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earthman2110
2004-Mar-16, 12:24 AM
I have a great idea... but thats why i dont work for NASA. Would it be possible to send out a probe, and "ride" the planet/comet/whatever to the very limits of our solar system? i read that Sedna has a 10,000 year orbit, but that it will be closest to us within the next 75 years or so. would this even be possible?

ToSeek
2004-Mar-16, 12:30 AM
I was wondering about that myself. Rendezvousing and/or landing would be the hard part.

Grand Vizier
2004-Mar-16, 01:17 AM
I thought straightaway about the hitchhiker scenario - but it has to be large scale and more long-term. These objects contain teratonnes of volatiles and who knows what all else (I wonder whether shortage of metals, in the chemical not astronomical sense, could be a problem). I could envisage a whole civilisation (or at least a large city-sized component of it) hitching a ride on one of these guys.

Course you need fusion power (at least) and a few other bits and bobs, but I bet you could make a 2,000-km body last 5,000 years (half an orbit at least). And if you run out of stuff, then you jump ship to the one next door...

Could be the answer to the Fermi Paradox, you know? Everyone who's anyone is riding around the universe on plutinos... Solar systems, planets? Been there, done that...

daver
2004-Mar-16, 01:21 AM
I have a great idea... but thats why i dont work for NASA. Would it be possible to send out a probe, and "ride" the planet/comet/whatever to the very limits of our solar system? i read that Sedna has a 10,000 year orbit, but that it will be closest to us within the next 75 years or so. would this even be possible?

There's no real point. If you hitch a ride on the object, you have to match speeds (and more) with it. If you match speeds, you're already on an orbit that will take you out there (very slowly). However, if you wanted to set up shop that far out, it might make a nice base.

Isaac Asimov in one of his essays suggested leap frogging from star to star on extended Oort cloud objects.

Anthrage
2004-Mar-16, 01:29 AM
I'm not sure landing would be too difficult. We have done something similar with NEAR and Eros, and NEAR was not designed for a landing. True, the distance and velocities involved are much different, but Sedna is also much larger. I also suspect that Sedna has a less complex rotation. If we were to give a group of engineers and mission planners the task, I think they would be up to it. Especially those who would be doing so, 50 years or more hence.

Power is a problem though. Assuming that could be taken care of, what kind of instruments would you want on such an orbiting platform?

frogesque
2004-Mar-16, 01:56 AM
Anthrage wrote:

Power is a problem though. Assuming that could be taken care of, what kind of instruments would you want on such an orbiting platform?

Top of my Wishlist, Radio telescope - think of the base line!

Anthrage
2004-Mar-16, 02:05 AM
A VVVLBA? ;)

Kaptain K
2004-Mar-16, 04:54 AM
I'd put a CHON (carbon, hydrogen, oxygen, nitrogen) food factory and a nuclear power plant on it. 99% of our food consists of those four elements and since it formed from the same protoplanetary disk as the planets, the rest of the elements needed are probably there also. With enough power, a self sufficient base would probably be easier there than on the Moon.

Brady Yoon
2004-Mar-16, 05:07 AM
i was wondering, how far is sedna from earth?

JohnOwens
2004-Mar-16, 05:30 AM
They're saying it's around 90 AU from the Sun right now, which would be close enough to its distance from Earth for most purposes (especially if that 90 AU only has one significant digit!). That's about 13.5 billion km (American billion), or around 8.4 billion miles.
At its closest approach to the Sun, they're saying 76 AU, which will be 11.4 billion km, 7.1 billion miles. But that's +/- 6 AU, so apparently there's still plenty of room for refinement of these figures.
For completeness, I'll add that for its greatest distance, the working number is 850 AU, 130 billion km, 80 billion miles. But it won't be out there for another 5,000 years or so.

Korben
2004-Mar-16, 08:06 AM
I think a problem here may be the energy source. There's no sense in sending a probe, when it eventually would be so far away from the sun that it couldn't operate long enough to obtain scientific results unless it used an energy source independent from the sun. I doubt that solar pannels would be efficient enough to supply the probe even on the voyage to Sedna itself - let alone research on the celestial body.

EDIT : Guys you are fast !! Ignore my post - it's been mentioned already...

Anthrage
2004-Mar-16, 09:19 AM
This is a very interesting idea. I've been mulling over it since last night, and I think that making use of these bodies with highly eccentric orbits is not as crazy or pointless as it may sound.

I must confess that I have always been concerned about the security of the human species over long periods of time. The environment in which we live is remarkably fragile, and any number of potential disasters could crush all of the eggs we currently are holding in a single basket. I have always found this to be a very uncomfortable situation to be in, as a species, especially willingly so. While I like most science-minded individuals favor the research and exploration motivations for space travel, fundamentally I very strongly want us to establish a few more baskets, as it were.

In the next century, if nothing befalls us, we may well get around to establishing colonies on the moon and Mars. Given that the technology and operational experience will likely exist then to make them possible and practical, I would hope that we might, before too long, go a step farther. From the perspective of species security and survival, it may serve to make use of these long period, eccentric orbit bodies, as arks - collections of self-sustaining humanity - which by nature and design, would be safe from at least some of the potential dangers to the inner solar system and it's population.

As mentioned, this idea has been proposed before, although I don't know if setting aside a section of the species in a (relatively) safe place was part of the motivation. Certainly, if Sendra's maximum distance from sol turns out to be 1000 AU (to use a round number), what that is less than .4% of the distance to the nearest star...were it even in the right direction, which it isn't in this, case, it is still quite a distance away. It is in fact well outside the heliosphere, having some sort of base which crosses the heliopause may be worth-while in it's own right.

On a side note, Voyager I is also about 90 AU from earth right now, moving away at an incredible speed of aprox. 3.6 AU a year. Sedna is 90 AU, in pretty much in the opposite direction.

In any case, one day these objects may become more than curiosities. with any luck, we'll live to see it. :)

AK
2004-Mar-16, 10:13 AM
On a side note, Voyager I is also about 90 AU from earth right now, moving away at an incredible speed of aprox. 3.6 AU a year.


You might find this interesting:

http://www.heavens-above.com/solar-escape.asp?Session=kebgcfmfihmaabeapkgacaci

Grand Vizier
2004-Mar-16, 11:05 AM
I'd put a CHON (carbon, hydrogen, oxygen, nitrogen) food factory and a nuclear power plant on it.

Go for it! But you have to have fusion if you're going to while away 5,000 years - can't imagine that there's a whole lot of fissionables there. Going to be plenty of deuterium, though - and what of Helium-3?


99% of our food consists of those four elements and since it formed from the same protoplanetary disk as the planets, the rest of the elements needed are probably there also. With enough power, a self sufficient base would probably be easier there than on the Moon.

There'll be CHON, for sure - but in what compounds - apart from water and CO2 ices (I'd have thought those ubiquitous)? And what about non-volatiles (presumably mostly silicates)?

The Stardust sample return should tell us a lot, but Wild 2 relates to the Kuiper belt and Sedna could be quite different (there's that red colour, for a start). Curses - at 3 times Pluto distance I can't see a mission any time soon - we'll be lucky if the Pluto mission gets off the ground...

Anthrage
2004-Mar-16, 11:28 AM
frogesque - Heh, Voyager I and Sedna are just about opposite eachother right now, 90 AU in either direction, for a total baseline of 180 AU. If only...

frogesque
2004-Mar-16, 12:25 PM
Anthrage wrote:

Heh, Voyager I and Sedna are just about opposite eachother right now, 90 AU in either direction, for a total baseline of 180 AU. If only...

Drools!

Grand Vizier
2004-Mar-16, 12:37 PM
frogesque - Heh, Voyager I and Sedna are just about opposite eachother right now, 90 AU in either direction, for a total baseline of 180 AU. If only...

Well, based on having searched only 15 percent of the sky, Mike Brown is saying that there may be another 5 or so of these objects close to perihelion - and lots more further out, of course. I suppose it wouldn't do any harm to check if there's anything near the Voyagers' trajectories.

But I'd reckon the odds aginst that happy coincidence are going to be - what? - billions to one (hand waves). That's assuming that some science results are required, which would need a fairly close encounter - though I suppose you'd get some useful info anywhere within a few million km (hand waves again) if you could do some imaging.

However, I'm also of the impression that the Voyagers' imaging systems, which have been shut down to save power, cannot be restarted - but could be wrong on that.

I agree, though - that would be really cool.

Anthrage
2004-Mar-16, 01:34 PM
Yes, the scan platform as been powered down. There are 7 science-capable instruments still functioning, although known that would be of much use in relation to a kuiper or oort type object.

I just thought it was interesting that we have one man-made object, and one natural object, similar distances away in opposite directions.

Does anyone know what Sedna's orbital velocity is? I could calculate it (roughly) I suppose, but I haven't been to bed yet and my head may explode. :)

Argos
2004-Mar-16, 01:47 PM
The sad thing about Sedna is that they abandoned the Greek pantheon. This way the solar system naming gets clumsy. Dreadful name... :cry:

Hamlet
2004-Mar-16, 03:48 PM
i was wondering, how far is sedna from earth?

It's currenly about 3 times further than Pluto.

jfribrg
2004-Mar-16, 04:00 PM
think of the base line!

I'm thinking of the parallax.

BTW: were any of the other spacecraft such as Voyager, Galileo, etc., ever used to measure the parallax of nearby (and not-so-nearby) stars?

Kullat Nunu
2004-Mar-16, 04:43 PM
The sad thing about Sedna is that they abandoned the Greek pantheon. This way the solar system naming gets clumsy. Dreadful name... :cry:

It's just a Kuiper Belt/Oort Cloud object, not a planet... #-o
Besides, if we started to name every large KBO after classical mythology, we would soon run out of names. Of course, if they find something definitely a planet like a gas giant or brown dwarf I would think that classical name would be more appropriate.

PS. IMHO Sedna is a nice name. :D

ToSeek
2004-Mar-16, 05:21 PM
IMHO Sedna is a nice name. :D

At least you can pronounce it, unlike that last one.

zebo-the-fat
2004-Mar-16, 05:29 PM
OK, we have a new planet .... what is that going to do to the astrologers?
Are they going to come up with a fudge to show that they knew about it and had already taken it into account? :evil:

Edoltc
2004-Mar-16, 07:26 PM
I don´t know. Why call it Sedna? It´s kind of a sad story. (http://www.hvgb.net/~sedna/story.html) If this is a planet, something like Diana or Minerva could be better. Now, and excuse me for this, but what it has to be (or do) to be consider a planet?

Ripper 2.0
2004-Mar-16, 08:16 PM
IMHO I would not give it the distinction of being a planet. I know this opens Pluto to being de-classified. It has long been debated, even before Sedna was found. I am sure we will find more planet sized objects in the Oort Cloud given time. I also think we should have stuck with Roman mythos for names. Otherwise we can go back to calling Neptune George.

Glom
2004-Mar-16, 08:29 PM
You mean Uranus. Uranus was originally named George by William Herschel.

nebularain
2004-Mar-16, 08:29 PM
It's just a Kuiper Belt/Oort Cloud object, not a planet... #-o

Actually - which one would it be? Kuiper Belt or Oort Cloud?

(BTW, the report I heard on CNN, assuming they reported correctly, said it was called a "planetoid", IIRC.)

Ripper 2.0
2004-Mar-16, 08:43 PM
I stand corrected.

Forgive my ignorance, where is the line drawn between the Oort cloud and the Kuiper belt?

Argos
2004-Mar-16, 11:05 PM
Besides, if we started to name every large KBO after classical mythology, we would soon run out of names.


Yes, but it seems to me that naming the solar solar system main bodies after Greek deities (although with Latin names), would organize things better.



PS. IMHO Sedna is a nice name. :D

I would substitute the adjective "dreadful" for "inadequate". Indeed, it´s an evocative name, but I think it does not fit right in this case. However, it could be a good name for a spaceship. :)

aurora
2004-Mar-16, 11:58 PM
I stand corrected.

Forgive my ignorance, where is the line drawn between the Oort cloud and the Kuiper belt?

Right now, it is a fuzzy line. Because, until now (maybe) nobody has ever even found an object in the Oort cloud. So up until now it has been theoretical.

We'll have to find a whole lot more objects out in that area before people can start drawing conclusions from observations.

Edited to mention the long period comets, some of which seem to come from the Oort cloud. Forgot about that. :oops:

JohnOwens
2004-Mar-17, 01:23 AM
Does anyone know what Sedna's orbital velocity is? I could calculate it (roughly) I suppose, but I haven't been to bed yet and my head may explode. :)

OK, buckled down and went at it: about 4.6 km/s at perihelion, 0.4 km/s at aphelion. Has a semilatus rectum (not that you asked, or anyone cares, but in case I need to know it for follow-up later) of about 140 AU, or 2.1*10^10 km. Current velocity, assuming the 90 AU current distance is about right, should be about 4.2 km/s.

Anthrage
2004-Mar-17, 01:38 AM
That's pretty impressive. By my rough calculations, Voyager I is currently traveling at about 17.3 km/s. Not a useful comparison perhaps, but an interesting one. :)

JohnOwens
2004-Mar-17, 01:58 AM
That's pretty impressive. By my rough calculations, Voyager I is currently traveling at about 17.3 km/s. Not a useful comparison perhaps, but an interesting one. :)

Well, if your rough calculations are correct, and my rough calculations are correct, escape velocity for that region around 90 AU out is about 4.4 km/s, which will keep Sedna from escaping (I feel a little bit safer about those numbers now), but let Voyager I keep going until it slows down to around 12.9 km/s. That would make it about 100,000 years to get to Alpha Centauri (if it were headed in the right direction).
I think we're going to need something faster someday. 8-[

Anthrage
2004-Mar-17, 02:30 AM
Cool stuff. Voyager I is actually headed in the general direction of the solar apex (the direction of the Sun's motion relative to nearby stars), and in about 40,000 years, with pass within 1.6 light years of AC+79 3888, a red dwarf 16.6 light-years away in the direction of (the constellation) Camelopardalis. Also, in the year 42,405, Pioneer 11 will pass within 1.65 ly of the same star. So, that will be two visitors, Pioneer then Voyager 1, AC+79 3888 will be getting from us. :)

Of course, if we haven't acheived interstellar travel in 40,000 years, then I suppose celebrating won't be on the menu, heh.

ToSeek
2004-Aug-24, 04:40 PM
Sedna's Origin Solved? (http://skyandtelescope.com/news/article_1326_1.asp)


The likeliest proposal, they find, is that Sedna was lifted into its present orbit by a star passing a few hundred a.u. from the solar system within 100 million years of the solar system’s birth, before the Kuiper Belt and Oort Cloud took shape. Such a close, well-timed brush would be plausible if the Sun, as seems likely, formed in a star cluster that’s now long since dispersed.

Brady Yoon
2004-Aug-24, 06:22 PM
The alien planet hypothesis sounds really interesting.

Kullat Nunu
2004-Sep-03, 07:03 AM
Looks like Sedna has finally been numbered, it is now asteroid #90377.

badprof
2004-Sep-03, 02:07 PM
If it has finally been numbered, then the discoverers will now have the privilage to propose a name for it.

Woouldn't it be interesting if someone had already proposed "Sedna" for a different asteroid! 8-[

Cheers

Kullat Nunu
2004-Sep-28, 11:47 AM
Asteroid (90377) 2003 VB12 is now (90377) Sedna. ;)

Kullat Nunu
2004-Sep-28, 01:12 PM
Wouldn't it be interesting if someone had already proposed "Sedna" for a different asteroid! 8-[

Actually someone did (http://cfa-www.harvard.edu/mpec/K04/K04S73.html)! But after the discovery of Sedna was published and because its name was published incorrectly. It should have been announced after the numbering, but with exceptional discoveries like this the naming procedure may change.