[watsisname]

981cm

Why?

I'm also proud to say I understand what you did there. Thank you physics course.

Sorry, astrophysics prefers CGS units for some reason.  It's terrible. D:

[Nuke]

Because **** decimals.

behold the glory of integer maths!!! need more precision? use a smaller unit of measure!

[Herra Tohtori]

....or, you know, exponents of ten tend to do the job too.

Like SI-prefixes.

[FlamingCobra]

Space thread, paging FlamingCobra.
-snip-

sorry. couldn't stay away.

Gah! Its 600 Light Years away! But I'm renaming it Alpha Pacifica.

It almost seems that Gliese 581 disappeared from the headlines. That system seemed the most promising since it was only 20 light years away. It had four to six planets around a Red Dwarf Star.

I've heard about that star. Not only that, but some of the "predicted planets" could have fallen in the goldilocks zone. I think the problem is we can't be sure whether or not all of the predicted planets exist.

On the subject of Keppler 22b, the NASA article doesn't actually say there is water on the planet. It merely says water could exist. I find this odd, as we have detected water vapor in the atmosphere of extrasolar planets before.

[The E]

Right now, we don't even know whether that planet has an atmosphere. In order to find out, we need get spectogram of the thing, which as of right now we don't have.

See also: http://blogs.discovermagazine.com/badastronomy/2011/12/05/kepler-confirms-first-planet-found-in-the-habitable-zone-of-a-sun-like-star/#more-41652

[watsisname]

I've heard about that star. Not only that, but some of the "predicted planets" could have fallen in the goldilocks zone. I think the problem is we can't be sure whether or not all of the predicted planets exist.

Predicted planets?

[Androgeos Exeunt]

Damn, and I thought we were finally making good headway in finding an Earth-like planet that we can live on.

[The E]

An Earth-like planet that we can live on. Yeah, right. First of all, we are getting better at finding exoplanets. Second, "Earth-like planet" covers a range from Venus to Mars in our solar system alone, neither of which are habitable.
Third, even if we find them, we can't get to them. The closest exoplanet we've found, Gliese 581c, is 22 light years from us, and we have no way at all to build a colony vessel that could get a group of canned monkeys there safely.

[Scotty]

And 100 years ago we had no way at all to build a vessel to get a group of monkeys to the moon safety.  Your pessimism is uncharacteristic and (while injecting some measure of realism into the discussion) ultimately non-constructive.  Hardly like your normal posts at all.

[newman]

An Earth-like planet that we can live on. Yeah, right. First of all, we are getting better at finding exoplanets. Second, "Earth-like planet" covers a range from Venus to Mars in our solar system alone, neither of which are habitable.
Third, even if we find them, we can't get to them. The closest exoplanet we've found, Gliese 581c, is 22 light years from us, and we have no way at all to build a colony vessel that could get a group of canned monkeys there safely.

Pretty much. Right now a manned mission to Mars is deemed a too risky and expensive endeavor, and with the lack of political will / reason to do so we're not even doing that. Going outside our system? Forget about it. Also, let's not forget that the methods of detecting exoplanets most often rely on detecting small footprints these planets leave behind rather than observing them directly. I'm guessing most of the space obsessed forumites know all these, but I'm going to go over the extrasolar planet detection methods just for the sake of argument.

RV (Radial Velocity) method relies on a doppler shift cause by a gravitational effect the orbiting planets have on the host star. This is why this method usually detects hot Jupiters - a big gas giant close to a star will have a larger effect on it's host star.

Gravitational microlensing depends on a target star being exactly in line with us and another star behind it. The star behind the target emits light, which the target star in front of it bends like a lens. Planets in orbit of the target star can have a measurable effect on it.

There's the best known transit method, that just measures the slight variations in magnitudes caused by a planet doing a transit and blocking some if it's star's light.

We even found some planets with direct imaging, but that method works best on huge planets with a very high orbital period. So nothing Earth-like.

There's also the pulsar timing method which was the one that discovered first exoplanets. The theory behind it is simple - you measure the timings of a pulsar and see if there are slight variations that can only be explained by the presence of an exoplanet. Given that this only works with pulsars, it's not in wide use anymore.

At any rate, yes with some methods it is possible to measure a "chemical footprint" a planet or it's atmosphere might have, but since most of the methods rely more on analyzing very subtle tell-tale signatures these planets leave behind rather than directly observing them, we really have no known way of confirming, for sure, that a detected planet would be habitable for us. In most cases, but not all, we can determine the orbital period, size, and whether or not it's in the goldilocks area. But it would kind of suck to send a multi-generational colony ship to a "new home" that turns out to be something like Venus.. Oh well, let's put it in reverse and go home now.

And 100 years ago we had no way at all to build a vessel to get a group of monkeys to the moon safety.  Your pessimism is uncharacteristic and (while injecting some measure of realism into the discussion) ultimately non-constructive.  Hardly like your normal posts at all.

You're making two mistakes here. The first is assuming that the challenge of colonizing an extrasolar planet is something even comparable to sending a few astronauts to the Moon to collect rocks. It's not. The task is exponentially more difficult by a margin large enough to make it completely non-feasible now or in any near foreseeable future. Unless we discover something that causes a sudden boom in technological development the likes of which we've never seen before, you can forget this happening any time soon. If you see man on Mars in your lifetime, consider yourself lucky.
The second mistake is confusing this with pessimism. If I understood E correctly, he's not saying it will never be possible. He just acknowledged it's very far away. Pretending it's not wouldn't be optimism, it would be having completely unrealistic expectations induced by not really understanding just how exponentially more difficult said task is compared to the Moon landing, or any endeavor mankind has made so far. To colonize an extrasolar planet, you need two things at the very least. One is detecting with any degree of certainty that a planet is indeed colonisable. The other is getting there. You can't do either yet.
Now, our extrasolar detection methods are advancing all the time and I wouldn't be surprised we'll be able to tell an incredible amount of things about a planet 20 years from now. But that still leaves you with two problems. One is, the statistical chances of finding a planet with atmo close enough to ours so we can breathe on it are rather slim. Meaning either learning how to terraform, or living in pressurized, sealed environments. Something I'd be reluctant to commiting on a life long basis to, myself. The other is, you still can't get there. And won't be able to for a long time. How long is long, I'd prefer not to speculate. But expecting manned extrasolar travel in this century is something I'd call unrealistic at best.

[Nuke]

And 100 years ago we had no way at all to build a vessel to get a group of monkeys to the moon safety.  Your pessimism is uncharacteristic and (while injecting some measure of realism into the discussion) ultimately non-constructive.  Hardly like your normal posts at all.

going to the moon was merely a cold war penis measuring contest. cold wars are good for space exploration. we need another one. we need to go glass those damn gliesians, and now we got keplernians to deal with too. we better get our **** together and nuke them or they will be invading us.


im curious of how feasable it would be to (eventually) construct a large railgun out in the outer solar system (like on pluto) with the sole purpose of firing small probes at near relativistic speeds at exoplanets and then have them send back telemetry about the solar systems it passes through. if you know enough about the target solar system you could probably get that probe to fly fairly close to the potentially habitable exoplanet. the biggest problem with this would actually be transmitting the data back to earth (maybe a quantum entanglement transmitter) where radio signals and lasers would attenuate greatly after a couple of light years. we know how to build railguns and we know how to get to pluto. this is one of those maybe in the next several hundred years kinda ideas.

[Bobboau]

just make sure the probe moving at near relativistic speeds doesn't hit the target planet, we don't want to start an interstellar war.

[The E]

And 100 years ago we had no way at all to build a vessel to get a group of monkeys to the moon safety.  Your pessimism is uncharacteristic and (while injecting some measure of realism into the discussion) ultimately non-constructive.  Hardly like your normal posts at all.

Okay, let's see. Let us assume that we find a habitable planet (habitable in this case being defined as a planet within the habitable zone of a stable star, with a confirmed nitrogen-oxygen atmosphere, and a surface gravity around that of Earth) in a system 100 light years away.
Let us further assume that c remains as the absolute speed limit, and that the laws of thermodynamics will remain valid.
Finally, we will assume a willingness to launch a colonization effort on behalf of humanity.
Here are the challenges we need to overcome:

1. Build a vessel sturdy and fast enough to get to our target.
2. This vessel needs to carry a crew complement large enough to give birth to a new variant of human civilization.
3. The crew needs to have a sampling of skills available to cover all eventualities.
4. The vessel needs to be able to essentially provide all the technological capabilities humanity possesses at that point, an agricultural/industrial complex in a box, if you will.
5. The vessel needs to be capable of ensuring the survival of the entire colony seed while in transit.

Let us tackle these points in random order. Starting off with 2 and 3, what would be an appropriate size for our colony seed? Personally, I believe we would be looking at a population figure north of several hundred thousand people. Why? Because, in order to be as disaster-proof as we can make this whole thing, we need to have enough people on board with a diverse enough skillset to, if needed, bootstrap the colony to a tech level where it can flourish on this new world without the toys we brought with us on our vessel. Note that it isn't enough to send along people who can operate the machinery, we want people who can design these things. Then we need people who can teach these skills to others. And people who can run the societal support structure all of the above implies.
Now, we need to look at number 4. Our vessel needs to be equipped with enough tools to do any form of terraforming our newfound planet may require, including having a feedstock of pioneer species to, if necessary, bootstrap a compatible biosphere from scratch. This necessitates advances in biology (especially gene manipulation and cloning) we do not have at the moment. The problem here is that we cannot be certain that there's going to be anything usable at the other end of our trip, so we best pack everything we can to make our new home usable for our purposes.
On to point 5. Obviously, this whole endeavour is pointless if there's a risk that a percentage of our colonists dies en route. Given that we're looking at a transit time of several hundred years, there are two possible approaches. Cryogenic sleep or a generation ship. The first one is as of now an unknown quantity. We do not know how, or even if, we can freeze a human being for a long period of time and wake him or her up again. However, given the other constraints, this is likely to be the most attractive option.
Generation ships run into a different set of problems. One, they require full self-sufficiency in order to feed all our canned monkeys. Two, the society needs to be set up in a way that guarantees that we do not lose essential skills in transit. Three, the society needs to be kept from blowing itself up over some stupid squabble. Four, this society needs to be able to make the transition from shipboard life to planet colonization. All of these require a degree of social engineering we do not have available at the moment.

Now, all of the above has implications on point 1. We need a vessel capable of transporting all of the above, fast enough, and safe enough to do some useful things at the other end. There are a lot of numbers involved here that are appropriately astronomical.


So yes. I am heavily skeptical of extrasolar colonization efforts. Barring the discovery of several magic wands to sidestep these issues, I am firmly convinced that we are not going to see the launch of such an effort in our lifetime. That does not mean it is impossible; just highly unlikely.

[newman]

im curious of how feasable it would be to (eventually) construct a large railgun out in the outer solar system (like on pluto) with the sole purpose of firing small probes at near relativistic speeds at exoplanets and then have them send back telemetry about the solar systems it passes through. if you know enough about the target solar system you could probably get that probe to fly fairly close to the potentially habitable exoplanet. the biggest problem with this would actually be transmitting the data back to earth (maybe a quantum entanglement transmitter) where radio signals and lasers would attenuate greatly after a couple of light years. we know how to build railguns and we know how to get to pluto. this is one of those maybe in the next several hundred years kinda ideas.

Don't see much of a reason behind doing this on Pluto. It's a classic case of using Earth-based spacial and distance awareness in space. Which doesn't work. Why? To move from one point to another on Earth, you need to apply constant force to move in most cases, because gravity, friction and drag will do their best to stop you. If you constantly have to transport something to the United States, then Mexico or Canada make for better departure points than Europe. Because they're closer and you need to spend less energy/resources to get there. Yes.
In space, things work differently. You don't need to constantly apply thrust to keep moving. Furthermore, you can use other gravitational sources to augment your speed  without spending a drop of additional fuel - if you calculate your trajectory well enough.

Two of the most difficult things to overcome in launching a probe are getting the thing in orbit in the first place, and financing the whole infrastructure needed to do it. Pluto would work great with the first thing, as it has a relatively low surface gravity. It would be pretty horrible with the other since the costs and technical challenges of setting up and maintaining the needed infrastructure would be prohibitively high. And there would be no reason. If you don't want to deal with all that pesky atmo and gravity to achieve orbit in the first place, then a Lunar base would serve much better. You don't need much fuel to achieve orbit, and you can use Earth, the Sun and possibly Jupiter/Saturn as gravitational slingshots for such probes. There's no need for a Pluto base just because Pluto is further away from Earth. Once you get going, you set up your transfer orbits and eventually reach solar escape velocity, it's going. A departure point far away from Earth just needlessly complicates matters. You'd probably end up firing probes back inside the solar system that way so you can use the Sun for gravity assist maneuvers to pick up more speed.

The second problem is that rail guns accelerate mass while it's being fired. Once the mass being fired has cleared the railgun, unless it has it's own propulsion unit, acceleration under it's own power is over and it's at the mercy of gravity. This means that to achieve speeds needed for a suggested space probe system you'd need to fire it at incredible accelerations. The G-forces would probably destroy the probe, or at least it's scientific and comm equipment. Rail guns are a "accelerate stuff very quickly to their max speed" kind of systems. For space probes you really want a slow-burning, fuel efficient system that is capable of producing a large delta-v over longer periods of time. You could, I suppose, have a rail gun assisted launch system on a low grav environment such as the Moon, fire a probe to give it initial speed (at an acceleration rate that doesn't tear it apart), and then do delta V with some sort of an ion drive or something, and using gravitational sources to gain more speed. Whether or not we'll ever do that will depend on how the tech advances and whether or not the cost/benefit ratio will go in it's favor.

[StarSlayer]

just make sure the probe moving at near relativistic speeds doesn't hit the target planet, we don't want to start an interstellar war.

Um...

Its Nuke.

[Androgeos Exeunt]

I keep thinking of Voyager 1. Thirty or so years on, it's still inside the Solar System, and it still needs another 14 millennia to do a single light year...

Yeah, we'll still be stuck here for a very, very long time.

[Kszyhu]

Perhaps that's why the Fermi's paradox exists - members of any existing extraterrestial species know how impossible colonizing the space is, so they simply don't bother.

[newman]

Maybe. But I prefer not to speculate on extraterrestrials that may or may not exist, may or may not have evolved in a way remotely similar to ours, and may or may not have concluded this or that

[LordPomposity]

just make sure the probe moving at near relativistic speeds doesn't hit the target planet, we don't want to start an interstellar war.

This is actually one of the big problems of first contact with other species--it's impossible to tell whether an incoming relativistic object has hostile intentions or not until it's far too late to do anything about it. And if you guess no and you're wrong, you can say goodbye to every inhabited surface in your solar system.

[redsniper]

just make sure the probe moving at near relativistic speeds doesn't hit the target planet, we don't want to start an interstellar war.

Just make sure the probe moving at near relativistic speeds DOES hit the target planet, hard enough to wipe out all life. We want to WIN the interstellar war. :arrrr: