Life elsewhere will someday be possible

Life elsewhere will someday be possible

This week's real news is the discovery of life on another planet. As Cambridge University's Nikku Madhusudhan said in the first sentence of his report: "The search for habitable environments and biomarkers in exoplanetary atmospheres is the holy grail of exoplanet science." And he has probably found the Holy Grail.

The planet orbits a star imaginatively named K2-18, about 120 light years from here. It is in the star's "Goldilocks Zone", where life could theoretically flourish because the temperature will allow water to remain liquid. (It will neither freeze nor boil off.)

Planet K2-18 b is far larger than Earth (8.6 times bigger) but it has an atmosphere containing carbon dioxide and methane, both commonly emitted by living things -- and also dimethyl sulphide, a trace gas that is definitely a strong "biomarker" for life. On Earth, it is exclusively produced by life, mostly by plankton living in bodies of water.

Dr Madhusudhan is understandably excited ("It's mind-boggling"), and at the same time professionally cautious.

It will take more observations by the James Webb telescope to confirm the "tentative" finding of dimethyl sulphide, but Dr Madhusudhan was feeling confident enough to say this:

"The atmospheric composition tells us that... there is an ocean underneath. It is very hard to get that composition otherwise. Planet-wide oceans and hydrogen atmosphere are just the right conditions to be able to host life similar to the conditions of what we see on Earth."

It's a triumph ("We found life!"), and at the same time no surprise at all ("What did you expect to find?").

If only one in a million planets was a host to life, there would still be approximately half a million life-bearing planets in this galaxy alone. There are over 30 galaxies in our Local Group, and up to 2 trillion altogether.

Indeed, we have managed to see only 5,000 planets so far, and Nasa says that 200 of them are potentially habitable. So there are probably lots of places with bacteria and maybe even algae and jellyfish. But what if only one in a million habitable planets has a civilisation on it at any given time?

That's about the right ratio for Earth: our civilisation is approximately 4,500 years old; the planet is about 4.5 billion years old.

If civilisations are really that scarce, then we might be the only one in this galaxy at the moment, and there would be no more than 2 trillion civilisations in all of the universe right now. Makes you feel special, doesn't it?

But let's get back to the neighbourhood. Unless there is some way around the cosmic speed limit (the speed of light), human beings will never travel much farther than the very nearest stars, and even those are probably too far for us to travel to.

However, there is a project currently under development to investigate the nearest star close-up.

The star is a red dwarf called Proxima Centauri, it's 4.2 light-years away, and one of its planets, Proxima b, is in the star's habitable zone and about the same size as Earth. We don't even know if it has an atmosphere, but it would be nice to know a bit more about it -- and Breakthrough Starshot is working on sending a probe there.

Breakthrough Starshot by Breakthrough Initiatives is a privately funded proposal to send a thousand-strong fleet of tiny sensor "chips" on a one-way trip to Proxima Centauri to get more information about that planet and its sun. (The high numbers are to allow for a good deal of attrition en route.)

The initial impulse would come from a gigawatt-range array of ground-based lasers pushing against the light sails that carry the chips. That would get the chips up to 20% of light speed, and the rest of the trip through the stars would be on cruise.

Launch is projected "within the next generation", and arrival for 20 years later (plus four more years to send the data back to Earth). And of course if you can do it for Proxima Centauri b, you can do it for any other celestial object of interest: no extra fuel is required.

The technology to do this does not currently exist, however the next- or second-next generations of existing technologies would probably suffice.

No conceptual leaps are required. Patience and persistence are essential -- but if this bird doesn't fly, another one will.

Nothing can stop the process now except nuclear war or climate collapse. So it's a definite maybe.

Gwynne Dyer is an independent journalist whose articles are published in 45 countries. His new book is 'The Shortest History of War'.

Gwynne Dyer

Independent journalist

Gwynne Dyer is an independent journalist whose articles are published in 45 countries. His new book is 'Growing Pains: The Future of Democracy (and Work)'.

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