The Week in Space and Physics: Nukes in Orbit

On nuclear weapons in space, the future of particle colliders, alternative magnetism and another Moon landing

Intuitive Machines head to the Moon onboard the Falcon 9. Image Credit: NASA/Kim Shiflett

In July 1962 the United States detonated a nuclear bomb four hundred kilometres above the Pacific Ocean. The immediate effects of the blast were spectacular. A bright flash of light lit up the night time sky, momentarily creating the illusion of a new sun in the firmament. Even as it faded an aurora lingered, dancing in vivid red flames from New Zealand to Hawaii.

Afterwards, radiation from the bomb stuck around. Energetic particles became trapped in the Earth’s magnetic field, forming an artificial radiation belt around the planet. In the weeks that followed at least six satellites failed, including Ariel-1, the first satellite launched by the United Kingdom.

Radiation belts are not the only harmful side effect of nuclear explosions in space. In October of 1962 a similar test by the Soviet Union sent a pulse of electromagnetic energy surging across Central Asia. The results were devastating: the pulse destroyed electrical grids and left a power station in flames.

Obviously, then, nuclear tests in space are a bad idea. The Soviet Union and United States agreed to outlaw them in a series of treaties, including the UN Outer Space Treaty of 1967. Ever since, as far as we know, space has remained free of nuclear weapons.

Is that about to change? In recent years space has become increasingly important in military affairs. Missiles and fighter jets are guided by GPS satellites. Military planners pore over satellite images to assess enemy movements and capabilities. Communications networks like Starlink have been crucial in Ukraine’s struggle against Russia.

Given this, it is not surprising that the world’s superpowers have been developing methods of attacking satellites. Four nations have proven their ability to shoot down satellites with missiles. Now, if reports of secret briefings by the US government are to be believed, Russia is turning once more to space-based nuclear arms.

The exact form of these new weapons is still unknown. But were a nation to detonate a nuclear bomb in low Earth orbit, the results could be catastrophic for systems like Starlink. Any satellites near the bomb would probably face instant destruction. Afterwards a new radiation belt would linger, imperilling any spacecraft that dared come near.

Of course, such a bomb would have unintended side effects. Radiation and debris could present a danger to astronauts, which Russia still sends to the International Space Station. The damage would not be limited to the intended target, either, since the radiation would affect all satellites in similar orbits. Both friend and foe of Russia would feel the fallout.

Whether Russia is really pursuing weapons of this kind is unclear. But one thing is undeniable. Space is becoming ever more crucial to modern warfare. So far, at least, combat itself has not reached orbit. But superpowers around the world are preparing for an age in which it does, and the very fact that nuclear weapons in space are once more being discussed is worrying.

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The Next Particle Collider

The Large Hadron Collider took ten years to build and cost five billion euros. In its fifteen years of operation it has smashed together protons and ions at energies unmatched by any other collider on Earth. In 2012 it spotted the first signs of the Higgs Boson, confirming many of our deepest theories of nature.

What it hasn’t done, however, is revolutionise those theories. The data coming from the collider has merely strengthened and confirmed the theories we already had. Questions about dark matter, dark energy and antimatter have all been left unanswered. Exotic new theories of physics, from supersymmetry to string theory, have been all but ruled out.

Over the next half decade scientists will upgrade the collider to run at even higher intensity. The resulting ‘high luminosity’ collider will probably produce a handful of new particles and help researchers study rare interactions. But expectations for revolutionary science are low. The Large Hadron Collider, physicists seem to have accepted, will not overthrow the established laws of nature.

The result has been a bit of a crisis for particle physicists. With no experimental evidence of new physics, many researchers in the field are now speculating, desperately searching for theories to solve the pile of unanswered questions. The result is a lot of talk about new forces and particles, but little in the way of solid evidence.

One possible answer to this impasse is to build an even larger collider. Earlier this month European researchers outlined a proposal for a future collider far bigger than the Large Hadron Collider. It would need a ninety kilometre long tunnel, they said, to be carved under the border of Switzerland and France. 

Once running, the collider would crash electrons into their antimatter equivalents, positrons. These collisions would take place at fantastic speeds, and involve energies ten times higher than anything achieved so far. That would put our theories of physics to a far tougher test and possibly stretch them to breaking point.

Despite the proposal, murmurs of dissent are rippling through the physics community. The new collider will cost a lot of money - perhaps sixteen billion euros - and has no guarantee of finding new science. Better to spend that money, some are saying, on experiments with a more certain outcome.

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A New Kind of Magnetism

Some metals, like iron, can form magnets. They can do this because of their electrons. In most material electrons spin randomly, pointing in all sorts of directions. In materials like iron, however, the electron spins align, so that they all point in the same direction. That results in an overall magnetic field which allows them to attract or repel other magnetic objects.

Magnets like this are called ferromagnets. About a century ago, however, physicists found another kind of magnetism, that they called antiferromagnetism. Here the electrons align again, but they do so in lines with alternating directions. This is an ordered system, which distinguishes it from materials where electrons spin randomly, but it is one which results in no overall magnetic field.

Ever since, physicists have believed that all magnetic materials fell into one of these two categories. Back in 2019, however, researchers in Switzerland found a material that seemed to defy this system. In 2022 they published a paper outlining a third category, that they called altermagnetism. Now they have gone a step further, and proven that this category really exists in reality.

Like antiferromagnetism, the new category aligns electrons with opposite spins. But it does so in a symmetrical crystal structure. That means the material has no overall magnetic field, but it does have some interesting electrical properties.

In theory that could help engineers develop new computing devices. Magnets are often used in computer memory, and altermagnets might allow hard drives to store more data than before. They could also be used in ‘spintronic’ devices, an emerging field that uses the spin of electrons to carry data and may allow for faster data processing.

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An Intuitive Moon Lander

If all goes to plan, Intuitive Machines’ Nova-C lander will touch down on the Moon tomorrow. The lander, which is the second privately built lander to head to the Moon this year, lifted-off onboard a Falcon 9 rocket last week.

The main goal of the lander is simply to demonstrate a safe landing. No private company has ever successfully landed on the Moon. All previous attempts have either failed enroute, or crashed during descent. So far only five nations have reached the Moon at all, with Japan becoming the newest member of the club in January.

If the lander does reach the surface, Intuitive Machines expect it to operate for about seven days. It will touch down close to the lunar south pole, a region that is of increasing interest due to the possible presence of water ice deep inside craters found there. This lander will not look for that water, but it will demonstrate several technologies that could pave the way for future robotic explorers of the lunar poles.