However, in terms of life support resources Spaceship Earth faces far more demanding challenges than human-built manned spaceships. Human-built manned spaceships are designated for a limited mission of known duration with pre-determined objectives and the appropriate mechanical systems and crew size and skills to accomplish those objectives. And the spacecraft is loaded with the required life support provisions, so there is no requirement for external resources.
By contrast Spaceship Earth has undefined and unlimited requirements:
• Mission Duration and Objectives: Unlike man-made space ships, Spaceship Earth has no planned mission objectives or termination. Barring some cosmic catastrophe, it will continue soaring through the vacuum for all time to come and experiencing whatever activities, human or natural, occur.
• Resources: Although Space-ship Earth is incredibly larger than the man-made spaceships, its resources are not infinite. It must support whatever activities are engendered by humans, animals, or the forces of nature (wind, waves, storms, earthquakes, and so forth) with internal resources and solar energy.
• Crew Size (Population): The current crew size (earth population) is about 7 billion humans, and the growth rate (as of 2012) was 1.2% annually, which, if that rate remains constant, means it will redouble about every 60 years.
The obvious question is, “If Spaceship Earth continues soaring through space for eons, with no external resources other than radiant energy, how long will it be able to continue providing life support?” There is probably no absolute answer, but there are several courses of action that could increase the availability of adequate resources for the foreseeable future.
Fossil fuels (oil, natural gas, coal, etc.) are apparently adequate to meet requirements for many years, but the earth is already ‘energy hungry.’ Even now some energy companies have turned to a new method called fracking to extract natural gas from rocks to augment supplies, and others are demanding new pipelines to deliver needed fuel to various regions of the US and other nations. Similar searches for stores of fossil fuels are occurring continually throughout the world. However, the natural processes that produce fossil fuels require eons, and they cannot reproduce these fuels as rapidly as we are consuming them. Eventually, Spaceship Earth will exhaust fossil fuel supplies.
Thus, even though there is no immediate threat of shortages, it would seem wise to use the time to shift to increased use of electrical energy derived from solar radiation which is more than sufficient to meet the energy needs of the entire earth for the foreseeable future with much less pollution than fossil fuels.
However, to capture the huge amount of solar energy that will be needed it is necessary to deploy a myriad of large solar panels either on the earth’s surface or in space and create new collection, storage, power conditioning, and distribution systems. This effort should begin as soon as practicable.
Spaceship Earth replenishes some consumables by various recycling processes. Some of recycling occurs naturally. For example the hydrological cycle (surface water evaporates, releases contaminants, rises into the air, cools, condenses, and falls back to the surface) and photosynthesis (carbon dioxide, created by human/animal respiration and by combustion processes, is absorbed by plants which extract the carbon and return the oxygen to the atmosphere). Numerous other materials are actively recycled in human created scientific processes, for example recovering metals from used cans, worn out machinery, and other metal products, and using animal waste as fertilizer to increase the yield of plants which in turn can be used as feed for more humans and animals.
However many recycling processes are considerably less than one hundred per cent efficient, and some loss of the substance being recycled normally occurs. Also, these processes may require heating, filtering, chemical treatment, and other methods which consume energy, create waste heat, produce waste products, and may require the addition of chemicals that are themselves limited to existing resources.
It seems it would be wise to carry out the necessary research to develop methods to recycle more different kinds of life support resource substances and to improve the efficiency of recycling methods to increase the yield.
Crew Size (Population)
Perhaps the most troublesome long-term problem that Spaceship Earth faces is the inability to control crew size (e.g., the population of the earth). Over hundreds of years the population of earth has consistently increased, sometimes rapidly and sometimes gradually, but there has never been a prolonged period of decreasing world population. As stated above, the estimated growth rate based on 2012 figures is about 1.2% per year which would cause population to redouble every 60 years. The current population is about 7 ½ billion, so in 60 years (2074) it will be about 15 billion and in 120 years (2134) will be about 30 billion. Clearly, Spaceship Earth with relatively fixed resources cannot continue to provide life support resources for an exponentially increasing crew size. Even with the present population many people on earth live at a subsistence level with limited food, questionable water purity, and few, if any, modern conveniences. It is easy to say the population growth rate should be reduced, but many people feel that trying to force any form of legal birth control on people is wrong and unacceptable. Nevertheless, uncontrolled increase in the crew size (population) of Spaceship Earth is not supportable for an unlimited mission duration with finite, fixed life support resources.
In closing, it should be noted that since Spaceship Earth is totally isolated in space, it is clear that the foregoing suggested courses of action can only be implemented by the crew, me, you, and all the rest of us, acting together.
Donald Peterson is a Winona native and NASA astronaut, where he served on the astronaut support crew for Apollo 16. He is currently retired and living near Houston, Texas.