[Space] Gliese 581

[Fred Brackin]

Originally Posted by johndallman

when they arrive, the survivors will no longer be young and dynamic, but middle-aged by TL10 standards.

Unless maybe you have TL10 Rejuvenation tech as in Bio-tech. Lifespans become indefinitely long if you do.

You could sue rejuvenation plus semi-realistic hibernation tech to keep the crew alive but "sleeping" for as long as the ship's self-repair systems will hold out. Very long trips could be survived that way and high speed propulsion wouldn't be such a necessity.

[Critical]

Originally Posted by Fred Brackin

To the best of my understanding the habitable zone of any M-class dwarf is going to be filled with tidally locked worlds. You'd need some sort of exotic scenario such as a double planet system tidally locked to each other but still spinning relative to the star or something like that.

I’m not sure why you would need precisely that scenario or why any such scenario would be “exotic.” Consider the simple case of a large planet with several moons that may or may not be tidally locked to the planet. In our own solar system, several of Jupiter and Saturn’s moons are not tidally locked, several others orbit fast enough for a long day/long night scenario to happen, and we essentially have a double planet in the form of Pluto and Charon.

Another interesting point about red dwarfs is that their UV output is minuscule and could allow planets in remote orbits to retain far more geothermal energy by way of not having their upper atmospheres thinned out by incident UV light. You could have an Earth-sized planet well beyond the Goldilocks zone that retains enough of its own geothermal heat that it can maintain liquid water on the surface for billions of years. In theory, even a rogue planet could exist like this, especially with one or more moons to engage in tidal heating processes.

There are so many red dwarfs compared to other stars, perhaps as much as 75% of the stars in the galaxy, that you are going to find all sorts of “exotic” scenarios if you examine enough of them.

[Fred Brackin]

Originally Posted by Critical

I’m not sure why you would need precisely that scenario or why any such scenario would be “exotic.”

There are so many red dwarfs compared to other stars, perhaps as much as 75% of the stars in the galaxy, that you are going to find all sorts of “exotic” scenarios if you examine enough of them.

As to the first, substitute "low probability" for "exotic" if you like the verbiage better.

As to the gas giant moon thing it still probably leaves you with an unhelpfully slow rotation rate relative to the sun.

Then there's the red dwarf thing. Yes there's a lot of them but you have to start out by eliminating all of them formed from the galaxy's primordial gasses. Those have solar systems that are all hydrogen and helium.

You need a third generation star formed from post-supernova gas clouds rich in heavier elements. The first generation of G-type stars have probably all left the main sequence. The first gen of red dwarfs is still here and will be for another 90 billion years.

Raw/undiferentiated stats about numbers of stars are seldom useful when talking about potential planets.

Ther habitability of some planet circling Gliese 581 can not yet be ruled out but it is for multiple reasons less probable than some lifezone planet circling a randomly selected G-class star.