Biosphere 2

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Biosphere 2 Habitat & Lung 2009-05-10.jpg

Biosphere 2 is an Earth systems science research facility located in Oracle, Arizona. It has been owned by the University of Arizona since 2011. Its mission is to serve as a center for research, outreach, teaching, and lifelong learning about Earth, its living systems, and its place in the universe. It is a 3.14-acre (1.27-hectare)[1] structure originally built to be an artificial, materially closed ecological system, or vivarium. It remains the largest closed system ever created.[2]

Biosphere 2 was originally meant to explore the web of interactions within life systems in a structure with five areas based on biomes, and an agricultural area and human living and working space to study the interactions between humans, farming, and technology with the rest of nature. It also explored the use of closed biospheres in space colonization, and allowed the study and manipulation of a biosphere without harming Earth's. Its five biome areas were a 1,900 square meter rainforest, an 850 square meter ocean with a coral reef, a 450 square meter mangrove wetlands, a 1,300 square meter savannah grassland, a 1,400 square meter fog desert, a 2,500 square meter agricultural system, a human habitat, and a below-ground infrastructure. Heating and cooling water circulated through independent piping systems and passive solar input through the glass space frame panels covering most of the facility, and electrical power was supplied into Biosphere 2 from an onsite natural gas energy center.[3]

Biosphere 2 was only used twice for its original intended purposes as a closed-system experiment: once from 1991 to 1993, and the second time from March to September 1994. Both attempts, though heavily publicized, ran into problems including low amounts of food and oxygen, die-offs of many animal and plant species, squabbling among the resident scientists and management issues.

In June 1994, during the middle of the second experiment, Space Biosphere Ventures dissolved, and the structure was left in limbo. It was purchased in 1995 by Columbia University, who used it to run experiments until 2005. It then looked in danger of being demolished to make way for housing and retail stores, but was taken over for research by the University of Arizona in 2007; the University of Arizona assumed full ownership of the structure in 2011.

Planning and construction

Biosphere 2 was originally constructed between 1987 and 1991 by Space Biosphere Ventures, a joint venture whose principal officers were John P. Allen, inventor and Executive Director, and Margret Augustine, CEO. Project funding came primarily from the joint venture's financial partner, Ed Bass's Decisions Investment. The project cost US$200 million from 1985 to 2007.[citation needed]

It was named "Biosphere 2" because it was meant to be the second fully self-sufficient biosphere, after the Earth itself.


The glass facility is located in Oracle, Arizona at the base of the Santa Catalina Mountains, half an hour outside Tucson. It is elevated 4,000 feet (1,200 m) above sea level.[4]

First mission

The first closed mission lasted from September 26, 1991 to September 26, 1993. The crew were: medical doctor and researcher Roy Walford, Jane Poynter, Taber MacCallum, Mark Nelson, Sally Silverstone, Abigail Alling (a late replacement for Silke Schneider), Mark Van Thillo, and Linda Leigh.[5]

The agricultural system produced 83% of the total diet, which included crops of bananas, papayas, sweet potatoes, beets, peanuts, lablab and cowpea beans, rice, and wheat.[6][7] No toxic chemicals could be used, since they would impact health. During the first year the eight inhabitants reported continual hunger. During the second year, the crew produced over a ton more food, average caloric intake increased, and they regained some weight lost during the first year.[citation needed]

They consumed the same low-calorie, nutrient-dense diet which Roy Walford had studied in his research on extending lifespan through diet. [8] Medical markers indicated the health of the crew during the two years was excellent. They showed the same improvement in health indices such as lowering of blood cholesterol, blood pressure, enhancement of immune system. They lost an average of 16% of their pre-entry body weight before stabilizing and regaining some weight during their second year.[9] Subsequent studies showed that the biospherians' metabolism became more efficient at extracting nutrients from their food as an adaptation to the low-calorie, high nutrient diet.[10]

Some of the domestic animals that were planned for the agricultural area during the first mission included four pygmy goats and one billy goat from the plateau region of Nigeria, 35 hens and three roosters (a mix of Indian jungle fowl (Gallus gallus), Japanese silky bantam, and a hybrid of these), two sows and one boar pig (feral), as well as tilapia fish grown in a rice and azolla pond system originating millennia ago in China.[11]

A strategy of "species-packing" was practiced to ensure that food webs and ecological function could be maintained if some species did not survive. The fog desert area became more chaparral due to condensation from the space frame. The savannah was seasonally active; its biomass was cut and stored by the crew as part of their management of carbon dioxide. Rainforest pioneer species grew rapidly, but trees there and in the savannah suffered from etiolation and weakness caused by lack of stress wood, normally created in response to winds in natural conditions. Corals reproduced in the ocean area and crew helped maintain ocean system health by hand-harvesting algae from the corals, manipulating calcium carbonate and pH levels to prevent the ocean becoming too acidic, and by installing an improved protein skimmer to supplement the algae turf scrubber system originally installed to remove excess nutrients.[12] The mangrove area developed rapidly but with less understory than a typical wetland possibly because of reduced light levels.[13]

Biosphere 2 suffered from CO2 levels that "fluctuated wildly" and most of the vertebrate species and all of the pollinating insects died.[14] Insect pests, like cockroaches, boomed. In practice, ants, a companion to one of the tree species (Cecropia) in the rainforest, had been introduced. By 1993 the tramp ant species Paratrechina longicornis, local to the area had been unintentionally sealed in and had come to dominate.[15]


Among the problems and miscalculations encountered in the first mission were overstocked fish dying and clogging filtration systems, unanticipated condensation making the "desert" too wet, population explosions of greenhouse ants and cockroaches, and morning glories overgrowing the "rainforest", blocking out other plants. In addition, construction itself was a challenge, such as manipulating the bodies of water to have waves and tidal changes was a difficulty.[16][17]

There was controversy when the public learned that the project had allowed an injured member to leave and return, carrying new material inside. The team claimed the only new supplies brought in were plastic bags, but others accused them of bringing food and other items. More criticism was raised when it was learned that, likewise, the project had been pumping oxygen inside, to make up for a failure in the balance of the system that resulted in the amount of oxygen steadily declining.[18]

The oxygen inside the facility, which began at 20.9%, fell at a steady pace and after 16 months was down to 14.5%. This is equivalent to the oxygen availability at an elevation of 4,080 meters (13,400 ft).[19] Since some biospherians were starting to have symptoms like sleep apnea and fatigue, Walford and the medical team decided to boost oxygen with injections in January and August 1993.

Daily fluctuation of carbon dioxide dynamics was typically 600 ppm because of the strong drawdown during sunlight hours by plant photosynthesis, followed by a similar rise during the nighttime when system respiration dominated. As expected, there was also a strong seasonal signature to CO2 levels, with wintertime levels as high as 4,000-4,500 ppm and summertime levels near 1,000 ppm. The crew worked to manage the CO2 by occasionally turning on a CO2 scrubber, activating and de-activating the desert and savannah through control of irrigation water, cutting and storing biomass to sequester carbon, and utilizing all potential planting areas with fast-growing species to increase system photosynthesis.[20]

Many suspected the drop in oxygen was due to microbes in the soil.[citation needed] The soils were selected to have enough carbon to provide for the plants of the ecosystems to grow from infancy to maturity, a plant mass increase of perhaps 20 tons (18,000 kg).[21] The release rate of that soil carbon as carbon dioxide by respiration of soil microbes was an unknown that the Biosphere 2 experiment was designed to reveal.[citation needed]

The respiration rate was faster than the photosynthesis (possibly in part due to relatively low light penetration through the glazed structure) resulting in a slow decrease of oxygen. A mystery accompanied the oxygen decline: the corresponding increase in carbon dioxide did not appear. This concealed the underlying process until an investigation by Jeff Severinghaus and Wallace Broecker of Columbia University's Lamont Doherty Earth Observatory using isotopic analysis showed that carbon dioxide was reacting with exposed concrete inside Biosphere 2 to form calcium carbonate, thereby sequestering both carbon and oxygen.[22]

Second mission

During the transition period between missions, extensive research and system improvements had been undertaken. Concrete was sealed to prevent uptake of carbon dioxide. The second mission began on March 6, 1994, with an announced run of ten months. Crew was Norberto Alvarez (Capt.), John Druitt, Matt Finn, Pascale Maslin, Charlotte Godfrey, Rodrigo Romo and Tilak Mahato. The second crew achieved complete sufficiency in food production.[23]

On April 1, 1994 a severe dispute within the management team led to the ousting of the on-site management by federal marshals serving a restraining order, leaving management of the mission to the Bannon & Co. team from Beverly Hills, California.[24]

At 3 am on April 5, 1994, Abigail Alling and Mark Van Thillo, members of the first crew, allegedly vandalized the project from outside,[25] opening one double-airlock door and three single door emergency exits, leaving them open for approximately fifteen minutes. Five panes of glass were also broken. About 10% of the biosphere's air was exchanged with the outside during this time, according to Donella Meadows, who had a communication from Ms. Alling in which she explained that they wanted to give those inside the choice of continuing or leaving, as she didn't know what they had been told of the new situation.[26]

Soon after that, the captain Norberto Alvarez (by then married to Margret Augustine) left the Biosphere. He was replaced by Bernd Zabel, who had been nominated as captain of the first mission but who was replaced at the last minute. Two months later, Matt Smith replaced Matt Finn.[citation needed]

The ownership and management company Space Biospheres Ventures was officially dissolved on June 1, 1994. This left the scientific and business management of the mission to the interim turnaround team, who had been contracted by the financial partner, Decisions Investment Co.[19]

Mission 2 was ended prematurely on September 6, 1994.[19]

Columbia University

After a successful turnaround by Bannon & Co. in December 1995 the Biosphere 2 owners transferred management to Columbia University of New York City which embarked on a successful eight-year run at the Biosphere 2 campus.[27] Columbia ran Biosphere 2 as a research site and campus until 2003,[28] at which time management reverted to the owners.

In 1996, Columbia University changed the virtually airtight, materially closed structure designed for closed system research, to a "flow-through" system, and halted closed system research. They manipulated carbon dioxide levels for global warming research, and injected desired amounts of carbon dioxide, venting as needed.[29] During Columbia's tenure, Columbia students would often spend one semester at the site.[citation needed]

Site sold

On January 10, 2005, Decisions Investments Corporation, owner of Biosphere 2, announced that the project's 1,600-acre (650 ha) campus was for sale. They preferred a research use to be found for the complex but were not excluding buyers with different intentions, such as universities, hotels, resorts, spas, etc.[30] In June 2007 the site was sold for $50 million to CDO Ranching & Development, L.P. 1,500 houses and a resort hotel were planned, but the main structure was still to be available for research and educational use.[31]

Acquisition by University of Arizona

Biosphere 2 sits on a sprawling 40-acre (16-hectare) science campus that is open to the public.

On June 26, 2007, the University of Arizona announced it would take over research at the Biosphere 2. The announcement ended fears that the structure would be demolished. University officials said private gifts and grants enabled them to cover research and operating costs for three years with the possibility of extending funding for ten years.[32] It was extended for ten years, and is now engaged in research projects including research into the terrestrial water cycle and how it relates to ecology, atmospheric science, soil geochemistry, and climate change. In June 2011, the University announced that it would assume full ownership of Biosphere 2, effective July 1.[33]

Biosphere 2 in 2015.

CDO Ranching & Development donated the land, Biosphere buildings and several other support and administrative buildings. The Philecology Foundation (a nonprofit research foundation founded by Ed Bass) pledged US$20 million for the ongoing science and operations.[33]


Biosphere 2 from the inside. Seen here are the Savanna (foreground) and Ocean (background) sections.
The Coastal Fog Desert section of Biosphere in 2005

The above-ground physical structure of Biosphere 2 was made of steel tubing and high-performance glass and steel frames. The frame and glazing materials were designed and made to specification by a firm run by a one-time associate of Buckminster Fuller, Peter Jon Pearce (Pearce Structures, Inc.).[34][35] The window seals and structures had to be designed to be almost perfectly airtight, such that the air exchange would be extremely slow, to avoid damage to the experimental results.[citation needed]

During the day, the heat from the sun caused the air inside to expand and during the night it cooled and contracted. To avoid having to deal with the huge forces that maintaining a constant volume would create, the structure had large diaphragms kept in domes called "lungs".[citation needed]

Since opening a window was not an option, the structure also required huge air conditioners to control the temperature and avoid killing the plants within. For every unit of solar energy that entered the structure, the air conditioners would expend approximately three times as much energy to cool the habitat back down.[citation needed]


A special issue of the Ecological Engineering journal edited by Marino and Howard T. Odum (1999), published as "Biosphere 2: Research Past and Present" (Elsevier, 1999) represents the most comprehensive assemblage of collected papers and findings from Biosphere 2. The papers range from calibrated models that describe the system metabolism, hydrologic balance, and heat and humidity, to papers that describe rainforest, mangrove, ocean, and agronomic system development in this carbon dioxide-rich environment.[36][37]

Praise and criticism

One view of Biosphere 2 was that it was "the most exciting scientific project to be undertaken in the U.S. since President John F. Kennedy launched us toward the moon".[38] Others called it "New Age drivel masquerading as science".[39] John Allen and Roy Walford did have mainstream credentials. John Allen held a degree in Metallurgical-Mining Engineering from the Colorado School of Mines, and an MBA from the Harvard Business School.[11][40] Roy Walford received his doctorate of medicine from the University of Chicago and taught at UCLA as a Professor of Pathology for 35 years. Shortly after leaving Biosphere 2's first mission, Mark Nelson obtained his Ph. D in 1998 under Professor H.T. Odum in Ecological Engineering.[41]

Questioning the credentials of the participants (despite the contribution in the preparation phase of Biosphere 2 of worldwide top-level scientists and among others the Russian Academy of Science), Marc Cooper wrote[42] that "the group that built, conceived, and directs the Biosphere project is not a group of high-tech researchers on the cutting edge of science but a clique of recycled theater performers that evolved out of an authoritarian—and decidedly non-scientific—personality cult". He was referring to the Synergia Ranch in New Mexico, where indeed many of the Biospherians did practice theater under John Allen's leadership, and began to develop the ideas behind Biosphere 2.[43] However, the original Biosphere 2 Science Advisory Committee, chaired by Tom Lovejoy of the Smithsonian Institution, in the report of August 1992 reported: "The committee is in agreement that the conception and construction of Biosphere 2 were acts of vision and courage. The scale of Biosphere 2 is unique and Biosphere 2 is already providing unexpected scientific results not possible through other means (notably the documented, unexpected decline in atmospheric oxygen levels.) Biosphere 2 will make important scientific contributions in the fields of biogeochemical cycling, the ecology of closed ecological systems, and restoration ecology." Furthermore, Columbia University assembled outside scientists to evaluate the potential of the facility, and concluded the following: "A group of world-class scientists got together and decided the Biosphere 2 facility is an exceptional laboratory for addressing critical questions relative to the future of Earth and its environment."[44]

One of their own scientific consultants came to be critical of the enterprise, too. Dr. Ghillean Prance, director of the Royal Botanical Gardens in Kew, designed the rainforest biome inside the Biosphere. Although he later recanted, acknowledging the unique scope of this experiment and contributed to its success as a consultant, in a 1983 interview (8 years before the start of the experiment), Prance said, "I was attracted to the Institute of Ecotechnics because funds for research were being cut and the institute seemed to have a lot of money which it was willing to spend freely. Along with others, I was ill-used. Their interest in science is not genuine. They seem to have some sort of secret agenda, they seem to be guided by some sort of religious or philosophical system."[45]

The ethnosphere: psychology and conflict

Much of the evidence for isolated human groups comes from psychological studies of scientists overwintering in Antarctic research stations.[46] The study of this phenomenon is "confined environment psychology", and according to Jane Poynter[47][48] not nearly enough of it was brought to bear on Biosphere 2.

Before the first closure mission was half over, the group had split into two factions and people who had been intimate friends had become implacable enemies, barely on speaking terms.[citation needed]

The faction inside the bubble came from a rift between the joint venture partners on how the science should proceed, as biospherics or as specialist ecosystem studies (perceived as reductionist and precisely contrary to the raison d'être of the experiment). The faction that included Poynter felt strongly that they should be making formal proposals for research for the Science Advisory Committee to evaluate. The other faction included Abigail Alling, the titular director of research[49] inside the bubble, and who sided with John Allen in blocking that move. On February 14, the entire SAC resigned.[50] Time Magazine wrote:

Now, the veneer of credibility, already bruised by allegations of tamper-prone data, secret food caches and smuggled supplies, has cracked ... the two-year experiment in self-sufficiency is starting to look less like science and more like a $150 million stunt.[51]

Undoubtedly the lack of oxygen and the calorie-restricted, nutrient-dense diet[52] contributed to low morale.[citation needed] The Alling faction feared that the Poynter group were prepared to go so far as to import food, if it meant making them fitter to carry out research projects. They considered that would be a project failure by definition.

In November 1992, the hungry Biospherians began eating emergency food supplies that had not been grown inside the bubble.[53] Poynter made Chris Helms, PR Director for the enterprise, aware of this. She was promptly dismissed by Margret Augustine, CEO of Space Biospheres Ventures, and told to come out of the biosphere. This order was, however, never carried out. Poynter writes[citation needed] that she simply decided to stay put, correctly reasoning that the order could not be enforced without effectively terminating the closure.

See also


  1. Biosphere 2 - Fast Facts
  2. Bahr, Jeff (2009) p.238
  3. UASCIENCE Fast Facts
  4. Specials
  6. Turner, Christopher (Spring 2011). "Ingestion / Planet in a Bottle". Cabinet Magazine. Retrieved 2011-10-20.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  7. Silverstone, S. and M. Nelson. 1996. "Food Production and Nutrition in Biosphere 2: Results from the First Mission September 1991 to September 1993." Adv. Space Res. Vol. 18, No. 4/5 pp. 49-61
  8. Walford, R., Mock D, Verdery R, MacCallum T. 2002. "Calorie Restriction in Biosphere 2 Alterations in Physiologic, Hematologic, Hormonal, and Biochemical Parameters in Humans Restricted for a 2-Year Period". The Journals of Gerontology, Series A, Volume 57, Issue 6, Pp. B211-B224.
  9. Walford, R.L., S.B. Harris, and M.W. Gunion. 1992. Calorically restricted low-fat nutrient-dense diet in Biosphere 2 significantly lowers blood glucose, total leukocyte count, cholesterol, and blood pressure in humans. Proceedings, National Academy of Sciences, USA, V. 89, n. 23: 11533-11537
  10. Christian Weyer, Roy L Walford, Inge T Harper, Mike Milner, Taber MacCallum, P Antonio Tataranni and Eric Ravussin, Energy metabolism after 2 y of energy restriction: the Biosphere 2 experiment, American Journal of Clinical Nutrition, Vol. 72, No. 4, 946-953, October 2000
  11. 11.0 11.1 Allen, John. Biosphere 2 the human experiment.
  12. Nelson, M. and W. Dempster. 1996. "Living in Space: Results from Biosphere 2's Initial Closure, an Early Testbed for Closed Ecological Systems on Mars." American Astronautical Society: Science & Technology Series. Vol. 86, pp.363-390. AAS 95-488
  13. Finn, M. 1996. Comparison of mangrove forest structure and function in a mesocosm and Florida. Ph.D. dissertation, Georgetown University, Washington D.C
  14. college-level textbook Biology by Neil Campbell and Jane Reece
  15. The Ant Problem
  16. Biosphere 2
  17. Trouble in the bio bubble
  18. Biosphere 2 Members 'aired out'
  19. 19.0 19.1 19.2 "BIOSPHERE 2: The Experiment". Retrieved 2008-01-14.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  20. Nelson, M, W. F. Dempster, N. Alvarez-Romo, T. MacCallum. 1994, Atmospheric Dynamics and bioregenerative technologies in a soil-based ecological life support system: Initial results from Biosphere 2. Advances in Space Research14 (11):417-426)
  21. Nelson and Dempster, 1996, op cit.
  22. Severinghaus, J.P. , W. Broecker, W. Dempster, T. MacCallum, and M. Wahlen. 1994. Oxygen Loss in Biosphere 2. EOS, Transactions of the American Geophysical Union, vol. 75, no. 3, pp. 33, 35-37
  23. Marino, B.D.V., Mahato, T.R. et al., 1999, The agricultural biome of Biosphere 2: structure, composition and function, Ecological Engineering 13: 199-234
  24. The project was put into receivership and an outside management team was installed for the receiver to turn around the floundering project. The reason for the dispute was threefold. Mismanagement of mission had caused terrible publicity, financial mismanagement and lack of research. People alleged gross financial mismanagement of the project, leading to a loss of $25 million in fiscal 1992. Poynter, pp. 325–26
  25. "Two Former Biosphere Workers Are Accused of Sabotaging Dome". The New York Times. April 5, 1994. Retrieved April 26, 2010.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  26. The Donella Meadows Archive: Biosphere 2 Teaches Us Another Lesson
  27. Broad, William J. (1996-11-19). "Paradise Lost: Biosphere Retooled as Atmospheric Nightmare". The New York Times.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  28. Arenson, Karen W. (2003-09-09). "Columbia University Ends Its Association With Biosphere 2". The New York Times.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  29. Marino, B.D.V., and Odum, H.T., Biosphere 2, Introduction and research progress, Ecological Engineering, 13, 314, 1999
  30. Nintzel, Jim (2006-02-16). "Bio Bust". Tucson Weekly.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  31. "Biosphere 2 bubble sold to developers". MSNBC. 2007-06-05.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  32. Ryman, Anne (2007-06-26). "UA to take over Biosphere 2 research". The Arizona Republic.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  33. 33.0 33.1 "Biosphere 2 to Have a Permanent Home With the UA". Office of University Communications, The University of Arizona. 2011-06-27. Retrieved 2011-06-27.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  34. John Allen, FLS. "Buckminster Fuller's Synergetic Algorithm and Challenges of the Twenty-First Century".<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  35. Paul Makovsky. "The Fuller Effect". Retrieved 21 November 2013.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  36. For a complete list of Biosphere 2 scientific papers and publications see
  37. For research projects and consultants during the first closure experiment:
  38. Discover, May 1987.
  39. Ecology, 73(2), 1992, p.713
  40. Ibid.
  41. Nelson, Mark. 1998. Limestone Wetland Mesocosm for Recycling Saline Wastewater in Coastal Yucatan, Mexico. PhD thesis, University of Florida.
  42. Cooper, Marc. "Take This Terrarium and Shove It", Village Voice, 1991.
  43. Poynter, pp. 17–20
  44. Dr. Michael Crow,Vice-Provost of Columbia University, Press Release December 20, 1994.
  45. Phoenix New Times, June 19, 1991.
  46. Science Notes 2000 - Only the Lonely
  47. Poynter, op. cit.
  48. YouTube - Biosphere 2 crewmember & author Jane Poynter interview
  49. Biosphere 2 Organization
  50. Poynter, p. 270
  51. Poynter, p. 270, quoting Time Magazine.
  52. "Calorie Restriction in Biosphere 2: Alterations in Physiologic, Hematologic, Hormonal, and Biochemical Parameters in Humans Restricted for a 2-Year Period -- Walford et al. 57 (6): 211 -- Journals of Gerontology Series A: Biological Sciences and Medical Sciences". ...despite the selective restriction in calories and marked weight loss, all crew members remained in excellent health and sustained a high level of physical and mental activity throughout the entire 2 years.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  53. Poynter, p. 247.
  • Allen, John P. (2009). Me and the Biospheres: A Memoir by the Inventor of Biosphere 2. Synergetic Press. ISBN 978-0-907791-37-9.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  • Bahr, Jeff (2009). Amazing and Unusual USA. Publications International, Ltd. ISBN 978-1-4127-1683-3.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  • Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  • Poynter, Jane (2006). The Human Experiment: Two Years and Twenty Minutes Inside Biosphere 2. Thunder's Mouth Press. ISBN 978-1-56025-775-2.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>

External links