Catching Sedna

[EzinX]

Yeah, the fact that we're not actively looking to visit these far-flung bodies already is kind of sad.

What human need is met by analyzing a far away and fast moving rock? We've already sent probes to far easier to reach objects, and there's plans in the works to possibly tow one home.

Do you have any reason to believe this rock will contain elements not already found on easier to access rocks, or contain information that would allow large advances in human technology?

[p331083]

Why would you want to go to Sedna(essentially a farther out Pluto) when vastly more attractive targets like Titan/Enceledus/Europa/Mars are much closer?

[Streetwind]

What human need is met by analyzing a far away and fast moving rock? We've already sent probes to far easier to reach objects, and there's plans in the works to possibly tow one home.

Do you have any reason to believe this rock will contain elements not already found on easier to access rocks, or contain information that would allow large advances in human technology?

Why would you want to go to Sedna(essentially a farther out Pluto) when vastly more attractive targets like Titan/Enceledus/Europa/Mars are much closer?

Why have both of you not read the opening post? Are five and chump change paragraphs too much text? Fine, I'll provide a TL;DR:

Sedna is either an Oort cloud object, which is something we haven't discovered anywhere else; or it is captured from interstellar space, which is also something we haven't discovered anywhere else. Additionally, it is not an object we can visit at our leisure whenever we decide we have time; there's a window spanning the next couple decades, and after that it will be gone for a time so incredibly long, it is impossible to predict if Humanity will still exist by the time it returns.

Arrowstar's optimization tool only contains major planet ephemerides out to 2050. I could calculate later trajectories, but I'd have to download different emphemerides. I could even put an upper limit constraint on the transit time if you want.

If that's not too much trouble for you, I would be interested in these numbers. Especially a jupter slingshot that would arrive sometime around either perihelion or crossing the ecliptic. And then maybe an accelerated trajectory doing less than 10 years one-way (as crazy as it sounds).

Edited August 10, 2014 by Streetwind

[EzinX]

Why have both of you not read the opening post? Are five and chump change paragraphs too much text? Fine, I'll provide a TL;DR:

Sedna is either an Oort cloud object, which is something we haven't discovered anywhere else; or it is captured from interstellar space, which is also something we haven't discovered anywhere else. Additionally, it is not an object we can visit at our leisure whenever we decide we have time; there's a window spanning the next couple decades, and after that it will be gone for a time so incredibly long, it is impossible to predict if Humanity will still exist by the time it returns.

First off, it would be pretty pointless if humanity doesn't exist - we won't be able to gloat over landing on an Oort cloud object if we're dead.

Second, the Oort cloud is a place. A place very far from the sun. Do you have any reason to believe that objects from this place are going to be hugely different than objects from a little closer in? I know that some of the lighter elements are going to be more common in colder objects. And I suppose geologists might enjoy trying to figure out how this particular Oort cloud object got there. But I'm not seeing it. It's unlikely that humans will gain enough knowledge to be worth the resources expended in getting it.

And before you say "all science is a risk", consider that there's a great deal of things we could research instead that we have a rational reason to believe might lead to new and valuable knowledge. Some instrument readings off a far off rock is not one of those things.

[indroth]

What human need is met by analyzing a far away and fast moving rock? ?

The need to know things.

[SciMan]

Actually designing something capable of going somewhere that nothing we have made has gone before in a reasonable time frame with a useful payload may push the technological state of the art in and of itself.

Case in point: the Apollo missions.

We didn't have the technology to do propulsive soft-landings in a vacuum before that. Or large multistage rockets. Or efficient Lox-LH2 engines. Or high thrust single chamber Lox-hydrocarbon engines. Or even how to restart an engine that doesn't use Hypergolic propellants engine in space.

Lots of propulsion and navigation technology, as well as the first integrated circuits.

Not to say we wouldn't have eventually figured those things out anyway, but I doubt we would have figured them out quite as quickly.

[EzinX]

Actually designing something capable of going somewhere that nothing we have made has gone before in a reasonable time frame with a useful payload may push the technological state of the art in and of itself.

Case in point: the Apollo missions.

We didn't have the technology to do propulsive soft-landings in a vacuum before that. Or large multistage rockets. Or efficient Lox-LH2 engines. Or high thrust single chamber Lox-hydrocarbon engines. Or even how to restart an engine that doesn't use Hypergolic propellants engine in space.

Lots of propulsion and navigation technology, as well as the first integrated circuits.

Not to say we wouldn't have eventually figured those things out anyway, but I doubt we would have figured them out quite as quickly.

This argument has been made many, many times. It does have some merit. With that said, you have finite money to spend on R&D and new engineering projects. You could spend the R&D money on areas that, based on past probabilities, are more likely to yield useful results. I can think of countless things we could research instead that would yield useful technologies humans can use right now.

Specifically, there are a whole bunch of technologies that could be researched that might lead to

1. Greater manufacturing capabilities

2. Functionally smarter (or actually smarter) humans

Either of those categories would lead to further gains, possibly even exponential gains in the future. There's dozens of topics that fit into my broad categorization : this includes more advanced conventional robots that can manufacture more of themselves, molecular manufacturing, more advanced software, forms of artificial intelligence, drugs to enhance human cognition, simulation of human brains in supercomputers...

A rocket that lands on a far off body doesn't really fit into either category. We know now it's possible, it's a matter of spending the R&D funding to develop a long life maintenance free nuclear reactor, and insanely robust ion engines and other components expected to survive without maintenance for decades.

That stuff is neat, but I cannot think of a way that it would really help the humans alive right now in the immediate future. If you have ideas, speak up. I'm not against long distance space travel, but this particular mission is incredibly difficult and it would have to be done in the near future. In the farther future, we can probably build some form of sentient computer that can be mass produced (whether the computer is running an emulation of humans or not is an aesthetic outcome) and robot factories that can be expanded exponentially. Once the entire moon has been converted into robots and computronium, launching a probe or 2 would cost negligible amounts of resources. Not to mention, these far future beings would probably be able to use antimatter or fusion or some other technology to visit Sedna whenever they want.

Edited August 10, 2014 by EzinX

[Streetwind]

Thankfully people exist who do not share that opinion, or we would not have the awesome Rosetta mission right now

[78stonewobble]

Well, stuff will stay unproven until you actually prove them.

I do keep hoping for new technology actual trials.

[mrfox]

Given that this is a "once in a civilization" opportunity, it would be interesting to discuss the likelyhood, benefits and obstacles of a manned mission.

[Streetwind]

I'm going to consider the likelihood of a manned mission negligibly small unless the quantum thrusters turn out to be real and practicable so we can build torchships with thrust-per-energy values an order of magnitude above all current electric propulsion systems. Even then, though, you're looking at a multi-year journey. And we still don't know enough about manned spaceflight outside the Van Allen belt to make any prediction as to how that will go...

...which still leaves us with speculation of course

[mrfox]

Its just that with a 10 hour transmission delay (one way) at point of closet approach, scant data on the properties of the body, and a limited window of time for study, it does scream for sending someone out there, an operator who can operate autonomously, able to make decisions on the fly, and and work at a decent pace.

Perhaps this is the one mission where the orion drive needs to be resurrected for.

Edited August 11, 2014 by mrfox

[78stonewobble]

I'd think that a bigger problem would be whether there is anything interesting about Sedna that warrants a cheap mission, a thorough mission or a manned mission?

Now... if Charon really was a mass relay then...

[Sky_walker]

Given that this is a "once in a civilization" opportunity, it would be interesting to discuss the likelyhood, benefits and obstacles of a manned mission.

Manned mission is out of question. You never send manned ships into unknown territory. Real life is not KSP.

Even unmanned mission is most likely too expensive to bother considering possible benefits from this mission.

Its just that with a 10 hour transmission delay (one way) at point of closet approach, scant data on the properties of the body, and a limited window of time for study, it does scream for sending someone out there, an operator who can operate autonomously, able to make decisions on the fly, and and work at a decent pace.

What you say makes no sense. Since when transmission delay has been a problem that we solve by sending humans?!

I'm going to consider the likelihood of a manned mission negligibly small unless the quantum thrusters turn out to be real and practicable

Quantum thrusters would change very little. Even if you'd want to believe that they work - thrust produced is next to nothing for a high energy consumption - energy that cannot be supplied through the solar panels. So you'd need RTGs. RTGs that you cannot dump into space at any point (unlike regular propellant). And that adds considerably to the mass and with that TWR it would most likely mean that it's totally infeasible.

I'd think that a bigger problem would be whether there is anything interesting about Sedna that warrants a cheap mission

Sedna is too far to get anything "cheap" there. Especially if you'd want to get into orbit (as opposite to New Horizons-style flyby mission) though IMHO chances of getting a spacecraft into the Sedna orbit are somewhere near zero, even solely due to the amount of Dv required.

Now... if Charon really was a mass relay then...

Real Life is not Mass Effect.

Edited August 12, 2014 by Sky_walker

[Streetwind]

Quantum thrusters would change very little. Even if you'd want to believe that they work - thrust produced is next to nothing for a high energy consumption - energy that cannot be supplied through the solar panels. So you'd need RTGs. RTGs that you cannot dump into space at any point (unlike regular propellant). And that adds considerably to the mass and with that TWR it would most likely mean that it's totally infeasible.

*snip*

Sedna is too far to get anything "cheap" there. Especially if you'd want to get into orbit (as opposite to New Horizons-style flyby mission) though IMHO chances of getting a spacecraft into the Sedna orbit are somewhere near zero, even solely due to the amount of Dv required.

Quantum thrusters, contrary to what you stated, are thought to produce far higher thrust per power invested than conventional electric propulsion methods, even on the lowest end of the estimates. That said, I too am totally skeptical of that concept and will remain so until proven otherwise.

Which isn't really a problem though, because we have the engines necessary to produce that dV today. Built, tested and qualified. The problem is not one of propulsion technology.

The problem is one of power generation. RTGs and Solar are completely impractical, as you stated. You'd need a nuclear reactor of some description, and we don't currently possess such a reactor (beyond a small-scale test article at NASA which would need to be upscaled, and even then lifetime hasn't been proven yet, and THEN there's politics). Of course, a Sedna visit wouldn't be launched today or in five years, but rather in something like 35 years. There's a lot that can happen in that timeframe.

And by the way, all of what I just said is merely a repetition of points already discussed earlier in the thread

[Sky_walker]

Quantum thrusters, contrary to what you stated, are thought to produce far higher thrust per power invested than conventional electric propulsion methods,

1) Where did I compare Q.t. to the conventional electric propulsion? Or better yet: where did I mention electric propulsion at all?

2) So far quantum thrusters don't produce any thrust at all as far as we're concerned. There's been some non-conclusive tests in very... doubtful testing conditions.

3) Thrust per power invested isn't the only part of equation. Thrust to weight ratio is equally, if not more, important (and in case of Q.T. it also includes weight of power generation systems).

Which isn't really a problem though, because we have the engines necessary to produce that dV today. Built, tested and qualified. The problem is not one of propulsion technology.

We have engines necessary to produce enough delta V to send probe through the Alpha Centauri system.

It's not about what we have - it's about what is feasible.

The problem is one of power generation.

And I did mention that.

Edited August 12, 2014 by Sky_walker

[Bacterius]

So has anyone tried to mod a planet into a similar orbit in KSP using hyperedit or whatever and intercept it? Could be fun, and maybe provide some perspective. Well, mostly fun. And time-consuming, with stock warp at least.

[Rakaydos]

2) So far quantum thrusters don't produce any thrust at all as far as we're concerned. There's been some non-conclusive tests in very... doubtful testing conditions.

Your confusing the Quantum Thruster concept with questionable science like EM Drive that nasa recently "tested."

[Streetwind]

So has anyone tried to mod a planet into a similar orbit in KSP using hyperedit or whatever and intercept it? Could be fun, and maybe provide some perspective. Well, mostly fun. And time-consuming, with stock warp at least.

At the very least it would be interesting to see how the game handles orbital periods that large

[Sky_walker]

Your confusing the Quantum Thruster concept with questionable science like EM Drive that nasa recently "tested."

Do I? https://en.wikipedia.org/wiki/Quantum_vacuum_plasma_thruster

If you'll look up at the sources you'll see that articles discussing Quantum Thruster are very much interconnected with EM Drive and usually contain tons of pseudo-scientific gibberish illustrated with some nice images like:

[Mr Shifty]

So has anyone tried to mod a planet into a similar orbit in KSP using hyperedit or whatever and intercept it? Could be fun, and maybe provide some perspective. Well, mostly fun. And time-consuming, with stock warp at least.

Not in KSP, but:

http://www.orbithangar.com/searchid.php?ID=610

[sal_vager]

Good thread Streetwind, stickied for September

[mrfox]

Manned mission is out of question. You never send manned ships into unknown territory. Real life is not KSP.

Even unmanned mission is most likely too expensive to bother considering possible benefits from this mission.

What you say makes no sense. Since when transmission delay has been a problem that we solve by sending humans?!

Never? We've only been a space faring species for just over 50 years. This encounter is 50+ years away. Try to open your mind up a little to discussing possibilities rather then shut out ideas with dogmatic trivia.

Transmission has not been an issue thus far, because we have never gone so far before. A manned mission can accomplish more given the limited time of the encounter. It would certainly cost a hell of a lot more, but thats more of a political hurdle than an engineering or scientific one.

[indroth]

Never? We've only been a space faring species for just over 50 years. This encounter is 50+ years away. Try to open your mind up a little to discussing possibilities rather then shut out ideas with dogmatic trivia.

Transmission has not been an issue thus far, because we have never gone so far before. A manned mission can accomplish more given the limited time of the encounter. It would certainly cost a hell of a lot more, but thats more of a political hurdle than an engineering or scientific one.

Unfortunately, 50 years from now robotics and automation will almost certainly have improved at a faster pace than human space flight, so it is likely that a manned mission will cost much more and be able to do much less. Rockets have hardly changed in the last 50 years, while computers are orders of magnitude smaller, lighter, faster and more energy efficient.

Still, that doesn't mean it isn't worth discussing. Also, a manned mission is definitely more entertaining.

[NERVAfan]

You don't need anything fancy for a Sedna flyby (well, RTGs are needed, but not necessarily reactors or ion propulsion)... just patience. The Voyagers are farther from the Sun than Sedna is now, and are still functioning.

Nuclear-electric is definitely an option, but launching an actual reactor into space is possibly politically shaky.

The more exotic possibility is a solar sail with a very close Sun flyby to get a huge push.

Either of those categories would lead to further gains, possibly even exponential gains in the future. There's dozens of topics that fit into my broad categorization : this includes more advanced conventional robots that can manufacture more of themselves, molecular manufacturing, more advanced software, forms of artificial intelligence, drugs to enhance human cognition, simulation of human brains in supercomputers...

I actually think strong AI stuff (especially self-replicating!) is probably too dangerous to mess with, at least until we have off-Earth bases where the research can be done (and not just ISS, electronic communication is too quick/easy; I'm talking far side of the Moon etc.)

The risk of strong AI going bad may be comparatively low, but the costs could be colossal, and we don't even know that the risks would be low (look how violent humans can be - I rather doubt we could make/teach something to be better than we are). And the benefits are small/nonexistent, or at least not really good for humanity/civilization in the long run even if they weren't hostile - they'd either end up replacing people or being slaves, IMO. So the risk/benefit ratio is very poor.

EDIT: Though I'm far from convinced AI (in terms of "computers" - not engineered biological brains or something) is even possible (and I hope it is not, for both practical and ethical reasons).