It might be at once the most common question anyone who works in the broad field of space is asked, and it's also one of the hardest questions to answer: why keep exploring space? There really is no shortage of reasons. Exploring space lets us answer those burning questions about the cosmos around us while simultaneously developing the technologies that make our lives better on Earth. But perhaps the most compelling reason is the most selfish one. Everything we do in space, every mission we launch, gives us more insight into our humanity and our place in the universe.
At the close of the Second World War, Nazi scientists and their V-2 rockets were among the spoils American soldiers brought home from Europe. A number of those V-2s and those scientists ended up at the White Sands missile range in New Mexico where American engineers and scientists hoped to learn the secrets behind the German missile and develop an American version. To this end, V-2s were reassembled and launched into American skies.
The more we learn about other planets the better we understand our own. The more Earth-like extrasolar planets we find the more we understand that we aren't the necessarily the most important thing in the universe.
On October 24, 1946, one V-2 launched with a 35-millimetre motion picture camera. On its three minute flight, this V-2 reached 105 kilometres before falling back to Earth. It landed in the desert near White Sands, and the camera was destroyed. But the film, housed safely in a steel cassette, survived.
The recovered film was developed and screened for the men at White Sands before it was released. The crude, black and white video showed a three minute flight from the missile's perspective. The Earth fell away and spun as the missile rose and rolled. When it reached its apogee, it showed the curvature of the Earth against the blackness of space. Those men, who were working on developing missiles for America, were the first men in history to see what the Earth would look like to aliens happening across our planet in the void. The footage and pictures were eventually made public, featured in media from newspapers to newsreels.
Our view of the Earth got better as the space age matured and progressed to manned flight. In 1961, Yuri Gagarin became the first man to see the Earth from space with his own eyes. For history's first space traveller, the view underscored the beauty of our planet, which we ought to work to preserve.
As men flew higher in Earth orbit, the pictures they brought back increasingly showed the Earth's curvature, highlighting its existence as a lonely sphere. Particularly the pictures from Gemini 11, which, in 1966, orbited 1,370km above the Earth. It was the furthest men travelled from home before the Apollo programme took men to the Moon and brought us a new perspective of our home planet.
Seeing the globe
On December 21, 1968, NASA launched its second Saturn V rocket, the behemoth built specifically for the lunar missions. This rocket took the Apollo 8 crew - Frank Borman, Jim Lovell, and Bill Anders - to the Moon, where they went into orbit briefly before returning home.
Two days after they left the Earth, the crew began their second live television broadcast. At one point they pointed their RCA slow scan camera out the window of their spacecraft to show the world itself. The black and white, grainy, three-quarters Earth took up a little more than a quarter of the TV screen at about 320,000km away. But it was a shade of the view to come.
The next day Apollo 8 reached the Moon, and as the spacecraft flew around the lunar far side, the crew became the first men to see the Earth rising over an alien horizon. Furiously snapping pictures with their onboard Hasselblad cameras to preserve the view, they took the famous Earthrise picture: our home planet, a tiny blue and white swirling marble, half lit and hanging in the sky over the foreign lunar landscape.
Apollo 14's Ed Mitchell hoped to change many men. Standing on the Moon gave him a sense of global consciousness marked by an intense dissatisfaction with the state of the world.
It's probably the most famous picture of the Earth. In full colour with stunning detail, it makes our robust home look like a fragile oasis. And it endures, frequently listed among the pictures that changed the world and is one of the most popular images of the Apollo era.
And it's a view only two dozen men have seen with their own eyes, one that affected each astronaut in his own way. Apollo 14's Al Shepard, who was also the first American in space, was brought to tears when he stood on the Moon and looked back at the Earth. Borman noted that the idealistic differences and nationalistic traits that tear us apart are invisible from a quarter of a million miles away.
Apollo 11's Neil Armstrong said that standing on the Moon didn't make him feel like a giant at all; it made him feel very small. For Apollo 15's Jim Irwin, our beautiful, warm, living object suddenly looked fragile and delicate enough for someone to crush it with a single finger.
Irwin further noted that a sight like that, seeing the Earth from the Moon, can change a man. And Apollo 14's Ed Mitchell hoped to change many men. Standing on the Moon gave him a sense of global consciousness marked by an intense dissatisfaction with the state of the world. International politics looked petty from the Moon, and he came home wanting to drag politicians to the Moon by the scruffs of their necks to point at the Earth and say, "Look at that, you son of a b#*ch".
Pale Blue Dot
The pictures of the full Earth from the space kept hold of the public's imagination. In the mid-1970s, manned missions were restricted to low Earth orbit, but NASA continued its robotic exploration of the solar system. And the agency continued to gather pictures of the Earth from distant vantage points. Notably with the twin Voyager probes that launched in the fall of 1977 to explore the gas giants Jupiter and Saturn. Voyager 1, the second of the pair to launch, turned around on its way out to photograph the Earth and Moon together. We finally saw, in one unedited picture, the Earth and Moon together in space. They are little more than a pair of grainy, blurry crescents, but one is obviously blue and white and the other a brownish grey.
But Voyager 1's most famous shot was a chance photograph. The spacecraft left Saturn in 1989 on a path that wouldn't allow it to visit any more planets. But it could still do science (and it's still taking measurements of the deep space environment) and take pictures. In 1990, when it was almost 6 billion kilometres from the Earth, Voyager 1 looked back and photographed Venus, Jupiter, Saturn, Uranus, and Neptune. It also captured the Earth, a barely blue pin point of light perfectly framed inside a scattered ray of sunlight.
From that distance the Earth looks unimaginably tiny. It was Carl Sagan who famously pointed out that everything we have ever known, everything that has happened, and everyone who has ever lived in all of human history exists on that tiny dot. If you didn't know it was in that picture, you wouldn't even see it. It is, on the surface, an unremarkable spec.
The Earth doesn't look much more impressive from the surface of Mars. NASA Spirit rover photographed the Earth from the red planet in 2004, a bright dot in the dim Martian pre-dawn sky. Last month, the Earth got a chance to post for an interplanetary portrait when NASA's Cassini spacecraft took a scheduled picture of the Earth from nearly 900 million miles away. In one image from the session, our planet is the brightest object in space but altogether overshadowed by the majesty of Saturn's rings in the foreground. Still, knowing that dot is the Earth makes the picture more meaningful for we who live here.
Discovering the Earth
In spite of their individual reactions when looking at the Earth from the Moon, the Apollo astronauts all expressed some awe at how inconsequential our planet is. And that, above anything else, is what the Apollo programme gave us. Bill Anders points out the irony that he and his crew on Apollo 8 went a quarter of a million miles to study the Moon but they really ended up discovering the Earth.
And that seems to be the case with all the missions that have launched since the Apollo programme ended - the Earth is always at the centre of every mission. Of all the pictures we've taken from various points in the Solar System, it's the ones that show the Earth that impact us the most. The more we learn about other planets, the better we understand our own. The more Earth-like extrasolar planets we find, the more we understand that we aren't the necessarily the most important thing in the universe.
Having a sense of where we stand in the universe is a profound and privileged perspective that we ought to keep in mind. Because we are, at the core, self-centred this way. It seems to be the case still that wherever we go to explore, be it Mars, Saturn, or the boundary of our Solar System, we always end up discovering the Earth and ourselves.
Amy Shira Teitel has an academic background in the history of science and now works as a freelance science writer specialising in spaceflight history. She maintains her own blog, Vintage Space, and contributes regularly to Discovery News, Scientific American, Motherboard, DVICE.
Follow her on Twitter: @astVintageSpace
The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.