Can we launch an interstellar probe with current tech?

What trip back home? We're talking unmanned probes here. Send pictures. No need to save any fuel.

One of my coworkers who seems to be especially conscious about managerial waste, loves to point out that the Voyager Program still has a program manager. He pictures him coming in to work once a year, checking to see if the probes are still transmitting, sayin "yup," and going home.

Hey, I'm talking about an unmanned exploration probe, not sending the Robinsons to set up a trailer park. The mission is its own point - exploration. If there are no habitable planets it doesn't matter - the point is to find out what IS there.

If there are no planets in Alpha Centauri, then why would you need a spacecraft there? There would be nothing to see besides the stars themselves and an occasional asteroid. You can do large-scale exploration and measurements via telescopes from Earth. Sending probes and/or humans really only makes sense when you want to do detailed exploration of planets. That's also the only reason why such a giant effort could be justified.

'Cause, closeup studies of the stars in a trinary system would be, like, boring, right?

And its not like our definition of a "habitable" planet could be wrong or anything, or that aliens couldn't be living around the stars in Dyson spheres (which don't have to surround the entire star, BTW). Nope. No chance of that.

No, but you could do 80% of these studies with an Earth-based telescope for a millionth of the price of an interstellar spaceship. Closeup studies of stars obviously aren't close up in the first place: you will have to do the "boring" exploration stuff like studying radiation spectra and things like that, whether you are in an orbit around the star or 4 light years away. So, of course, there are many things to be learned, but presence is not required for many of them.

If we actually built an interstellar spaceship, are you actually arguing we send it to orbit a star and take radiation readings? We know of at least a few hundreds of exoplanets. We know these worlds are there; if we spend hundreds of billions of borrowed money on a space adventure, these worlds would be the logical choice.

Of course our understanding of the habitable zone could be wrong. But actually it is very likely that our understanding is correct. That is because we know how organic compounds work and that they can only exist in a set of environmental conditions. Of course alien life could be different from our understanding of organic life. But actually it is very likely that alien life will be organic in nature. We understand that chain molecules can be formed by quite a few elements, but only carbon has all the properties that makes it so suitable for life. It could be different, but that's not very likely.
When designing an interstellar mission, you can't just randomly choose a direction and see if you encounter anything on your way. Because chances are that, besides some visible stars, you'll never encounter anything at all: space is, after all, almost absolutely completely empty. And because the technological, economical and financial barriers are so high for interstellar missions, we can't simply send a million of vessels in a million of directions. So we would have to choose where to go, and the most logical place would be the place where there are many interesting things to explore. To know what we could find in a given place, we have to scout the place before we go there. If it turns out that it's not very likely that there are a whole lot of interesting things, then obviously a different destination with a higher probability to encounter interesting things is preferable.

To see the stars in that system close up would be a important milestone in human history.

I think you're not understanding just how much more we could understand by getting close up to it. The ability to compare it to our star and note the differences and the similarities would be tremendous. The ability to get close up pictures of Proxima as well and it's relationship to the two big stars would be important.

You can't study Alpha-Centauri like we study Sol. The ability to get a probe in orbit that could see the stars and how they interact with each other would be awesome. There is only so much you can do by telescope on Earth. Why do you think we've got Hubble and the Solar Dynamics Observatory. Imagine putting a probe into orbit around Alpha-Centauri that is a mixture of both satillites. Not only could we watch the stars up close but we could use the "Hubble" part to look back at us.

You can't get stuff like this of ALpha-CEntauri from Earth: http://sdo.gsfc.nasa.gov/

http://www.youtube.com/watch?v=KawL6Hfhd5c&feature=player_embedded

Alpha-Centauri is our closest neighbor at just over four light years. The "first" of any probe or human spaceship capable of reaching such distances will go there first.

If anything choosing Alpha-Centauri as the first stop for any interstellar craft will also give us valuable information on traveling through space. Since we are unlikely to have FTL communications having a probe only four years away would get us back valuable data quickly as compared to sending such a probe far out into space.

Or encorporate a numer of repeater satellites into the design so it can deploy them at regular intervals.

Same reason humans do most things: Just Because.

Human exploration has been based on many things - commerce, trade routes - but one that we always get a bit a thrill from is the sheer bloodyminded stupidity of doing it because we can.

And really, we may just find something there.

I'm all for doing exploration just because we can. But the fact remains that you'll need a damn good reason to get a huge sum of other people's money to pay for your space adventure. A reason beyond because we can.

Because history has shown us that the nation which has turned inward is doomed to decline.

Oxmyx is right...you wouldn't bother sending a probe to any system without first knowing if there were planets worth studying there. And, given very limited resources, you'd probably choose those planets most like Earth for study, in the interest of finding life on them.

I don't think Alpha Centauri will be the destination of the first interstellar probe UNLESS someone finds an Earth-like planet there. That it's the closest nearby star system doesn't automatically make it a prime target. If there were a KNOWN Earth-like planet in some system a few light years farther away, it would be better to bypass AC and aim for it.

Perhaps so, but the cost of outwardness is many orders of magnitude greater once it encompasses outer space...

If it were up to me, we'd be devoting resources to a fleet of massive, honest-to-god generational ships. Ugly, hulking things composed of a big rotating cylinder in the middle to approximate gravity for the habitation and food production areas, with a main command/communication module in the front and a reactor/propulsion module in the rear. Outboard of the habitation cylinder would be launch/maintenance bays for ore collection shuttles and processing/manufacturing facilities for refining the ore into construction materials. The crew could then repair their ship and deploy satellites as needed without having to all of those materials with them.

I'm sure you wouldn't have to much trouble finding people to crew these things knowing they would likely not make it back to Earth in their lifetime. Hell, I'd go.

It does if the goal is to get it done in a human attention span, which is what I'm shooting for with this topic. It's a first mission. A proof of concept. A "let's see if we can do it" thing. It's an unmanned Apollo 8. I'm looking for a minimum-time mission so the people who started it will still be alive when the first signal comes back.

We can shoot the probe out to 51 Pegasi, where we know there are planets, but our great-great-great-etc-grandchildren may have already warped out there and set up a science outpost there by the time it gets there.

Hence the nearest star, regardless of what we may find. Whatever we find will by default be interesting, important and groundbreaking.

Earth like planets are pretty likely. The system has two main sequence stars similar to our own sun. Within the confines of our own solar system, there already exist several worlds that fit within the broad bracket of "earth like". Mars had rivers and lakes and seas of liquid water in the past. Venus is physically almost a match for Earth in size, mass and surface gravity.

If that's anything to go on, and if our theories of solar system formation are correct, then it's likely that there are somewhat "earthlike" planets orbiting many, or even most, main sequence stars.

Let's take a look at our neighborhood, shall we? Here's a map of stars 16.3 lightyears from Earth. Let's suppose that the fastest we're able to get a probe up to is .5C (just to make things easy on everyone). The closest star which is like our own is α Centauri A, which is approximately 4.3 lightyears away. The next closest star like our own sun is Epsilon Eridani, some 10.3 lightyears away. There are a lot of dwarf stars close to us, as well as some rather large stars. The red dwarf stars are unlikely (based on current assumptions) to have life friendly planets around them, while the large stars are going to have to have planets orbiting pretty far away from the star, if you hope to find life on them.

So, if we weed out the red dwarf stars (since those are the cooler stars), and go at .5C towards the best candidates for habitable planets, we have:
α Centauri A @ 4.3 LY, so 9 years to get there, 13 years after we send the probe, we get a message from it saying that its arrived.
α Centauri B @ roughly the same distance.
Sirius A @ 8.6 lightyears, so 18 years to get there, plus another 8.6 years after it arrives that we know about it. 26.6 years in total.
Epsilon Eridani @ 10.5 LY, so 21 years trip, with it being nearly 32 years after it was launched before we know anything.
Procyon A @11.1 LY, 22 years to get there, 33 years before we know anything. Of course, Procyon A looks to be nearing the end of its life, so there might be nothing but a bunch of dead worlds there.
61 Cygni is basically the same distance away as Procyon A, so the same numbers apply.
Epsilon Indi A @ 12 LY, 24 to get there, with it taking 12 more before it phones home.
Tau Ceti, roughly the same distance as Epsilon Indi A, so its the same in terms of arrival times.
Groombridge 1618 @ 16LY, so that's 32 to go, and 48 before we hear anything.

Bear in mind that an unmanned probe to any of those stars is going to be "on its own" for the entirety of its journey. The closest we've come to doing anything like that is the New Horizons probe. If a probe costs $100 billion for every lightyear you wish it to travel from the Earth, then you're going to want to make a short hop to see if you've figured out the kinks, additionally, if there's a problem, you'll know about it sooner, than you would if you were sending a probe to a world much farther away.

What's a ruined civilization worth to ya?

It's actually not very unlikely that there could be planets in Alpha Centauri. But it surely doesn't help that all planet finder programs of NASA and ESA were cancelled.

But unless there are interesting planets there, nothing is learned. So why bother? If it turns out the Alpha Centauri system has NO planets, would you still think it worth spending the incredible amount of money to send a probe there?

Hopefully, there'll be something closer than 51 Peg. But, if there isn't, I don't see someone spending billions to probe an empty system just because it's close. Astronomers will already know a great deal about the system just from long-range observations...

Our generation (and a great many--perhaps all--generations to come) has to face the fact that interstellar exploration is just not going to happen on a satisfying timeline. I doubt anyone posting here today will even be alive when the first human object reaches a nearby solar system, let alone for the 5, 10, 20 years it takes for the probe's messages to come back to us.

I think you're grasping. Long before we're ready to launch interstellar probes, we'll know plenty about the nearest stars; unless we're REALLY lucky, the very nearest ones may turn out to have little to interest us.

The last statistic I heard is 100 million Earth-like planets among the Milky Way's 600 billion stars. On average, that's 1 in every 6000 star systems.

I suspect the incremental cost per light year will be pretty low. After all, the spacecraft can't be restocked in any way en route. And once you're reached crusing speed, another light year is only a matter of time.

Just sayin' that outwardness (in the sense of probing or travelling to the stars) may not be feasible for many, many years (if ever).

I'm not trying to be a wet blanket here--I want to see interstellar exploration as much as anyone--but I think a lot of the expectations about what will happen and when are just...unrealistic.

The thing is, if we wanted to do interstellar exploration right now, we would have to spend a great amount of our industrial, financial and social resources on such a project. Considering how hard it is to get funding for small space probes like the ones we're launching now, it's next to impossible to get orders of magnitude more resources for an interstellar probe. We're not talking about billions or hundreds of billions, we're talking about trillions of dollars. It's simply not realistic that resources of these magnitude would be spent on a mission which returns radiation readings and scientific data for one star out of trillions. Such a mission gets even more unrealistic when you factor in that you can get some of this data via long-range observation. People will look at the residual gain: you can spend 5 billion dollars on a space telescope which returns 50% of the data, or you can spend trillions of dollars on a relativistic space probe which returns 100% of the data. It actually makes way more sense to spend a fraction and get some, rather than spending orders of magnitude more but without getting orders of magnitude more data.
The only case I can see where it's actually possible to get these levels of funding and resource commitment, is when there's strong evidence that there's a habitable planet with alien life out there. In this case a space telescope doesn't help, because you would want to do close-up exploration on this alien planet.
But interstellar exploration just for the sake of it isn't going to happen in the near future. That could change, though. If we develop technologies one day which enable us to build cheap interstellar probes, then it's much more realistic to send a few of them in a few directions to see if they find anything interesting.

That all depends upon the propulsion method, but for every extra year in transit, you're probably going to want another layer of redundancy, so that you still have a working probe when it arrives.

[Khan] Time is a luxury you don't have, Admiral.[/Khan]

I'd add also that, although a space telescope might only get you 50% of the data, you can re-use it for many, many stars. Would you rather know 50% about thousands of star systems, or 100% about one?

The payoffs, however, even if we didn't find any interesting planets will still be huge.

I smell an economic stimulus package!

The problem, of course, is that you can say that you'll gain the same information or nearly the same information by long range observations, but the only way to prove that this is the case, is to actually go there. On one of the last Apollo missions, an astronaut happened to glance down as he shifted his foot on the surface and noticed a patch of orange soil. A totally random event, completely unexpected, and not possible by remote observation, but it changed our understanding of the Moon significantly.

You give people far too much credit. They won't even look at that much. Half of them can't even understand what their government does, let alone a massive scientific undertaking. However, if lots and lots of them were told that their jobs were directly tied to such a mission, then you can bet your ass they'd be all for it.

That'll just bring the nutters out who think aliens are Satan's agents.

You know, I'm sure people said the same thing in the early 1960s about going to the Moon.

Maybe, but the Voyagers have stayed operational for more than 30 years and may last another 10-15; I suspect an interstellar mission will have reliability at least as good if not better. I don't think keeping the electronics working that long is too big a problem.

I dunno. This page says a 1-meter beam spreads out to 10 km by the time it just gets to the Moon. You'd think we could do better than that if it came to it, but . . .

Ah, well then. Thanks for running some numbers.

I do not understand this attitude at all. Never have.

Parts of them have been failing, however, so while we're still getting data back from them, its not the full set. There's also the issue of what happens to all that stuff "just sitting around" as it were on the way to the destination. I've dealt with satphones which would take time to get used to working again, if they'd sat for a few weeks without being used. Used regularly and there was no problem, but if they were idled for a couple of weeks, then you'd have a lot of dropped calls for a couple of days until you got the devices back up to speed again. No clue as to why that was, but that's what happened.

I don't why some of you arguing. The first probe that is capable of interstellar travel will go to Alpha Centarui. It will go because it's close by and it gives us the ability to see results of it's journey rather quickly as compared to other stars.

Even if we've lucked up and invented a FTL probe we will hit Alpha Centauri first.

I say so.

Zod says so.

And that means you do to.

C'mon, dammit. It's not the destination, it's the journey. At least, that's what I tell myself when I run.

Seriously, I can't see why getting off of this rock isn't reward enough. And I think it's a narrow view that only conceives of a single-stage economic jizzbomb that bankrupts the entire planet.

First, you build reusable orbital shuttles to ferry raw materials to build an ore-processing and manufacturing plant on the moon. In the process, you learn the unexpected shit about doing that stuff in space.

What are you manufacturing? Why, a shipyard facility in a high orbit. Keep the cost down by mining as much of the raw material as possible from the moon.

Now, we don't go straight for the deep-space cruiser behemoth on the first try. Instead, start out small with a test platform ship to work the early bugs out of the reactors and engines you intend to use, as well as your method of simulating gravity, growing food, producing oxygen, etc. Take it (plus a couple of those shuttles in a small hangar) out on gradually-longer trips until you finally reach Mars. Plant the UFP flag, etc.

Probably already 20-30 years into the project at this point, but now you recreate your test bed on a massive scale. Build redundancy on top of redundancy into everything. Even your ore processing/manufacturing facility is recreated on this bigger ship, and it carries a small fleet of the multipurpose shuttles you built at the start. What you're really building now is a mobile station, or a city in space. Thousands of people on this fuckin' thing. First trip is a wide arc to the edge of the solar system and back.

Now it's time to build more shipyard facilities and mass-produce the generational ships with all the lessons learned exploring Sol system while you recruite and train crews for them all.

There's a broad spectrum of responses here, eh?