The Week in Space and Physics
On a Martian magnetosphere, the James Webb and exoplanets, Europe's astronauts and Russia's new module at the ISS
What does it take to make a barren, toxic world inhabitable? Those who speak about colonising Mars – Elon Musk, for example – often give the impression that this is little more than an engineering challenge. The reality, unfortunately, is different. Planets are complex, dynamic things, and controlling them is far from trivial.
Take, for example, the lack of a Martian magnetosphere. On Earth this magnetic shield stretches hundreds of miles above the planet and offers crucial protection from the whims of the Sun. Without it the atmosphere would gradually fade away, swept into space by the solar wind. Violent flares would irradiate the surface, destroying the ozone layer and making life all but impossible.
If we ever want to colonise Mars, then, we would need to find a way to construct an artificial magnetic shield. That – like modifying the climate – turns out to be easier said than done; a task that in reality would consume enormous time and resources.
A recent paper, published by researchers in Britain and America, took a serious look at the problem. There are, they think, three possible ways a Martian magnetosphere could be created. Future settlers could try to restart the planet’s core – long dormant – so that a natural field re-emerges. If that doesn’t work, they could try placing magnets in orbit, thus creating an artificial magnetic field. Or, as a third option, they might try pumping vast amounts of highly magnetic plasma around the planet.
The first – restarting the core – is little more than a fantastic dream. Though Mars has a molten iron core, the authors of the paper conclude that warming it enough to restart magnetism would take a huge amount of heat. So much, indeed, that even a billion atom bombs detonating deep underground would still fall far short. And – even if we somehow get it started – we have no idea how long it would keep working.
The second option relies on technological breakthroughs that could be decades or centuries away. Engineers would need to encircle the plant with electromagnets, each fueled by an orbiting nuclear fusion reactor. The magnets themselves would be built of novel materials, designed to be light enough to reach orbit.
All that would take a huge industrial base on Mars. Even if we had the necessary technology – nuclear fusion is hardly yet feasible on such a scale – that kind of Martian industry is at best centuries in the future. The idea, indeed, needs so much material and engineering that it would be a stupendously complex problem; one doomed to certain failure.
Creating an artificial plasma layer, as the third idea suggests, is more practical. Mars has two small moons – Phobos and Deimos – which the researchers suggest could be mined and converted steadily into plasma. Over time that would produce a plasma belt which, eventually, would create its own magnetic field – and a shield around the red planet.
Even so, even that third option is barely possible with today’s technology. Terraforming Mars - turning it into a new Earth - belongs to the far future; to a time when science and engineering look very different. For now, then, Earth is our only option.
James Webb: Exoplanets
The James Webb Space Telescope continues to move slowly towards a late December launch. After a slight delay last week, engineers this week started pumping fuel into the telescope. That should take around two weeks, after which a crane will hoist the spacecraft into Ariane rocket that will carry it into space.
Some of the most exciting targets of the James Webb are exoplanets: those mysterious worlds circling distant stars. Though astronomers have found traces of thousands of such planets, few have ever been seen in detail. The reason for that is simple: planets are small, relatively speaking, and unlike stars emit no light of their own.
Instead astronomers look for the effects of planets on their host stars. Some wobble, as big planets drag them around. Others dim repeatedly, a sign of a planet passing regularly in front of it. These approaches can reveal certain parameters of a planet - how big it is, how long its orbit is, even its density. But they miss other, more interesting details.
The James Webb, astronomers hope, will be able to pick out traces of exoplanet atmospheres. That should allow us to work out what they are made from - whether nitrogen, like Earth, or carbon dioxide, like Venus. Though that won’t be quite enough to say if they have life, it should be enough to give a vague sense of a planet and its weather.
As rays of light pass through an atmosphere – on Earth or any other planet – they the gases they encounter slightly alter them. This gives those atmospheres a characteristic colour, which, if analysed carefully, can tell you what gases are present in it.
More precisely, each gas in an atmosphere absorbs certain wavelengths of light, essentially subtracting them from the light passing through it. Since scientists know which wavelengths are absorbed by each gas, measurements of light can reveal the gases that must be present.
The hard part, of course, is getting those measurements. Again, astronomers must look at the effects of planets on stars. But instead of a dimming or wobble, the James Webb will instead look for a slight change in colour as a planet passes in front of the star.
One key target is the TRAPPIST-1 system. Lying forty light years away, the solar system is one of the biggest known: containing seven Earth sized planets. Astronomers plan to repeatedly observe it in the years after launch - observations that should tell astronomers much more about those planets. Are they, indeed, hostile toxic worlds like Venus? Or might one appear startlingly Earth-like, with nitrogen, oxygen and even - perhaps - faint traces of biology?
European Astronauts?
Europe’s space agency, ESA, is somewhat of an outlier among such institutions. For one thing, it does not reflect the interests of any single nation, instead combining funds and ambitions from twenty-two smaller nations. For a second, it has no ability of its own to send astronauts to space – and has, historically, placed little priority on doing so.
So far all Europe’s astronauts – of which there are just two dozen – have reached space on Russian or American vehicles. That stands in sharp contrast to other space faring nations. America and Russia have each put more than a hundred people in space and each have their own human rated rockets. Even China and India - two rising powers - are rapidly developing their own human spaceflight systems.
Could that change? In a recent declaration – known as the Matosinhos Manifesto – ESA hinted at putting more focus on human spaceflight. The plans – which are somewhat tepid, it must be said – could involve building a new spacecraft, one that gives ESA its own ability to launch astronauts.
Still, caution is advised. ESA has been here before – even going so far as to design a European space shuttle during the early 1990s. Faced with high costs and cheaper foreign alternatives, however, ESA has always ended up putting their plans on ice. That, despite the fine words, is unlikely to change anytime soon.
Russian Adds a New Space Station Module
A decade ago, Russia drew up plans to build a successor to the International Space Station (ISS). The plan, known as OPSEK, would have served as a kind of spacecraft assembly facility: building vast interplanetary ships in orbit. From this base Russia could have sent astronauts across the Solar System: to Mars, to Jupiter and even to Saturn.
The scheme proposed building the new space station around the International Space Station. New modules would be built on Earth, launched and then docked with the existing station. When enough of the new station was in place, Russia would undock from the ISS and slowly drift away.
Though mission planners ultimately deemed the idea impractical, Russia did start building key parts of it. One – the Prichal docking module – would have served as the heart of the station, a module where ships could dock, undergo construction in orbit, and eventually separate for an interplanetary voyage.
Despite abandoning the plan that motivated Prichal, Russia last week launched the new module and docked it at the space station. That means the Russian half of the station now has a brand new docking station – but no plan to ever use it. In theory the module could serve as a node for future expansion, allowing Russia to connect advanced new modules to the space station.
Since Russia intends to withdraw from the international project in the next few years; it seems unlikely that any new modules will ever be sent. Indeed, the only modules Russia is now constructing are officially intended to be part of an entirely new Russian space station. Russia’s new module, then, seems more a testament to a failed dream than any true expansion of abilities.
If you enjoyed this post and haven’t subscribed already, then why not subscribe to our One Blue Planet newsletter or share it with a friend? If you subscribe, you’ll get two free emails a week covering the latest news and findings from physics, astronomy and the space industry.