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Red Giant Sun
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| EvilPanda | Date: Friday, 03.06.2016, 12:24 | Message # 16 |
 Observer
Group: Newbies
United Kingdom
Messages: 7
Status: Offline
| I think by the time the Sun becomes a Red Giant, and we don't become extinct before then, we'll definitely have the technology to move the Earth outwards to stay in the habitable zone. I watched a documentary that said if we used asteroids that make close encounters with Earth once every 6,000 years, we could remain in the habitable zone. If we can't do that, we can always use the melted ice worlds that SpaceEngineer mentioned earlier as colonies.
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| spacer | Date: Friday, 03.06.2016, 12:27 | Message # 17 |
 Star Engineer
Group: Users
Israel
Messages: 1258
Status: Offline
| anyway for my opinion until then if we wont get extinct we probably be allready across the stars
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
Edited by spacer - Friday, 03.06.2016, 12:27 |
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| Wicker1M | Date: Sunday, 05.06.2016, 05:07 | Message # 18 |
 Astronaut
Group: Users
United States
Messages: 57
Status: Offline
| Quote EvilPanda (  ) we'll definitely have the technology to move the Earth outwards to stay in the habitable zone
What sort of technology would we need to move the Earth outwards of its present orbit?
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| Watsisname | Date: Sunday, 05.06.2016, 07:36 | Message # 19 |
 Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
Status: Offline
| We already have moved Earth's orbit, as well as the orbit of every other planet in the solar system, by flying spacecraft past them for gravitational assists. A gravitational assist or "slingshot" is just like a perfectly elastic collision.
Of course, the change in the orbit is minuscule since the ratio of the masses is so huge. (For fun, try calculating how much the impact of the asteroid that killed the dinosaurs shifted Earth's orbit.) But if we can fly a whole bunch of asteroids past us, such that the total mass is comparable to that of Earth (or better yet, re-use the same asteroids over and over), then it could be doable.
There was a paper a while back that discussed the idea of looping the same asteroid back and forth between Earth and Jupiter, so that essentially we transfer orbital energy between the two planets. Jupiter is a lot more massive than Earth, so this doesn't change its orbit as much as it changes ours.
To give an idea of the scale of the energy transfer required, the total energy (gravitational potential plus kinetic) of a circular orbit is -GMm/2r. (Yes, the total energy is negative.) Expanding Earth's orbit from its present location to, say, Mars' orbit (1.5AU) would require an energy boost of about 9x1032 joules. A close flyby can transfer about 108 joules per kilogram of flyby mass. Let's say we use an asteroid similar to Phobos (1016kg). Then each flyby transfers ~1024J. So we'd need... oh my, about a billion flybys to do it. Which should make sense -- Earth weighs about half a billion times more than Phobos.
So, yeah. "Doable", in the sense that it would require very precise orbital maneuvering of a very massive asteroid a lot of times.
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| FastFourierTransform | Date: Sunday, 05.06.2016, 10:15 | Message # 20 |
 Pioneer
Group: Local Moderators
Spain
Messages: 542
Status: Offline
| Quote Watsisname ( ) There was a paper a while back that discussed the idea of looping the same asteroid back and forth between Earth and Jupiter, so that essentially we transfer orbital energy between the two planets.
Wow! interesting idea. Show me please 
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| Watsisname | Date: Sunday, 05.06.2016, 10:56 | Message # 21 |
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Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
Status: Offline
| Astronomical Engineering: A Strategy For Modifying Planetary Orbits
Not much to see since it's paywalled, sadly.
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| JackDole | Date: Sunday, 05.06.2016, 11:52 | Message # 22 |
 Star Engineer
Group: Local Moderators
Germany
Messages: 1742
Status: Offline
| Quote Watsisname ( ) We already have moved Earth's orbit, as well as the orbit of every other planet in the solar system, by flying spacecraft past them for gravitational assists. A gravitational assist or "slingshot" is just like a perfectly elastic collision.
Does anyone know the novel 'Nemesis' by Isaac Asimov?
(Who still wants to read this novel, perhaps should not look into the spoiler.)
Don't forget to look here.
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| steeljaw354 | Date: Sunday, 05.06.2016, 13:31 | Message # 23 |
 World Builder
Group: Users
Pirate
Messages: 862
Status: Offline
| Why would you want to send a red dwarf into the solar system and mess everything up?
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| JackDole | Date: Sunday, 05.06.2016, 15:39 | Message # 24 |
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Star Engineer
Group: Local Moderators
Germany
Messages: 1742
Status: Offline
| Quote steeljaw354 ( ) Why would you want to send a red dwarf into the solar system and mess everything up?
Maybe my expression was ambiguous.
Not into the solar system, but away from the solar system.
Don't forget to look here.
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| butterarmyxjrblx | Date: Saturday, 25.06.2016, 01:20 | Message # 25 |
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Astronaut
Group: Users
Pirate
Messages: 71
Status: Offline
| Personally, I think we will survive. What happens is since this is not for 5 billion years, Humanity's technology is that of a Type 3 Civilization by the time the sun goes giant. We would have colonized other solar systems likely by that time, the lifelong question is answered by then, so long as the sun doesn't go supernova, we live.
"You can't spell Challenge without change. You need to change to overcome challenges." -Bo Dallas
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| Watsisname | Date: Saturday, 25.06.2016, 01:52 | Message # 26 |
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Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
Status: Offline
| Actually it takes less than a billion years to start having serious effects on life on Earth. But yes, I think by then humans will either be extinct or inter-stellar anyway.
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