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Joh45
2012-Jun-04, 04:14 AM
Hi everyone, I'm a new member, this is my first post, and my name is Joh because I tried to enter John into the first game i ever played and pressed end too soon.

I recently listened to the May 31st 2012 episode of a podcast called astronomy cast and it reminded me of extra solar or nomadic worlds, which are planets without stars that freely "drift through interstellar space". They were likely ejected from their solar systems long ago. I thought of an idea and I wonder if someone else already thought of it or if it is a good/possible idea in any way. My idea is for a ship or probe to hitch a (very long) ride to another star using a nomadic planet that may happen to pass both our sun and the target star. In my mind, this could take less fuel than flying all the way to another star. The resources of the nomadic planet could also be used for refueling or if some very crazy humans were going, for food and life support. Also, I think it might be possible for a nomadic planet to be going in the opposite direction of the rest of the galaxy, if that's the way it was originally flung out of its system. If this were possible it could maybe be used to increase the speed of a ship/probe relative to the target star. Or in other words it would be like when two cars drive past each other and the intersection point comes sooner than it would if they were both going in the same direction and one was only going faster than the other. Anyway I am only a temporary Photoshop image editor and I listen to random pod casts all day. I just wondered what actual astronomers would think of my idea of hitching a ride on a nomadic world. If someone else has already thought of it, I'd like a link to the article, but I searched for it and didn't find it.

Thank you for reading this. ;)

antoniseb
2012-Jun-04, 11:26 AM
Hi Joh, welcome!

The hardest part of your plan is getting lucky enough to spot such a planet at a time you have the resources to catch up with it.
Aside from that, keep in mind that the surface of such a planet (or outer layers if it is a gas giant) will be very cold.

Jeff Root
2012-Jun-04, 11:56 AM
Probability is very, very much against anyone counting on
such a plan. It could be a good plan if a "rogue" planet
happens to be coming your way, and you don't care where
it goes after it passes, you just want to go with it. But
that also depends on the planet being in some way
habitable. Maybe such a planet would be useful only for
the protection it could give from space radiation. It might
have a magnetic field that would protect a spacecraft in
low orbit from some radiation. Even if it had no magnetic
field, the bulk of the planet could be helpful in blocking
cosmic rays from part of the sky. If it is possible to land
on the planet, and it has a significant atmosphere, that
atmosphere would block cosmic radiation.

If the planet has a solid surface and tolerable gravity, it
might be useful for its gravity, so that you don't have to
spin all the way to your destination.

A drawback would be that designing a system to fly to
the planet, land on it, survive on it for a very long period
of time, then take off from it and go somewhere else
would be considerably more complex and complicated
than one which goes directly to the target destination.
Probably slower, too.

-- Jeff, in Minneapolis

.

dtilque
2012-Jun-07, 09:27 PM
As to whether it will save fuel/energy, the answer is no.

Every once in a while someone has the same idea about hitching a ride on a comet to get to the outer solar system. The problem with that idea is that it will take just as much energy to match orbits with the comet as it would to just go straight to the outer solar system without going to the comet. The same applies here.

Ara Pacis
2012-Jun-08, 04:32 AM
As to whether it will save fuel/energy, the answer is no.

Every once in a while someone has the same idea about hitching a ride on a comet to get to the outer solar system. The problem with that idea is that it will take just as much energy to match orbits with the comet as it would to just go straight to the outer solar system without going to the comet. The same applies here.I second this notion. The only potential advantages are shielding, by flying behind it or landing on it for raw materials, but by the time it got to where we're going, we, if we had a constant acceleration, would already be there.

Romanus
2012-Jun-09, 08:57 PM
To echo what everyone has already said: the time and energy spent getting to a rogue planet would be better spent going directly to the star / planetary system of interest.

Oh, and welcome to BAUT. :)

Jeff Root
2012-Jun-09, 10:45 PM
It isn't obvious to me that spending 20,000 years in a
cramped spacecraft with limited supplies would be better
than spending 70,000 years on a planet with mountains,
plains, water ice, metal ores, atmosphere, and so forth.
You'll get awful bored in 20,000 years when you can't
stop to get out and run around every once in a while.
If you take the planet, you have space and resources to
develop whole new civilizations on the way.

-- Jeff, in Minneapolis

NEOWatcher
2012-Jun-11, 12:00 PM
To echo what everyone has already said: the time and energy spent getting to a rogue planet would be better spent going directly to the star / planetary system of interest.
I agree that it's better, but there's one more thing to consider... the gravitational attraction of the rogue.
If it's big enough, you can pull a little more momentum from its gravity. It's probably not enough to make much difference, but it is a factor.

Ara Pacis
2012-Jun-11, 07:06 PM
I agree that it's better, but there's one more thing to consider... the gravitational attraction of the rogue.
If it's big enough, you can pull a little more momentum from its gravity. It's probably not enough to make much difference, but it is a factor.Or use the Oberth Effect?


It isn't obvious to me that spending 20,000 years in a
cramped spacecraft with limited supplies would be better
than spending 70,000 years on a planet with mountains,
plains, water ice, metal ores, atmosphere, and so forth.
You'll get awful bored in 20,000 years when you can't
stop to get out and run around every once in a while.
If you take the planet, you have space and resources to
develop whole new civilizations on the way.Chances are it's mighty cold on the surface of that planet.

NEOWatcher
2012-Jun-11, 07:32 PM
Or use the Oberth Effect?
No "or" about it. It's more of an "and". You need that gravitational yank to take advantage of the Oberth effect.

Jeff Root
2012-Jun-12, 08:38 AM
Chances are it's mighty cold on the surface of that planet.
Yeah. So? Conditions would be horrible. Would they be
worse than conditions in a spacecraft?

Whether a source of energy is available on the planet
(fission or fusion, most likely) makes a huge difference.
On a spacecraft you have to get by with what you bring
with you.

-- Jeff, in Minneapolis

NEOWatcher
2012-Jun-12, 11:37 AM
Yeah. So? Conditions would be horrible. Would they be
worse than conditions in a spacecraft?
Yes; the planet would act as a heat sink and draw the heat away. In a spacecraft, it is much slower because of the vacuum.
So; you would need a lot of insulation on anything contacting the planet and hope there isn't an atmosphere.

eburacum45
2012-Jun-12, 08:23 PM
Some rogue planets would have warm lakes surrounding geothermal heat sources, buried under kilometres of ice. Astronauts could in theory use these as resources to live 'off the land' for an indefinite period.

I doubt that rogue planets would be useful spaceships, as they would probably not be going the way we want to go; one might as well use the solar system as a spaceship, and wait till other stars come to us. Gliese 710 will be along in a million years or so, for instance. But some rogue planets might be desirable destinations in their own right.

Ara Pacis
2012-Jun-12, 10:43 PM
No "or" about it. It's more of an "and". You need that gravitational yank to take advantage of the Oberth effect.Ahh, I thought you were thinking of a gravity tractor or slingshot assist instead.


Yeah. So? Conditions would be horrible. Would they be
worse than conditions in a spacecraft?

Whether a source of energy is available on the planet
(fission or fusion, most likely) makes a huge difference.
On a spacecraft you have to get by with what you bring
with you.Yeah, it might have some useful stuff, but if you want to use it as a temporary (or permanent) residence, you'll need to bring a lot of heaters and fuel and/or a lot of spray-foam.


Some rogue planets would have warm lakes surrounding geothermal heat sources, buried under kilometres of ice. Astronauts could in theory use these as resources to live 'off the land' for an indefinite period.

I doubt that rogue planets would be useful spaceships, as they would probably not be going the way we want to go; one might as well use the solar system as a spaceship, and wait till other stars come to us. Gliese 710 will be along in a million years or so, for instance. But some rogue planets might be desirable destinations in their own right. Maybe if it has enough residual heat in it, it can be para-terraformed with a large roof to keep heat in. Of course, lets hope it would also have a decent exo-atmosphere and magnetic field to help with any meteoroid encounters or energy bursts, although the planet may be travelling so slowly that we won't have to worry about it the same way we would a world-ship. Then again...

I wonder what are the likely sizes of a rogue planet (jovian?) and if larger ones would retain any moons where tidal heating might continue.

neilzero
2012-Jun-13, 03:26 AM
With some improvement in our present technology, we can land on a "nomadic world" passing slowly thought our inner solar system. Slower than about 50 kilometers per second is unlikely unless it did a backwards sling shot manuver with a local planet or our Sun. As it left the solar system, the Sun's gravity would slow it by about 10? more kilometers per second, so it would take thousands of years to get to the closest star, unless it passed though the inner solar system at about 3000 kilometers per second = 1% of light speed. We have not found anything (within a billion light years, bigger than one atom) with that high proper motion, so far. Worse, a soft landing on it would involve incredible cost, with any likely near term technology advance. Following is my incredibly costly proposal: We launch one thousand star ships equipted with nuclear power plants powering lasers. Each craft also has a photo voltaic array, which is typically pointed toward the sun. Rarely and briefly each array receives the laser beam from a similar craft. This provides a backup propulsion, a small speed boost and a source of electricity, for when the nuclear plant is beyond ecconomical repair and we are too far from the sun to get more than trivial electricity from the Sun. About 100 years into this program we have perhaps 900 of the craft in a narrow line passing through the Kupier Belt and Oort Cloud. Most of them are decellerating as they need to return to the vicinity of Earth for a major overhaul, but some can still send a laser beam to the few out bound starcraft. So there is a wide variety of speeds, a tiny variation in direction, so possibly, one of the 900 will be able to land on the nomad planet which will be moving a bit slower than it was or will be closer to the Sun. I find it is unlikely we will spend this kind of money in this century, but maybe. After 2099, technology advances we have not even dreamed of are possible, so perhaps we will hitch a ride on a nomad planet in the far future. It would make sence to attempt the landing on anything available if it was unlikely even great grand children would survive (due to life support failures) the return trip to the vicinity of Earth which would likely take more than a century. The laser can also function as a back up radar, a search light and a backup communications link back to Earth. Neil

Ara Pacis
2012-Jun-13, 03:38 AM
Actually, I take back what I said about a frozen rogue planet. A small one could be frozen, but from the wikipedia article, they may actually stay warm due to thicker atmospheres due to less photodissociation and solar ablation.

Jeff Root
2012-Jun-13, 06:55 AM
Yeah, it might have some useful stuff, but if you want
to use it as a temporary (or permanent) residence,
Is is temporary or permanent when the trip takes more
than ten times the length of recorded human history?

I assume that the rogue planet is moving at high speed
compared to nearby stars, but very, very slowly compared
to the speed of light. I assume that it won't pass close
to a good destination solar system until it has travelled
at least a few dozen light years. Hence my arbitrary
figure of 70,000 years.



you'll need to bring a lot of heaters and fuel and/or a
lot of spray-foam.
Only enough to build and operate the factories where
we'll make more from local raw materials. 99.999%
of everything used on the trip will be extracted from
the planet, in contrast to living on a spaceship, where
99.99999% of everything needed is loaded aboard
before leaving the Solar System.

-- Jeff, in Minneapolis

NEOWatcher
2012-Jun-13, 12:21 PM
Ahh, I thought you were thinking of a gravity tractor or slingshot assist instead.
Both, actually. I just wanted to point out the assistance of it's gravity and/or movement.

Ara Pacis
2012-Jun-16, 09:15 AM
Is is temporary or permanent when the trip takes more
than ten times the length of recorded human history?You tell me, it's your imagination.


I assume that the rogue planet is moving at high speed
compared to nearby stars, but very, very slowly compared
to the speed of light. I assume that it won't pass close
to a good destination solar system until it has travelled
at least a few dozen light years. Hence my arbitrary
figure of 70,000 years.How long does it take to get to it? Form it to something else? Why bother leaving? I assume words will still have meanings and semantic conventions for temporality might still be used in some manner. Maybe your passengers will sleep the whole time, or sleep in shifts, or have an active matrix-like sleep, or will be genetically or pharmaceutically enhanced for superannuation. Whatever it is, translate my question into their conceptualization and get back to me on what they will consider temporary or permanent depending on their lives in your proposal.


Only enough to build and operate the factories where
we'll make more from local raw materials. 99.999%
of everything used on the trip will be extracted from
the planet, in contrast to living on a spaceship, where
99.99999% of everything needed is loaded aboard
before leaving the Solar System.

-- Jeff, in MinneapolisHow long will it take to get to the planet, will it be so short a ride that you won't need to bother with recycling technologies? Do you plan to let population explode so much that you'll need rogue-planetary levels of resource exploration for them to survive?