The Duel
Is space exploration worth it?
YES
Marcus Chown
NO
Deirdre Nansen McCloskey
YES
Paradoxically, space exploration teaches us about the Earth. And the things that we learn are arguably priceless because they are crucial to our survival.
The critical point is that other planets show us what the Earth would be like if things were different. So, for instance, we can see what the Earth would be like if it were smaller or larger, hotter or colder, if it had a different atmosphere, and so on.
Venus is Earth’s twin in terms of its mass. Yet when space probes visited the planet in the 1960s, they discovered that Venus is actually Hell. Beneath impenetrable sulphuric acid clouds is a surface hot enough to melt lead, and a crushing atmosphere 100 times thicker than the Earth’s. What has happened on Venus is that carbon dioxide, which on Earth is locked up in chalk cliffs, has seeped out into the atmosphere, creating runaway greenhouse warming.
Mars, by contrast, warned us of the danger of catastrophic cooling. When Nasa’s Mariner 9 space probe arrived in 1971, it sent back pictures of an enormous dust storm, reflecting sunlight back into space and dramatically cooling the planet. This caused Mariner 9 scientist Carl Sagan and others to realise that a terrestrial nuclear war would pump smoke from burning debris into the stratosphere and plunge Earth into a devastating nuclear winter.
But not all space insights are so prosaic. The Apollo 8 photograph of the Earth rising above the Moon taken on Christmas Eve 1968 is widely credited with galvanising the environmental movement, burning into our collective consciousness an indelible image of our tiny fragile home lost in the infinite blackness of space.