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Proxima Centauri

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Interstellar Flight

Want to be cheered up at the end of this benighted year? Okay, how’s this? It’s starting to look like interstellar travel may be possible in a time frame that would be manageable for human beings.

No, it’s not a cure for cancer. But we know that we are bound to find that eventually, so long as our civilisation is not destroyed by war or global warming or a random asteroid strike. Until very recently, our understanding of science told us that travel even to the nearest stars will never be possible.

That may still be true, for the answers are not all in yet. But last April the US National Aeronautics and Space Administration gave James Woodward and the Space Studies Institute a Phase 2 grant under the NASA Innovative Advanced Concepts programme.

They got a Phase 1 grant in 2017 to work on their proposed space drive. They made enough progress to keep NASA happy and themselves credible, and they have now been funded to test new designs that increase the thrust produced by their Mach Effect Gravity Assist (MEGA) drive. If that scales up satisfactorily, we will one day be able to build spaceships that go to the stars.

I must admit that I really enjoyed writing that last line, for all my life I have been told that interstellar travel is only science fiction. Real space flight is ruled by Russian scientist Konstantin Tsiolkovsky’s classic rocket equation of 1903, which says that a rocket can get into space by expelling enough of its mass (fuel) at high velocity, but also says that the payload and/or the speed is strictly limited.

More payload or more speed is possible, but only by burning more fuel. You must carry that fuel all the way from launch, which makes the vehicle heavier, which requires more fuel, and so on.

The ‘tyranny of the rocket equation’ is what makes space flight so expensive, and interstellar travel by rocket impossible. For a manned spaceship to reach the nearest star (Proxima Centauri, 4.2 light years), slow down again when it gets there, and do it all within one human lifetime, it would have to burn an amount of fuel roughly equal to the total mass of the Sun.

The fuel is the problem, not the distance. If you didn’t have to bring the fuel with you, sending a 400 kg. payload to Proxima Centauri and putting it in orbit around the most Earth-like planet would require a few years’ acceleration at a modest 1g, a maximum speed of 0.4c (four-tenths of light-speed, so no major relativistic effects), and a few years’ deceleration at the far end. It would arrive in around 20 years.

All recent proposals for interstellar flight have therefore abandoned rocketry and assumed ultra-light vehicles that carry large sails and are pushed by Earth-based lasers or by the solar wind. Two problems: the push dies away before they have travelled even one light-year, and they have no way of stopping at their destination.

So along comes Dr James Woodward, who published his first peer-reviewed article on the Mach effect in 1990, and Dr Heidi Fearn, his colleague at California State University, Fullerton. They worked on the theoretical physics of the Mach effect, they built miniature models of a space drive that doesn’t need to burn a propellant and tested them, and gradually the space community began to take them seriously.

NASA is certainly taking them seriously now. Contrary to what some of their critics claim, what they are doing does not violate fundamental physical laws like ‘every action must have an equal and opposite reaction’. However, it does run contrary to our daily experience of those laws by exploiting some of the more arcane aspects of quantum physics.

I’d explain the Mach effect in greater detail, but I barely understand it myself. Suffice it to say that their MEGA drive uses electricity to produce mass fluctuations within a block of metal, which in turn propels the drive forward without burning fuel. What is it pushing against? All the rest of the mass in the universe.

This isn’t a sure thing. There is still controversy over whether the ‘push’ is real, or just an electrical or magnetic effect that creates a false positive. But NASA is willing to spend money on it, and a lot of other scientists are now following up on Woodward’s and Fearn’s work.

It would open the doors to the rest of the universe for us. Exploration, colonisation, unlimited resources, perhaps contact with other intelligences – all of that becomes much more possible than it would be if we must remain forever confined to this one small planetary system. And of course it would make getting around this system a great deal easier: the Moon in four hours, Mars in 2-5 days, Jupiter in 7-8 days.

How’s that for (potentially) good news?
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To shorten to 725 words, omit paragraphs 9 and 11. (“All…destination”; and “NASA…physics”)

Space Dreams

Some other contender for the title of Curmudgeon of the Year may emerge before the end of December, but at the moment it looks like Mark McCaughrean, senior adviser for science and exploration at the European Space Agency, will win in a walk. When Elon Musk unveiled some details of his plan to create a large human settlement on Mars in the journal New Space in June, McCaughrean tweeted as follows.

“It’s a wild-eyed investment pitch, pumped up by the enthusiasm of fanboys brought up on comic-book sci-fi, wrapped in evangelism of saving humanity from itself and the problems we’ve brought on this planet, a kind of modern-day manifest destiny,” he said, waving his stick angrily in the air. (I made that last bit up.)

“I’m less concerned about making humans a multi-planetary species than I am about making the Earth a sustainable multi-species planet, before we go gadding off colonising the solar system,” he continued. Harrumph. Science journalists always have the phone numbers of grumps like this, because every science story has to have a quote from somebody saying that it’s a bad idea – but it does sound like McCaughrean is in the wrong job.

I’m writing this now, although McCaughrean’s rant happened almost two months ago, because I’m currently on Baffin Island, just about the least hospitable place on Earth that has sustained a long-term human presence.

The ancestors of the present Inuit inhabitants arrived here a thousand years ago without even metal tools, and it occurs to me that if they could make a go of it here, then people with currently available technologies can probably make a go of settling Mars.

The red planet gets much colder than Baffin, its air is not breathable, the water is frozen in the soil, and the lack of a magnetic field lets hard radiation get through to the surface during solar storms, but a human colony on Mars is not impossible.

It may never be the million-strong settlement that Musk imagines a century from now, but he never said he was going to build that himself. What he is building is an Interplanetary Transport System (ITS) that would get people there for as little as $200,000 each. Then just stand back and watch as people with ideas about what could be done on Mars put their money down.

Musk is already building and testing elements of the ITS. He has a brilliant record as a high-tech entrepreneur (the Tesla electric car and the existing generation of Space-X launch vehicles). He has already successfully landed booster rockets, which is the key to making the system reusable. And this is his life’s work.

Jeff Bezos’s Blue Origin launch vehicles are also landing successfully, so the reusability problem is cracked – which will automatically cut launch costs at least tenfold. And other blue-sky space projects are practically tripping over each other as the ideas multiply.

Russian tech billionaire Yuri Milner’s ten-year Breakthrough Listen project is buying thousands of hours of time on the world’s most powerful radio telescopes for researchers seeking signs of civilisations elsewhere in the galaxy. There is “no bigger question in science,” said Prof. Stephen Hawking, who is an adviser to the project.

The 100-Year Starship project, funded partly by NASA, was founded in 2012 to explore the technologies needed to make interstellar space travel a reality a century from now. It is now joined by Icarus Interstellar, whose Project Persephone is working on the design of a ‘generation ship’ that could serve as an interstellar lifeboat for some tiny portion of the human race if the Earth faced disaster in the next century.

Then there is the StarShot project, also backed by Yuri Milner. It’s a five-year, $100 million research programme to design a system of tiny probes consisting of single chips, no bigger than a postage stamp, that would fly to nearby star systems to do close-up observations as they sweep through.

Weighing only one gram, the SpaceChips would be put into orbit, then sent on their way by an array of ground-based lasers focussed on a small light-sail: only a few square metres. The lasers would blast them up to one-fifth of light speed in a few minutes, and then they cruise for twenty years or so until they reach their destination – in the first instance, Proxima Centauri, the nearest star

You couldn’t choose a better target, because astronomers have found an Earth-sized planet circling Proxima that is within that star’s “habitable zone” (where water remains liquid). “We will photograph it close-up,” said Avi Loeb, chair of the advisory committee. “Will it be blue from its oceans, or green from its vegetation, or yellow from its deserts? We will find out.” Get the technology right, and you could do it with thousands of stars.

Like all of these projects, StarShot will require the solution of dozens of difficult technical problems, cost a small fortune, and take years, decades or a lifetime. But it is exhilarating to know that all these projects are underway. At last, the ambitions of the innovators and the explorers begin to match the scale of the task.
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To shorten to 725 words, omit paragraphs 3 and 14. (“I’m less…job”; and “You…stars”)