The Week in Space and Physics

On alien technology, magnetic tunnels, private space stations and problems with Lucy.

For decades men and women have searched the skies for alien radio signals. That this has so far proved fruitless is perhaps not all that surprising. Space is big, radio signals can come on any one of countless different frequencies, and radio technology is, anyway, a rather primitive approach to interstellar communications.

We might, some thinkers now suggest, have more luck looking for signs of alien engineering. These, the logic runs, should be easier to spot and harder to hide – if, indeed, aliens aren’t seeking to contact us. What, though, might that engineering look like? And if it exists, how can we distinguish it from natural objects in the sky?

At a fundamental level, the need to gather and control energy drives civilization. As they grow more advanced, so does the ability to control energy. One can picture, on a grand scale, our own global civilization in this way: advancing through the ages from simple wood fires to complex nuclear reactors.

It is reasonable, then, to think that an even more advanced civilization – perhaps thousands of years more developed than us – would build power stations of enormous complexity. They may even, some have suggested, place gigantic solar farms around stars. These “Dyson Spheres” could conceivably allow them to channel and control an enormous amount of energy. Enough, indeed, to power an interstellar empire.

Some astronomers have taken the idea even further: suggesting aliens may seek to harness black holes for energy. Black holes, of course, emit very little energy; instead appearing as a kind of “cold star”, pulling in energy from the rest of the universe. If some of this energy could be diverted, the reasoning goes, it could be put to useful application.

A recent paper from the National Tsing Hua University in Taiwan, however, pours cold water on this idea. The power that can be obtained in this way, they calculate, is far too low to be useful. Instead they point to the energetic disks of dust and debris that sometimes swirl around black holes. These disks, swept up in the black hole’s powerful gravity, could – the authors say - be harnessed for power generation.

If so, an alien civilization would need to build some kind of massive structure around the black hole. That – like a Dyson Sphere – should leave a distinctive signature in the sky. The authors reckon it would get rather hot – a consequence of the enormous amount of energy flowing through it – and we could spot that heat from Earth. One possibility, they say, is to look for black holes that seem unusually hot in certain wavelengths.

Astronomers may well now do that. Previous measurements of black holes have captured much of the necessary data. Analysis of that data could reveal interesting targets - and if any are found, astronomers could take a closer look.

Realistically, however, their chances look low. Predicting how a civilization a thousand years more advanced than us would generate energy is a fools’ game: something no more possible than a caveman imagining a nuclear reactor. Astronomers might be better off sticking with the radio signals, at least for now.

A Magnetic Tunnel Surrounds our Solar System

Astronomy is a rather unusual science. Unlike almost every other branch of science – from quantum physics to genetic theory – experiments rarely play a part in the astronomy. Most astronomical objects are, after all, vast in size. One can hardly put a star in a laboratory and experiment with it. Instead astronomers must watch the night sky carefully, and glean what details they can from their visions.

This results in some oddities. Our own galaxy, for example, remains somewhat mysterious. Astronomers can tell you, in quite extraordinary detail, what is happening in a galaxy fifty million light years away – yet, we have almost no idea what lies on the other side of the Milky Way. Even the exact shape of our galaxy – probably a spiral, perhaps with a bar in the centre – remains uncertain.

Our fixed place within the galaxy is the reason for this. Though we can clearly see distant galaxies, our view of the Milky Way is frequently obscured by clouds of dust and gas. Its centre, a region richly populated with stars, black holes and drifting dust, blocks our view of what lies beyond. It should, astronomers think, look much like the side we can see, but whether it really does is, at least for now, almost completely unknown.

Even around our own Solar System we sometimes have trouble working out the true structure of things. For decades astronomers have known about two odd sources of radio waves in the sky. Both appear to be big, a thousand light years or more long. Both are magnetic structures, shaped like long filaments or ropes stretching through space.

The origin of these structures has been unclear since their discovery, but one researcher – Jennifer West at the University of Toronto – suggests that they are actually the same object. She posits that an enormous tunnel stretches across hundreds of light years. But - since we happen to lie within that tunnel - we cannot fully see it.

Instead, the two structures are actually, she thinks, the walls of this tunnel, curving away from us. The implications for Earth, however, are minor. The walls lie hundreds of light years away, and it should have little impact on us or our Sun. Indeed, such tunnels could stretch across much of the galaxy; forming part of its extensive magnetic field and providing a route for gas and debris flowing from supernova explosions.

Space Stations Go Commercial

The idea of a fully private and commercial space station has been growing in strength over the past few years. NASA, eyeing the possible demise of the International Space Station by the 2030s and unwilling to pay tens of billions to build a new one, has encouraged the concept.

Three companies – Nanoracks, Lockheed Martin and Voyager Space – have now announced plans to build such a station. This, named Starlab, would be a little under half the size of the International Space Station. It would support a research lab, and could host up to four astronauts at any one time.

According to Nanoracks, the station would be available for scientific and manufacturing purposes, sold, presumably, to whoever is willing to pay for such capabilities. That would likely include NASA, but potentially also universities, start-up companies and – probably – rich people who merely fancy spending a few days in orbit.

Nanoracks say the station could be in orbit by 2027. Though that date will almost certainly be delayed – few ambitious space projects happen on schedule – Nanoracks is not the only company expressing interest in an orbital outpost. Both Blue Origin and Axiom Space are planning to build their own stations over the next few years.

Lucy Stumbles

A week ago NASA launched their latest interplanetary mission, Lucy. Over the next few years the spacecraft will head out as far as the orbit of Jupiter, giving astronomers a close up look at two clouds of asteroids found there. That mission may, however, be threatened by an issue detected shortly after Lucy left the Earth.

The spacecraft is powered by two sets of solar panels, together providing about half a kilowatt of power, even when Lucy is eight hundred million miles from the Sun. One of those solar panels, however, does not seem to have deployed properly. Operators believe the panel is only partially unfurled, which is likely to reduce the amount of power it can generate.

Whether that is a serious threat to the mission or not remains to be seen. NASA has stressed that all other parts of the spacecraft are working well, and Lucy is already travelling towards its eventual destination. Even if the solar panel issue limits the power available, mission planners will likely try to find alternative ways to carry out the planned experiments. They have, after all, several years to come up with ideas - Lucy’s first encounter with an asteroid will not come until 2025.

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