how would the first interstellar probe find all the planets, asteroid fields...

[Stormbringer]

and cometary belts upon arrival at Alpha Proxima? I mean find planetary bodies measure and calculate their orbits and the orbits of any moons  in Trojan orbits or regular orbits. find accurately their positions and distances from their star and so forth. If i wanted to build an interstellar probe how would i enable this objective for the probe? what equipment? what software? what techniques?

[Vultur]

I would assume all planet-sized bodies in a system that close would be identified already by telescopes on Earth or in near-Earth space, before an interstellar probe was launched. That's probably only a couple decades away, if that. There have already been surveys good enough to rule out gas giants (at least reasonably close in) I think, and the FINDS Exo-Earths project is supposed to start up again in a couple of years as the  Alpha Centauri A and B separation increases (as seen from Earth). I don't know if anyone is looking for earthlike planets around Proxima, but it ought to be possible -- likely even easier given the star's smaller mass.

Given the scale of a solar system, it would make much more sense to choose a probe's trajectory once you already know where the planets are.

[Jim]

and cometary belts upon arrival at Alpha Proxima? I mean find planetary bodies measure and calculate their orbits and the orbits of any moons  in Trojan orbits or regular orbits. find accurately their positions and distances from their star and so forth. If i wanted to build an interstellar probe how would i enable this objective for the probe? what equipment? what software? what techniques?

The issue will be propulsion.  Braking to be captured into the system and then the ability to maneuver.

[Stormbringer]

I would assume all planet-sized bodies in a system that close would be identified already by telescopes on Earth or in near-Earth space, before an interstellar probe was launched. That's probably only a couple decades away, if that. There have already been surveys good enough to rule out gas giants (at least reasonably close in) I think, and the FINDS Exo-Earths project is supposed to start up again in a couple of years as the  Alpha Centauri A and B separation increases (as seen from Earth). I don't know if anyone is looking for earthlike planets around Proxima, but it ought to be possible -- likely even easier given the star's smaller mass.

Given the scale of a solar system, it would make much more sense to choose a probe's trajectory once you already know where the planets are.

i have been following that and awaiting it's commencement.

however the habitable zone is close in to red dwarfs like proxima. you have to stare into the sun to see them. proxima had a spurious detection of a jupiter sized planet as has Barnard's star. statistically though each and every red dwarf has a 66 to 100 percent chance to have a planet. (in the habitable zone if i recall correctly) This despite  the complete lack of detections around the nearest ones so far. even the famous recent Alpha Centauri (spectrum type k) b detection is now disputed.

be that as it may how would a freshly arrived interstellar probe perform it's stellar mapping mission?  i know that propulsion and stopping will be a prodigious problem and i am therefore ignoring that part of the equation.

How does it set up a baseline to accurately determine distances and angles for computing orbits? is there existing software for this sort of task?

it has to know precisely how far from the star it is and then be able to turn angles to planets. it has to be able to spot planets in order to do that. then track them. then use trig and geometry to transfer angles and other mathematical procedures to plot a portion of the orbital path to fit it to the correct ellipse. i presume it might deploy a few subordinate observatory "satellites" flying in formation to form a long baseline for better accuracy?   

[Vultur]

I'm really a fan of concepts like going to the very outer solar system and even somehow traveling to Alpha Centauri .  But for a practical science mission to occur, an interstellar probe is going to need time travel capabilities.  Otherwise a generation would pass by and the technology change would be so much, we'd wonder why we sent a probe there in the first place.

If Voyager I and II were hypothetically just arriving at Alpha Centauri, the data received would be images, and that might be ok.

The Voyagers were launched 37 years ago. That's probably a bit beyond what is feasible for Alpha Centauri, but with nuclear pulse propulsion it could probably be done in 80-100 years (supposedly that can get up to ~5% of lightspeed).

I guess I'm thinking of hypothetical explorers from Iceland sending an unmanned wooden boat out into the ocean 150 years ago, hoping that someone in America would send back a bottle with a note in there saying "yep were here".  If the boat eventually makes it back to Iceland in 300 years... They'd receive the note and probably say "who cares, we already knew that"?

300 years is possibly too long, yes.

But it is far from a foregone conclusion that the next few centuries will show the radical pace of change the last few have shown. If that rate slows down, then a longer mission would become more practical.

Also, I think we'll hit a practical limit in what can be done with telescopes from interstellar distances. It would be premature to send a probe before we had the general layout of the system pinned down by telescopes, but I really can't see telescopes ever competing in terms of resolution (yeah, theoretically, you could do a solar-system-wide interferometer or something, but I really don't see that ever happening).

[hop]

How does it set up a baseline to accurately determine distances and angles for computing orbits? is there existing software for this sort of task?

Fundamentally shouldn't be too different from what existing automated asteroid, KBO etc surveys do. Making it completely autonomous wouldn't be easy, but an interstellar probe would need autonomy far beyond anything we've done anyway.

Compared to the other problems of an interstellar mission, this seems like very very minor detail.

[Stormbringer]

i am deliberately hand waving the extremely formidable problems with getting there in the first place. I am aware of the issues with that.

I want to know how the probe does its first tasks when it gets there. and thats stellar system mapping. that does not even approach the difficulty of subsequent planetary mapping, intelligent selection of probe targets, for subordinate orbiters, landers, subs and flyers or what to do if there is life, intelligent life and life that is either curious about the strange new things in the neighborhood or hostile and able to do something about it.

[ChrisWilson68]

Compared to the other problems of an interstellar mission, this seems like very very minor detail.

That's it exactly.  It's a solvable problem and much, much easier than getting the probe there.  We already have lots of instruments we send up on spacecraft of various kinds.  We don't bother with making them completely automated because it's more useful to let people control them from time to time since they're only a few light minutes away.  But taking existing instruments and writing algorithms to automatically use them isn't particularly hard or interesting.  By the time we get the propulsion issue nailed down, the set of instruments available probably will have changed, so working out the details of exactly how the instruments would be controlled would have to be re-done for the new suite of instruments.

[RonM]

and cometary belts upon arrival at Alpha Proxima? I mean find planetary bodies measure and calculate their orbits and the orbits of any moons  in Trojan orbits or regular orbits. find accurately their positions and distances from their star and so forth. If i wanted to build an interstellar probe how would i enable this objective for the probe? what equipment? what software? what techniques?

The issue will be propulsion.  Braking to be captured into the system and then the ability to maneuver.

Jim's right, propulsion is the problem. However, the probe can do a lot with just a flyby. At 0.05c the probe would be on target for 5 to 10 days, depending on the size of the star system.

IR telescopes will be able to identify the various objects in the system. The probe's trajectory plus the observation over time will get all the data needed for the survey. Sophisticated programming will allow the probe to choose targets to observe with other instruments.

We'll have a pretty good idea where all the big planets are, so the flightpath could have the probe pass close to one or more of the planets.

Now if you are talking about a probe that can stop in system, then we would have selected its destination from the planets we already know about.

Without sci-fi level AI we would not be able to design a probe that could make decisions on where to drop landers or negotiate with the locals.

[JohnFornaro]

When the alternative propulsion experimenters adhere to generally accepted experimental protocols, and abandon pointless approaches based on faulty theories, and provide repeatable experiments available to the scientific community, then it might become possible to get to the nearest star.

Until then, great self pleasure can be administered by contemplating the suggestions of the OP.

[ncb1397]

and cometary belts upon arrival at Alpha Proxima? I mean find planetary bodies measure and calculate their orbits and the orbits of any moons  in Trojan orbits or regular orbits. find accurately their positions and distances from their star and so forth. If i wanted to build an interstellar probe how would i enable this objective for the probe? what equipment? what software? what techniques?

The issue will be propulsion.  Braking to be captured into the system and then the ability to maneuver.

Jim's right, propulsion is the problem. However, the probe can do a lot with just a flyby. At 0.05c the probe would be on target for 5 to 10 days, depending on the size of the star system.

Fly by is best. No point in sticking around if there isn't anything interesting there in the first place. Worst case scenario would be getting there, orbiting, and there being a bunch of dust and small asteroids/comets. Would be better just to zip by, image all the planets, and use the star's gravity to manuever for another fly by of another star. You can go twice as fast vs having to accelerate and then decelerate.

[hop]

No point in sticking around if there isn't anything interesting there in the first place. Worst case scenario would be getting there, orbiting, and there being a bunch of dust and small asteroids/comets.

You wouldn't launch an interstellar mission to a target like that in the first place. Telescopes that can detect and characterize the atmosphere of earth sized planets the nearest stars is much, much easier than launching an interstellar mission. It's pretty much within reach of current technology, albeit not at current funding levels.

If astronomy continues on it's current trajectory, all the nearby planetary systems should be pretty well characterized before any interstellar mission launched. Even if we started working all-out on an interstellar mission today, it would be decades or more before it launched.

A mission that went into orbit would generate far more data than two very fast flybys.

Would be better just to zip by, image all the planets, and use the star's gravity to manuever for another fly by of another star. 

There aren't that many reachable stars to begin with (see http://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs), and if you are moving at a useful interstellar velocity, flying even very close to a star won't change your direction that much.

[AlanSE]

I always pictured a close approach to the star itself, provided that a sufficient heat shield could be built. This is trivially the place with the largest Oberth effect, and the only relevant question is how close you could get.

A stellar close-approach would also be the most obvious strategy for departure in the first place. If you're going to build the thermal management systems for one pass, might as well do two.

After you do your initial burn to capture into a heliocentric orbit, a pass by its exo-Jupiter would be ideal (but require advance planning). By that point, your velocity will be mostly outward from the sun, so this would only be useful to help circularize - not killing extra velocity.

But all this would only apply to extremely slow trips. Close approach to the sun will be at escape velocity on the order of 200 km/s, but it depends heavily on assumptions. You only get major Oberth benefit if your interstellar velocity is much less than that. This is a tremendous boost to chemical engines, but not futuristic nuclear propulsion.

[Stormbringer]

No point in sticking around if there isn't anything interesting there in the first place. Worst case scenario would be getting there, orbiting, and there being a bunch of dust and small asteroids/comets.

You wouldn't launch an interstellar mission to a target like that in the first place. Telescopes that can detect and characterize the atmosphere of earth sized planets the nearest stars is much, much easier than launching an interstellar mission. It's pretty much within reach of current technology, albeit not at current funding levels.

If astronomy continues on it's current trajectory, all the nearby planetary systems should be pretty well characterized before any interstellar mission launched. Even if we started working all-out on an interstellar mission today, it would be decades or more before it launched.

A mission that went into orbit would generate far more data than two very fast flybys.

Would be better just to zip by, image all the planets, and use the star's gravity to manuever for another fly by of another star. 

There aren't that many reachable stars to begin with (see http://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs), and if you are moving at a useful interstellar velocity, flying even very close to a star won't change your direction that much.

it is enough in addition to the triple shot chances afforded by AC a,b and alpha proxima there are 5 red dwarfs within 10 light years each with a 66 percent chance to not only have a planet within the life zone or an almost 100 percent chance to have a planet somewhere in the system; with neptune or above sized planets already excluded by observational data for barnards star and alpha proxima you have wolf 359 Ross (forgot the number and leylande twins. then there is a g type and a k type in the mix which will be studied for planets closely within the next three years or so. you have two wise brown dwarfs at 7 light years. with red dwarfs now statistically a gold mine for planets and fortuitously abundant nearby we need  to start thinking about this.

actually there is fair reasons for including not just the stars within 10 light years but 15 or even 20 light years though it might be a couple of generations before you get close data from such a probe at it's target. but the first fruits are a G and a K and 5 M dwarfs within 10 light years. those should be first. why we haven't studied them observationally yet i'll never know. we have had the requisite technology for these studies for at least a decade now. they should have been the priority target for observation.

and even if it takes 100 years or even more the probe is not useless until it gets there. it can do science all along the way. vehicle performance and incident data, design testing, interstellar medium characterization, interstellar object search and detection, telescopic and other instrument data, SETI active emitter and pattern searches, long distance Earth technological and bio-signature studies, fundamental physics, all sorts of great things.

such probes could even test under real mission conditions systems needed for later manned ships. test the reliability of radiation and impact protection, see how closed loop those advanced life support systems really are; service life of power systems, precision of navigation and position locating systems. probably thousands of things an armchair enthusiast like me cannot even think of.

[Vultur]

But all this would only apply to extremely slow trips. Close approach to the sun will be at escape velocity on the order of 200 km/s, but it depends heavily on assumptions. You only get major Oberth benefit if your interstellar velocity is much less than that. This is a tremendous boost to chemical engines, but not futuristic nuclear propulsion.

Yeah, that's probably too slow.

I think a big Orion/Daedalus style nuclear-pulse ship is probably the best option since solar/beam-powered sails would tend to be light and thus not have much shielding against interstellar dust.

[Nilof]

Sirius B would probably be usable for a gavity assist at useful interstellar speeds. White dwarfs have much deeper gravity wells than stars, and a close flyby of one would give a very high science payoff.

A probe could pass through the Sirius system and continue on to Procyon... which also has a white dwarf companion allowing for a second gravity assist. It should be able to continue on to Pollux. Or 55 Cancri.

EDIT: I made a graph of the maximum deflection angle(in degrees) on flybys of Sirius B as a function of ship speed(as a fraction of the speed of light).

[ncb1397]

and even if it takes 100 years or even more the probe is not useless until it gets there. it can do science all along the way. vehicle performance and incident data, design testing, interstellar medium characterization, interstellar object search and detection, telescopic and other instrument data, SETI active emitter and pattern searches, long distance Earth technological and bio-signature studies, fundamental physics, all sorts of great things.

I'll add to that list. Being out even 1 light year would really help for finding accurate distances to other objects in the milky-way. The parallax method really doesn't work well when the two reference points are within the solar system and the object is 10,000+ light years away. Without that method, you basically are judging by apparent brightness, which is fraught with innaccuracy and guess work. If the two observation points are 1 light year away and the object is 10,000 light years away, you could theoretically get a pretty accurate result. 

Anyways, I think the space between stars might be just interesting in its own right. There could be a ton of stuff out there or very little. I guess if we don't find much out there, that is a worthy scientific result in and of itself. On the other hand, you could have massive rogue planets(even gas giants) out there with their own moons(star systems in their own right that were not massive enough to ignite nuclear fusion). With tidal flexing, potentially the moons could harbor life.

[hop]

I'll add to that list. Being out even 1 light year would really help for finding accurate distances to other objects in the milky-way. The parallax method really doesn't work well when the two reference points are within the solar system and the object is 10,000+ light years away. Without that method, you basically are judging by apparent brightness, which is fraught with innaccuracy and guess work. If the two observation points are 1 light year away and the object is 10,000 light years away, you could theoretically get a pretty accurate result. 

There are much, much cheaper ways to do this...

Anyways, I think the space between stars might be just interesting in its own right. There could be a ton of stuff out there or very little.

We actually have a fair idea how much "stuff" is out there, and again there are much cheaper ways to improve those estimates.

On the other hand, you could have massive rogue planets(even gas giants) out there with their own moons(star systems in their own right that were not massive enough to ignite nuclear fusion).

Space is big. Really, really big. Even if the prevalence of rogue planets is orders of magnitude more than the currently accepted values, the chances of actually encountering something at a distance you can detect it from the interstellar probe would negligible.

[ncb1397]

Space is big. Really, really big. Even if the prevalence of rogue planets is orders of magnitude more than the currently accepted values, the chances of actually encountering something at a distance you can detect it from the interstellar probe would negligible.

We haven't exactly baselined an instrument, so this is pretty meaningless. There was some reports of finding a planet a couple times more massive than Jupiter at 100 light years through gravitational lensing, so you don't necessarily have to be that close given the right instrument and circumstances. Closer is generally better though which would be the point of a probe vs a telescope. The link below suggests they are sufficiently common that a probe covering enough space with the right instrument would be able to find them (and more importantly, investigate them).

The research produced evidence that roughly two nomads exist for every typical, so-called main-sequence star in our galaxy. The new study estimates that nomads may be up to 50,000 times more common than that.To arrive at what Strigari himself called "an astronomical number," the KIPAC team took into account the known gravitational pull of the Milky Way galaxy, the amount of matter available to make such objects and how that matter might divide itself up into objects ranging from the size of Pluto to larger than Jupiter.

http://www.dailygalaxy.com/my_weblog/2013/10/rogue-planets-may-help-seed-microbial-life-in-the-universe-todays-most-popular.html

This would suggest that of the dozen or so systems within 10 light years, there is something like 1 million nomadic objects big enough to be classified as a planet. It should also make apparent that these so called "accepted values" for the prevalance of nomadic objects don't actually exist. If all you snag though are smaller objects which the astronomical community classifies as non-planets..I guess that kind of sucks but is sort of arbitrary. Anyways, this is all dependant on how you classify "close enough to find" and "close enough to characterize", the speed of the probe, a value for the amount of interstellar bodies. This highlights another point, these are all estimates until you actually go out there and prove the estimates right or wrong. Anything less is based on a myriad of assumptions not sufficient for the highest level of scientific certainty.

[ncb1397]

I'll add to that list. Being out even 1 light year would really help for finding accurate distances to other objects in the milky-way. The parallax method really doesn't work well when the two reference points are within the solar system and the object is 10,000+ light years away. Without that method, you basically are judging by apparent brightness, which is fraught with innaccuracy and guess work. If the two observation points are 1 light year away and the object is 10,000 light years away, you could theoretically get a pretty accurate result. 

There are much, much cheaper ways to do this...

All would be less accurate. GAIA might do 10,000+ light years down to 10% accuracy but a system with the equivalent angular accuracy that has reference points that are 100x as far apart can do the same thing for objects 100x as far as way and not be off by 1000 light years+ for the closer up stuff.

We actually have a fair idea how much "stuff" is out there, and again there are much cheaper ways to improve those estimates.

Our problem isn't lack of ideas, it is lack of credibility in those ideas. When you get estimates that are off by 5 orders of magnitude, you have a scientific problem. We wouldn't accept values for the age of the earth between 4 billion years and 40,000 years. That is almost the difference between young earth creationism and the scientific consensus. Now you have the cosmic microwave background potentially being explained by dust and our ignorance is seemingly getting embarrassing.