The Year in Space and Physics

A look back at the trends and news of 2024

NASA’s Solar Dynamics Observatory captured this image of a solar flare – as seen in the bright flash on the right – on May 14, 2024. Credit: NASA/SDO

The past year has shown the remarkable things humanity can achieve. Two, in particular, stand out. First, in October, was the capture of Starship mere minutes after it had launched: a feat in which engineers steered a rocket the size of a twenty-story building back to Earth, and then settled it, gently, on a waiting frame.

The other, accomplished just days ago, was a probe’s flight through the corona of the Sun. No other spacecraft has ventured so close to a star, nor has one ever reached such high speeds - the Solar Probe, as it neared the Sun, traversed almost two hundred kilometres in a single second.

There have been other fantastic achievements this year, of course. NASA sent the Europa Clipper toward Jupiter; ESA retrieved the first scientific data from its Euclid telescope. The James Webb telescope observed the most distant galaxies known, and scientists laid out plans to build new particle colliders to probe the foundations of nature.

None of these would be possible without the hard work and vision of thousands of people working together. The age of the lone genius is long gone, if ever it was really here. It was only by standing on the shoulders of giants, Newton once said, that he could make his discoveries: it is only by focusing on a shared vision, today, that we can achieve great things.

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The Year of the Sun

In January of 2024, as I looked ahead at the year to come, one thing stood out. The year, I wrote then, would belong to the Sun. That prediction proved true: the past year has witnessed two solar eclipses, auroral displays unmatched in a century, and in the past few days, the closest-ever visit of a spacecraft to our star.

Of the two eclipses, by far the most watched was that of April. It carved a path of darkness across North America, stretching from the Pacific coast of Mexico to the Atlantic coast of Canada. Some fifty million people are thought to have stood in the path of totality. The annular eclipse of October, by contrast, passed almost without notice. It took place over the Pacific Ocean, touching only the very southern tip of South America.

Eclipses alone, of course, do not make a year special. But 2024 was also the year in which the Sun reached the peak of its eleven-year cycle. And because the last peak, in 2014, was unusually weak, this year has seen the Sun at its most active in at least two decades. That meant the year’s total eclipse was marked by an unusually visible corona, but it also brought some dramatic aurora.

Those aurorae were most visible in May, when a series of solar flares combined to produce the most intense solar storm seen in decades. On the night of May 10th, the aurora was seen as far south as Hawaii - an event that had not happened, reports said, in more than a century.

Such a powerful event is unlikely to be repeated any time soon. But we did learn, this year, that the Sun is likely capable of even stronger superflares. Tree ring records speak of enormous flares in years 774 and 993 AD. Others, a study of fifty thousand sunlike stars found, probably occur on the scale of once per century or so.

This year has also been one of unprecedented exploration of our Sun. The Parker Solar Probe made four flights through the Sun’s atmosphere, the last of which - on Christmas Eve - flew closer to the Sun than any spacecraft has ever done before. Proba-3, a mission to create artificial eclipses and so to study the corona, launched in December. And other probes, including the Solar Orbiter, continue to study our star.

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NASA’s Annus Horribilis

For NASA, 2024 might be a year better forgotten. The low point came in the summer, when Starliner, a capsule supposed to bring cargo and astronauts to the space station, suffered an embarrassing failure. The astronauts it carried there, on a mission supposed to last no more than a few weeks, are still in orbit seven months later.

That was an embarrassment for Boeing, the company that built Starliner. But it was also a setback for NASA, who had hoped the capsule would offer an alternative to SpaceX’s Dragon, and so guarantee that America always has a spacecraft able to fly humans on hand. Boeing and NASA may well try to fly Starliner again, although as of yet no date has been announced for a fresh attempt.

NASA’s Moon program, Artemis, is also in trouble. Under the original plans, 2024 was supposed to have been a year of triumph; one in which American astronauts once again set foot on the Moon. Instead the program is mired in delays. Though the uncrewed Artemis I flew around the Moon in 2022, the second mission, Artemis II, will not fly until 2026. Artemis III - which NASA still insists will carry astronauts to the surface - is now planned for 2027.

On the science side, NASA can at least celebrate the launch of Europa Clipper, a spacecraft that will explore one of Jupiter’s most intriguing moons. Yet even here the problems cannot be ignored. NASA has laid off hundreds of talented engineers over the past year, including many that worked on Clipper, and seen its ambitious plans to bring rock samples back from Mars put on ice.

Bizarrely, the agency also chose to abandon VIPER, a lunar rover that had been built at great expense. Instead of launching the fully assembled and tested rover, NASA decided to abruptly cancel the project. Scientists have loudly complained but, so far at least, NASA seems more likely to scrap the rover for parts rather than send it to the Moon.

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The Rise of the Machines

The Nobel Prize this year was awarded for breakthroughs that aided the development of artificial intelligence. It was a controversial decision, not least because artificial intelligence is more a field of computer science than of physics. Yet the innovations do have their roots in physics, and the development of such intelligent machines does offer benefits to the field.

One day, perhaps, machines will be capable of consuming the entirety of our knowledge, ingesting the data from immense experiments and then of outputting grand new theories of nature. We are not there yet. But artificial intelligence has started to aid researchers in parsing and analysing the data generated by modern experiments.

Take, for example, that created by the Large Hadron Collider at CERN. It can collide particles at an incredible rate, creating as much as one petabyte of data (equal to a million gigabytes) in a single second. Hidden with all that information are - we hope - the signs of new particles, of interactions unknown to physics, and thus of new theories beyond our present understanding.

For that, though, researchers must take the generated data and reconstruct the collisions it reports. That is, of course, a challenge for human eyes. The sheer volume of data is one problem, but so too is the fact that the most interesting outcomes are often the rarest. Machine learning and artificial intelligence have already helped researchers here - and will do so even more in the years to come.

Similar problems afflict astronomy. Here, too, telescopes and observatories are producing petabytes of data, containing everything from exploding stars to possible alien signals. Astronomers don’t have the time or ability to watch everything that is happening, but intelligent machines might - and they could, by working with human researchers, help pick out the most interesting things to study.

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China Launches a Thousand Sails

China brought back the first rocks from the farside of the Moon as part of the Chang’e 6 mission. Those rocks complement a set from the near side brought back in 2020 on Chang’e 5, and together represent the first moon rocks carried back to Earth since the days of the Space Race.

Analysis of the new rocks might have solved the mystery about why the Moon has two very distinct sides. But they also showcase the increasing abilities of China in space. The country now has launched multiple moon missions, has achieved the first landing on the far side of the Moon, and has a space station in orbit around the Earth.

Last year the country also started building out satellite constellations to rival SpaceX’s Starlink system. One, known as Qianfan or “Thousand Sails”, has put more than fifty satellites in orbit, and has plans to grow that to fifteen thousand by the end of the decade. A second constellation, Guowang, put its first satellites in orbit on December 16th.

To really compete with America and SpaceX, however, China needs new rockets. The past year has seen a mixed record on that front. True, China did launch over sixty times - but that is still only half of what SpaceX achieved. And it still lacks a reusable rocket, and must aim to do far better when it comes to safety and handling space debris.

The real prize for Chinese rocketry, though, will be a Moon rocket. The country has plans to put astronauts on the lunar surface by 2030, and is building the Long March 10A rocket to take them there. A first launch could happen in 2026, and perhaps even before NASA manages to launch Artemis II. The next footprints on the Moon are still likely to be American, but day by day the chances are growing that they will instead be Chinese.