In all geologic time, the responsibilities are on our generation ... including you ...

6.6 Ecological Issues and CELSS

To date, when humans have gone to space, they have brought with them all the air they needed to breathe, their water and their food. All wastes created were either flushed into space or returned to Earth in their original form. (The water astronauts drank was often a byproduct of electric power generation by chemical means - hydrogen-oxygen fuel cells.)

Gaseous wastes were recycled by machines -- carbon dioxide was processed to produce oxygen, by "physical-chemical" processes.

In order to become self-sufficient in space -- independent from Earth -- we will need to grow our own food in space. We can use machines to recycle urine and water vapor in the air to produce drinkable water, but it will eventually become more desirable and economical to recycle our human wastes naturally rather than only by machines, and to do so naturally in conjunction with food production. Machines would be used only to sterilize and purify water that has already been cycled through the artificial biosphere.

On Earth, animals breathe in oxygen (O2) from the air and breathe out carbon dioxide (CO2) as a waste. Plants absorb this carbon dioxide from the air, and using the energy of sunlight plus water and materials from the soil and air produce sugar, starch and other things -- based on a process called photosynthesis. Plants emit oxygen as a waste. That completes the animal-plant cycle. In this cyclic manner, animals and plants are mutually dependent upon each other. Plants produce both food and oxygen for animals. In turn, animals produce carbon dioxide for plants. In addition, animals produce excrement wastes which enrich the soil. Dead plants also enrich the soil and are not wasted.

This natural cycle can be moved to space, in whole or in part.

Early experiments in the 1950s and 1960s focussed on recycling air using algae, not food crops. Flat tanks of algae were put under artificial light in order to absorb carbon dioxide that humans had exhaled in closed chambers, and emitted the oxygen for the humans to breathe. It was found that each human required about 8 square meters of algae for equilibrium. (The algae tanks were generally stacked as shelves so that they took much less than 8 square meters of floor space.)

More recent research has expanded this to include production of edible food, and recycling of human excrement wastes and dead plant wastes in the food cycle.

In the early years of space colonization, we will use a combination of natural systems and machines. We can always import pure oxygen and water from asteroidal materials, as well as carbon dioxide if we wish. It's not necessary to produce a completely closed system. However, it is important to maintain healthy and highly productive crops, which requires waste management and recycling skills.

The technologies required may be broken down as follows:

  • Exchange of oxygen and carbon dioxide between plants and animals (aka air revitalization)
  • Production of food (aka edible product production)
  • Breakdown of human wastes (aka wastewater treatment)
  • Composting of plant wastes
  • Purification of water for drinking
  • Elimination of pollutants from air

This field of study -- regenerative life support systems -- is called "Controlled Ecological Life Support Systems (CELSS)" (also called Closed... instead of Controlled... though "closed" is probably not attainable for awhile). There is a wealth of information from various institutions around the world on this topic, including papers presented at conferences dealing with lunar and asteroidal materials utilization.

CELSS is the focus of most of the rest of this webpage.

Note on the word "biosphere"

In some circles, the word "biosphere" is used instead of CELSS to refer to large closed systems. However, just as frequently, the word biosphere refers to Earth or one of Earth's ecosystems, not to space based CELSS systems. For example, if you search databases for the word "biosphere" you will get a lot of hits on remote sensing of the environment on Earth by NASA satellites, and the Mission to Planet Earth (MTPE) program. But you will also get hits on Biosphere 2, Bios-3, and Biosphere J, all CELSS experiments for space colonization.

A better database search word is "CELSS" (for Controlled Ecological Life Support Systems ... or alternatively Closed Ecological Life Support Systems). > Space Colonies > Ecology, CELSS


PERMANENT needs a PHP / MySQL (actually, MariaDB) programmer. Are you a PHP / MySQL programmer interested in getting into space development as a career, or already working in space development? Or do you know somebody else who might be interested?

There is an ongoing process to update this website in 2019 with a target relaunch in 2020.
This website is actually very out of date. Much of the website text content was written in the 1980s to early 2000s, but that's a different matter. As regards PHP / MySQL, some offline databases go into the 2010s, as regards professional publications, engineers, companies, etc., and this is what we need programming help with. We are updating our databases on people, organizations, publications, and other things, for open source space development for all.

The current status is we have some working databases which we have been using internally for a long time for organizing professional publications, and to track people (authors, R&D people, other professionals, quality volunteers, journalists, etc.) and organizations. We want to put information online for the general public pending a security review of the programming code.

Step 1 is fixing some bugs in what we already have, the PHP code. It is functional, and been used a long time, but there are some bugs.
Step 2 will be improving the system. Some small improvements would help its usability.
Step 3 will be a security check for putting it online for the general public to be able to access and use, but with reasonable protection against hackers.
After Step 3, the main mission is accomplished, as regards PHP / MySQL, though of course we hope to keep people engaged and happy, and the sky's not the limit.

This is a volunteer, unpaid role at this point in time. A limited paid role would be considered on a tight budget, such as for at least bug fixing with some minor improvements, and/or a security review of our code before it goes online publicly. If you or one of your friends or associates may be interested, please send an email to spaceprogrammer at ... of course this domain.

Reasons to do something yourself:

  • It will help save life on our special planet -- be part of the solution in your generation.
  • It will create and secure a better future for your children and grandchildren.
  • It could be an interesting, cool, and a fun adventure for your life!

You can join us and volunteer to help out,

... or ...

If you're short on time, you can just donate:

The Permanent Space Development Foundation, Inc., is a 501(c)(3) nonprofit organization.
If you would like to make a quick donation to our humanistic cause,
then please click on one of the buttons below (which go to PayPal).

... or by cryptocurrency (which is NOT tax deductible), you can donate into any of these wallets:





... or ...

Suggest this website to other people and organizations.

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Leave information about yourself in our people, companies, and organizations database.

If you are interested in hiring our expertise, anywhere in the world, please contact us.
We have people in the USA and Thailand, and can travel or consult by internet.
You can call anytime, 24/7, at +66-8-1135-7977

Text by Mark Prado, Copyright © 1983-2020, All Rights Reserved.
Many website artistic design elements by Sam Fraser, Copyright © 1999-2020, All Rights Reserved.

Except where specifically stated otherwise,
Copyright © 1983-2020 by Mark Evan Prado, All Rights Reserved


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