The Steppenwolf: A proposal for a habitable planet in interstellar space

[james_davis_nicoll]

Via Randy McDonald:

The Steppenwolf: A proposal for a habitable planet in interstellar space

Rogue planets have been ejected from their planetary system. We investigate the possibility that a rogue planet could maintain a liquid ocean under layers of thermally-insulating water ice and frozen atmosphere as a result of geothermal heat flux. We find that a rogue planet of Earth-like composition and age could maintain a subglacial liquid ocean if it were ~3.5 times more massive than Earth. If a rogue planet had about ten times higher water mass fraction or a thick cryo- atmospheric layer, it would need to be only ~0.3 times the mass of Earth to maintain a liquid ocean. Such a planet could be detected from reflected solar radiation and its thermal emission could be characterized in the far-IR if it passed within O(1000) AU of Earth.

Comments

[scott-sanford.livejournal.com]

Get your planet going
Head out of the system
Looking for adventure
In whatever comes your way

Yeah, darlin'
Gonna make it happen
Take the world in a love embrace
Fire all of your guns at once
And explode into space

This is interesting, but there's no commentary on how long this is stable. Without insolation, I suspect it is not viable over deep time. Millions of years, yes, but hardly a good idea for the really long haul.

On the other hand, this would make a breathtaking brute force generation ship.

Decelerating at the other end seems problematic.

[connactic.livejournal.com]

But what if you added a bunch of Gabon-style natural fission reactors to the mix? You could end up with some sort of deep-space intelligent space squids?

[scott-sanford.livejournal.com]

I'm assuming radioactive decay heat is included in the original calculations. You can get more heat out by concentrating the radioisotopes, but that 'burns' them faster.

Besides, you can't stop there. That's alien space bat country.

[connactic.livejournal.com]

yeah- looking it up I had some epic fails on both geology and the timescales of evolutionary biology.

Still, the wandering home of the interstellar space squids would make a great Traveller adventure.

[peter-erwin.livejournal.com]

I'm assuming radioactive decay heat is included in the original calculations.

Yes; the assumption is a combination of residual heat from planetary formation plus radioactive decay, along the same lines as the Earth.

(Concentrating radioactive isotopes won't "burn" them faster, unless you're talking about actual fission, which isn't part of the underlying model.)

As for timescales, the article has this remark:
"A Steppenwolf planet's lifetime will be limited by the decay of the geothermal heat flux, which is determined by the half-life of its stock of radioisotopes (K-40, U-238, Th-232) and by the decay of its heat of formation. These decay times are ~1-5 Gyr, so its lifetime is thus comparable to planets in the traditional habitable zone of main-sequence stars."

[beamjockey.livejournal.com]

I was going to complain that "fire all of your guns at once" doesn't make a lot of sense in this context, but then realized that it doesn't make sense in the original, either, so you get a pass.

The lyricist was apparently groping for a suitably abrupt image, to build up to the exploding into space and all, and settled on firing all of your guns. At once. Even though a gun, let alone multiple guns, is not a part of a motorcycle, and firing a bunch of guns would not, in general, assist in the operation of a motorcycle.

Firing a bunch of guns, in the backwards direction, might actually be helpful in moving a planet-- provided their muzzle velocity exceeds the planet's escape velocity; otherwise it's kind of pointless.

[joenotcharles.livejournal.com]

Could be a metaphor for spark plugs and pistons. Which, of course, still wouldn't work if you fired all of them at the same time.

[scott-sanford.livejournal.com]

I was only going to riff on the first verse, the two altered lines having occurred to me, but I looked up the lyrics and found the second verse was oddly apropos in this context. In fact, I'm not sure what if anything it means in the original song; 'put some cool sounds here,' probably.

[johnreiher.livejournal.com]

Sounds like Bronson Alpha and Bronson Beta on the road again!

[neowolf2.livejournal.com]

Your last phrase made me think of the song "On the Woad Again".

I know, I know: picts or it didn't happen.

[beamjockey.livejournal.com]

"On the Rogue Again?"

[rwpikul.livejournal.com]

That's where Elan is.

[oh6.livejournal.com]

That would have made for an interesting alternative fate for the iced-over planet in Across the Sea of Suns, although it doesn't really fit the story.

[johnreiher.livejournal.com]

It also brings to mind the short story "A Pail Full of Air".

[joenotcharles.livejournal.com]

"The Mondas", surely?

[mmcirvin.livejournal.com]

The Big Finish audio "Spare Parts" was the first thing I thought of.

Well, that and some stuff in Cities in Flight, but I forget if any of the rogue planets there were naturally that way.

[dbdatvic.livejournal.com]

There's also a McAndrew Chronicles story related to this (Charles Sheffield), titled _Rogueworld_. The rogue world is not warm at the start of the story...

--Dave