Comment: Feedback Physics World  February 2017

Cosmic sceptics?

In response to Margaret Harris’s editorial in the Physics World Focus on Astronomy and Space (December 2016), in which she describes herself as a “space sceptic” when it comes to putting people on Mars or interstellar travel, but is fascinated by the practical side of space exploration.


As an astrobiologist working with NASA on planetary protection and risk communication – avoiding harmful contamination during robotic and human missions to the Moon and other celestial bodies, based on Article IX of the Outer Space Treaty – I share some of Harris’s concerns about longer-term space activities, particularly those associated with human missions beyond low-Earth orbit.

When I find myself feeling sceptical about the wild, far-out proposals of future humans going to Mars or of commercial space tourists, I take a deep breath and think of the Wright brothers and what they must have thought about in those early years. I don’t imagine that people working on planes for the First World War or on early passenger aircraft would have imagined flying long distances with hundreds of people on-board, or would have dreamt of crossing a country or an entire ocean in just hours.

I keep my perspective about the longer term by realizing that it’s the next generation or beyond that will tackle the problems – technical, legal, ethical and otherwise. You may be interested to know that we have already been collaborating with ethicists and others about “societal” questions. In fact, at a recent NASA workshop on human missions, there were discussions about how to blend ethics into the future protocols. What if an astronaut is infected by a possible Martian microbe: would you bring the crew back to Earth? The situation is comparable to questions that arise around international air travel and appropriate quarantine when a pandemic strikes on Earth today.

Within astrobiology, it’s important and helpful to recognize different time frames – years to decades, decades to centuries, and even centuries to millennia (on the scale of human civilization). We don’t have to tackle everything at once.

Margaret Race

SETI Institute, California, US

I agree with Harris’s pragmatic viewpoint on space exploration, for the remainder of the duration of the lifetimes of seniors like me. We have enough problems to solve on Earth that exporting humans en masse to other planets is clearly not a viable option. Additionally, space is hostile on many levels to DNA-based life forms. It is much safer to send robots and exploration vehicles out into the unknown. It would be valuable if the fruits of such exploration were also used to improve conditions for people and all other life on Earth.

Probably the greatest danger on the horizon is climate change and its effects, including long-term global atmospheric warming, ocean acidification, methane release, loss of river and ground water, climate chaos and wildfires, habitat loss for both people and wildlife, and rising sea levels.

Richard Swan

Kapiti, New Zealand

Harris’s assessment about the practicalities of interstellar travel is exactly right. The limitations of such missions is news to most, and this sobering reality doesn’t get air time. And as she suggests, the drivers for Mars remain awe-inspiring, but probably not economically practical for many generations, if ever. Still, observations from Earth with next-generation telescopes, such as the James Webb Space Telescope, the Thirty Meter Telescope and the Square Kilometre Array, will lead to new insights about profound mysteries such as the nature of dark energy and the formation of structure in the universe. Meanwhile, small, innovative projects can continue the search for intelligent life in the universe, or shed light on how rare and precious we humans are.

Geoff Kegley

Santa Rosa, California, US

Harris says that putting humans on Mars in the next 10 years is ethically dubious and I agree with this. It is not right for human beings to venture to space until all “space junk” is salvaged and methods are developed to completely eradicate future space junk – so it is reused or recycled while in space or using some other method.

I also feel it is not ethical for humans to venture to other planets until the environmental damage to Earth caused by the human race is amended and we ensure that such damage does not occur elsewhere. We have not yet developed an understanding of – or skill in – existing as a healthy part of life on planet Earth. Those who venture to other planets need to be aware of what it is like to achieve ecological success. If such a mindset is not considered to be vital, the chances of damaging a new planet increase.

Christina Laurikainen

Traveston, Queensland, Australia

I am a chemist, but have also written a science-fiction novel that looks at the problems with sending people to Mars, going beyond the fundamental issues of a high-risk “there-and-back” mission. The basic problem as I see it is that you have to send enough people with varying specialities to make survival plausible – with a surgeon, say, you need two at the very least. It follows that you’d also need a lot of supporting infrastructure, and make as much as you can on Mars. But how could this be done? How do you make metal supports for a dome to grow plants? The basic rock is basalt. The various elements are there, but not in a very friendly form. The geological processes that have led to ores on Earth are probably not the same on Mars, and while small amounts of haematite may have been found,it is nowhere near enough, and they may well be in the wrong place.

We also need a far better propulsion system than chemical rockets, and we need energy systems that can process basic rock to extract metals and other useful elements, as well as for land transport. So before we think about sending a team of humans to Mars, we need to do a lot more research. We should not consider that sort of expedition until we have the technology to make the expedition plausible.

Ian Miller

Lower Hutt, New Zealand