The Week in Space and Physics: A Revolution Postponed?
On a challenge to the standard model, the future of Europe's astronauts, Starship and Artemis, and Euclid.
Two years ago researchers at Fermilab announced a result that shook the foundations of physics. It involved a slight oddity in the magnetism of the muon, a sister particle to the electron, which seemed to hint at the presence of particles and forces beyond the known laws of nature. At the time it was heralded as the opening shot of a revolution; a discovery that could usher in a new age of physics.
Such a breakthrough is sorely needed. Over the past few decades, physicists have built a theory of fundamental forces and particles they call the standard model. It is fantastically successful: probably the most successful theory of all time. No experimental evidence has ever contradicted one of its predictions, and the particles it proposed - notably the Higgs Boson - turned up as expected.
Yet in some areas the standard model is lacking. It does not account for gravity - a force currently described by Einstein’s relativity. Indeed, the standard model is incompatible with relativity, since the two theories view nature in two very different ways. Other mysteries, like those of dark matter and dark energy, are left unexplained by the standard model.
Many physicists thus believe a deeper theory must underlie the standard model. Just as Einstein once revealed a more profound truth behind Newton’s theories, so today’s physicists dream of unveiling a more fundamental and elegant theory behind both the standard model and general relativity. Yet doing so has proven hard.
The problem lies in the success of the standard model. Newton’s theories, by the time Einstein came along, had well understood difficulties. Einstein used those to break the theory open, reformulating it in a more fundamental way that resolved Newton’s difficulties. The standard model, by contrast, has no known experimental flaws. With no clear areas to attack, physicists have struggled to uncover a deeper understanding.
The results at Fermilab two years ago seemed to change that. Researchers had sought to measure the magnetic moment of the muon, a parameter for which the standard model gives a prediction. Yet the number that came up in the experiments was different from that prediction; an outcome that hinted at the presence of unknown physics.
New data, published last week by Fermilab, has given them more confidence in that experimental value. Yet the results are not as good for physicists as they might seem. Over the past few years theoretical physicists have been reworking their calculations of the muon’s magnetic moment using new computational approaches. As they have done so, the theoretical value of the magnetic moment has moved closer to the experimental one.
By 2025, Fermilab hopes to release a final value for the magnetic moment. At the same time, theoreticians are working to update the standard model’s prediction for the same parameter. If they still disagree - which is still very much a possibility - the door will be open to a revolution in physics. But should they agree, which now looks more likely, the standard model will have notched up yet another victory.
A New Path for Europe’s Astronauts?
Unlike Russia or America, Europe has historically paid little attention to human spaceflight. The continent’s space agency, ESA, has preferred to focus on building telescopes, satellites and probes. Some of these, of course, have been big successes, including Rosetta, Gaia and, most recently, Euclid.
Yet when it comes to astronauts, Europe has less to boast about. It currently has just six active astronauts, with five more in training. They, when they travel to space, must rely on foreign rockets and capsules - the continent has no human-rated options of its own. Unlike Russia, China or America, it has never built a space station. The closest it came was the Columbus module, which forms part of the International Space Station.
There are signs, however, that ESA is quietly changing the way it thinks about human spaceflight. Its latest astronaut recruitment included five new “career” astronauts, but also eleven “reserves”. At the time, the role of these reserve astronauts was somewhat unclear, as ESA confirmed they will get limited training and no guarantee of a trip into space.
In recent months, two countries - Sweden and Poland - have signed deals with Axiom, a private company, to send astronauts into orbit. The Swedish astronaut, Marcus Wandt, is now likely to fly to the space station in January. Poland has not named their candidate, though it seems likely to be Sławosz Uznański, a member of the ESA astronaut reserve.
Does this signal a new way forward for European astronauts? By creating the reserve, ESA seems to have told its member states they can have astronauts if they are willing to pay for them. But more significantly, ESA is also showing it is open to partnering with commercial providers of human spaceflight.
That could become more important in the decade ahead. As the International Space Station comes to the end of its life, several private companies are now planning to build replacements. ESA, which has no plans to build a station of its own, might choose to rely on those private companies instead of foreign agencies like NASA.
The current move to work with companies like Axiom may be an early shift towards this new approach. For Europe, which has invested little into human spaceflight, joining forces with private providers may give it the means to put astronauts in orbit for a far better price.
Starship and the Moon
America’s return to the Moon kicked off last year with Artemis I, an uncrewed flight of the SLS rocket and Orion capsule around the Moon. That should be followed late next year by Artemis II, a flight that will follow a similar trajectory but this time carry a crew of four astronauts.
In late 2025, or more likely early 2026, the third Artemis mission should see the first lunar landing in five decades. Yet, as NASA warned last week, this schedule is looking hard to meet. Of particular concern is the readiness of Starship, the spacecraft that should carry astronauts down to the Moon’s surface and back.
SpaceX needs to demonstrate several technologies before that can be done. First, and most obviously, Starship actually needs to reach orbit. But even once it does, SpaceX needs to show they can refuel it in orbit - a challenging task - and also fly an unmanned test flight to the Moon’s surface.
Somewhat strangely, NASA has only asked SpaceX to prove Starship can land on the Moon, not necessarily take off again. SpaceX has shown that Starship can lift-off and land on Earth - though it has only done so successfully once. The Moon, of course, is a more hostile environment, and one far harder to access if anything does go wrong.
That demonstration was originally planned for next year. Yet given the current progress of Starship, it is far from certain that SpaceX will be able to meet that goal. If they cannot, NASA will either have to delay Artemis III, or push the landing towards Artemis IV, currently penciled in for 2028.
First Light for Euclid
ESA has high hopes for Euclid, their latest space telescope. From its vantage point some one million miles from Earth, the telescope will chart the positions of billions of galaxies; mapping out one third of the night sky in total. This, ESA’s scientists hope, will allow them to trace the presence of dark matter and dark energy across the cosmos.
Yet when ESA turned the telescope on a few weeks ago, they encountered a problem. Stray light appeared in its images, creating an unwanted pattern that threatened its mission. At blame, engineers realised, was a small gap in the telescope. That allowed sunlight to spill in, disturbing the sensitive optics needed to observe distant galaxies.
Fortunately engineers found that rotating the telescope helped. At the right angles, indeed, the telescope can operate as intended, free of any unwanted sunlight. In images released at the start of August ESA showed off the performance of the telescope. Scientific activities, they say, will start within a few months.