All Astronautical Evolution posts in 2022:

Is Private Space Travel Environmentally Responsible? (April)

How Will the First Astronauts on Mars Spend Their Time? (February)

All Astronautical Evolution posts in 2021:

Questions for Human Analogue Simulators of Mars (December)

Black Arrow and Prospero Fifty Years On (October)

The Inspiration4 Mission Begins to Fill In the Bottom of the Transport Pyramid (September)

Are Richard Branson, Jeff Bezos and their clients real astronauts? (August)

Planetopolis in an Age of Climate Change (July)

Planetopolis (January)

All Astronautical Evolution posts in 2020:

Stellar Engines (August)

Voyage to the Large Magellanic Cloud (July)

Why the Human Exploration of Space? (May)

Artificial Gravity for the Journey to Mars and Return (April)

Cruising in Space (March)

All Astronautical Evolution posts in 2019:

The Destiny of Civilisations – Fire, Iron and Gold (November)

The Destiny of Civilisations – A Problem for SETI (November)

The Holy Grail of Space (October)

Return to the Moon, 50 Years On (August)

The Case for Interstellar Flight (June)

SpaceX Dragon 2 Success (April)

Killing the Doomsday Fallacy (Feb.)

All Astronautical Evolution posts in 2018:

How Far Can We Take the Copernican Principle? (Dec.)

Dawkins and the McGraths: a Biologist versus two Theologians (Nov.)

The Atheism Question (Oct.)

The Religion Question (Sept.)

I, Starship (June)

Back to 2017:

Scenario Block Diagram Analysis of the Galactic Evolution of Life (Nov.)

Comments by Alex Tolley (Oct.)

Elon Musk’s “Great Martian” (Oct.)

Elon Musk’s Mars Plans: Highlights from His Second Iteration (Sept.)

What is a Supercivilisation? (Aug.)

Quantifying the Assumptions Behind the METI Debate (July)

Five Principles of a Sustainable Manned Mars Programme (June)

Pale Red Dot: Mars comes to Oxford (May)

Back to 2016:

Elon Musk and Mars: Looking for a Snowball Effect (Oct.)

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2019: The Doomsday Fallacy, SpaceX successes…

2018: I, Starship, atheism versus religion, the Copernican principle…

2017: Mars, Supercivilisations, METI…

2016: Stragegic goal for manned spaceflight…

2015: The Pluto Controversy, Mars, SETI…

2014: Skylon, the Great Space Debate, exponential growth, the Fermi “paradox”…

2013: Manned spaceflight, sustainability, the Singularity, Voyager 1, philosophy, ET…

2012: Bulgakov vs. Clarke, starships, the Doomsday Argument…

2011: Manned spaceflight, evolution, worldships, battle for the future…

2010: Views on progress, the Great Sociology Dust-Up…

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Talk presented to students at the International Space University, May 2016

Basic concepts of Astronautical Evolution

Options for Growth and Sustainability

Mars on the Interstellar Roadmap (2015)

The Great Sociology Debate (2011)

Building Selenopolis (2008)


Issue 164, 3 April 2022 – 53rd Apollo Anniversary Year

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Is Private Space Travel Environmentally Responsible?

The following article appeared in Room, the space journal of Asgardia, Winter 2022 issue (no.30) (published January 2022), p.59-63. In print the article was edited; here it appears in its full original form.

“Everybody in the world needs to do this.”

Famed Star Trek actor William Shatner was describing his feelings to Jeff Bezos after his brief spaceflight in Blue Origin’s New Shepard NS-18. “Everybody in the world needs to see it. It was unbelievable.”

Launch of Blue Origin NS-20

While the younger folks sprayed one another with champagne, Shatner remained thoughtful. One could hear his inner Captain James T. Kirk as he continued: “This comforter of blue that we have around us. We think, Oh, that’s blue sky. And then suddenly you shoot through it all of a sudden, as though you whip off a sheet off you when you’re asleep, and you’re looking into blackness. Into black ugliness. And you look down. There’s the blue down there. And the black up there … There is mother and Earth and comfort, and, there is … is there death? Is that death? … Look at the beauty of that colour. And it’s so thin. And you’re through it in an instant. … What you see is black. And what you see down there is light. And that’s the difference. … What you have given me is the most profound experience I can imagine. … What I would love to do is to communicate, as much as possible … the vulnerability of everything. This air which is keeping us alive is thinner than your skin.”

This life-changing glimpse of cosmic reality was christened the Overview Effect by Frank White in his 1987 book of that title. He quotes from several astronauts and cosmonauts who experienced similar feelings, including Apollo 11 command module pilot Michael Collins: “I really believe that if the political leaders of the world could see their planet from a distance of … 100,000 miles, their outlook would be fundamentally changed … by causing them to realize that the planet we share unites us in a way far more basic and far more important than differences in skin color or religion or economic system.”

Again, Soyuz T-5 cosmonaut Anatoly Berezovoy wrote: “the longer you stay in orbit the more you value normal life on Earth. Any person who has been in space values his own place on Earth in a new way. He begins to think more, and his thoughts become broader and his spirit kinder.”

It should be clear that if more of the world’s rich and powerful people – politicians, company directors, opinion leaders – could be exposed to the Overview Effect of seeing our planet Earth from space, the result would be greatly beneficial. This is the promise of private passenger spaceflight, or pioneering space tourism, which after a decade’s hiatus since the last private visit to the ISS is now at last beginning to pick up momentum again.

Not everybody left behind on Earth has been so favourably impressed. Writing in the Daily Mail, one well-known commentator described Richard Branson’s and Jeff Bezos’s initial suborbital flights as “an utterly pointless exercise in inflating egos that already dwarf the size of the average planet”, “proof of the arrogance and skewed priorities of mankind.” He concluded with a warning to Bezos that he would do better to concentrate on climate change “as he blasts off … and contaminates our fragile atmosphere with yet more carbon” (he did not say how much carbon he thought might be emitted from a rocket burning pure hydrogen).

Yet despite the overblown rhetoric there is a fair question to be answered: can increasing levels of passenger traffic to space be reconciled with the need to reduce the polluting impact of our civilisation on the fragile environment on which we all depend?

The natural point of comparison is with the aviation industry. In 2019, before Covid-19 depressed international travel, some 4.4 billion air travellers accounted for the burning of 285 million tonnes of jet fuel, averaging around 65 kg per person. But how fuel-intensive is a flight to orbit in comparison with a typical air journey?

Take SpaceX’s Crew Dragon capsule and Falcon 9 rocket. With four people on board, the kerosene needed for an orbital launch comes to 39,000 kg per person. But the technology is still at a primitive stage compared with that of airliners, which have seen continuous refinement to serve growing markets over the past century, ever since the first war-surplus machines were converted for commercial passenger use in 1919.

Skylon in flight

Assuming space passenger transport continues to evolve, then by the time it matures it may be using a vehicle like Skylon: the well-known futuristic design for a single-stage-to-orbit spaceplane that grew out of the Rolls-Royce/British Aerospace HOTOL project of the 1980s. The current iteration of this design, Skylon D1, under development at Reaction Engines in Oxfordshire, uses 77 tonnes of liquid hydrogen fuel to carry a 15 tonne payload module into orbit. Optimised for passengers, the 200 cubic metre volume would accommodate 24 people, each one therefore accounting for about 3200 kg of hydrogen fuel.

Finally, to return to New Shepard: with its design complement of six passengers the fuel burned amounts to 290 kg per person for a sub-orbital hop up to 100 km and back.

In summary: for every kilogram of kerosene jet fuel used to transport a conventional air passenger on a single journey, a New Shepard space tourist would consume about 4.5 kg of hydrogen fuel, a future Skylon passenger about 50 kg, also pure hydrogen, and a traveller in today’s Crew Dragon about 600 kg of kerosene.

It’s now possible for us to get space and air travel into proportion. In 1990 global air travel first passed a level of one billion passenger movements per year. Let’s imagine that space passenger traffic is held down to just one per cent of this, in terms, not of seats to space, but of fuel burned, and hence emissions of water vapour and carbon dioxide.

Then at today’s technological level, represented by Crew Dragon, it would still be permissible for over 10,000 space passengers to fly per year. At the more sophisticated level represented by Skylon, achievable after a few decades of further development of technologies, vehicles and markets, over 100,000 people could visit space per year – say 80 flights per week worldwide of 25-seater spaceplanes. At the same time, in both cases several times that number could experience suborbital hops to just above the von Kármán line.

The conclusion has to be that air pollution from space passenger traffic at these levels would remain a tiny proportion of that from present-day world aviation in general, which in turn accounts for only five per cent of the global emissions from industry. Since space travel will always be much more expensive than air travel, it will remain a niche market.

Yet the benefits of even so tiny a number as a few tens of thousands visiting low Earth orbit per year would be profound. We’ve already discussed the Overview Effect. We’ve seen that it should not remain the exclusive property of government scientists and test pilots, but rather it needs to be shared with artists, public figures, decision makers and opinion leaders worldwide.

Ultimately, what is at stake is whether our industrial civilisation can survive in the long term. In order to do so, it must continue to develop, and this requires growth on a multiplanetary scale. But while an individual trip to orbit still costs tens of millions of dollars, and launches beyond low Earth orbit are limited to occasional multi-billion-dollar Artemis missions, serious expansion to the Moon, Mars and beyond will not be possible.

In order for a project such as the space nation Asgardia, or Elon Musk’s plan for a self-sustaining Mars city, to become a reality, the space passenger transport industry needs to mature, raising its reliability and safety to airline standards and reducing the ticket price to orbit by at least two orders of magnitude. Clearly, this is the goal of SpaceX’s current development work on “Starship” and “Super Heavy” in Texas.

Without that continued growth, the outlook for human civilisation on one planet is not good.

Natural disasters with global effects – notably asteroid impacts, supervolcano eruptions and ice ages – could trigger civilisational collapse. Nuclear weapons have not gone away, and neither has the kind of aggressive nationalism willing to use them. Even a mature democracy such as that of the USA can fall into political disarray when both right and left are captured by extremist views which compete in an escalating culture war. Social change will continue as the global population rises further, its increasing demand for cheap energy in slow-motion collision with the opposing demand to end the use of fossil fuels in order to combat the spectre of climate change.

I am suggesting that the key to addressing all these problems lies in the human imagination.

On the one hand, there is the view that human society can only be saved through a massive reduction of its industrial activities in order to bring it back into balance with nature. New technology is seen as the problem, not the solution. In its most extreme form the whole culture of European progress, its gender and racial hegemony, imperialism and capitalism, over the past 500 years is believed to be a tragic mistake which must be corrected, a blind alley which leads only to environmental exhaustion and collapse.

However, a return to pre-industrial society would itself not be possible without inflicting enormous destruction on both people and property. A low-tech future can be implemented only by global tyranny or global war. Voluntary renunciation of the benefits of industrialisation and going back to a simpler way of life may appear attractive to the jaded palates of the well-off in the rich world, but to vast populations in developing countries the lure of those benefits is an irresistible engine of growth.

Therefore the only practical and humane way forward is to continue the trend of growth and development of the past 500 years to its logical conclusion. New technologies are, on balance, more creative than destructive. The immense sufferings of recent history were not in vain: they are the birth pangs of a new and better order of society. The intellectual guiding principles of the Enlightenment – reason, tolerance, science and democracy – are still valid today. The challenges of managing the environment and of managing ourselves are great, but we are equal to those challenges.

The growth in space passenger transport can now be seen in its true light. The point is not – as in the malicious caricature of space advocates that one sometimes sees – for the rich to abandon Earth and find a Planet B, an Earth 2.0, to pollute and destroy in turn. This absurd fantasy collapses on its first contact with astronomical reality: even Mars, with its superficially Earthlike landscapes, presents immigrants with surface conditions far more hostile than the worst that human irresponsibility, pollution and war could ever wreak on Earth.

Rather the point is to lead the development of the high-tech future. New technology may create new problems, but those can be addressed and solved. Energy sources such as solar power, nuclear fission and in due course nuclear fusion can be the basis of a sustainable civilisation for trillions of years into the future. While an integrated global society on Earth, isolated from its interplanetary environment, is vulnerable to collapse, its diaspora on a Solar System – and ultimately an interstellar – scale promises to strengthen it through diversification, and to preserve all that we value of the human heritage for as long into the future as we care to imagine.

Destroyed Russian vehicle

As leading thinkers at the British Interplanetary Society have been saying for many years: the choice which humanity faces is between a space age, or a return to the stone age. I like to illustrate this in terms of popular TV serials: either our future will look like Star Trek, complete with the philosophical musings of Captain Kirk, or it will become as desperate and violent as Game of Thrones.

Meanwhile there is much work to be done before the high-tech future is secure. In space travel in particular, the key focal points must be on full and rapid reusability, thus allowing rockets and spacecraft to amortise their manufacturing costs, both financial and environmental, over a hundred or more flights; the switch from dirty fuels to relatively clean methane and hydrogen; and the build-up of traffic levels high enough to lead to economies of scale and technological maturity. As I demonstrated above, the number of launches per year to achieve this can still be low enough to represent an acceptably low fraction of humanity’s global emissions.

At the same time, I have been arguing for more sustainable practices in the running of our everyday lives: the goal of low environmental impact is equally necessary for industrial cities on Earth and for future cities in space, on the Moon and Mars, and beyond (see Room, Spring 2021, p.86-91). This is another area in which progress in space is aligned with that on Earth.

These will be the points to watch for in near-future developments, but we should never lose sight of the ultimate goal of making the best of humanity and the best of technology work together in a future of endless creativity and discovery.

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