With commercial space travel already becoming a multibillion-dollar industry, green investors are faced with a conundrum.
On the one hand, some ecologists regard recreational space travel as a massive squandering of the Earth's resources. But those involved in the industry argue that space travel, when it enables detailed monitoring of the Earth's surface and atmosphere from space via orbit, is essential to the preservation of the its dwindling natural resources.
This is rapidly becoming a controversial topic among those in the investment community who wish to square their conscience with their investment portfolios. Virgin Galactic, a flagship for the future in entrepreneur Sir Richard Branson's Virgin group of companies, is offering seats on its next space flights for US$200,000 (Dh734,620) each, although passengers can reserve a place for as little as $20,000. The space programme is open to adults over the age 18 in reasonable health. All anyone needs is a little cash to join "the space set", the 21st century's new elite.
But environmentalists deplore what they see as irresponsible joyriding on space rides. Anyone shocked at the way petrol-guzzling SUVs burn fossil fuels will become apoplectic at the thought of rich tourists in search of the ultimate travel kick using space rockets to propel half a dozen people into space with no apparent ecological gain.
However, people in the commercial space sector see space tourism as an essential funding element in an industry that, far from polluting the planet, is the only thing standing between Earth and ecological Armageddon.
Some in the space industry are going a step further and claiming there would not even be an environmental movement were it not for space travel.
"The first shots of the Earth from space led in part to the modern environmental movement; people saw for the first time the thinness of our atmosphere and the fragility and beauty of our planet," says Stephen Attenborough, a director at Virgin Galactic.
Space industry supporters also argue that effective future conservation of the Earth's resources is totally dependent on space travel. Extra-terrestrial observation enables the prediction of natural upheavals such as tidal waves and earthquakes. It also allows farmers to forecast droughts and other natural disasters affecting food production. From a purely ecological viewpoint, it would also be impossible to monitor fully slow moving environmental disasters, such as the melting of the polar ice caps without extraterrestrial help.
According to space industry pundits, the limited nature of the Earth's mineral resources can only be remedied by off-planet mineral mining. While distant planets being mined by hardy futuristic space miners has been a staple of science fiction for decades, the reality may be more prosaic and more realistic. Some of the Earth's closer neighbours have now been discovered to have vast potential mineral resources.
The Moon itself, Earth's closest neighbour, is now perceived to be rich in valuable metal. In its history, it has experienced lava flows that turned into rocks that are now enriched with titanium in concentrations far higher than what is found on Earth. Maps from a robotic Nasa science satellite circling the Moon have been reported to show deposits as rich as 18 per cent.
Although the costs of mining the Moon may currently be prohibitive, the solution is seen as long term. If the space industry's predictions are correct, the cost of space travel will plunge over the coming decades to a level where it will be commercially feasible to mine the Moon.
In focusing on the Earth and the limited nature of its resources, environmentalists have largely written off space as a vast emptiness. But the space industry believes that mankind has only begun to scratch the surface of space's vast potential resources. Increased solar energy outside the Earth's orbit is one example of a potential resource that could be harnessed for mankind's benefit.
But the world's environmental jury is still out on whether it can accept that commercial space travel can be seen as "green". Greenpeace says it has yet to reach an official position on the subject.
Part of the reason is that the space industry has had bad press with ecologists in the past. At the time of the first manned Moon landings in 1969, there was international criticism from alternative movements that the money spent in putting a man on the Moon could be far better spent in feeding the world's starving millions. But in the period since then, the cash resources that once flowed into space travel have not been diverted into fighting famine and poverty.
According to the space industry, it is time for the ecology movement, in general, and green investors, in particular, to review their green credentials.
But investors should continue to take a hard look at the space industry's actual environmental achievements rather than relying entirely on its optimistic predictions.