The Week in Space and Physics: America and the Moon

On Peregrine and Artemis, an alien zoo, Starship's next flight and a ring of galaxies

The Moon rising over the Atacama Desert. Credit: P. Horálek/ESO

It was a bad week for America’s lunar ambitions. On Monday came the failure of Peregrine, a privately built probe that could have become the first American lander on the Moon in half a century. Then, on Tuesday, NASA announced a delay to Artemis II and III, a pair of missions that should see American astronauts return to the lunar surface.

The problems with Peregrine emerged soon after the spacecraft had reached space. Although the new Vulcan launcher successfully sent it towards the Moon, something then went wrong with the probe’s propulsion system. At blame, Peregrine’s operators have said, was a faulty valve that probably caused a fuel tank to explode.

Although the operators managed to stabilise the spacecraft, and so point its solar panels properly towards the Sun, the loss of fuel made a landing impossible. Instead Peregrine has followed a high orbit taking it several hundred thousand miles from Earth. Before long, however, the spacecraft will start falling back to Earth, and it will eventually be incinerated in the atmosphere.

This, then, is a rather disappointing end for the Peregrine mission. Nevertheless, the company behind the mission has plans to send another lander as soon as November, and potentially a third one in 2026. Intuitive Machines, another company, also hopes to send a lunar lander in the next few months.

The delay to Artemis, meanwhile, came as much less of a surprise. It has been clear for a while that NASA had no hope of landing astronauts in 2025, as they had previously aimed for. Though America has a tested moon rocket - the SLS - they still lack a lander to ferry humans to the surface, and spacesuits for them to wear.

Both of these crucial items are delayed. Starship, the spacecraft that will serve as a lander, is yet to reach orbit, let alone the Moon. Even once it is capable of that, NASA wants to see an uncrewed dry run, something that has no chance of happening by next year. Work on the spacesuits, meanwhile, has only just started, making them equally unlikely to be ready in time.

A report released in December estimated that NASA could be ready for landing by early 2027. For now NASA is officially targeting a landing in September 2026, with Artemis II - a crewed mission that will fly-by the Moon - also delayed until 2025. Both goals are probably still optimistic - so don’t be surprised to hear of another delay in the future.

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Do We Live in a Zoo?

Where are all the aliens? The basic ingredients for life - at least, life as we know it - seem to be widespread across the cosmos. Sunlike stars are found in abundance, as are rocky planets. The chemical building blocks for biology have been spotted in comets and in dust clouds across the galaxy. 

It seems unlikely, then, that the only place it got started was Earth. And if there is indeed life elsewhere, then it also seems reasonable that intelligence should also have appeared. And with it - since the universe has already been around for fourteen billion years - should have come advanced civilizations, capable of spreading across the galaxies.

Where are they then? No alien civilization has ever - as far as we reasonably know - turned up to meet us. None has been spotted in the skies, despite telescopes searching for signs of their influence. Few plausible traces of alien technology have been found - and none, certainly, that could not be easily explained away.

This puzzle is often known as the Fermi paradox, named after the Nobel Prize winning physicist who first raised it in 1950. Over the seven decades since, various ideas have been raised to explain the absence of aliens. Some argue that intelligent life is simply vanishingly rare, or prone to self destruction. Others think they are hiding, either out of fear or out of a desire to preserve us.

That last idea was the subject of a recent paper in Nature Astronomy. In it they point out that most solutions to the Fermi paradox are flawed, since they assume that all alien civilizations would meet a similar fate after venturing out into space. This, they say, is unlikely. Indeed, the only way they find to reconcile the paradox is if the galaxy happens to be dominated by a single advanced civilization.

Such a civilization, they say, could be enforcing a kind of cosmic zoo across the galaxy. Primitive civilizations like ours may be subject to strict rules, preventing alien contact until some future date. But this, they concede, is also unlikely, since we see few signs of such an advanced civilization. Exactly why aliens would choose to do such a thing is also unclear.

The only remaining option, they conclude, is for intelligent life to be incredibly rare. After all, life thrived on Earth for billions of years before civilization appeared. Perhaps ours is one of the few planets on which such a remarkable thing happened. And that, indeed, would make it all the more important to preserve it.

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Flight Number Three for Starship

Starship could fly again in February, SpaceX said last week. As with the two previous flights, the main issue once again seems to be securing a launch license. This must be approved by the Federal Aviation Authority and, according to SpaceX, they have listed a number of actions the company must take first.

Though no public information has been revealed, a similar list was released before Starship’s second launch. That time SpaceX was asked to modify parts of the rocket’s design to ensure it could fly safely and to improve several of the engineering processes followed by the company. 

For Starship’s first two flights, the company targeted a suborbital trajectory. Had all gone to plan, the rocket would have lifted-off, flown most of the way around the world, and fallen back to Earth somewhere close to Hawaii. Of course, neither flight actually got that far - though the second attempt did at least reach space.

According to Elon Musk, however, SpaceX is now hoping to reach orbit. Attempt number three could see Starship lift-off, reach orbit, and then conduct a series of tests before firing its engines to bring it back into the atmosphere. Most important of those tests will be a demonstration of fuel transfer from one tank to another inside Starship.

Though that might seem rather trivial, it is actually an important step on the road to proving Starship can refuel in orbit. That, in turn, is a key component of SpaceX’s - and NASA’s - plans to land on the Moon later this decade. A more sophisticated test, of transferring fuel from one Starship to another, should follow within a year or two, according to Musk.

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A Ring of Galaxies

Nine billion light years from Earth lies a vast ring of galaxies. The structure, recently discovered by a researcher at the University of Central Lancashire, is extraordinary in scale. In diameter it measures more than a billion light years across; its perimeter stretches for more than four billion.

That makes it one of the largest cosmic structures ever found. It also, since such large things should not really be possible, hints at so far unknown forces shaping the early universe. One possibility is the presence of a “cosmic string”, a hypothetical fracture in space created soon after the Big Bang. Such objects have never been found, but some theories suggest they could have played a role in the way galaxies spread through space. 

Whatever its cause, the ring also seems to lie close to another huge and mysterious structure, that one shaped like a giant arc. Both objects appear to be larger than modern cosmology should allow - and both, therefore, suggest we are missing something important.