A new golden age for space exploration?

Countries around the globe are launching successful missions. The question is whether they will compete or collaborate

January 08, 2019
An image of Ultima Thule returned by the New Horizons spacecraft. Photo: NASA/UPI/PA Images
An image of Ultima Thule returned by the New Horizons spacecraft. Photo: NASA/UPI/PA Images
I can’t remember a year that kicked off with quite as much excitement about space as this one, which partly explains why I found myself sitting in the BBC studios at an absurd hour on the morning of New Year’s Day to talk about it. The Chinese space programme was about to land its mission Chang’e 4 on the far side (don’t say the dark side) of the Moon, while NASA’s New Horizons spacecraft was fast closing in on a bizarre object in the outer reaches of the solar system called Ultima Thule, revealing with unnerving seasonality that it resembles nothing so much as a giant snowman. And all in the year that marks the 50th anniversary of the first Apollo moon landings.

There’s more on the way, though not so imminently. The BepiColombo mission, a collaboration between the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA), is currently hurtling towards Mercury, the smallest and least explored of our neighbouring planets. But it won’t arrive there until 2025, because, ESA’s adviser for space exploration Mark McCaughrean explained to me as we munched soggy toast at the BBC, it must take a circuitous route to shed all the speed it gathers as it travels inwards towards the Sun, allowing it to enter orbit around the planet. ESA should also this autumn launch a space telescope called CHEOPS to investigate the known planets around other stars, while NASA’s Mars InSight lander, which touched down on the red planet last November, will be getting down to work drilling into the surface and sensing seismic vibrations to better understand the planet’s interior. And JAXA’s Hayabusa 2 spacecraft and rovers are currently busy investigating the asteroid 162173 Ryugu, on which the first two rovers touched down last September.

Humankind is, then, currently studying the solar system from its innermost to outermost regions. And with both the Moon and Mars under renewed scrutiny while we remember Neil Armstrong’s first footprint in the lunar dust, there is bound to be discussion of the prospect of getting a human presence once again beyond earth orbit—perhaps first on the Moon, then Mars.

Chang’e 4 landed safely on the Moon on 3rd January—the first time a spacecraft has touched down on the far side, which has previously only been photographed from orbit. It has now despatched its rover, called Yutu 2 (“Jade Rabbit,” referring to the animal companion traditionally ascribed to the Chinese moon goddess Chang’e). So far, the mission leaves no doubt about China’s space capabilities, and one might be tempted to interpret the remark of the project’s chief designer as Yutu 2 drove down its ramp—“a small step for the rover, but one giant leap for the Chinese nation”—as a piece of trolling directed at NASA. Claims of a new “space race” are rather overblown—there is more collaboration than competition these days, and ESA in particular is talking with China about joint astronautical missions for the Chinese modular space station, which is scheduled to be fully operational by 2022. But all the same, the potential for some rivalry between China and the US can’t be denied, not least because both are currently led by “strong men” who like to come first. If humans do eventually get back to the Moon, my money would be on them calling home in Mandarin.

But New Horizons offers a striking alternative to all this Apollo-redux enthusiasm. Only robotic missions could venture that far into our cosmic neighbourhood (as Frank Close has explained, quite apart from the time and distance humans would receive fatal doses of space radiation on such a long voyage). And New Horizons in particular has revealed what riches are to be found on its edge. The images it took of Pluto in 2015, with mountains of frozen nitrogen and complex patterns on its icy surface, not only stunned planetary scientists but began to show what an intriguing environment the Kuiper Belt—the halo of icy and rocky bodies beyond the last real planet Neptune—actually is.

Pluto itself, along with its moon Charon, are now recognised as belonging to this family of astronomical objects, named after the Dutch-American astronomer Gerard Kuiper.The main part of the Kuiper Belt extends from Neptune’s orbit around 4.5 billion km away out to a distance of about 7.5 bn km. Pluto and Charon were the only specifically identified bodies within it until the discovery of another, called Albion, in 1992.

There may be up to a billion or so of these objects, but they seem all to be no larger than the “dwarf-planet” size of Pluto, and are mostly much smaller – too small, then, to image in any detail from Earth. This was why, until New Horizons, Pluto itself had been known only as a fuzzy blob. Other relatively large known Kuiper Belt objects include Eris, Haumea and Makemake, with diameters around two-thirds of Pluto’s, or less. They have been seen so far only as hazy spots of light, although Haumea’s shape has been deduced indirectly to be an egg-like ellipsoid.

Ultima Thule is another of these objects, and reveals now how profoundly unspherical they can be. It appears to consist of two roughly spherical, icy bodies stuck together just like the head and body of a snowman, reaching about 33 km from one tip to the other. The two-lobed object, welded together by gravity, spins around every 15 hours, and has a rusty-red surface owing to chemicals formed from the effects of space radiation on the frozen methane and nitrogen thought to coat it. (Charon has patches of similar hue.)

The New Horizons flyby, said McCaughrean, “is the first mission which has got to the very edge of our solar system” and been able to image Kuiper Belt objects close-up. These bodies “remained unaffected for the four and a half billion years since the sun first formed,” he added, “and therefore contain a record of the early evolution of the solar system.” That’s why they are scientifically interesting: New Horizons gives us a chance to, in effect, rummage around amongst the pristine stuff from which the solar system is made.

That illustrates the key difference between human spaceflight and uncrewed missions. The former attempts to exploit notions of a kind of manifest destiny to venture to the stars—the Columbus myth rewritten for the space age. But it is the latter that are the real vehicles for science, and which have done most to broaden our horizons and deepen our knowledge about our own little corner of the universe.