Is a trip to explore the Alpha Centuri system actually feasible?

[sophiecentaur]

Mars is undoubtedly feasible.

I wonder what the probability of a fatality would be in any foreseeable project?

 

[Borg]

I wonder what the probability of a fatality would be in any foreseeable project?

Hopefully, they will take plenty of potatoes.

 

[sophiecentaur]

Hopefully, they will take plenty of potatoes.

It annoyed me just how easily I accepted that Daymon character's hijinks. I just believed it all.

 

[bob012345]

In other words, not anywhere close to feasible. You're trying to make a spot of moisture sound like an almost full glass of water.

No, not like this. That's a common dreamer's refrain, but it misses the critical other side of science and technology's coin: it doesn't just make previously not possible things possible, it give us a better understanding of what is actually not possible.

...and that's in addition to the fact that most popular examples of this are wrong.

Can you give an example of what's conclusively impossible given any possible future technology in regards to getting to Alpha Centauri?

 

[Borg]

It annoyed me just how easily I accepted that Daymon character's hijinks. I just believed it all.

I liked Daymon's character. It was the contrived wind force problems that were dreamt up that tended to annoy me. For example, everyone had to leave immeadiately because of a dust storm that was going to tip over the rocket. However, that apparently wasn't a potential concern for the rocket left unattended for years at Schiaparelli Crater which was completely undisturbed by the time that he got to it. The reality is that the Martian dust storm would be felt as little more than a breeze. Of course without the openening scene's "8600 Newton wind", he wouldn't have been stranded in the first place.

And then there's the tarp that kept the hab sealed for over 7 months when the original entry port only lasted about three. It even managed to survive debris hitting it in a later mega-dust storm.

 

[sophiecentaur]

I liked Daymon's character. It was the contrived wind force problems that were dreamt up that tended to annoy me. For example, everyone had to leave immeadiately because of a dust storm that was going to tip over the rocket. However, that apparently wasn't a potential concern for the rocket left unattended for years at Schiaparelli Crater which was completely undisturbed by the time that he got to it. The reality is that the Martian dust storm would be felt as little more than a breeze. Of course without the openening scene's "8600 Newton wind", he wouldn't have been stranded in the first place.

And then there's the tarp that kept the hab sealed for over 7 months when the original entry port only lasted about three. It even managed to survive debris hitting it in a later mega-dust storm.

Oh, you're just being 'sensible'.

 

[bob012345]

Oh, you're just being 'sensible'.

The mass of the dust in the wind must also be considered. While the air itself may be thin, a raging dust storm is moving large amounts of dust fast which might impart quite a force.

 

[Vanadium 50]

Mars is undoubtedly feasible.

I disagree. I don't think we are that far away - a small number of decades - but I don't think it's feasible today.

1. The space agencies are discussing missions on this timescale.
2. We haven't executed a Mars sample return mission, which is easier and probably politically necessary (ESA uses the word "essential") before sending people to do the same thing.
3. A mission to Mars (Austere Human Mission to Mars as the baseline) would be ~twice as long as any human has spent continuously in space.

Finally there's Akin's Laws:

The three keys to keeping a new human space program affordable and on schedule:

1. No new launch vehicles.
2. No new launch vehicles.
3. Whatever you do, don't develop any new launch vehicles.

We can't do Mars today. Alpha Centauri is 500,000x farther.

Alpha Centauri is not yet even a remote possibility

I agree with that!

 

[russ_watters]

Can you give an example of what's conclusively impossible given any possible future technology in regards to getting to Alpha Centauri?

Scientific theories/principles/facts are highly specific, not broad and generic like that. Science tells us things like:
1. Conventional rockets can't exceed the speed of light.
2. Conventional rockets would need a million kg of fuel per kg of payload for a trip such as specified in the first few posts of the thread.
3. The solar wind travels at 400 km/s.

The other side of the coin, which I was responding to, is very broad and generally a factually wrong accounting of history. Common examples are claims that scientists believed it was impossible for humans to fly or exceed the speed of sound. Neither of these were true.

 

[Greg Bernhardt]

We can't do Mars today.

Just for clarification, when you say "can't" does that mean not possible under any circumstance? For example, travel to Alpha Centauri is impossible under any current circumstance, but if say the human race's survival was dependent on merely reaching/landing on Mars by say late 2019. With Earth's collective and motivated support would that also be impossible? Or are you just saying it's impossible given the state of the world and its agencies?

 

[anorlunda]

Can you give an example of what's conclusively impossible given any possible future technology

If we want to imagine boundless future technology, then there is no reason for space ships at all. We'll simply have transporters to beam us to and from other planets at light speed (or FTL if you want to imagine that too.)

Of course I'm being sarcastic, but there's a point here. If we postulate fantastic future technologies, then why must those technologies be limited to a narrowly constrained vision of the "space cowboy" model of Harrison Fords zipping around in Millenium Falcons? Future technology should be imagined to be as wide in direction as it is advanced in scope.

 

[Vanadium 50]

Just for clarification, when you say "can't" does that mean not possible under any circumstance?

That's why the word "today" is there. We do not have the technology needed to send a person to Mars and get them safely back.

 

[nikkkom]

That's why the word "today" is there. We do not have the technology needed to send a person to Mars and get them safely back.

"Today" is actually not strictly defined. I most probably can't go to South Pole literally today - it would take me several days, if not weeks, to reach it if I start going about it RIGHT NOW.

It's a stretch to interpret it like that, I know.

The oppositely "stretched" meaning of "today" is "our today existing technology and industrial base". If you define "today" this way, Mars mission is already possible. We definitely know how to reach Mars. We have rockets with enough payload capability (Mars craft will need assembly in LEO). We have spacesuits. We have experience running multi-year space station missions, thus life support and water recycling are in the bag as well. We have people and production facilities to build all this.

We have all the tech we need if, for some reason, we would want to fly to Mars just to make the mission happen. (Which I don't advocate. Flags and footprints are not useful, we need a base).

 

[BWV]

What about slamming into interstellar dust particles at relativistic speeds and destroying the ship - how much of a potential problem is that?

If we got to be a Kardashev II civilization, which might be a prerequisite for considering interstellar travel, manufacturing antimatter in bulk through some conversion of solar energy would not be a significant problem, assuming it could be stored

 

[Vanadium 50]

The oppositely "stretched" meaning of "today" is "our today existing technology and industrial base".I

I think a reasonable definition of of "today" is that one could write a purchase order today for everything that mission would need, that industry would be responsive to that purchase order, give a delivery date with financial consequences if missed, and that no intermediate or test flights are necessary. In short, you can buy it and launch it. In NASA terminology, technological readiness level 9. I would guess that they are around 3 or 4.

Let us keep in mind that the Viking missions put ~650 kg on Mars. A lunar module - pretty much the lower limit you need for a manned landing - is 25x heavier. (An d alpha centauri is half a million times farther than Mars)

And PS...remember Akin's Laws!

 

[Haelfix]

If we are talking about Manhattan project level mobilization of industry, Academia and various government organizations, and a blank check was given by various governments of the world to clear the red tape. I have no doubt that a successful manned mission to Mars could be undertaken in under a decade, possibly sooner (depending on favorable transfer windows etc)

The biggest issues are still human safety related. The fact that with current tech, we are looking at a 7 month trip one way (which is right at the edge of plausible for biological entities to endure) is probably not quite good enough. Also some sort of shielding will likely be necessary in order to minimize elevated risks of exposure to solar radiation. So these two facts necessitate new designs with factor of two or three improvement over 1980 tech (which is probably not that hard to beat, especially if nuclear propulsion is allowed).

It's hard, but probably not as hard or as implausible as the original Mercury and Gemini programs (which were triumphs of engineering and science).

 

[Vanadium 50]

we are talking about Manhattan project level mobilization of industry

That we might do it in the future does not mean we can do it today.

 

[sophiecentaur]

If we are talking about Manhattan project level mobilization of industry,

That project was a real tiddler, compared with a serious space expedition. It was based on a bit of a gamble; they weren't sure it would work until the first test but there were good reasons to believe it would. At the moment, there seem to be some fundamental good reasons why a trip to another star would not be possible within any foreseeable future.
But what amazes me is that there is a section of people who find it such an attractive idea that they are not asking the sort of questions that they would normally ask before contemplating spending most of their wealth and resources on a project. It would be like selling your house and car for a lottery ticket which might deliver a prize to somebody you don't even know.
Just consider the other projects that would be very feasible and which would tell us so much more about our Universe for a fraction of the cost.

 

[Vigardo]

Sorry, I´ve not readed the complete thread (too long) but I think the following recent (2016) video from Ryan Weed (the antimatter propulsion guy) would be interesting for you. Particularly, at minute 12 or so he shows some estimations about how long would it take traveling to Pluto, Alpha Centaury, etc... using some 1g acceleration capable propulsion system.

Weed´s video:

 

[Vanadium 50]

Sorry, I´ve not readed the complete thread (too long)

Translation: Sorry, my time is too valuable to listen to what you have to say, but you should listen to what I have to say.

But what amazes me is that there is a section of people who find it such an attractive idea that they are not asking the sort of questions that they would normally ask before contemplating spending most of their wealth and resources on a project.

Good point.

 

[nikkkom]

The fact that with current tech, we are looking at a 7 month trip one way (which is right at the edge of plausible for biological entities to endure)

What? Astronauts "endure" ~170 days on ISS rather routinely, and some dip into 200 days.

 

[anorlunda]

What? Astronauts "endure" ~170 days on ISS rather routinely, and some dip into 200 days.

Yes, but the ISS is protected by the Earth's magnetic field. There's quite a difference. Back in the days of the Apollo Project, radiation was a big concern. The astronauts once had to take special precautions to protect themselves from a solar event that happened en route to the Moon. There was even concern that the event could have been lethal; although it turned out be much less than that.

My favorite strategy is to send me as the astronaut to Mars. I am old enough that the gestation period of most radiation-induced cancers are longer than my life expectancy. That makes old people sort of immune to moderate levels of radiation, that could threaten younger people.

 

[Borg]

What? Astronauts "endure" ~170 days on ISS rather routinely, and some dip into 200 days.

Those days are spent inside a giant magnetic field called the Van Allen belt.
anorlunda beat me to it.

 

[nikkkom]

> What? Astronauts "endure" ~170 days on ISS rather routinely, and some dip into 200 days.

Those days are spent inside a giant magnetic field called the Van Allen belt.

I know that.
However, word "endure" means experiencing some sort of physical or psychological stress.
Radiation does not cause either, you don't feel it.

Radiation on Mars trip (+ trip back) is estimated to increase cancer risk by ~5%. Not exactly appetizing prospect, not a show-stopper either. Loggers experience ~0.1% yearly fatality rate. Over a 30 year career, that'll be ~3%. People still go into that profession.

 

[Vanadium 50]

Radiation on Mars trip (+ trip back) is estimated to increase cancer risk by ~5%.

By whom? I am unaware of any study where humans were exposed to that much radiation for that long a time. How well do we know 5% is 5% and not 1/2% or 50%?

 

[Haelfix]

That project was a real tiddler, compared with a serious space expedition. It was based on a bit of a gamble; they weren't sure it would work until the first test but there were good reasons to believe it would. At the moment, there seem to be some fundamental good reasons why a trip to another star would not be possible within any foreseeable future.

I was talking about a trip to Mars. Alpha Centauri is currently in the realm of science fiction, and indeed it might simply be outside of mankinds ken to ever reach that, even with the benefit of thousands of years of technology.

What? Astronauts "endure" ~170 days on ISS rather routinely, and some dip into 200 days.

Well presumably we would like to have a return trip, and I believe it's never the case that the orbits match to do a direct return without requiring some delay. So you are really looking at a ~ 2 year total travel time unless we can manage to speed up the engines by several factors. Also we really don't know what the combined effects of all this are. It's not just radiation, you need to keep your bones from becoming to brittle, your heart from atrophying etc which likely requires some pretty serious medical interventions during the trip. Suffice it to say, unless we are going for Sputnik level of safety precautions, this is likely the hardest problems to solve for the trip and would need some direct and likely controversial testing. Still I don't think any of this is fundamentally impossible, and it really is just a question of collective will. Of course realistically, I don't see it happening in my lifetime for various reasons..

 

[sophiecentaur]

I don't see it happening in my lifetime for various reasons..

If you were a Schoolchild then I could imagine something could happen in your lifetime. If you are near my age then probably no chance - unless something happens in international politics or if a Mars Lander finds some life sign, The race wold be on, then.

 

[Vanadium 50]

Well presumably we would like to have a return trip, and I believe it's never the case that the orbits match to do a direct return without requiring some delay.

It's complicated. With enough fuel, you can come and go whenever you want. I believe there are some ~600 day missions where you have a good-but-not-great inbound followed immediately (typically under 5 days) by a good-but-not-great return. It's not clear to me you would learn a lot from the short stay that you didn't learn from a precursor sample return mission.

 

[ad infinitum]

Accelerating at 1g for one year would would get you to 70% the speed of light and for a deceleration and return trip would need to be repeated 3 more times. Assuming even vey high engine efficency a good deal of your thrust would be consumed by accelating your fuel need for your return trip. Your ship would need to have at least for it's initail departure more than 90% composed of fuel. But it would bepossible throreticaly.

 

[sophiecentaur]

Accelerating at 1g for one year

What is so special about 1g in this exercise? The main concern is surely the Energy involved. It's eye wateringly vast.

 

[neilparker62]

I would say very simply if we want to go to Alpha Centauri, then we have to believe we can! And most likely we need to 'evolve' considerably as a species. The ask is several orders of magnitude greater than (for eg) the Apollo project and would probably require global co-operation on an unprecedented scale. Dare to dream at least!

 

[Al_]

I find the whole thing depressing in the extreme. That coupled with an article in the current issue of Scientific American which states that, while life may exist on other planets in our galaxy, the odds of having it reaching (or exceeding) our level of intellectual evolution is slim to none.

Don't be disheartened. I think we will gradually colonise outward in the Solar System, using forms of nuclear energy as we move further away from the Sun. Then the objects of the Kuiper belt and the Oort cloud will entice us out further. One day, some pioneers will realize they are halfway to another star.

 

[sophiecentaur]

we have to believe we can!

Belief is not enough for any aspiration. There are some basic constraints that are just fundamental. One constraint is available time and the way human politics and

I think we will gradually colonise outward in the Solar System

This is an example of the romantic "Go West young man" view that has be extrapolated way beyond where it started. In the process of 'going West' and colonising the Americas, humans managed (you could say the almost had to) to destroy the environment by killing indigenous humans and animals and felling most of the forests. That was in a very benign situation for their survival. Colonisation of almost anywhere on Earth has been shown to be a profitable deal; the returns have been enormous.
Whatever timescale you are thinking of for colonising the Solar System, you need to ask "why and where". Putting a flag up on a satellite of Jupiter would be a very expensive exercise. Where would be the profit? Getting there would probably require us to have found a much improved source of Energy, which would probably mean that we would also have solved the materials problem. The only point could well be to plant a flag or, possibly shoot a "Love Planet" TV show.

 

[stefan r]

...There are some basic constraints that are just fundamental. One constraint is available time...

We have several hundred million years before the Sun cooks off the oceans. We can delay that to more than a million with comparatively minor efforts.

In other words, not anywhere close to feasible. You're trying to make a spot of moisture sound like an almost full glass of water.
...

Evidence of a drip either proves that there is a drain or the glass will fill. It will continue filling until something changes.

Mars is undoubtedly feasible. While many unknowns remain, we have technologies proven capable of getting there. Alpha Centauri is not yet even a remote possibility. We simply lack the technology needed to even attempt sending a probe that far. IMO, colonization of all the habitable places in the solar system is more likely than us developing the technology needed to launch an interstellar probe.

Your statement allows for colonizing the solar system. That means humans can live and breed off of Earth. When that barrier is crossed there is nothing preventing interstellar arc ships.
We already demonstrated space flight at10^-4c. Engines with the ability to move fleets at 10^-3c have already been designed. I do not see a reason why we could not get there in less than 5,000 years.
I can think of reasons why we might fail but those reasons also apply to colonizing Mars or the asteroid belt.

 

[rootone]

What is so special about 1g in this exercise?

Nothing is special.
I mentioned it in the original post for the reason that 1g (while hard to achieve),
It means humans on board won't be affected by issues of bone loss or similar.