For the 21st century explorer Mars would have to be the number one travel destination. If that’s you, you might try your luck with Mars One, a privately funded mission to colonise Mars led by Dutch entrepreneur Bars Landsorp.

If you’re selected, it’s a seventh-month one-way only trip. The first four human volunteers are scheduled to blast off in 2026 in the hope of setting up a colony. Scientists, engineers and others in the space industry say the mission is not feasible. But it is the ethics of the enterprise that concern me here.

Some years ago I was among a group of bioethicists asked to ponder the morality of sending humans into space for several months or years.

At the time NASA was considering the idea of sending astronauts to Mars – with no real way of organising a flight home. (Since then NASA has developed plans for a three-year return trip to Mars in 2035.)

I told NASA that exploration in situations of terrifying and serious risk was not new. 

Asking if human long-duration space flight is ethical means asking the same questions that Englishman Robert Falcon Scott should have asked before setting out on his doomed mission to the South Pole. What are the technical constraints and what needs to be invented? What preparedness is needed and what is the cost? What information is needed for the crew to consent? 

History tells us that Scott arrived at the Pole a month after Roald Amundsen claimed it for Norway. Scott died along with his entire company on the way home. They were hopelessly unprepared  – taking French olives and raspberry jam and inadequate  gloves. Amundsen by contrast learned survival skills from peoples who lived in the Arctic before setting out. Scott’s example teaches us that bravery is not enough: realistic preparation is crucial. 

The risks of long-haul human space flight have been known for years. In 2002 a NASA committee wrote a list. These included the health hazards posed by space radiation; the possibility that the crew could sabotage the mission – based on studies of isolated communities and the psycho-social issues that can arise; physiological risk, including bone and muscle loss in microgravity; and medical risk – including the difficulties of treating injuries and illness in space. Several years later, all these factors remain.

The Canadians, the European Union and the Japanese conducted studies of their own and reached the same conclusion. Space is the harshest possible human environment, exceeding conditions anywhere on the planet. Crucially, more is unknown about the physical and mental challenges of space travel than is known. 

Assessing risk in a situation of utter unknowability is complicated. In the face of this uncertainty risk analysts have put forward the RABA concept (Risk Associated with the Best Alternative). A bad outcome of the best considered alternative might be easier  to accept than charging in like Scott without adequately considering the risks. But there are limits to rational arguments about the risks of space colonisation: we don’t know what we don’t know.

So what makes risk ethical? Historically it has been one thing: consent. The ethical considerations change if we think of the crew as military personnel.
We expect soldiers to face considerable risk. And think of the pioneers who travelled to remote and desolate places with no thought of return.

So what did I advise NASA? Exploring space is an awesome enterprise – but it has to be done at awesome cost. The process has to protect the astronauts as much as possible. The mission must be done publicly for peaceful purposes, by free people, with the results considered common stock. 

But before we set out we need a far-reaching public discussion of what space travel means to us – and what we are prepared to sacrifice for it. 

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