Planetary Conditions at the Core of the Milky Way

[rjoshb]

I understand that Alpha Centauri is about 4 light years away, and that the average distance to the closest surrounding 1000 stars is significantly further. In the core of the Milky Way stars are close packed. I wonder what those conditions would be like on a planetary body there. Could there be Earth like planets at the core of the galaxy, would radiation levels be accepatable to mammals and earth species in general? Would be there enough light to read a newspaper (not the big print editions either) at night? Finally, if NASA gets their advanced propulsion designs going on an industrial scale, would non-relativistic travel to other star systems be possible? If anyone has asked these questions before I apologize in advance, but an inquiring mind would like to know.

 

[harmonicaman]

I would suggest that galaxies have "Habital Zones" much like stars. Too close to the core would be too "Busy" for civilizations to develop. It has been speculated that if you are too far out on the fringes of the galaxy you may lack necessary heavy elements for life; but that's just speculation...<br /><br />I'm sure that being too close to the core (or even within 100 LY's of a BH or something very energetic like Eta Carinae) would be problematic for civilization.<br /><br />We are fortunate to find ourselves in a quiet arm of the Milky Way, far away from the complicated cosmic environment found near the core.

 

[tony873004]

In the core, stars are closely packed and travelling rapidly. Stars probably pass near other stars often enough that they may strip each other of their planets. So planets orbiting stars near the core may be rare.

 

[dragon04]

Between the gravitational interactions, radiation and sheer proximity of stars near the center of the galaxy, I'd find it extremely doubtful for biological life to exist.<br /><br />As far as interstellar travel even to the Centauri system, non-relativistic travel isn't <b> impossible </b>, but would take tens of thousands of years.<br /><br />Take New Horizons for example. It will be the fastest ever probe, travelling at 31,000mph. At that velocity, if I did my math right, it would take about 92,880 years to make the trip to Proxima Centauri.<br /><br />Non-relativistic interstellar space travel just isn't feasible. Unless perhaps you envision a huge "space ark" or some other kind of generation ship that can support a biosphere over those kinds of time spans.<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[Aetius]

Maybe machine-based intelligence would prefer the core of a galaxy. All that radiation might make a nice power source, and I bet the supermassive black hole at the heart of the Milky Way offers one hell of a gravity assist for interstellar expansion.<br /> <br />Self-replicating, self-aware machines could also harvest every world for resources, regardless of whether it lies in a Habitable Zone for carbon-based life.<br /><br />Besides, the mere threat of being exposed to Windows will probably keep the alien machine life away from Earth. <img src="/images/icons/wink.gif" />

 

[mikeemmert]

On the other hand, Oort clouds might very well have a finite number of objects in them (what a concept!) and run out of material.<br /><br />See this for bunches and bunches of information about that.

 

[dragon04]

I'm sure any Oort cloud DOES have a finite number of significant impactors that could pre-empt the development of life, but with the density of stars and gravitational interactions, it would likely be a shooting gallery towards the core.<br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[dark_energy]

<blockquote><font class="small">In reply to:</font><hr /><p>Maybe machine-based intelligence would prefer the core of a galaxy. All that radiation might make a nice power source, and I bet the supermassive black hole at the heart of the Milky Way offers one hell of a gravity assist for interstellar expansion. <br /><br />Self-replicating, self-aware machines could also harvest every world for resources, regardless of whether it lies in a Habitable Zone for carbon-based life. <p><hr /></p></p></blockquote><br /><br />Transformers, robots in disguise.<br /><br />Although, I would assume that silicon-based lifeform would be very rare, if non-existent, without the intelligence of carbon-based life forms to build them. <div class="Discussion_UserSignature"> </div>

 

[yevaud]

We really live in a very narrow band of conditions conducive to life as we understand it. I think the region of space around/near the galactic center would prevent sentient life from appearing. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[toymaker]

Not really. From what I remember from discussions on the subject on the forum a travel to Alpha Centauri with technologies within our knowledge base (that is that currentely we can safely assume will be available and do not contradict known laws of physics) could take only around 40 years maybe 20 even.

 

[Aetius]

Yeah. Obviously, carbon-based life would build them for their own purposes, but eventually a self-aware unit capable of replicating itself might just leave the task assigned to it and strike out on its own.<br /><br />You always hear of people talking about using highly capable robots to build infrastructure for humans on other worlds. What if a robot felt that its time would be better spent doing something for its own kind instead of ours? <img src="/images/icons/wink.gif" />

 

[rjoshb]

So, this would mean that when Sagan did his Cosmos speil regarding the calculation for the number of habitable systems, his population was much larger than it really is? My point was that if the stars were closer it would be much easier to get around.

 

[dragon04]

<font color="yellow"> Not really. From what I remember from discussions on the subject on the forum a travel to Alpha Centauri with technologies within our knowledge base (that is that currentely we can safely assume will be available and do not contradict known laws of physics) could take only around 40 years maybe 20 even. </font><br /><br />A mission time of 20 to 40 years would require relativistic flight. You're talking velocities of .1 to .2c<br /><br />Which, we could do with an Orion starship. But since no nation is allowed to have nuclear bombs in space, that's not an option.<br /><br />Which leaves us with chemical engines. I would like to take this opportunity to correct an earlier error. After NH swings by Jupiter, it will be travelling at 47KMPH. That would cut the transit time to Proxima Centauri down to a mere 60,000 years, give or take.<br /><br />Ion propulsion isn't geared towards large mass spacecraft, and NEP isn't a reality yet either.<br /><br />NEP is an interesting idea. Check the article out at<br /><br />http://www.thespacesite.com/space/future/electric.php<br /><br />Based on figures given on this site, now you can hit Proxima in about 10K years.<br /><br />So, as I said, there are no reasonable transit times to stellar neighbors at non-relativistic speeds.<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[toymaker]

''A mission time of 20 to 40 years would require relativistic flight. You're talking velocities of .1 to .2c <br /><br />Which, we could do with an Orion starship. But since no nation is allowed to have nuclear bombs in space, that's not an option. ''<br />Again-that is just a political problem, not technical. Likewise nothing stops us from colonisation of the Moon or Mars Mission today from technical point of view.<br />Hopefully political climate will change in the future.<br />It doesn't however effect our possibilities in theoritical thinking based on existing technical knowledge.<br />Therefore saying that something is impossible based on political climate of today, rather then knowledge of today seem a bit manipulative.<br />We don't know what the political climate of one hundred years of five hundred in the future will be. <br />After if saying optimistically that Solar System would be colonised then it is more then likely that there would be political entities based in regions remote enough that they would be independent from control of any remaining forms of nation states.

 

[dragon04]

You're still missing the meaning of the original question.<br /><br />He's asking about non-relativistic spaceflight. What part of this don't you understand? <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[toymaker]

I only opposed saying that certain methods of propulsion are impossible in the future because of political climate of today.

 

[nexium]

Clearly we can build Orion, but my guess is performance will be much inferior to the projections, after long costly delays and huge cost over runs. Orion will shorten the lives of millions of humans with extra radiation, even if launched from LEO = low Earth orbit. Should it reach 0.1 c, I predict the radiation due to coliding with the few subatomic particles in space will degrade the electronics to non-workable by half way to Centarii Proxima. The trip takes 43 years at 0.1 c average speed. It takes about as much energy to slow down at Centarii as it took to accellerate to 0.1 c. Neil

 

[rjoshb]

OK, here is a crazy thought. People at U of Houston have been discussing lunar solar power stations for years. To power the earth they are talking covering 15% of the lighted surface. Now assuming that grandiose power scheme, what if a Really Big Laser (RBL) was built to drive a "lightship". Assuming such an interstellar vehicle could be built, and the RBL could keep firing for years and decades, wouldn't we have the capacity to reach .1c speeds, or even greater velocities? I suppose the trick would be to slow down (lol). Anyway, putting this all into a moon base plan would be interesting. I'll leave that for another post.

 

[toymaker]

''Orion will shorten the lives of millions of humans with extra radiation, even if launched from LEO = low Earth orbit''<br />Why should be Orion launched in LEO and not in Asteroid Belt or beyond Pluto ? After all we aren't talking about specific time in the future, but future in general and knowledge we know today. <br />As to electronics-there was already a topic about shielding in the forum, I don't think its as desperate s you present it.If its 43 years then its ok with my opinion that saying trips to nearby stars will have to take "thousands of years" isn't quite correct.

 

[toymaker]

I think there was a thread about designing realistic spaceship for interstellar travel on forum before the Great Crash that wiped out all posts.<br />It might be useful to restore such threat-I will probably do it but with restrictions on concepts to avoid unnecessary talk on warp, or wormhole concepts.<br />

 

[silylene old]

Toymaker - I remember that old pre-crash thread, it had hundreds of posts discussing pusher plates and how to shield the front of the craft (perhaps with a huge ball of ice). It was interesting. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[nexium]

Nearly all of the Moon's surface has sunlight about 50 % (average) of the time on a 27 day cycle instead of a 24 hour cycle. A few mountain peaks near the poles of the moon are thought to be sunlit 90 plus % percent of the time, but tracking mirrors and/or tracking photovoltac are required to get even one gigawatt average output. Really big lasers would likely accelerate space craft to 0.0001 c in a few million miles. Many medium size lasers on small asteroids thoughout the inner solar system, might permit 0.001 c over about a billion mile path. An added advantage is it might be practical to stop the rotation of small asteroids to permit receiving sunlight 24/7/365. More correctly the asteroids would be tide locked to the Sun. Neil<br />