Debunking Interstellar Travel: Separating Fact from Fiction

[sophiecentaur]

Via taxes: in many countries "we" do. Same goes for medical fees. The US is one of the rare exceptions of first-world countries where this is not standard.No one suggests to start construction in 2017. "Current technology" in this context means we have an idea how to build things and we had working prototypes already, which means something like TRL 5-6 - a fission reactor is fine, a fusion reactor is not. Of course such a spacecraft would need 20+ years of dedicated development, then a lot of construction work, and you probably want such a spacecraft to fly around in the solar system for at least 10 years to see if that works before it leaves the solar system.

My point about taxes is that we pay the bare minimum and much less than we fork out for our own family. How much of GDP goes on foreign aid? That's how this sort of spending would be viewed. No obvious returns from what we would pay. By " we ", I don't actually include myself.
Personally, I think taxes should be much higher and charities should not be needed.

 

[mfb]

There is an obvious return from such a project: Huge advantages in many different scientific disciplines. The research done would improve our knowledge of humans, of biological ecosystems, of societies with small groups, low-tech manufacturing processes, radiation shielding, rocket propulsion, long-distance data transmission, ...

 

[mheslep]

... Of course such a spacecraft would need 20+ years of dedicated development, then a lot of construction work,...

200 years? The ISS in LEO, with its 100 KW of PV array, had something like 20 years dedicated development. The largest fission reactor ever designed for space was in the 100 KWe range, ever launched in the KWe range.

 

[mfb]

200 years: see electricity. You can research a lot in 20 years with sufficient funding. I don't see a research chain that would necessarily need more than 20 years, but I wrote "20+" which includes the option for more than that. But not 200.

 

[mheslep]

200 years: see electricity.

Electricity was developed over that time by the efforts of individuals across the globe, and by a system that paid handsomely for incremental improvements. There never was a central plan that imagined, 'lets start with Franklin and Faraday, so that 200 years later we'll have the modern, partially nuclear powered, electrified city'.

You can research a lot in 20 years with sufficient funding

If a lot means the output of a few thousand scientists and engineers working on, say, the next Moon base, sure. An interstellar, multi-generational mission needs a million times that notion of 'a lot', and there is no means of productively coordinating the efforts of so many and so much, nor should there be absent an imminent global emergency.

 

[mfb]

Electricity was developed over that time by the efforts of individuals across the globe, and by a system that paid handsomely for incremental improvements. There never was a central plan that imagined, 'lets start with Franklin and Faraday, so that 200 years later we'll have the modern, partially nuclear powered, electrified city'.

That was not my point. We had so much progress in the last 200 years that people in 1816 could not even imagine what we can do today (e. g. because they didn't know about nuclear energy at all). Today we are closer to building a shitty but working interstellar spacecraft than the people in 1816 were to building the ISS or New Horizons, simply because we have the basic technologies that can be used for such a spacecraft : we can go to the drawing board and make concepts. You cannot make a concept of a nuclear powered spacecraft if you don't even know if atoms exist.

If a lot means the output of a few thousand scientists and engineers working on, say, the next Moon base, sure. An interstellar, multi-generational mission needs a million times that notion of 'a lot'

It mainly needs things scaled up in terms of construction. Developing habitats for 1000 people is not 100 times more difficult than developing habitats for 10 people. You can take the 10-people-habitat and build it 100 times. It also needs research in many other aspects, but where does the factor 1 million come from? Sure, we don't have funding today, but with sufficient funding a huge amount of scientists could work on the open issues.

I don't suggest that we should do that. I say that it is not impossible.

 

[sophiecentaur]

The interstellar project would be fun, no doubt. But the resources needed have been ignored by those in favour of it.
A much more valuable project (for everyone) would be to sort out the Earth's ecosystem. Why is this such a poor relation project? Not boy racer enough?
The two projects are so demanding as to be mutually exclusive, imo.

 

[nikkkom]

I do not understand this "whole world need to participate" part. I think it stems from the idea that we would skip the step of extensive development of interplanetary ships and infrastructure before building interstellar ships.

Of course, that would not happen. It does not make any sense to do so.

Moon/Mars/asteroid bases and industry will come first, since they are much easier. This will result in several developments. Many things which we know are definitely possible, but did not yet master, will become reality. Such as reliable closed loop life support systems, industrial production in space (first for low-tech materials - metals, fuel, oxygen and other gases, then for almost everything), medical research and countermeasures against radiation and zero-g.

And it also would result in significantly expanded industrial capacity. Now, merely orbiting 1000 tons of anything in LEO costs tens of billions. If we'll have, say, fuel factories on Callisto and steel factories on asteroids producing and shipping millions of tons every year, that's a complete game changer.

 

[nikkkom]

The interstellar project would be fun, no doubt. But the resources needed have been ignored by those in favour of it.
A much more valuable project (for everyone) would be to sort out the Earth's ecosystem.

From where I sit, Earth ecosystem is fine as it is. And we shift from fossil fuels to renewables already.

 

[mheslep]

Today we are closer to building a shitty but working interstellar spacecraft than the people in 1816 were to building the ISS or New Horizons,

Understood, and I disagree. In 1816 there was already of half century of lighter than air flight, a century of Newton and two and half centuries of Copernicus. Orbits were understood, that is, we knew at least where to go though the engineered means were still unknown. Now, there is no known target, nor a means to communicate effectively with an interstellar ship and learn anything from one, even unmanned, over a gap of hundreds or thousands of years of message time. Experiment and iteration based on outcomes is the main way human knowledge currently progresses, perhaps the only way, and without a FTL work-around that kind of progress is not feasible with interstellar travel.

I guess that the more apt comparison between current technology and a shitty interstellar craft is the gap between the earth-centric notions of the Ancient Greeks and the ISS/New Horizons. That is, I suspect several transcendent leaps the size of Newton's laws of motion are still required, probably both on the scientific side and on the political-spiritual side of human existence.

 

[nikkkom]

Now, there is no known target

We are fast improving our planet detection capabilities. We already detected several thousands. We are taking crude spectra of some exoplanets.

nor a means to communicate effectively with an interstellar ship and learn anything from one, even unmanned, over a gap of hundreds or thousands of years of message time.

This is not a requirement for interstellar travel.

Experiment and iteration based on outcomes is the main way human knowledge currently progresses

True. And we will have plenty of experiment and iteration building ships and flying to ever more distant KBOs. Sedna is at 76 AU at perihelion. More distant KBOs will be found.

 

[mheslep]

...Such as reliable closed loop life support systems, industrial production in space (first for low-tech materials - metals, fuel, oxygen and other gases, then for almost everything), medical research and countermeasures against radiation and zero-g.

What you describe might well suffice for some kind of long term, man-made, orbital artificial habitat. A large can in space. Though adequate, it would be inevitably inferior to the protections and resources offered by its planet of origin. The space-can idea however has little to do with interstellar anything, as there is no prospect of a habitable destination, no means for effective IS communication, no means for IS energy production at that scale and time period, ...

 

[nikkkom]

What you describe might well suffice for some kind of long term, man-made, orbital artificial habitat. A large can in space. Though adequate, it would be inevitably inferior to the protections and resources offered by its planet of origin.

How "planet of origin" is even relevant to the needs of an interstellar ship? Interstellar ship is not a planet.

The space-can idea however has little to do with interstellar anything

Closed-loop life support system is not just close, it's the same thing on a station and on a ship: how to keep people alive in an artificial craft in space.

 

[mheslep]

How "planet of origin" is even relevant to the needs of an interstellar ship? Interstellar ship is not a planet.

What you described ( reliable closed loop life support systems, industrial production in space ..., medical research and countermeasures against radiation and zero-g.) is not an interstellar ship, but a long term, self-sufficient space based habitat, as long as it remains within a couple AUs of the sun for power. No destination, no means of self-contained power source, no fractional speed of light propulsion. As such, what's the point?

 

[mheslep]

True. And we will have plenty of experiment and iteration building ships and flying to ever more distant KBOs. Sedna is at 76 AU at perihelion. More distant KBOs will be found.

I don't follow how visiting solar system based KBO's with unmanned spacecraft has any relevance to interstellar travel to objects 10^6 more distant.

 

[nikkkom]

I don't follow how visiting solar system based KBO's with unmanned spacecraft has any relevance to interstellar travel to objects 10^6 more distant.

Try "visiting solar system based KBO's with manned spacecraft "

 

[nikkkom]

What you described ( reliable closed loop life support systems, industrial production in space ..., medical research and countermeasures against radiation and zero-g.) is not an interstellar ship, but a long term, self-sufficient space based habitat

Which is half of the steps necessary to build interstellar ships. When someone decides to design one, it's quite useful to have those technologies already available COTS.

 

[mheslep]

Try "visiting solar system based KBO's with manned spacecraft "

Why would be the point of manning such a craft, a flying nuclear reactor with a pilot for some 20 years, which must return over similar period, in order to investigate the geology of some space rocks?

 

[nikkkom]

Why would be the point of manning such a craft, a flying nuclear reactor with a pilot for some 20 years, which must return over similar period

What was the reason people sailed to Australia? And where did I say anything about returning?

 

[mheslep]

What was the reason people sailed to Australia?

To go to a known destination with plenty of resources and live. Well worth the risks. Cook, the discoverer, returned.

And where did I say anything about returning?

This is still about KBOs? You imagine manned 20 year suicide missions to distant space rocks and ice-balls?

 

[nikkkom]

To go to a known destination with plenty of resources and live. Well worth the risks.

Interstellar ships and ships to KBOs will depart to known destinations too. Not to unknown ones.

This is still about KBOs? You imagine manned 20 year suicide missions to distant space rocks and ice-balls?

Delete "suicide" and add "to establish a colony".

 

[mfb]

The interstellar project would be fun, no doubt. But the resources needed have been ignored by those in favour of it.
A much more valuable project (for everyone) would be to sort out the Earth's ecosystem. Why is this such a poor relation project? Not boy racer enough?
The two projects are so demanding as to be mutually exclusive, imo.

I don't think they are mutually exclusive. I think they are closely linked. Sure, you don't have a complex climate in a spacecraft , but understanding the flow of various chemicals is necessary both for Earth and the spacecraft . A spacecraft would have to be a completely closed ecosystem, and we have an example of such a system here on Earth, with many nearly closed subsystems.

From where I sit, Earth ecosystem is fine as it is. And we shift from fossil fuels to renewables already.

Tell that people who get a hurricane every other year. Or every year in a few decades. Or people living in places that will be deserts soon. If "we" shift away from fossil fuels, why does the global oil and coal consumption go up every year?

In 1816 there was already of half century of lighter than air flight, a century of Newton and two and half centuries of Copernicus. Orbits were understood, that is, we knew at least where to go though the engineered means were still unknown.

Orbits were understood, sure - trajectories to other stars are understood today as well. That is not the point.

The planet around Proxima Centauri is an interesting target, and PLATO/TESS/JWST/E-ELT/GMT/TMT should find many more interesting planets in the next 10-20 years. Given the rapid progress of exoplanet discoveries in the recent years (out of 3500 known exoplanets, 99.8% were discovered in the last 20 years, ~65% in the last 3 years), I can't even imagine how many more we will know in 50 years.

Both radio waves and lasers work for communication over distances of light years . They won't give you a fullHD stream, but that was never the requirement.

Launching a rocket needs physics completely unknown in 1816. Launching an interstellar spacecraft does not need physics unknown in 2016. It just needs a lot of engineering. We are in a way better position than the people in 1816 were for a rocket launch.

 

[sophiecentaur]

I don't think they are mutually exclusive.

I think they would have to be because of the extreme commitment of resources / money for either. The priority would clearly be in favour of an Earth Repair project - for the whole population, rather than a project which would benefit only the crew. I am assuming that any useful final destination would be too far for useful communications (bandwidth limited) and certainly for any useful trade or importing of materials. It is far too short sighted to talk in terms of life support on a ship of some kind. It would be essential to think in terms of a long term living environment on a suitable planet. All the technology for maintaining Earth's ecosystems would be needed PLUS the (over trivialised) terraforming that would be needed.
There is far more involved than just getting a number of people to some destination hundreds of light years away. Why is that task the only one that is considered by the enthusiasts?

 

[nikkkom]

I think they would have to be because of the extreme commitment of resources / money for either. The priority would clearly be in favour of an Earth Repair project

What "extreme money" are you talking about? Solar doubles every 2.5 years. Even if this trend slows down, in 20-30 years, more than half of all generation will be solar. And most importantly, solar *no longer needs subsidies* - solar power stations are competitive with other generation even today, and will get even better with economies of scale. From now on, it will grow "automatically", without special efforts, by virtue of being a good investment. In fact, I have hard time imagining how anyone can possibly stop it now.

 

[sophiecentaur]

You really think that "solar" is all that's needed to reverse all the adverse effects that we are having on the Earth? That's a very limited picture of the situation.

 

[Ugo]

Hi Folks,

What is your opinion on this article? It suggest that interstellar travel is a fantasy.

http://www.scientificamerican.com/article/interstellar-travel-as-delusional-fantasy-excerpt/#

Yet, I read articles about institutions like NASA investing in various conceptual propulsion systems.

Are they wasting their time?

Regards
B

Interstellar travel is a certainty if we do not vanishes as a specie. We just do not have the right technology yet. Right now it is science fiction, but science fiction is fertile and creative for ideas and sometimes leads the path to technological advances. DaVincy thaguht of submarines before they've ever existed. So does creativity leads science or science leads creativity?

 

[Ugo]

Interstellar travel is a certainty if we do not vanishes as a specie. We just do not have the right technology yet. Right now it is science fiction, but science fiction is fertile and creative for ideas and sometimes leads the path to technological advances. DaVincy thaguht of submarines before they've ever existed. So does creativity leads science or science leads creativity?

Creativity leads science, because without any ideas, there wouldn't be innovations and improvements. Interstellar traveling is an achievement. So there is a bunch of ideas coming out of it...as fiction, so delusion...it is a process...we just need to decide how much ressources we put into it...

 

[mheslep]

The planet around Proxima Centauri is an interesting target,...

Yes, for a space telescope. The point is that we have no idea about any planets that would support a landing via suitable gravity, surface, and atmosphere, much less habitable planets. In that sense for interstellar travel we are still pre-Copernican. For would be space travelers who need a habitable planet for their grand children after 4-500 yrs in space, else they die in space, and the odds are hugely against that one planet supporting life? No thanks.

 

[mheslep]

What "extreme money" are you talking about? Solar doubles every 2.5 years. Even if this trend slows down,

New solar stops quite quickly, as predicted by all the serious studies, after 10% share of load or so. Germany reached 9% generation share by solar with a large feed in tariff, and has slowed to 2% new solar capacity per year, with 0.8% per year required to replace decay.
https://www.energy-charts.de/energy.htm

more than half of all generation will be solar

.
Impossible without either i) storage or ii) moving most of the demand across both the diurnal cycle and across the seasons. Currently there are no utility battery storage projects anywhere in the world, nor any planned, that could backup a medium sized thermal plant for a half day.

And most importantly, solar *no longer needs subsidies* - solar power stations are competitive with other generation even today, and ...

Not so. Unsubsidized interrmittent power only slightly competes with the build of new dispatchable or baseload plants, as these plants *must* be built to supply a reliable grid. Germany continues to build new coal; California continues to build new natural gas plants. So a decision to build new solar competes with the marginal cost only, i.e. whether or not to *run* these existing plants when solar is available, which costs 2 or 3 cents per kwh. When the solar share is quite low, utility solar (not rooftop) can be competitive given some slight excess in the existing grid capacity which solar can retire.

There's only one way with current technology to retire a fossile fuel based grid, proven several times over: nuclear power.

 

[nikkkom]

New solar stops quite quickly, as predicted by all the serious studies, after 10% share of load or so. Germany reached 9% generation share by solar with a large feed in tariff, and has slowed to 2% new solar capacity per year, with 0.8% per year required to replace decay.

Germany has no suitable sunny and sparsely populated areas for large-scale solar. Europeans currently are looking at Sahara for their solar needs.

Impossible without either i) storage

And storage is quite possible.

Currently there are no utility battery storage projects anywhere in the world, nor any planned, that could backup a medium sized thermal plant for a half day.

Currently, and for next ~5 years, such batteries are not *needed* - solar generation coincides with peak load. Since solar is still low % of all installed power, existing non-solar powerplants are more than enough for night load. Why build huge battery storage which will stand idle?

Pilot projects in ~50 MWh range are underway.

There's only one way with current technology to retire a fossile fuel based grid, proven several times over: nuclear power.

Nuclear is not competitive with coal, and has badly tarnished PR image. There are doubts that nuclear industry learned their lessons and will stop dousing us with Cs-137. After each SNAFU, they say that "this time, we learned what went wrong, and it will not happen again". And then it happens again. I'm not impressed.

 

[sophiecentaur]

It would need a really, really good reason not to leave.

I totally disagree. You would need to be totally backs to the wall to swap living on Earth for the Risk and the boredom of a long (years and years or even generations) space voyage with no certainty of a good destination.
There is a saying, used by all sea-going boat owners. "You should never consider stepping down into your life raft. i.e. only when your boat is actually sinking should you contemplate actually getting into the raft. It is the same as with the glamourised stellar exploration. Only when you can supply yourself with a 'life raft' that's as comfortable as Earth would you want to leave Earth. No little spaceship would ever be a good alternative. Any craft that's big enough and earth-like enough would involve more cost than actually sorting out a bad situation on Earth.
The potential 'Spacers' on this thread seem to think that providing an near enough Earthlike existence at the destination would somehow be easier than sorting out the Earth. So far, the only 'improvement' needed for improving Earth that this thread has suggested has been to use Solar energy sources. That is clearly nothing like enough. At least, on Earth, we have a vast number of systems involving the established flora and fauna which are doing a significant job of maintaining Earth's environment. On the 'target' planet, there would be nothing that could be relied on to do the same for us. The native life (if there were any) could as likely be totally hostile as 'on our side'. So, would we just blast it all flat and start again?? Get real.

I loved that Scientific American article - the enthusiasts really should read it and factor it into their opinions.

 

[sophiecentaur]

Interstellar travel is a certainty if we do not vanishes as a specie.

What sort of magic law says that we should not expect to vanish at some point? The same sort of reasoning that makes some people believe in everlasting (personal) life, I guess. Very comforting for those who need it but a totally groundless assumption.

 

[mfb]

I think they would have to be because of the extreme commitment of resources / money for either. The priority would clearly be in favour of an Earth Repair project - for the whole population, rather than a project which would benefit only the crew. I am assuming that any useful final destination would be too far for useful communications (bandwidth limited) and certainly for any useful trade or importing of materials. It is far too short sighted to talk in terms of life support on a ship of some kind. It would be essential to think in terms of a long term living environment on a suitable planet. All the technology for maintaining Earth's ecosystems would be needed PLUS the (over trivialised) terraforming that would be needed.
There is far more involved than just getting a number of people to some destination hundreds of light years away. Why is that task the only one that is considered by the enthusiasts?

It is never about having the money - it is about the will to spend it. Anyway, as I mentioned before: a lot of research would help both the Earth and a future spacecraft , and a lot of research for a spacecraft would help people on Earth as well. Research on terraforming (which is optional) has applications in the solar system as well.

Yes, for a space telescope. The point is that we have no idea about any planets that would support a landing via suitable gravity, surface, and atmosphere, much less habitable planets.

The planet around Proxima Centauri has a suitable gravity. We can probably work with its surface. It does not need to have a great atmosphere. The spacecraft which arrives there is nearly self-sufficient. Every planet with a solid or liquid surface and reasonable gravity is better than the working spacecraft . We know already that the planet around Proxima Centauri has this.

What "extreme money" are you talking about? Solar doubles every 2.5 years. Even if this trend slows down, in 20-30 years, more than half of all generation will be solar. And most importantly, solar *no longer needs subsidies* - solar power stations are competitive with other generation even today, and will get even better with economies of scale. From now on, it will grow "automatically", without special efforts, by virtue of being a good investment. In fact, I have hard time imagining how anyone can possibly stop it now.

I like your optimism, but (a) it only doubles 2-3 years in countries with a small fraction of solar power, (b) increasing the fraction above ~15% will lead to huge stability issues with the power grid as (c) we don't have an affordable large-scale storage solution yet (you still need power when it is cloudy, for example). Which also means "no longer needs subsidies" is misleading: it needs regulations giving it priority over conventional power plants, which increases their price in times when the sun does not shine - we pay for it, just at different places. And even with this huge advantage of not caring about the time of production, it is not yet competitive in many places where power is needed. Germany for example pays several billion dollars of direct subsidies every year for its ~10% solar energy share, estimates about the total subsidies (spent plus future commitments) are ~250 billions.

Nuclear is not competitive with coal

It is much better than coal if you include the costs induced by the exhaust of coal power plants. And then there is still the CO2 which leads to huge indirect costs.

will stop dousing us with Cs-137

Oh come on. Coal power plants emit more activity than nuclear power plants. Which is completely irrelevant compared to other damages done anyway.

But I think this is getting off-topic.

 

[nikkkom]

I totally disagree. You would need to be totally backs to the wall to swap living on Earth for the Risk and the boredom of a long (years and years or even generations) space voyage with no certainty of a good destination.

A lot of people on Earth find their life very boring. Work,home,work,home,work,home...

The potential 'Spacers' on this thread seem to think that providing an near enough Earthlike existence at the destination would somehow be easier than sorting out the Earth.

I think we do not need to "sort out the Earth" as it is. Our biggest problem is that most of Earth population is still living under tyrannical and/or kleptocratic governments, and thus have poor, dangerous and miserable lives. The West's efforts to improve the situation are half-hearted and often ineffective. However, I digress.

You completely miss the point if you see interstellar travel as "escape from a sinking boat". People would want to fly to other stars even if Earth and Solar System is in perfect shape and life there is okay.

Somehow you cannot fathom the fact that if _you_ don't find it interesting to go onto an interstellar expedition, _others_ will find it worthwhile.

Finally. Another repeating thought here is that "interstellar expedition must find an Earth-like planet at the destination". Not at all. If people on this expedition already had in their past history Mars colonies, bases on Callisto and asteroids, they don't need an Earth-like planet.

 

[nikkkom]

>> Nuclear is not competitive with coal

It is much better than coal if you include the costs induced by the exhaust of coal power plants. And then there is still the CO2 which leads to huge indirect costs.

I disagree about "much better", but "better" was not even the metric I used. "Nuclear is not competitive with coal" - this means that an investor who decided to invest in building a powerplant would choose coal (or something else) over nuclear.

This is supported by numbers. Since 1996, only four new units are being built (at Vogtle and V.C.Summer). Watts Bar 2 was 80% complete in 1990 but finished only this year; half-completed Bellefonte was scrapped. Levy County project is put on hold before construction is started (switching to natural gas plant). Meanwhile, operational units are being closed (San Onofre, Crystal River, Kewaunee, Vermont Yankee, Fort Calhoun).