The idea that Earth has unlimited capacity to provide for human desires and absorb human wastes was undermined when the first pictures of the planet from outer space were published.

The US Ambassador to the United Nations, Adlai Stevenson, stated in 1965:

We travel together, passengers on a little spaceship, dependent on its vulnerable reserves of air and soil; all committed for our safety to its security and peace; preserved from annihilation only by the care, the work and, I will say, the love we give our fragile craft.

In 1966 Kenneth E Boulding (1966), a professor of economics, used the same analogy in his classic essay, 'The Economics of the Coming Spaceship Earth'. In it he described the actual economies of industrialised countries as 'cowboy' economies, 'the cowboy being symbolic of the illim­itable plains and also associated with reckless, exploitative, romantic, and violent behavior, which is characteristic of open societies'. He wrote of the need for a 'spaceman' economy which recognised the planet has limited supplies and a limited capacity to extract wastes. In this economy people would have to find their place 'in a cyclical ecological system which is capable of continuous reproduction of material form'.

While a cowboy economy maximises production and consumption as desirable goals, and success is attained by continually increasing the throughput of materials and energy, a spaceman economy tries to minimise throughput in a closed economy. In such an economy the aim would be to:

• limit extraction and pollution

• decrease consumption

• continuously reproduce the material form

• increase stock maintenance - goods would be built to last as long as possible.

Economic success in a spaceman economy would be measured by the 'nature, extent, quality, and complexity of the total capital stock, including in this the state of human bodies and minds'.