May be an interesting place to send a space probe some day

[Luzr]

Exactly! I still do not quite understand why everybody is so dedicated about colonizing planets...

Well, of course our solar system has an expiration date and before that even we could be hit by a gamma ray burst or some other cosmic catastrophy that can not be prevented. In all these cases mankinds only chance of survival is if it has already colonized a planet, or multiple planets in another solar system.
So if we want to insure a long term survival of mankind, we have to expand to other solar systems or better other solar systems.
The survival of the human species should always be the highest goal.

Sure, but why planets?!

Once we get out of gravity well, why fall for another one? Plus, it looks like the number of habitable planets is severly limited. And the planet is a big target.

Number of habitats is virtually unlimited, even in solar system (of course, once we learn how to build one...). It seems to be easier to move habitat out of path of cosmic catstrohy than to move planet. And many more habitats make many more distant targets as well.

I simply see zero advantage of colonizing planets for survival of human species. It is more like total waste of resources...

[DeltaV]

A recent image of asteroid Vesta taken by the Dawn probe from 3200 miles:



What a circus it would be if an anomalous, technological artifact is discovered on some asteroid...

[Betruger]

And... So far there really aren't any planet sized bodies with Earth like atmosphere/magnetosphere. Indoor/underground radiation-shielding volumes that are large enough to feed that instinctive need for open spaces are far enough in the future that it's nowhere near being a consideration in most people's minds.

I'm thinking something like 8 cubic mile underground amphitheaters on the moon, with half mile high ceilings would be more than adequate. Wouldn't it be fun to fly to your favorite catch and release trout stream via a human powered hang glider?

For sure But that's not anytime soon, unfortunately.

Exactly! I still do not quite understand why everybody is so dedicated about colonizing planets...

Well, of course our solar system has an expiration date and before that even we could be hit by a gamma ray burst or some other cosmic catastrophy that can not be prevented. In all these cases mankinds only chance of survival is if it has already colonized a planet, or multiple planets in another solar system.
So if we want to insure a long term survival of mankind, we have to expand to other solar systems or better other solar systems.
The survival of the human species should always be the highest goal.

Sure, but why planets?!

Because it's a far fetched idea (massive life supporting structures in the void) within a far fetched concept (outer space colonization) for most people.

A recent image of asteroid Vesta taken by the Dawn probe from 3200 miles:


What a circus it would be if an anomalous, technological artifact is discovered on some asteroid...

Tell ya what.. Pictures and data for Ceres are what I'm impatient for. It seems it could be as good as Mars. A different kind of world, but all things considered it could be as worthwhile.

The habitability would be different - a giant igloo basically, and the dV IIRC is not really better than Mars, but the gravity well is so much smaller that gravity-wise it'd make for really cheap giant space station.

[Skipjack]

IMHO it is either planets or rotating space stations that are suitable for colonization. Unless we figure out a way to do artificial gravity, which we dont even know yet whether it is possible at all.
We can at least imagine a way to make Mars somewhat more habitable.
Artifical gravity? Not so much.

[Betruger]

Has low/micro gravity been ruled out as feasible human environment? I thought that was still TBD.

[Skipjack]

Has low/micro gravity been ruled out as feasible human environment? I thought that was still TBD.

Well, unless you want to spend several hours a day doing workouts, your muscles will deterriorate. There are other averse effects from microgravity that have just recently been discovered. There may be a cure for some of these, but generally it is not a desirable environment. It is not always that comfortable either.

[Betruger]

We're talking about colonization, so.. Isn't the prospect for these people to settle down and spend the rest of their lives in those ecosystems? Not so much their inability to return to Earth gravity but to stay in good health on e.g. Ceres.

That gravity disadvantage of bodies like Ceres is mitigated by the other consequence - orbital access is easy. So if conventional artificial gravity is not practicable on/under the surface, orbital centrifuged habitats could feasibly be visited often enough.

[Skipjack]

They would need at least several hours in a centrifuge every day, AFAIK.
Also, once your muscles deterriorate beyond a certain point, your joints, bones and breathing start to suffer and you will basically loose all chance of ever returning to a world with gravity. I dont think any of this is desirable. Also, anything within the solar system would be hit by the same gamma ray burst (if we imagine such a catastrophy). So for mankind to survive, we have to leave this solar system one day.

[Tom Ligon]

L4 and L5 are quasi-stable. Over the course of ten thousand years objects might come and go from them, but they can hang in a long time. Objects don't stay AT these points, but oscillate back and forth thru them, and may well move a third of an orbit or so away at times.

I believe the Lagrange points qualify as a subset of orbital keyholes, which is to say modifying an object oscillating thru one even a little can have profound effects on subsequent orbits. In any case, any Trojan asteroid (and there are probably more out there) is, from an energy standpoint, pretty easy to get to from Earth, and probably not too hard to nudge back closer to Earth. The challenge would be to brake it into a stable orbit around Earth itself, which would require scrubbing off some energy.

We have technology on space probes today in the form of xenon ion engines (see N-STAR and DS-1) which could be used to power "gravity tugs." Basically you use continuous gentle thrust to park a probe near an asteroid or comet. The probe feels an attractive force due to the gravity of the body, and counters it with thrust. The force works both ways, so the body feels a gentle tug, too. We're talking about effects on the order of 30 km of orbit change after a decade, which is not great but can be a lot when targeting a keyhole.

Bottom line, they don't get much easier to tow back to Earth than a Trojan, and we should be thinking about this. There is a push on to mount an asteroid exploration, and this is a good target.

[JoeP]

A recent image of asteroid Vesta taken by the Dawn probe from 3200 miles:

<image snipped>

What a circus it would be if an anomalous, technological artifact is discovered on some asteroid...

"I was turning away when my eye caught a metallic glitter high on the ridge of a great promontory thrusting out into the sea thirty miles to the west. It was a dimensionless point of light, as if a star had been clawed from the sky by one of those cruel peaks, and I imagined that some smooth rock surface was catching the sunlight and heliographing it straight into my eyes. Such things were not uncommon. When the Moon is in her second quarter, observers on Earth can sometimes see the great ranges in the Oceanus Procellarum burning with a blue-white iridescence as the sunlight flashes from their slopes and leaps again from world to world. But I was curious to know what kind of rock could be shining so brightly up there, and I climbed into the observation turret and swung our four inch telescope round to the west..." - from "The Sentinel" by Arthur C. Clarke (text: http://econtent.typepad.com/TheSentinel.pdf)

I loved that short story. I think this story was the basis for the monolith in 2001 A Space Odyssey.

[Betruger]

They would need at least several hours in a centrifuge every day, AFAIK.
Also, once your muscles deterriorate beyond a certain point, your joints, bones and breathing start to suffer and you will basically loose all chance of ever returning to a world with gravity. I dont think any of this is desirable. Also, anything within the solar system would be hit by the same gamma ray burst (if we imagine such a catastrophy). So for mankind to survive, we have to leave this solar system one day.

Yes and it's not too incredible (I wouldn't do it at that cost, but who knows, this is speculation from our relatively distant past to that time) that with furnished enough living infrastructure on a body like Ceres, if there are no health issues with living without gravity, that people would accept to give up returning to Earth or other high gravity environments.

And like I said this is our speculation here and now. Then and there we might get to a point where health issues with low grav could be nullified and/or reversed. We're not colonizing Ceres for probably 50 years. Once or twice 50 years is a long time in medical science.

[Luzr]

They would need at least several hours in a centrifuge every day, AFAIK.
Also, once your muscles deterriorate beyond a certain point, your joints, bones and breathing start to suffer and you will basically loose all chance of ever returning to a world with gravity. I dont think any of this is desirable. Also, anything within the solar system would be hit by the same gamma ray burst (if we imagine such a catastrophy). So for mankind to survive, we have to leave this solar system one day.

This is so much shortsighted, sorry...

Do you insist that human biology is something that is not allowed to change?

Or perhaps a bit of genetic engineering could fix a couple of issues w.r.t. to living in the space?

If you think it is hard, compare difficulity with engineering challenges involved in "leaving the solar system"...

(Plus, of course, I still think that not all of our descendants must have biological form. But I guess I am a little bit radical there

[Skipjack]

This is so much shortsighted, sorry...

Do you insist that human biology is something that is not allowed to change?

Or perhaps a bit of genetic engineering could fix a couple of issues w.r.t. to living in the space?

If you think it is hard, compare difficulity with engineering challenges involved in "leaving the solar system"...

(Plus, of course, I still think that not all of our descendants must have biological form. But I guess I am a little bit radical there

Well, currently we do not know whether it can be done even in theory and what the consequences would be.
That was my point. Plus what is the point of having a genetically engineered species emmigrate from our planet, if there are probably quite a few HUMANS willing to do the same.
It is very hard to change the genetic makeup of a grown up human, not impossible, mind you, but the question is how many people would like their genes being messed with and how much can be changed later in life.
Anyway, all that would mean very limited emmigration/colonization.
I think it would be easier and more beneficial to just improve our propulsion technology so that the gravity well of a roughly earth type planet would not be a problem anymore. If you are serious about space colonization, you should do that anyway.
The leaving the solar system part is a long, long term goal and necessary if you want to guarantee the survival of the species. Even settling on Ceres wont do that. Gamma ray bursts could easily sterilize the entire solar system at once... Since they are happening at the speed of light, there is no warning either. It is the ultimate apocalypse.

[Luzr]

Well, currently we do not know whether it can be done even in theory and what the consequences would be.

Unlike leaving solar system and finding another habitable planet, we at least have a clue that changing genom might be possible some day.

That was my point. Plus what is the point of having a genetically engineered species emmigrate from our planet, if there are probably quite a few HUMANS willing to do the same.

Because HUMANS are not best suited to live in space?

Anyway, all that would mean very limited emmigration/colonization.

As compared to "leaving solar system"? How many 100% HUMANS, if ever, will ever be able to do so? Do you understand energies involved to get to closest star in 100% HUMAN lifetime?

I think it would be easier and more beneficial to just improve our propulsion technology so that the gravity well of a roughly earth type planet would not be a problem anymore. If you are serious about space colonization, you should do that anyway.

How many "roughly earth type" plants do we have available?

Since they are happening at the speed of light, there is no warning either. It is the ultimate apocalypse.

Fortunately, they have not sterilized solar system in last 2 billions years, that makes them for our part of universe quite unlikely...

[Betruger]

Didn't we debate this discrete point already?

Arguing/predicting more than 1-2 (1 IMHO) centuries in the future is just too fraught with uncertainty for a subject like expansion into space and medical science.

Anyway, all that would mean very limited emmigration/colonization.

As compared to "leaving solar system"? How many 100% HUMANS, if ever, will ever be able to do so? Do you understand energies involved to get to closest star in 100% HUMAN lifetime?

At the expected time scale of our ability to reliably travel interstellar distances, human lifetime could have become completely inhuman to us now.

Plus what is the point of having a genetically engineered species emmigrate from our planet, if there are probably quite a few HUMANS willing to do the same.

If we do not know the specifics of such medical treatments, we can't know that probability. If the treatments are as unobtrusive as e.g. a 1 week battery of shots and 2 week convalescence, it wouldn't seem like much of a price for living on some space station or dwarf planet.

how many people would like their genes being messed with and how much can be changed later in life.

How many people would like metal and electronic hardware in them? Synthetic limbs? How many/few people will agree to hardware in their skulls that's only noticeable on X ray scans and by the fact they're 2x as smart?
And all of those are chump change. People who today are into major "body mods" will come up with ever-more "crazy" stuff. Kids who grow up at the time will acclimatize and express themselves thru that just like they did with omnipresent internet and electronic gadgets recently and increasingly miniaturized and embedded and powerful electrogizmos tomorrow.

I think it would be easier and more beneficial to just improve our propulsion technology so that the gravity well of a roughly earth type planet would not be a problem anymore.

It's not so mutually exclusive a choice. We can do both. Pursue whichever or both are best suited to getting us ahead into space at any given time/place.

The apocalypse thing is a non issue. Nothing you can do about it until you do have interstellar capability, so no use fretting about it.