Earth-Like Planets In Our Neighborhood

goran72 sends in a story out of the Chicago AAAS meeting contending that Earth-like planets with life-sustaining conditions may be spinning around stars in our galactic neighborhood — we just haven't found them yet. "'So I think there is a very good chance that we will find some Earth-like planets within 10, 20 or 30 light years of the Sun,' astrophysicist [Alan Boss]... told his AAAS colleagues meeting here since Thursday. ... The images from those new planets, he added, should identify 'light from their atmosphere and tell us if they have perhaps methane and oxygen. That will be pretty strong proof they are not only habitable but actually are inhabited. I am not talking about a planet with intelligence on it. I simply say if you have a habitable world. ... Sitting there, with the right temperature with water for a billion years, something is going to come out of it. At least we will have microbes,' said Boss."

Comments

impossible dream?

[phantomfive]

Lately I've been really pessimistic about the whole thing, I mean, really, who cares? Even if there were intelligent life on planets that close, we would only be able to exchange communication once every 10 years, not enough to actually learn their language, and we would never be able to travel to visit them, right?

So realistically, there is not much point except for dreamers and space geeks. Might as well spend the effort here on earth. On the other hand, what if we could travel out there? Wouldn't it be COOL? I might actually meet a girl. Just kidding.

I want to believe that we will be able to travel long distances one day, hyper speed and all that, but it's pretty hard to see how it could happen.

Re:impossible dream?

[Jane Q. Public]

Man, you ARE pessimistic. As well as wrong.

Once it became known that a civilization existed in a particular star system... and they knew about us... communication could be continuous both ways, not just back-and-forth like a walkie talkie every 10 years.

Starting with math: primary numbers, Fibonnacci sequence and other natural patterns, on to addition, subtraction, etc... then to logical propositions and conclusions... we could communicate an entire language and maybe even a couple of encyclopedias in the time it took for ONE 10-year round trip of communication.

And with ion drives, or Bussard ramjets (especially if they are Pellegrino-style vehicles that pull instead of push), maybe we could get there in, say, 50 years or so. And spend most of that time in something like cold sleep. There have been advances in that direction, too. Do we have the technology to do this? No. But we might in 10 years, or 20.

Of course, we would have to decide what and how much to send in our communications. There could be very real danger. I do not think most people understand just how deadly we (and by implication, they) could be, given enough time and effort, even to a civilization light-years away.

"Flying to Valhalla", by Charles Pellegrino, is a work of fiction. It is the book in which he introduced a totally new (but perfectly sound from an engineering standpoint) style of interstellar ship construction. As controversial as Pellegrino is as a person, there is no doubt that he is, as the saying goes, "wicked smart". There are some very plausible cautions in his book.

Re:impossible dream?

[shawb]

I honestly am not convinced that we'd need any brand new branch of physics to send someone to a star 10 lightyears away. When you start accelerating to high speeds, time dilation comes for free with the package. I remember someone showing me the math a while ago, but I don't remember who it was so they may have been full of it, but anyways... for traveling large distances under constant acceleration you can pretty much use classic Newtonian physics from the point of view of the traveler, as reaching relativistic speeds causes space to constrict rather than time if you are the traveler rather than the stationary observer.

What does this mean for traveling interstellar distances? If you can carry enough reaction mass or somehow collect it on the way, simply accelerate at a comfortable rate until you are halfway to the destination, then turn around and begin deceleration at the same rate for the second half. working the numbers shows that accelerating at 9.8 meters per second per second will get you halfway to a destination 10 light years away in 2.2 years. 4.4 year one way trip, 8.8 year round trip. All with 1G of acceleration so you would have no need for exotic technology to simulate gravity to maintain health. There would physiologically be no need for sleep/stasis for the travelers. Stasis may, however, prove to be more energy efficient and psychologically easier than being cooped up in a spaceship for about 9 years.

Granted, the relativistic effects would need to be taken into account for plotting the course, as the destination planet will have been traveling through space for much more than 10 years. And when you get home your descendants will probably have died of old age.

Re:impossible dream?

[meringuoid]

Mind you the chances that we will be in the near vicinity of a civilization that communicates by radio waves that we can pick up is possibly quite slim- we've only been doing it for less than a hundred years.

And how much longer are we going to be doing it, with everything converging onto the Internet? If the earth lights up as a radio source in the early 20th century, but has gone dark again by the dawn of the 22nd because almost everything is now connected to fibre, what hope is there for SETI?

Re:Polluted by life?

[artor3]

Do you have a source for that? It seems hard to believe that Earth could have shed the equivalent of half its current mass in genetic material alone...

Re:Polluted by life?

[OeLeWaPpErKe]

For a planet to "shed" anything except perhaps hydrogen or helium, that stuff has to overcome escape velocity, which (until rockets were invented in the 20th century), requires an (volcano or meteorite) that would incinerate any complex organic compounds and render DNA a fine ash.

Those arguments may be true, but it's been proven that bacteria do get blasted out of earth's orbit without getting cooked.

Furthermore, for both spores and viruses the getting cooked is simply not a problem. (viruses contain dna which could fall into a pool of organic but dead compounds and start life, it doesn't matter that the virus itself is dead)

There have been spores tested, and the verdict is that they can survive at less than 10cm to an atomic explosion. This means that moulds that formed on the inside of the detonator of a nuclear bomb would probably contain a few things that will survive the blast*. Undoubtedly viruses can do the same.

(4 billion years) * (2 billion tons per day) / (5.9736Ãf--10^24 kg) in percent

Less than 1% of Earth's mass is at a temperature that even permits life to exist. As for the part that actually consists of life, you can measure it in parts per million and still need scientific notation.

This would not be a problem (even though you're obviously right that the amounts quoted are ridiculous), since earth receives constant doses of dust from space and loses "dust" (with probably life in it) to space. The net mass change of the earth over long periods would be negligeable, in fact it would probably gain mass slowly, despite regularly blasting tons of life into space.

* even though atomic bombs have nowhere near the killing capacity they're rumored to have. One atomic bomb can kill, at best, about 50000 people, in a dense city block less than 1 square kilometer. To kill of "all" humans you'd therefore need to set off 148 million atomic bombs, or about 25 million 150 megaton hydrogen bombs (and there would still be survivors)