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Posted by: YesRushGen Sep 4 2008, 05:27 PM

Hi all, I am a frequent lurker here at UMSF and rarely post. I came across the following link today and I found it a fascinating read. I thought I would share for any interested persons who had not read this before.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19890007533_1989007533.pdf

Cheers!

Kelly

Posted by: Juramike Sep 4 2008, 06:53 PM

Project Longshot (from link above) proposed using existing technology to get to the Centauri system and would take about 100 years.
(faster loading summary here: http://en.wikipedia.org/wiki/Project_Longshot )

Project Daedalus, proposed about 10 years earlier, would've used not-yet-invented technology to get to the Centauri system and it would have had a flight time of 50 years. Here's a quick summary link: http://en.wikipedia.org/wiki/Project_Daedalus

(Interesting that existing technology would only double the proposed flight time to the nearest star. The key quote from Wiki was that "although some technological development would still be required" - probably for the inertial confinement fusion thruster.)

I'm guessing the selection and funding process would also take at least 100 years....

Posted by: JRehling Sep 4 2008, 10:09 PM

This seems like an exercise in continual obsolescence. Whenever you launch something like that, you're tempting fate that long before it arrives, you would have a faster way to get there.

A triple-star system is also a highly risky target. There may be nothing to see but stars and comets (which you wouldn't really see, because you wouldn't be lucky enough to pass close to one). Epsilon Eridani might be a better investment. We could actually target the known planet for a close flyby.

Imagine a Voyager-type craft coming into our solar system at an oblique angle traveling 10% the speed of light. Let's say it identified the major planets up until the last day before arrival and planned observation sequences for them. It wouldn't come very close to any planets but by luck. It also might get stuck in several cases having a closest approach of a planet that showed only a crescent. Most of the encounters would be on the order of a few to tens of AU away. The screamingly fast trajectory would mean that the planets would display very limited rotation/weather during the encounter. And, for reference, consider the MRO image of Jupiter and the Jupiter image taken by Cassini from Saturn orbit.

http://photojournal.jpl.nasa.gov/jpegMod/PIA08899_modest.jpg

http://www.planetary.org/image/PSP_002162_9030_cut_b.jpg

The MRO one suggests some excellent science could be done from 4 AU away, but it would mainly be one (highly multispectral) snapshot and that's it. And that's a heavy camera to lug along.

A still better investment would probably be better telescopes in our solar system which could show us multiple extrasolar planets before we try to blast past a few of them many decades from now and get just a teacupful of science.

Posted by: Juramike Sep 5 2008, 01:48 AM

I absolutely and totally agree. One really neat concept I like is a 150-km space hypertelescope made from 150 3 m linked space telecopes.

Check out Figure 8 in Luc Arnold's 2008 article which simulates how Earth would look at a 10 light year distance from such a flotilla of linked scopes. (Looks pretty dang good!) And the technical ability to launch this is much, much closer to our grasp and probably attainable within our lifetimes.

Luc Arnold, Space Sci. Rev 135 (2008) 323-333. "Earthshine Observation of Vegetation and Implication for Life Detection on Other Planets: A Review of 2001-2006 Works". doi: 10.1007/s11214-007-9281-4 Freely available http://arxiv.org/PS_cache/arxiv/pdf/0706/0706.3798v1.pdf.

-Mike

Posted by: JRehling Sep 5 2008, 07:35 PM

For what it's worth, take that Jupiter image and imagine that our interstellar craft got one picture of Mars, at that resolution, and it was in a half phase. The science value of the image would be pretty low. I mean, as a novel data point, it would be astonishing, but as far as beginning to perform comparative planetology on it, forget about it. And spectroscopy, which is actually interesting, seems much more plausible to do from our solar system and putting the money you'd spend on propulsion on light-gathering.

Also, it's interesting to contemplate, if/when we do get images of terrestrial-class bodies with more than ten pixels of diameter, how clear their skies will be. In our solar system, excluding the Earth as a biased data point, of the terrestrial planets with atmospheres, we have:

Mars -- usually >90% clear, but sometimes totally obscured by dust; spectroscopy is not racking up major successes except when the spatial resolution is exceptional
Venus -- the surface is only visible with radar and thermal IR; prospects for spectroscopy are hypothetical
Titan -- IR actually does some good work here, but spectroscopy is still tough

And the prospect of radar-mapping a cloudy terrestrial body while a craft moving at 0.1 c blasts through the system is laughable. That seems impossible even in principle if you wanted to get any geomorphology information. Radar resolution drops off with the fourth power of distance, so forget about it. Cassini can't even use RADAR effectively on Enceladus due to the large relative velocity.

Posted by: Del Palmer Sep 6 2008, 12:38 AM

If we ever develop the technology to accelerate a spacecraft to 0.1c, one would hope we would also be able to slow-down from 0.1c at the other end. Seems a waste to take all that time/resources reaching the target star system, to then just flyby at high velocity. You'd want to take fields and particles instruments along, to do science that cannot be done from Earth.

Posted by: JRehling Sep 6 2008, 12:59 AM

I wonder if a special sort of ballute system could be used to aerobrake on the other end. Something radically different from anything you'd use at conventional velocities. Something like a strand of spider silk a million km long that dragged through the atmosphere of a giant planet producing very low drag for a very long time. Although I can't think of any particulars that would make sense, but then I've only been thinking about it for a minute.

It would also be valuable simply to get the craft into the plane of the system which could be arbitrarily easy if the system happens to be aligned correctly. Slicing through our solar system at right angles, if you flew right by Saturn, you'd be no closer than 3 to 20 AU from the other planets. You could have a good pass in the inner solar system, but in the ideal case, say you flew right between Earth and Venus or Earth and Mars, you'd only see the night side of one at C/A.

It'd be a nice problem to have, though...

Posted by: centsworth_II Sep 6 2008, 01:42 AM

I'd say you better start braking quite a distance from the star system you are approaching, not waiting until after you have entered the system. Maybe a solar sail that would be extended to use the radiation from the target star to slow the craft down. Sort of a solar parachute.

Posted by: Stephen Sep 8 2008, 05:50 AM

For the record, Project Daedalus would have targeted Barnard's Star, a red dwarf, not the Alpha Centauri system (G type + K type + a (distant) red dwarf).

That aside it could also be argued that both projects would be relying (in one way or another) on "not-yet-invented technology".

Due to the great distance at which the probe will operate, positive control from earth will be impossible due to the great time delays involved. This fact necessitates that the probe be able to think for itself. In order to accomplish this, advances will be required in two related but separate fields, artificial intelligence and computer hardware. AI research is advancing at a tremendous rate. Progress during the last decade has been phenomenal and there is no reason to expect it to slow any time soon. [Page 4 of http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19890007533_1989007533.pdf]

AI is arguably another one of those "not-yet-invented" technologies. AI research may well have been "advancing at a tremendous rate" when this report was created back in 1988 but the sad reality remains that here we are in 2008 , twenty years on from that report, and artificial intelligence remains "not-yet-invented".

To make matters worse, to the best of my knowledge researchers still have only the vaguest of ideas about how to go about creating one. (In fact it could be argued we know more about the principles of creating a functioning fusion reactor or thermonuclear pulse propulsion than we know about the principles for creating a functional artificial intelligence!)

I don't doubt artificial intelligence will be invented some day, but at the same time until the principles are understood nobody will be creating an AI except through sheerest accident.

======
Stephen

Posted by: JRehling Sep 8 2008, 07:51 AM

[...]

Posted by: Stephen Sep 8 2008, 08:03 AM

1) Proxima Centauri is so far from its companions that Alpha Centauri is for all practical purposes a binary rather a triple star star system; and a http://en.wikipedia.org/wiki/Alpha_centauri at that.

2) Epsilon Eridani is 10.5 light years away, over twice the distance of Alpha Centauri, and therefore over twice the mission time (200+ years) for a Project Longshot-type craft. If NASA or anybody else was going to send a mission that far and of that length I suspect many would probably prefer it be sent a smidgin farther, to Tau Ceti, which although 11.9 light years away is, unlike Epsilon Eridani (but like the Sun and Alpha Centauri A), a G-type star.

3) Epsilon Eridani's "known planet" is almost certainly a gas giant. I suspect any mission sent that far this soon will more likely be looking for (and at) habitable worlds. Whether Epsilon Eridani has any of those, of course, is unknown. That said, I notice that Epsilon Eridani's is apparently in a highly eccentric orbit, approaching the star as close as 2.4 AU and receding as far as 5.8 AU (according to http://www.solstation.com/stars/eps-erid.htm at Solstation.com). I'm not an astronomer, but it seems to me that that kind of orbit for a planet 1.5 times the mass of Jupiter at that kind of distance possibly hints that planets closer in (if they exist, or still exist) may be in a similar state, which in turn may not bode well for their habitability.

That's a fair point, especially for missions of 100 or 200+ years duration.

But that said, it seems to me that an argument of that sort could easily have been levelled at Voyager to keep it on the ground: why bother sending out flyby probes to such farflung places as Jupiter and Saturn to obtain "just a teacupful of science" when building better telescopes back home on Earth or in Earth orbit would have yielded just as useful a result?

Not until Voyager actually went out there and showed what it could do were attitudes like that no longer viable; and of course if Voyager (or Pioneer) had not gone then Galileo, Cassini, and New Horizons would almost certainly have not gone either.

It's a bit like the missions of Columbus and Sputnik. There will always be arguments, often persuasive arguments, against making the effort. Not until somebody shows it's not only possible but worth the effort will attitudes change in the places that matter and the balance of the argument shift.

======
Stephen

Posted by: ugordan Sep 8 2008, 08:38 AM

That argument certainly couldn't stand up for Voyager as they were flown with existing technology and would on paper (and did) provide science well beyond anything possible from the ground, even today. Consider the Uranus and Neptune encounters and the science they produced. Now consider the resolutions we get from the ground.

This is almost diametrically opposite to sending a lone probe on a 100+ year journey for basically only a couple of hours of distant planetary observations as JRehling pointed out. There's a cutoff in resolution depending on flyby distance at which you might as well stay on the ground and just build a larger telescope than send an inferior instrument on site. Voyagers were well inside this cutoff distance so the science paid back big time, an interstellar probe would be well outside of it. This is not even considering the length of time you could usefully observe a target while flying at an appreciable fraction of light speed.

Posted by: Stephen Sep 8 2008, 12:52 PM

I'm not an AI researcher, but with all due respect I completely disagree with that statement!

1) For a start who would decide which were the "interesting" planets and which weren't? The researchers back home on Earth before it leaves or the spaceprobe itself on the spot on the fly? If the latter, then that merely begs the question: how often do the MERs themselves decide which is an interesting target and which is not?

If the answer to that is "never" (because the researchers make all those kind of decisions themselves), then that leads us to the next question: could the MERs make such decisions if the researchers allowed them to?

If the answer to that is "no" then how is the sort of decision-making that would be required for an interstellar probe "way below the level that has already been exhibited by the MERs"?

It seems to me you have it the wrong way round! Being able to navigate deftly around a rock (which, as I understand it, is about the level of the MERs capabilities) is several orders of magnitude (at least) below a decision like (for example) deciding that that funny-looking soil with all that white stuff my wonky wheel just dug up is ever so much more interesting than that pretty rock with the nice layering I was making for over yonder.

2) Just how do you define "interesting" anyway? For example, if have a target-rich environment what are the criteria and priorities it would use to decide the few targets it would be able to concentrate its attentions on? Would those be rigidly programmed in prior to launch or would they be a thing the probe would be able to work out for itself based on previous observations it had made? For example, suppose the probe had to choose for a close flyby between a planet that looked like a white billiard ball but with spectroscopic signs of water ice, another which had what looked like craters interspersed by icy plains, a third that was smothered completely in craters, and another that looked like a diseased pizza but with a hint of sulphur dioxide. If that was all it had to go on which would it choose and how would it choose it?

3) Being able to decide which are the interesting targets on arrival is only a fraction of what the computing systems (if you want to call them that rather than "AIs") onboard any interstellar probe will require.

Consider the MERs. They may be able to find their way around rocks, but if in doing so they get caught in a sand trap, even a teensy weensy one like that last time Opportunity got stuck at Victoria Crater, and you rapidly reach the limitations of their intelligence. Instead of being able to work out for themselves how to get themselves out they have to rely on human intelligence back on Earth. Now that is not their fault. The MERs were never designed to get themselves out of those kind of problems. However, those are also the very kind of situations an interstellar probe will need to be able to deal with all by itself. The probe will be completely and utterly on its own. Going into safe mode and waiting for mission control back home to get it out of the fix will not be an option if its two or three light years out.

Granted that some of these problems may be standard ones humans back on Earth may be able to anticipate and work out solutions for it in advance. Others, however, will almost certainly not be. In fact given a mission lasting 100 years, or even 50 years, I would say the latter sort are an inevitability. If the probe gets into trouble it has to be able to diagnose and analyze the problem and devise a solution. If one solution does not work, it has to be smart enough an capable enough to try other alternatives, including ones its makers back on Earth may not have planned for, let alone anticipated. It also has to know how to back out a solution if it doesn't work and which ones can't be backed out of (and so which ones you don't try unless you absolutely have to).

That sort of capability goes way beyond anything the MERs have.

And of course heaven help the probe if should ever get into the kind of life-and-death situation Spirit experienced back at the start of its mission. Yet even that an interstellar probe will need to somehow be able to cope with. If it cannot, then the odds of its surviving to complete its mission will probably be not good, for it will be depending more on sheer luck and good engineering to keep itself out of trouble than having the capability available to get itself out of any trouble it might find itself in.


Perhaps.

I can't help wondering though how useful those are going to be. For example, how close would a probe have to be before it could detect (say) nitrogen or oxygen or water in a kind of spectrograms the probe would have available to it--bearing in mind:

1) That the instruments it will be carting along will probably have a limited resolution;

2) The results are not likely to be all neatly available all at once but will accumulate over a period of time as the probe approaches the Centauri system, thus it may not necessarily have all the necessary information until quite late, if at all;

Above I gave an equally optimistic example myself that presumed the probe would have the telescopic capability of the Hubble telescope built in. More realistically, the kind of pictures the probe would likely be presented with (and on which it would have to make its decision) would contain a single tiny point of light a few pixels across (at best) with (at best) a few vague smudges on it. Similarly, the spectrograms may well be composed of some indeterminate squiggles that may well be interpretable in several different ways rather than in one single unmistakable fashion.

In other words, the kind of data it may be presented with to make a decision upon may well be sort that even a trained human being of high intelligence and long experience may well have problems making a competent decision on the basis of. It may also be the sort that may require the kind of lengthy study, special enhancement techniques, and access to a library of reference material that the probe may or may not have available.

BTW, note that thus far I'm making the same assumption other people here seem to be making: that the probe would be a flythrough (albeit Longshot would have been at 5% of c rather than the 10% being assumed above). However, in the particular case of the Longshot probe, the proposal was in fact for an orbiter, not a flythrough; and of Alpha Centauri B at that rather than the more Sun-like Alpha Centauri A. In that context note the study's rationale (p28): "Beta was chosen as the target star because it is a dK-Type star, about which we have very little data, while Alpha is a G2 type star like our own, which we have studied extensively." In other words, the star rather than any accompanying planets would have been the mission's primary target. The probe's instrument package would presumably have been tailored accordingly.

Once in orbiter the probe's manoeuvring capabilities, and thus its ability to do flybys of any promising looking planets, would (presumably) have been limited.


Glad to hear it. But that is arguably not what most of us non-AI researchers would term "artificial intelligence" (even granted that my own use of "AI" was a mere shorthand because I did not want to keep typing out "artificial intelligence").

That said, it is true my intended interpretation was indeed that of a thinking machine, and thus by implication one with a human-like intelligence. Or so at least I interpreted the Project Longshot proposal's own words: "This fact necessitates that the probe be able to think for itself." (pg 4)

The authors presumably did not use that word "think" lightly.

How many of the systems do you work with or know of could be said to "think for [themselves]"?

I don't doubt that many if not all those systems are extremely capable. They may even have some degree of learning capability. However, I will also hazard a guess that many if not most of those specialise in particular areas; and probably (in general) narrowly defined ones at that. Outside their particular speciality, however, would I be correct in assuming they would (probably) be at sea?

Why such an approach may have its uses on such a probe, especially among its various subsystems, the primary computing system will almost certainly need to have something approaching human intelligence, learning capability, and problem-solving capability. In other words something approximating a human mind, albeit I draw the line at the definition you imply with your reference to "mind[s] that can cry and love and so on". I think you're confusing the human mind with human emotions, many if not most of which arguably have physical causes that little to do with intelligence. You don't need to cry, for example, to exhibit intelligent.

To send out such a probe with a capability less than that would to hobble the mission even before it left the ground, as the Project Longshot team clearly recognised.

Remember, this will not be any MER-style mission with a team of human problem solvers only a few light minutes away. For all practical purposes it will be cut off from human assistance for most of its journey. If it gets into trouble it will have to get out of that trouble all by itself.

Are present-day artificial intelligence systems up to that level?

======
Stephen

Posted by: ugordan Sep 8 2008, 01:09 PM

I can understand where JRehling's idea of prioritization and automatic selection comes from. If the probe had a very limited delta-V budget and was going at 0.1c, it would have to make a decision a long, long way out. It would basically have to work with unresolved spectroscopic data only - maybe looking for spectral signatures of interest or temperature data deduced from thermal IR spectra. It would then be a matter of automatic targeting of the craft in a manner similar to what Deep Impact did. Not entirely unreasonable and seems doable even with today's technology. The problem is in getting data to select from.

Take into consideration a flyby mission that has a 10 km/s delta-V correction capability and let's say it's initially targeted right at the star and the star system presented itself head-on, as a bullseye pattern. For the probe travelling at 0.1c to be able to target a planet at 1 AU from the star with the onboard delta-V capability, the probe would have to burn all the available propellant while still being 3000 AU from the star. How much can you figure out from spectra at that distance?
10 km/s is a hefty delta-V for today's standards, having a 1000 km/s budget really helps, but how do you get that sort of performance with any reasonably light probe? It would have to be reasonably light if you wanted to accelerate it to 30 000 km/s in the first place.

I say let's build huge space telescope arrays here instead. At least we wouldn't have to worry about them ablating away while hurtling through space at record speeds.

Posted by: Stephen Sep 8 2008, 01:26 PM

With all due respect I think you've missed my entire point!

BTW, while the Voyagers that were flown used existing technology, they were cut down missions from a much more ambitious Grand Tour project that never got off the ground. Also the missions that were flown were originally funded only to go to Jupiter and Saturn. Uranus and Neptune were a bonus. What we would now call an extended mission; and even then only Voyager 2 got to go on it (so to speak). In the original Grand Tour the other probe would have gone to Pluto.


Project Longshot was to be an orbiter, not a flythrough. It would have orbited Alpha Centauri B.

In addition a primary purpose of the Longshot mission would have been long-baseline astrometry. You can't do that from the ground on Earth or even from a telescope in solar orbit, no matter how powerful it may be. The telescope needs to go out as far from the Earth as it can; and the farther out it goes the better the resolution.

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Stephen

Posted by: hendric Sep 8 2008, 04:16 PM

I think the issue with AI's is a bit of a non-problem. We regularly update software in-flight, why not with this probe? Say you need to start doing your planning 5 years before arrival, and it takes about 10 years to get your SW to the spacecraft, then your spacecraft can run an AI designed up to 85 years in the future to detect,plan, etc for the landing. Just be sure to launch with a seriously over powerful CPU (well, a couple anyways for backups etc obviously) and a ridiculous amount of extra memory.

Plus, the scientists planning the launch will already know the inclination of the system, right? Instead of aiming for the center of the star, the aimpoint could initally be targeting the habitable zone on the side moving away from Earth. Of course, you'd have to aim for where the system will be in the future, since it would move quite a bit in those 100 years.

Given a sufficiently large telescope, the algorithm for choosing which planets to visit should be fairly simple, right? If there is planet with oxygen in the atmosphere, go there. If not, if a planet has liquid water, go there. If not, if a planet has between .2 and 5 Earth masses, go there. If not, if there is a planet within the habitable zone, go there. If not, attempt to flyby as many of the planets as possible. This would miss Titan, but catch Earth, Venus, and Mars.

With knowledge of a Jovian class planet, would it be possible to plan slingshots through to other planets? That might be too dangerous if they have moon systems similar to ours...Or radiation environments...

Anyways, the AI issue should be easily tractable. The bigger issue is how much mass you expect to send. At a minimum you'd need a nuclear reactor powered spacecraft of some sort, a large telescope for planning the visit, and a giant radio antenna for communicating back home (or maybe a laser comms). And redundant on top of redundant systems. Maybe 100+ kilo kg? (10x Hubble)

This all raises an interesting question: If someone sent a similar probe through our system, would we be able to detect it? Or would it zip by completely unnoticed? If the homeworld is in constant communications, we might see the beam once the spacecraft and sun are sufficiently aligned. But most likely, once the software is updated, the homeworld will be listening for any results instead of transmitting...I think we probably wouldn't notice an interstellar probe, unless it is of the giant-RAMA-spaceship type...

Posted by: jasedm Sep 8 2008, 05:18 PM

And once all that were achieved, the hope would be that none of the instruments would go into 'safe' mode during any putative flyby.....

Posted by: ugordan Sep 8 2008, 05:20 PM

Hell, if you have enough capability to accelerate to 5 or 10 % of light speed and then brake at the end, you don't need slingshots. If you don't slow down on the other hand, there's no planet that's going to bend that trajectory (more like a straight line) anyway. Even the star itself would have trouble affecting something going some 50 times its surface escape velocity.

Posted by: JRehling Sep 8 2008, 08:10 PM

[...]

Posted by: JRehling Sep 8 2008, 08:35 PM

[...]

Posted by: ilbasso Sep 8 2008, 09:47 PM

What kind of AI did our computers have or software did they run 85 years ago? Ahhh.....

This is not a trivial issue, as many of our esteemed UMSF members find as they try to deal with data tapes from the 1960's in weird formats for tape readers that no longer exist. Is our attention span good enough to maintain working knowledge of software for a 100 year long mission?

Although, if Ray Kurzweil is correct, then humankind will have reached "The Singularity" by about 2050 and our intelligence will start spreading through the cosmos at the speed of light anyway. So maybe our minds will already be at Alpha Centauri by the time the probe arrives!

Posted by: Stephen Sep 9 2008, 08:26 AM

1) What constitutes a "seriously over powerful CPU" and a "ridiculous amount of extra memory"?

Think back to the computing hardware that is currently flying in the Voyagers and you will see how that is not a serious proposition! What would have seemed like a "seriously over powerful CPU" and a "ridiculous amount of extra memory" back in the 1970s is now a mere drop in the proverbial bucket required by much of the software now running on the computing hardware of 2008, let alone the kind likely to be available in the 2060s (1970s + 85 years...), even granted that much of that power in current software tends to be used to display increasingly sophisticated graphical GUIs.

2) I doubt a single CPU, no matter how "seriously over powerful", will be able to run an AI. The human brain seems to make massive use of parallel processing to do the same job, so I suspect (just MHO) the hardware required to run an intelligence of an artificial kind will probably need to do the same as well. The upside: the probe's designers will not necessarily need to include "seriously over powerful" CPUs. Less sorts would probably suffice. The downside: they may well, however, require a very large number of such CPUs, which in turn may tax the power requirements of the probe (amongst other things).

3) As for updating software in flight, sure it's done now although I doubt if anyone's done what you seem to be contemplating: adding the AI **after** launch rather than as before (as part of the original design).

I am however wondering though what the data rate would be for the probe at a distance of 2 or 3 light years from Earth and the size of the update. I notice the Project Longshot paper says: "A laser with an input power of 250 kilowatts would allow for a data rate of 1000 bits per second at maximum range." If we take that as our starting point, then assuming 8 bits per byte (and ignoring the issue of other bits like parity bits etc consumed in the transfer), that equates to about 125 bytes/second, 450,000 bytes per hour, or 10.8 megabytes per day. A software update of about 1 gigabyte would therefore take about 100 days to upload.

Of course this would pale beside the timespan required if the probe, having received the update, then had to verify the uploaded software with Earth (to ensure it was received correctly). If the probe by then was (say) 3 light years out it would be six years (+ another 100 days) after Earth uploaded the last byte that the first of the data to be verified came back. Then a further 3 years before the "OK to proceed" signal could be sent.

In other words, a single 1 gb update could take over a decade to accomplish. (3 years + 100 days to upload update, 3 years +100 days to verify, 3 years to send "OK to proceed".)

Even if the verify were not needed (because the uploaded data was self-verifying) the time involved would not be that much shorter unless the probe did not require Earth's approval to implement the update.

(Of course all of the above assumes that everything uploaded correctly and did not have to be re-sent!)

Are artificial intelligence algorithms "fairly simple"?

Not to mention time consuming. I seem to remember it taking an awful long time for Galileo, Cassini, et al to get around using only gravitation slingshots.

Besides, who will be planning such slingshots? The experts back on Earth or the AI on the probe?

======
Stephen

Posted by: Stephen Sep 9 2008, 08:45 AM

This is hindsight talking. Up until Voyager arrived our own Titan was certainly a prime target, however nobody realised that Titan was completely swathed in clouds. Had that been recognised would NASA have still sent Voyager 1 on a trajectory that got it nicely close to Titan but also denied it the opportunity of proceeding on to Uranus and Neptune like Voyager 2 or would it have sent on one that retained the Uranus/Neptune option?

A probe not equipped, or at least ill-equipped, to peer beneath the clouds of Titan (or a Venus for that matter) may well decide that lots of snaps of Rhea's geology would provide a richer data set than lots of snaps of Titan's clouds, especially if the Rhea trajectory also allowed it to proceed on other targets whereas the Titan one did not.

======
Stephen

Posted by: ugordan Sep 9 2008, 08:54 AM

Yes, they would have. The information gathered by Voyager 1 was still crucial (in particular the radio occultation) in determining the radius, temperature and pressure profiles of the atmosphere and basically paved the way for Huygens and established a model for Titan's possible surface conditions, which holds up pretty well even now. Had Voyager 1 failed immediately before the Titan flyby (and thus already having provided a view of the global haze shroud), NASA would still have retargeted Voyager 2 at Titan. This alone is sufficient proof that NASA realized Titan was a high priority target even from distant groundbased observations, high enough to forgo possible Uranus/Neptune encounters if necessary. They would have thrown even the kitchen sink at Titan if they needed to to get this data.

Also, hindsight talking or not, if you're unable to determine from very far away if a world is interesting, you can write off your close approach ideas whether you have Godlike AI or not. There simply will not be enough propellant to retarget the craft once you get close enough to actually resolve the body. As JRehling said, this constrains the parameter space so much that even humans wouldn't be able to do a much better job at picking targets based on a couple of spectra alone. You're stuck with distant data to work with.

Posted by: djellison Sep 9 2008, 10:29 AM

Whilst personally, I consider this entire thread to be more about science fiction than anything else (check the forum rules for what that means) - I will pick you up here.

The MER's have had several significant flight software updates that have given them abilities not even considered before launch. It depends where you definition of AI lies - but go-and-touch, automated DD/Cloud watching, D-star etc, are all abilities that were developed long after landing and uplinked to a vehicle designed, built and launched without those abilities in mind. It's not unreasonable to say that the MER's that drove in their primary mission lacked intelligence (but not autonomy), and the MER's today have both an element of intelligence and autonomy.

Posted by: hendric Sep 9 2008, 09:10 PM

Are we talking about a probe being launched in the 70's or today? I was assuming today. If it was still in the 70's, then the hardest part of the AI will not be determining which objects to visit, which is trivially simple, but detecting objects at all. But, on the other hand, any AI, primitive or not, would be given a vast amount of time to make a decision, with constantly improving data being input into the process. After all, the decision does not need to be made real-time. The data could be captured in a month, and then a year spent processing it. Even 1970's era equipment could give you an answer in that amount of time.

Modern CPUs are vastly overpowered for what the probe would need. It is possible to purchase CPUs with 8+ cores on them. I think an AI in the terms of what is necessary (image taking, planetary object recognition, intensive imaging of objects, determining score, selecting primary targets, adjusting course) wouldn't really need to be much, given the relatively small sample size (what's the most planetary objects we'd expect? 30?) and the large amounts of time to make a decision. (months - years)

As others have said, it's done all the time now. Many probes are sent out with the flight software updated en route. (I seem to recall a spacecraft being sent out without any encounter software, just cruise software. Was that the MER's? I forget!) SW is the hard part of any design. Once the HW is proven and in the air, all you've got is time to refine SW.

You would never implement an update like this. You would just send your update continuously. I doubt the update would be 1GB, but even with that, you can send 3 1/2 copies of that data in one year, and need not worry about validation, since the probe would validate the data as it received it through CRCs, much like a BitTorrent. With modern error detection and correction codes 3.5x the data gives you ridiculous amounts of redundancy. Data transmission is a very well-studied field; any reception problems would be very temporal, and many simple algorithms can deal with that. Look at how well cellphones send and receive data through ridiculously difficult conditions: moving receiver, multipath, shared spectrum, etc.

That's assuming 1970's technology of course. With modern technology, I wouldn't be surprised if there was a 10 to 100x improvement just due to the ECC codes.

Well no AIs are not simple, but AI in term of predicting the course of a hurricane or identifying a person on a photo is orders of magnitude more complicated than looking at 30 planetary objects and deciding the one or two to visit based on a couple of parameters, and then plotting a course to them.

Posted by: JRehling Sep 9 2008, 09:28 PM

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Posted by: JRehling Sep 9 2008, 09:32 PM

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Posted by: JRehling Sep 10 2008, 02:16 AM

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Posted by: brellis Sep 10 2008, 02:34 AM

I play on a 25 year old Kurweil keyboard; does that get me a ticket on "The Singularity"?

How about a nano-level self-generating type of craft that is committed to staying in touch with us? We could be testing that technology here in our own SS some time soon.
Recent articles about solar sail craft that could be precursors to interstellar craft -- http://www.planetary.org/programs/projects/solar_sailing/20080623.html, http://www.space-travel.com/reports/New_Developments_On_The_Road_To_Cosmos_2_999.html

Posted by: Greg Hullender Sep 10 2008, 03:01 AM

There's a good bit of serious information on the JPL AI group's page:

http://ai.jpl.nasa.gov/public/

In particular, there is/was a satellite, EO-1 (Earth Observing One), which is using some of their planning algorithms to select science targets. In this paper, they claim a 100-fold increase in science return, measured as science events per megabyte:

http://ai.jpl.nasa.gov/public/papers/sherwood_spaceops06_autonomy.pdf

From reading this, though, it required at least weekly human intervention; given a broad plan, it could work out the details, but it couldn't extrapolate from one week's results to construct a good plan for the next one. (Assuming I'm reading this correctly; planning algorithms matter a lot in my own research, but this paper isn't actually about the algorithms -- it's much higher level.)

Things like the Mars Rovers use custom-built planning software, but the JPL AI team is actually trying to build a platform that future missions can work from. That'll be really great if it works. Best of all, it'll involve papers I can even justify reading! :-)

--Greg

Posted by: ilbasso Sep 10 2008, 06:06 PM

One other comment about AI software updates - in flight software updating works well. However, experiments in advancing AI are demonstrating that the basic architecture of the computer system (e.g., massively parallel processors) could well need to be modified to more closely mimic the functioning of an intelligent nervous system. At least as far as I understand, you can't do that kind of redesign once the probe is launched.

Posted by: JRehling Sep 10 2008, 06:54 PM

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Posted by: imipak Sep 10 2008, 09:23 PM

Full-featured Artificial Intelligence: Hard, with a capital H.
Artificial intelligent-enough-to-cope-with-this-well-bounded-problem-domain: relatively easy.

It's still very hard in absolute terms, of course, but it's not Hard in the CS (or AI or philosophy of consciousness) sense. I agree with JRehling; we could conceivably build computers to handle the problem with today's technology, given sufficient budget.

Going back to basic mission architecture -- one way of overcoming the problem of slowing down enough to enter solar orbit might be not to do so. Instead the relatively heavy, fast-moving mothership could jettison several very light planetary probes. These could then brake with $[sufficiently_advanced_technology] of choice, without having to slow lots of superfluous superstructure designed for the multi-decade deep space portion of the mission. Perhaps that braking wouldn't be enough to reach planetary orbit, but stretching a (say) 10 day encounter to 100 or 1000 days would be good. Maybe these small vehicles could use the powerful transmitter of the (still relatively close) mothership to relay comms back to earth... though that suggests a DSN-scale antennae on the mothership to receive from the probes. :?

Posted by: stevesliva Sep 10 2008, 10:56 PM

You are looking for the word "autonomy." Or autonomous.

Posted by: Greg Hullender Sep 11 2008, 02:16 PM

Just to put a word to it, we say a problem is "AI-hard" to mean the computer would need to be able to think at least as well as a human being in order to solve it. At present, we are nowhere close to building a true artificial intelligence, so if a problem is AI-hard, that means we cannot solve it even in theory.

I agree with JR that this problem isn't "AI-hard". As I posted earlier, the EO-1 satellite seems to have demonstrated that JPL already has software to find scientifically-interesting targets. In fact, odds are good that that software will be very important on future missions to places Neptune, since it lets you make much better use of your precious communications bandwidth.

My own research, on "Practical Dialogue Systems" is aimed at finding a useful, tractable subset of the AI-hard "General Dialogue Problem," so this is the kind of stuff I think about/work on every day, albeit not in a space context.

--Greg

Posted by: Phil Stooke Sep 15 2008, 08:25 PM

"the EO-1 satellite seems to have demonstrated that JPL already has software to find scientifically-interesting targets."

Admittedly, I know nothing about this, but I would imagine that the EO-1 software referred to is based on a list of pre-defined things that might be interesting, which could be hard to adapt to a reconnaissance of a new planetary system.

I imagine the procedure would have to be something like this:

1. Repeated surveys during approach to identify planets, with more added to the list as the spacecraft gets nearer (obviously easy to do, Voyager-like).

2. Track objects from survey to survey and compute orbits (should be relatively easy).

3. Repeat 1 and 2 in higher resolution sequences to characterize satellite systems (less time to act but should be relatively easy).

4. Attempt to characterize the objects: size, albedo, temperature, which have rings, which have atmospheres (presumably this can be done, but how soon before the flyby?)

5. Prioritize the highest resolution observations (that looks like the hardest part to me, without human intervention).

But I repeat, I know nothing!

Phil

Posted by: Greg Hullender Sep 15 2008, 09:11 PM

This would probably be a more interesting discussion in the context of something like the proposed Argo Neptune flyby -- or even just the Jupiter Trojan flyby portion of that mission. Heck, even New Horizons might be able to use something similar. (We should ask Alan if they have considered anything like the EO-1 software.)

--Greg

Posted by: djellison Sep 15 2008, 10:13 PM

NH doesn't need it. They know roughly what they're going to see, and they need to schedule each and every tiny second of that flyby to get the data they need by hand.

Posted by: Greg Hullender Sep 15 2008, 11:55 PM

Perhaps. On the other hand, suppose, for example, some unusual feature were seen during approach. The software could (in theory) make sure it got shots of it during closest approach. Or if it spotted another satellite, it could try to get a shot at close approach -- or at least get shots at different phase angles. Yeah, that's weak. :-)

I'll admit the lesson of EO-1 seems to be more for orbiters -- since that's what it was. The claim that it increased the quantity of scientifically-interesting events by a factor of 100 really caught my eye. A Neptune orbiter might have lots of trouble getting enough bandwidth to send back a steady stream of video, but if the software could intelligently pick and choose, that might allow the use of a smaller antenna -- or a higher-resolution camera.

In the case of a flyby, though, perhaps it's just not that hard to simply store everything and then send the results back over time. I suppose, then, what makes the proposed Alpha Centauri flyby unique is the assumption that the designers would have no idea at all what to expect. That the probe would have to choose all of its targets by itself.

--Greg

Posted by: jsheff Sep 20 2008, 05:15 AM

For me, Project Longshot would carry a lot more scientific credibility if they hadn't made the amateurish error of designating as Beta Centauri the star that should properly be referred to as Alpha Centauri B. The destination star system is composed of Alpha Centauri A, Alpha Centauri B, and Alpha Centauri C (or Proxima Centauri), all revolving around their common center of gravity. Beta Centauri is a different star system entirely - hundreds of light-years beyond Alpha Centauri and unrelated to it aside from being by chance located in roughly the same part of the sky as seen from Earth, and hence designated by us - arbitrarily - to be in the same constellation. That's an elementary error that seems to carry right through the Project Longshot report.

I hope they're not as sloppy in designing the fusion engines.

- John Sheff
Cambridge, MA

Posted by: Hungry4info Sep 21 2008, 01:38 AM

Well... I had the same confusion when I was younger...

... like the age of six or seven

Posted by: Stephen Sep 23 2008, 03:14 AM

Since this discussion still seems to be sputtering along I'll add another 2 cents.

Claiming a problem as being unsolvable "even in theory" is to claim that no solution for that problem exists. An obvious example would be trying to build a space probe which could ATTAIN light speed.

On the other hand, having a problem which was merely very hard to solve--and the statement that researchers were "nowhere close to building a true artificial intelligence" would seem to be inferring that--is a different beastie altogether. An example would be trying to build a space probe which could reach very high rates of c. Such a probe would doubtless be very difficult to build, and would probably require technology, materials, techniques, etc not available or even feasible today. In the end it may even turn out to be so difficult (or at least so costly) that it may not be worth the effort of trying to build such a probe. But being hugely difficult and impractical that is NOT the same as being impossible.

Given that context, I would argue your statement was self-contradictory. Being "nowhere close to building a true artificial intelligence" is not the same as being unable to build one "even in theory". Has anyone ever demonstrated that being able to build a "true artificial intelligence" was impossible "even in theory"?

Glad to hear it. I take it then that it was Opportunity rather than Steve Squyres and his team who made the recent decision to head off for Endeavour crater.

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Stephen

Posted by: Stephen Sep 23 2008, 03:41 AM

Well, I guess that depends on whether artificial intelligence researchers are trying to solve the problems they face by reinventing the wheel or by finding out first how Mother Nature has solved those same problems then using her solution(s) as at least the starting point for their own.

After all, it only took Mother Nature several billion years (using her trial and error methods of natural selection) to figure out how to go about it even if we're only talking about intelligence of the level of a fish or a trilobite. I imagine modern researchers will be hoping to find their own solutions a tad sooner.

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Stephen

Posted by: JRehling Sep 23 2008, 04:05 AM

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Posted by: Vultur Sep 23 2008, 12:07 PM

I don't really understand the need for massively complex AI. Sure, it can't be directed by humans, but if we're talking a flyby speed this high, the possible choices are VERY limited.

It seems like the flowchart you'd need would be like this:

If a planet/moon has oxygen or methane, go as close as possible to it using all instruments on planet.
If not:
If a planet/moon has an atmosphere at least Mars density but less than gas giant density, go as close as possible to it, use all instruments
If not:
Go as close as possible to planet/moon with radius closest to 8800 miles (Earth's), but take pictures of star as well rather than prioritizing everything to planet
If no planets at all:
Go as close as possible to star and use everything on it.

Posted by: JRehling Sep 23 2008, 03:50 PM

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Posted by: Vultur Sep 24 2008, 12:38 AM

Exactly. And I think short of sci-fi (read: not in the foreseeable future) technology, those will be the huge issues for something like this. A lightsail-launched probe doesn't seem that far beyond our current tech. Sure, the laser would be millions of times bigger than any built before, but the principles would be the same -- more an engineering issue than one of fundamentally new technology, rather like how we went from Explorer 1 to the Apollo/Saturn V system in a decade.

Posted by: Stephen Sep 24 2008, 05:56 AM

Hmm. I wonder how many times in the history of the space program that sentiment has been expressed before--only to have reality come crashing down with a loud thump when, after many years and the spending of large amounts of money, the engineering requird turns out to more complicated and more expensive than contemplated in the original proposal.

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Stephen

Posted by: Greg Hullender Sep 24 2008, 06:34 PM

We have no physics that suggests how we could exceed light speed, and we have no theory in computer science that suggests how we could build a machine that thinks. Yes, we have the example that people do think (and no examples of anything moving faster than light) but we have absolutely no clue how people think. A lot of bright, talented people have wasted lots and lots of time trying to build reasoning algorithms inspired by how they imagined the human brain to work, and, so far, that work is a frighteningly complete failure.

Giving up on the idea of building a machine that can think is the first step to constructing useful systems in this area.

Actual working systems today to do things like speech recognition, handwriting recognition, machine translation, etc. use highly mathematical, highly statistical, explicitly non-organic algorithms. These things do not simply scale up into human intelligence, though. Even with unlimited hardware and unlimited raw data, none of these things is going to start to reason. They just do a better job at their narrow task.

If you want to get some idea of the state of the art, Mitchell's "Machine Learning" http://www.amazon.com/Machine-Learning-Mcgraw-Hill-International-Edit/dp/0071154671 is an excellent graduate-level text for general machine learning, and for the natural-language end of the problem, the recently-published second edition of Jurafsky and Martin's "Speech and Natural Language" processing http://www.amazon.com/Language-Processing-Prentice-Artificial-Intelligence/dp/0131873210 is hard to beat. A more difficult, but perhaps more to-the-point text would be Duda, Hart, and Stork's "Pattern Classification" http://www.amazon.com/Pattern-Classification-2nd-Richard-Duda/dp/0471056693.

Speculating about AI work when you have not read any of the basic materials is a lot like speculatinig about space travel when you don't understand the rocket equation. This is a hard problem, and lots of really smart people have worked on it for a really long time. I believe it will help make a contribution to unmanned space flight through algorithms such as the EO-1 used, but no one will confuse these with anything resembling actual human thought.

--Greg

Posted by: JRehling Sep 25 2008, 05:18 PM

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Posted by: djellison Sep 25 2008, 08:00 PM

Want to get personal - take it elsewhere. First and final warning for all. No debate.

Posted by: Mark6 Oct 23 2008, 08:53 PM

I think a good rule of thumb is - never launch anything that would take more than 50 years to reach its destination. http://www.tsgc.utexas.edu/archive/design/foci/^* mission is thus a valid objective. By the time it reaches Inner Oort Cloud, it will be obsolete, but not ridiculously so, and it will do good science along the way. A "50 year probe" every generation (say, every 25 years) would be a good incremental buildup to a true interstellar mission.

^* Horrid choice of background in the web page!

Posted by: stevesliva Oct 23 2008, 10:28 PM

Does the 50-year rule assume only advancements in propulsion, or also advancements in remote sensing?

Of course, I can think of counterexamples that make remote sensing less of an issue. So what if Voyager had taken fifty years to reach Neptune? Still would be the best photos of Neptune we've got. If Pioneer had taken fifty years to photograph the Galileans, though...

Posted by: Mark6 Oct 24 2008, 12:33 PM

Sorry, but I do not understand your point. Yes, remote sensing could make a probe obsolete before it reaches its destination, but I thought the main discussion was "How to develop intertsellar capability incrementally without building white elephants doomed to be overtaken within their lifetime?" Also, some things can not be done remotely even in principle. Looking at your target from multiple angles, for example.