murphy presents the following considerations to the answer for this question:
Of the variety of biological systems that we tested with the Lunar material, the plants were most unique in their response. For example [in Figure 3], the five jars of liverwort that you see illustrated on the top gave much increased growth in the presence of Lunar material. This effect was noted for ferns, a number of tissue cultures such as tobacco and corn, and certain higher plant species such as lettuce. Now the exact reasons for this beneficial response are unknown at the present. However, it is likely that some trace mineral, or perhaps even a physical property of the Lunar material is interacting with the minerals we furnish to give a more desirable medium for plant growth. This is a very exciting discovery and one that was totally unexpected in the tests conducted in the Lunar Receiving Laboratory" (Murphy ¶ 12).
Figure 3: Increased Growth in The Presence of Lunar Material (Murphy ¶ 12).
Contemporary Research Regarding Lunar Greenhouse
Dr. Volker Kern, Paragon's Director of NASA Human Spaceflight Programs conducted plant growth experiments in space on the U.S. Space Shuttle. He notes: "Scientifically it will be very interesting to understand the effects of the Moon and one-sixth gravity on plant growth" (Lumar Gardening ¶ 10). In addition to being grown on Earth, plants have been grown in basically zero gravity, Kern reports, however they have never been grown in fractions of gravity.
According to Susan L. Steinberg, Doug W. Ming, and Don Henninger (2002) in "Plant Production Systems for Microgravity: Critical Issues in Water, Air, and Solute Transport Through Unsaturated Porous Media," millions of dollars have been "spent" during the past 15+ years on flight experiments with plants. Most of the experiments, albeit, have not been considered major successes. Environmental factors, including light, air quality, and ventilation impact plant growth in microgravity, however, control of water, air, and nutrients in the root zone, relate more limiting effects. "Development of plant growth systems for microgravity has been driven by mass, volume and power constraints; water and/or media containment; water/air phase separation; and the need to recycle water, nutrients, and growth media" (Steinberg, Ming, and Henninger, 2002, p. 4). Understanding the effect of microgravity on plant physiological functions, according to Steinberg, Ming, and Henninger (2002), constitutes the key to successful plant research or crop production in space.
Mission advantages, as noted earlier in this paper, include the transforming of astronauts' exhaled carbon dioxide into oxygen; satisfying natural craving for "something green"; providing relaxation from harsh environment; reducing the weight of the supplies transported from Earth (Greenhouses for Mars); supplementing packaged food from Earth. These reasons also constitute reasons that confirm for future space missions, lunar greenhouse will prove vital. One particular disadvantage of a lunar greenhouse, according to Karen Miller, in "Greenhouses for Mars," noted in experiments that NASA's Office of Biological and Physical research supported, relates to the moon's low-pressure environment. In the environment of…