Is it time to give interstellar travel a shot?

[SargeRho]

You can use lasers to communicate over interstellar distances. It's not too hard to outshine a star in a specific wavelength.

[Red Iron Crown]

We need to get our interplanetary program together before we even think about interstellar, IMHO.

Why send out a craft that could be outrun by a newer craft maybe 25-50 years from now?

By that argument nothing will ever get launched.

[Guest]

At the speeds we can currently go, an interstellar colony ship with trees ecosystem built in makes no sense (except as a desperate arc if earth is really in a bad shape) because by the time we reach a life friendly planet for our specie (thousands of travel years) we'll probably have found way better engines on earth maybe even warp drive so we may reach it faster later on

Edited March 12, 2014 by RevanCorana

[SargeRho]

You'll have to ask yourself "how much faster do we want to go?"

If you can send a ship out at 20% the speed of light heading for Alpha Centauri, and 20 years later find a way to make a ship go twice as fast, the ship will be close to initiating the decelleration procedures. You can't predict technological progress. If you can build a probe that goes twice as fast shortly after the first one is launched, but different instruments on it.

And the OP didn't say anything about crewed ships. It's best to start with uncrewed ships to explore, prospect and perhaps even prepare the system ahead of the colonists.

[DarkStar64]

I'm not surprised nobody has mentioned the most often overlooked challenge of travelling at relativistic speeds.

Space isn't a perfect vacuum. There are particles everywhere. If you are going 0.1 c that means you are slamming into protons at 0.1c. (or approx 5MeV). You will also be slamming into neutrons at 5MeV. This is a nice energy level for nuclear reactions to occur. In particular, neutron bombardment. The front of your spacecraft will undergo gradual nuclear synthesis and inevitably, radioactive decay from the onslaught of MeV particles. I suppose a buttload of lead shielding would do the trick, but remember that it will break down over time.

This is why we need force fields!

But yes you could put a giant shield at the front of the interstellar ship, not only to protect from that but to also protect against micro-meteors.

[SargeRho]

A beryllium shield should do the trick. Also you can use a magnetic field to either divert particles directly, or carry a cloud of ionised gas around that serves as shield.

[Seret]

Let's learn to walk before we try running, eh?

[Dispatcher]

I think it makes sense to actually expand into the solar system first, as we will doubtless learn much, which we can then apply toward any such effort.

[Camacha]

Has anyone adressed the problem of equipment having to last 500 years or more yet? Though even a fifth of that will pose big problems.

[SargeRho]

Building such equipment isn't actually a problem at all. While it will be expensive, everything we have today is built with a minimum acceptable lifetime in mind, which makes it much cheaper to produce. We can easily build things that last for centuries. The original incandescent lightbulb still works today, and it's well over a century old. Look at Voyager 1, it's going to be almost half a century old by the time its RTGs cease producing enough power. The only real damage to its systems was when a radiation measuring device was toasted last time I checked. And there's the probe that recently came by, it isn't very young either, and still works.

[AngelLestat]

But a solar sail probe to alpha centauri very well planned it would not cost much 50 years into the future.

The cost would be similar to explore the europa oceans.

Also shielding with a solar sail, does not represent any problem. Becouse is too thin. You get just a tiny hole, is not enoght to inturrup any circuit imprented in the sail.

About comunications, laser is a good way, but also diverge, the power to transmit is the real issue, if a solar sail was made to be reflective it would not be good to absorb energy. So if you have something of power it would be most to be used in sensors or to run the IA software of the sail. With interstellar comunications there is a big gap between transmit 1kbs or 1mgs.

So anything that can help with comunication its welcome.

Edited March 12, 2014 by AngelLestat

[Camacha]

Building such equipment isn't actually a problem at all. While it will be expensive, everything we have today is built with a minimum acceptable lifetime in mind, which makes it much cheaper to produce. We can easily build things that last for centuries. The original incandescent lightbulb still works today, and it's well over a century old. Look at Voyager 1, it's going to be almost half a century old by the time its RTGs cease producing enough power. The only real damage to its systems was when a radiation measuring device was toasted last time I checked. And there's the probe that recently came by, it isn't very young either, and still works.

Not true. There is a lightbulb that has worked that long, but most have burned out. That will not do in space.

Also, making stuff that lasts becomes exponentially difficult when adding the years. While on Earth products are typically made for a lifespan of anywhere between less than a year to 30 years, anything over that is a) hardly done, so we lack experience and it is almost impossible to test (and you can totally forget iterative design).

You are gravely underestimating the difficulties of building something that is garanteed to work for 200 years and we probably need a lot more than just that. Electronics do wear and just beefing them up will only get you so far (as well as it causes problems with the level of complexity you can still achieve).

Edited March 12, 2014 by Camacha

[SargeRho]

It's still not a technical problem to build such systems. You will want redundancy, lots of redundancy, on an interstellar probe. The problem is entirely economical, and depends on how much you want to spend on the systems. For example, if a system is only used for a few years, such as the first stage engine of a daedalus type probe, or equipment intended to probe the layers of our solar system, you wouldn't spend too much. On the computers in turn, you'd want to spend a lot, and have plenty of redundancy and safety systems. Perhaps by the time we send out an interstellar probe, we'll have something along the lines of semi-organic electronics that repair themselves.

[Camacha]

It's still not a technical problem to build such systems. You will want redundancy, lots of redundancy, on an interstellar probe. The problem is entirely economical, and depends on how much you want to spend on the systems. For example, if a system is only used for a few years, such as the first stage engine of a daedalus type probe, or equipment intended to probe the layers of our solar system, you wouldn't spend too much. On the computers in turn, you'd want to spend a lot, and have plenty of redundancy and safety systems. Perhaps by the time we send out an interstellar probe, we'll have something along the lines of semi-organic electronics that repair themselves.

I still feel you are still not understanding the problems involved. We have never built such a system, let alone one for an incredibly hostile environment. You can go and plunk (the equivalent of) hunderds of probes together, put your faith in statistics and hope that one survives the journey, but I do not have to explain to you why that is not a very desirable approach. We just do not know how to build something that reliable and without any experience, sending a probe off will be a huge gamble at best. We do not have the technology and we do not have anything better than a wild stab in the dark - even if you attempt crazy redundancy.

Long story short - as things are now, the probe will most likely go silent somewhere in the middle and that is that.

Edited March 12, 2014 by Camacha

[SargeRho]

I do understand the problems involved. We know how to build electronics that last for a while, and I doubt we'd send an interstellar probe before we can accelerate it to at least 5% the speed of light or so, which would mean an 100ish years trip time to alpha centauri. It's not going to be too big of a problem building electronics that last that long actually.

[Camacha]

I doubt we'd send an interstellar probe before we can accelerate it to at least 5% the speed of light or so, which would mean an 100ish years trip time to alpha centauri.

The thread title asks whether now is the time, and the answer is quite clearly no. We do not even have the right kind of electronics to send off.

It's not going to be too big of a problem building electronics that last that long actually.

Would you care to substantiate that claim, in light of the counterarguments given?

[SargeRho]

Voyager probes. Their electronics have by now lasted for what, 40 years? And seem to still be pretty dandy out there, and V1 is by now in Interstellar space. One way to protect electronics from radiation is by using larger transistors. You won't need a 22nm i7 for an interstellar probe. The other is polyethylene, and water. At relativistic speeds, you won't need much shielding behind your ship since most of the particles will be in front of you.

And I think a solar sail coupled with an ion engine could get a small probe up to 5% of the speed of light.

Edited March 12, 2014 by SargeRho

[Camacha]

Voyager probes. Their electronics have by now lasted for what, 40 years?

That just confirms my point. One of our most reliable probes is a mere 36 years old. With current or even realistic future technology we need to span a lot more years than that. It is nice that we have a 100 year old lightbulb, but building a highly complex spacecraft that can reliably do the same is another matter completely. Yet we need it to be more reliable than that.

One way to protect electronics from radiation is by using larger transistors. You won't need a 22nm i7 for an interstellar probe.

Unfortunately this works both ways. The larger your transistors, the less advanced/quick they will need to be and the more power they will consume. Not great in an interstellar void without many external energy sources. Sending a probe out on a journey for hundreds of years means going very big when it comes to transistors and die size. And let us not forget that transistors have only been around since 1947. Any evidence on 60+ years operation is at best anecdotal and beyond that we simply do not know. What about the other couple of hundred years? We know literally nothing about the wear, degradation and other problems during that time.

We are not even talking about the (un)reliability of storage and the problem of standards changing back on earth over such a period.

And I think a solar sail coupled with an ion engine could get a small probe up to 5% of the speed of light.

Do you have any numbers for that estimate?

[SargeRho]

So what do you suggest we do? Build the electronics needed for such a probe, let them run for half a millenium, and as consequence wait until then before sending an interstellar probe? Using technology that hasn't been tested to the point you ask for is done rather frequently in space exploration. Hell, the engines of the LEM in the Apollo missions were flown fresh off the assembly line, with no test firing because they could only be run once before the hydrazine wrecked them. Curiosity's Sky Crane wasn't tested beyond the point of "Yup, It'll spring into action." because there is no way to test it on Earth.

[Camacha]

I would like to pose a related question, though. Might it be interesting to launch a dedicated successor to the Voyager probes? Specifically built to explore the region outside our solar system and the little understood parts along the way (Oort cloud and such). Such a time span should be feasible, and with some clever slingshotting we should be able to reach even higher speeds.

My only question would be - is it useful?

[Camacha]

So what do you suggest we do? Build the electronics needed for such a probe, let them run for half a millenium, and as consequence wait until then before sending an interstellar probe?

I am simply explaining that sending an insterstellar probe is - most likely - currently useless.

Using technology that hasn't been tested to the point you ask for is done rather frequently in space exploration. Hell, the engines of the LEM in the Apollo missions were flown fresh off the assembly line, with no test firing because they could only be run once before the hydrazine wrecked them. Curiosity's Sky Crane wasn't tested beyond the point of "Yup, It'll spring into action." because there is no way to test it on Earth.

The LEM design was proven and Curiosity's skycrane was tested in every which way possible. They could not test it in an environment exactly like on Mars, but also not completely unlike Mars.

[SargeRho]

It could be useful two-fold. Firstly to gather science, and secondly, to test the daedalus-type engines. You could shoot one 1 lightyear out, to explore the oort cloud and kuiper belt, and perhaps have the probe return, and brake into Earth orbit. You could use a magnetic sail to do that, testing that technology too while you're at it.

In doing so you could expose electronics to the interstellar medium, test interstellar-capable engines, and test interstellar parachutes, and do lots of science all at once.

It's not a strawman at all. Both weren't tested in the conditions they would have to operate in, and the timespan they would have to operate for in those conditions. The LEM was tested in conditions very close to its final use, but not quite either. Spirit and Opportunity also vastly outlived their intended livetimes. My point is: You don't have to test things for the time they will be operating for, and most of the time, you can't. You can merely design them in such a way that they will survive the expected stresses for a given ammount of time.

Edited March 12, 2014 by SargeRho

[Camacha]

It could be useful two-fold. Firstly to gather science, and secondly, to test the daedalus-type engines. You could shoot one 1 lightyear out, to explore the oort cloud and kuiper belt, and perhaps have the probe return, and brake into Earth orbit. You could use a magnetic sail to do that, testing that technology too while you're at it.

In doing so you could expose electronics to the interstellar medium, test interstellar-capable engines, and test interstellar parachutes, and do lots of science all at once.

I am not sure about returning to Earth, but I think a lot of scientist would love a chance to get a close up view of the outer solar system in more detail. I feel our main focus probe wise should be our inner solar system, but we must not ignore the rest.

Long lasting power and a huge dish seem solid requirements

Spirit and Opportunity also vastly outlived their intended livetimes.

Does that not merely establish we have a hardly perfect understanding of wear and how long machines will last? Machines operating around a decade also do little to predict problems when trying to build things that will last centuries. That's building a bike, driving it across town and being confident you can build a car that will take you around the world. The whole deal is just a different order of magnitude.

[Camacha]

You can merely design them in such a way that they will survive the expected stresses for a given ammount of time.

That is exactly what I have been saying. We do not know what happens to transistor type electronics over such an extended period of time in a hostile environment. Our oldest anecdotal evidence is a little over 60 years old and that is hardly comprehensive. We know little about what to expect when it comes to the external factors of the interstellar void and we do know even less when it comes to our own equipment. We are pretty much clueless. Anyway, I do not think it is very useful to go over this repeatedly

[SargeRho]

I am not sure about returning to Earth, but I think a lot of scientist would love a chance to get a close up view of the outer solar system in more detail. I feel our main focus probe wise should be our inner solar system, but we must not ignore the rest.

Long lasting power and a huge dish seem solid requirements

A small fission reactor will suffice to keep it powered, I think.

You can use the engine bell of a Daedalus-type engine as radio dish, or you can (and tbh, should) use lasers for communication, if just for the bandwidth.

Does that not merely establish we have a hardly perfect understanding of wear and how long machines will last? Machines operating around a decade also do little to predict problems when trying to build things that will last centuries. That's building a bike, driving it across town and being confident you can build a car that will take you around the world. The whole deal is just a different order of magnitude.

No, I don't think so. I think it establishes that we can with comparative ease build things that will overcome the stresses they are expected to be subject to, and often exeed them.