Some things are almost too extraordinary to comprehend. Take what is almost the smallest and simplest measurement from the New Horizons space probe which has just passed Ultima Thule: it is travelling at 32,000 miles an hour – more than 50 times faster than an average passenger airliner. In fact, it’s close to magic: Puck boasts in A Midsummer Night’s Dream that he can girdle the Earth in 40 minutes; New Horizons could do it in 50. This is not an easy speed at which to control anything. Yet, while moving that fast, and so far from Earth that it takes radio signals, travelling at the speed of light, more than six hours to reach it, the probe has been flown within 2,400 miles of a lump of rock 20 miles long which is itself hurtling through space in an orbit it has kept since before the Earth was formed.

As Nasa announced the mission’s success, China was attempting to place a lander on the far side of the moon to help to decide whether a radio telescope could some day be built there, entirely screened from the interference of earthly civilisation. Nasa has already managed to put another spacecraft in orbit around a tiny asteroid, only 500m in diameter and much closer to Earth than Ultima Thule: the plan here is to land on the rock, collect samples, and return with them to Earth by 2023. There are two Nasa probes on Mars, sending back a stream of data, videos, and even the sounds of the wind on an alien planet. Space exploration demands extraordinary technologies, and has helped to produce some of them. But it also requires extraordinary human qualities: for astronauts, great bravery, but for everyone, ingenuity, imagination, discipline, and even a sort of altruism. The scientists and engineers, and the astronauts themselves, all need to work for decades for little material reward: New Horizons will bring nothing back but knowledge. There is nothing to exploit in the outer reaches of the solar system, just the boundless satisfaction of understanding the universe a little bit better.

The technology continues to get better and cheaper. Its role in the economy becomes steadily more central. While proper space exploration remains the preserve of governments, commercial exploration of the near-Earth orbit is cracking on. In fact our economy has extended into orbit for decades now. Without satellite communications and GPS information the world would come to a chaotic halt. The civilian – and the military – uses of imagery from space are now impossible to count.

There is a danger here. It is not that of commercial exploitation but of the malevolently intended and unprofitable uses. The most obvious is the possibility of militarising space. In one sense, space has been militarised ever since the launch of the first intercontinental ballistic missiles, but there are new threats, involving the destruction of an enemy’s targets, such as their satellites, which we can only hope remain entirely theoretical.

More immediately, space exploration has become a fashion among the unfathomably rich, such as Jeff Bezos and Elon Musk, who are running rival private space programmes. The use of huge rockets in the tech billionaires’ demonstrations of manhood isn’t entirely comical. It speaks of a dream that they can leave the Earth and all its messy problems far behind. It is a negation of the message of that first great picture from space – Earthrise – which showed us all sharing one planet. That is still who we are. And you cannot escape to the final frontier if you screw up the planet you start from.

• This article was amended on 3 January 2019 because an earlier version compared the speed of the New Horizons probe to being “more than 50 times faster than anyone alive on Earth has travelled – unless they are a military pilot or an astronaut”. That meant to compare the 32,000 miles an hour to more than 50 times faster than an average passenger airliner.