At 2.51am on Monday 15 July, engineers at India’s national spaceport at Sriharikota will blast their Chandrayaan-2 probe into orbit around the Earth. It will be the most ambitious space mission the nation has attempted. For several days, the four-tonne spacecraft will be manoeuvred above our planet before a final injection burn of its engines will send it hurtling towards its destination: the moon.
Exactly 50 years after the astronauts of Apollo 11 made their historic voyage to the Sea of Tranquillity, Chandrayaan-2 will repeat that journey – though on a slightly different trajectory. After the robot craft enters lunar orbit, it will gently drop a lander, named Vikram, on to the moon’s surface near its south pole. A robot rover, Pragyan, will then be dispatched and, for the next two weeks, trundle across the local terrain, analysing the chemical composition of soil and rocks.
The Indian spaceship will not be alone on the lunar surface, however. China’s Chang’e-4 has been operating flawlessly since it landed on the far side of the moon in January. Its arrival was later followed by the appearance of Beresheet, a probe built by the Israeli non-profit organisation SpaceIL. It reached the moon in April but crash-landed. SpaceIL has since announced that it intends to have another shot.
At the same time, the US has pledged to set up lunar laboratories in the near future, while Europe and Russia have also revealed plans to launch complex missions. Suddenly, everyone’s going to the moon.
But why? What has suddenly made Earth’s main satellite so popular? After Neil Armstrong and Buzz Aldrin’s historic mission in July 1969, public and political interest in future human space flight evaporated rapidly. Already bogged down in a vastly expensive war in Vietnam, the US government abandoned its Apollo programme.
The decision disappointed scientists but, given that Apollo was costing 4% of the US federal budget at the time, the cancellation was not surprising. Since then there have been only a handful of robot missions to the moon, and human ventures have been restricted to missions in low Earth orbit, with special attention being given to the International Space Station. However, that focus now appears to be changing to more distant goals.
One reason for this shift is that the moon’s exploitation has simply reached a stage that mirrors past explorations on Earth, says David Parker, director of human and robotic exploration for the European Space Agency. He sees particular parallels with our conquest of the south pole.
“The timetable of the exploration of Antarctica mirrors that of the moon in an uncannily close manner,” Parker says. “At the beginning of the century, there was a race to reach the south pole and then no one went back for 50 years – just like the moon in the 60s. Then we started building bases in Antarctica. We are now approaching that stage with our exploitation of the moon.”
Antarctica was opened up by technological advances – motorised vehicles, air transport, radio, and other developments – that are mirrored in the new sciences of machine learning, sensor technology and robotics. These promise to transform lunar colonisation in one crucially important way: by reducing the need for the continual presence of humans in hostile environments.
“There is a huge cost gap between manned and unmanned missions, and it is increasing all the time,” says Britain’s astronomer royal, Martin Rees. “With each advance in robots and miniaturisation there is less need to put a man or woman into space or on to the moon, and that saves money.” For a space agency like Nasa, which has to manage on a budget that is little more than 10% of funding in its heyday, that is certainly a key issue.
And the success of China’s Chang’e-4 probe provides an example of what can be achieved without human involvement. It is the first vehicle ever to alight on the moon’s far side, and has continued to operate without problems, despite having to survive prolonged periods when temperatures have plummeted to below minus 180C during lunar nights. (These last for 14 Earth days. Apollo schedules were planned to make sure astronauts landed only during daytime on the moon.)
Exploiting these advances in robotics to aid human activity on the moon will form the backbone of the forthcoming US Lunar Gateway project. Nasa plans to use America’s giant Space Launch System rockets and Orion crew-carrying capsules – both in the final stages of development – to build a smaller version of the International Space Station that would orbit the moon. Partners from Europe, Canada, Japan and other countries have been invited to take part in Gateway, which would be constructed over the next decade.
Gateway would be used by astronauts to operate robots working on the lunar surface a few dozen kilometres below them. These automated machines would be used to set up radio telescopes, to harvest minerals, to search for ice and water and to study how lunar rocks could be used as building materials for a lunar colony. Ultimately a craft would one day carry humans down to work on the moon in colonies prepared for them by robots.
“And that is good news for Europe,” adds Parker. The European Space Agency is collaborating with Nasa over Gateway’s construction – by providing the propulsion units for the Orion spaceships that will ferry astronauts to the Gateway station in lunar orbit. “We should therefore be in a strong position to have a European astronaut taken to the moon,” he says.
The scientific gains from studying the moon from missions such as Gateway would be considerable, adds Jeffrey Kargel, at the Planetary Science Institute in Tuscon, Arizona – a scientist who is particularly keen to exploit the moon’s geological history. On Earth, tectonic processes have wiped out rock records before 3.8 billion years ago. “But on the moon we already know that Earth-derived meteorites [rocks blasted out from an impact with Earth] are preserved in accessible samples gathered by Apollo astronauts,” Kargel says. “From early Earth meteorites we could learn about the origins of our planet’s continents, the first traces of an ocean on Earth, the composition of the primordial atmosphere – and the origin of life.”
Parker is equally enthusiastic about the moon’s potential for study. “It has lain virtually undisturbed for the last 4.5 billion years,” he says. “It is a museum of the history of the solar system.” He argues that the potential rewards from such a lunar outpost mirror those already gained from bases set up in Antarctica. “The hole in Earth’s ozone layer was discovered by polar scientists who are also doing crucial work on the impact of climate change and global warming on our planet. That is the kind of return we could get from setting up Gateway.”
There are other reasons to return to the moon, however. For many space enthusiasts, its exploration and exploitation is necessary if we are to make the next giant step in space: sending people to Mars. “That is the real goal for humanity,” says Parker. “However, getting humans there safely is going to be an incredibly difficult undertaking. We will have to learn first how to conquer the moon.”
In building and running the International Space Station, humans have learned how to master space close to Earth. It orbits about 400 kilometres above the Earth, says Parker. “By contrast, the moon orbits 400,000 kilometres distant from the Earth, a thousand times farther away. Mastering a hostile environment that distant will require us overcoming all sorts of technological hurdles. Then we will be better armed when we start looking at Mars, which is 400 million kilometres away – a million times farther from Earth than the space station. This is going to be a long process.”
Rees sounds a note of caution. “There is a tendency to see Mars as the solution to all our problems on Earth. We will just move on to a new planet and save our species. But that is a dangerous delusion. We have to solve Earth’s problems here and now. Coping with climate change may seem daunting but it will be a doddle compared with surviving on Mars.”
However, there is another, more poignant reason for returning to the moon and it is one that focuses on the individuals who visited 50 years ago. Only six Apollo missions made it to the lunar surface, each crewed by two men. Thus only 12 humans have ever walked on the moon. They all were male; were born in the 20s and 30s in midwest America; were either only children or the eldest in their families – and, with the exception of Apollo 15’s James Irwin, all had been Boy Scouts. On their way to and from the moon, each earned $8 a day, minus a fee for a bed on their Apollo spacecraft.
The crucial point is that these are the only humans who have ever had first-hand experience of standing on another world and only four of them are still alive: Apollo 11’s Buzz Aldrin (now aged 89), Apollo 15’s David Scott (87), Apollo 16’s Charles Duke (83) and Apollo 17’s Harrison Schmitt (84).
“Given their age I think we could soon find ourselves in a time when there are no humans left with first-hand memory of another world,” added Rees. “Like millions of other people, I will find that sad.”
The question facing space scientists is therefore straightforward: is there a chance another human might walk on the surface of the moon before the last Apollo moonwalkers die? Until recently, the answer would have been “probably not”. The timetable for Gateway’s construction was modest and slow, and astronauts would probably not have used it to reach the lunar surface for at least a decade.
But that timetable was recently thrown into confusion when the US vice-president, Mike Pence, announced in March that the White House was directing Nasa to accelerate the human component of the Gateway project so that astronauts could fly down to the moon’s surface by 2024. Many doubt that this will be possible. No lander craft to make this descent has yet been designed, for example.
Nevertheless there is the prospect that this change of timetable will allow a US astronaut in the near future to step on to the lunar surface so that a surviving Apollo astronaut will witness another human following in their footsteps.
The crucial point is that when the Apollo astronauts were flying to the moon, it seemed science fiction had come true, says Rees. “It would be good if we can bring back that sense of wonder, if nothing else.”
