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

[sophiecentaur]

There is a variation where you don't use the hydrogen as fuel, but just reaction mass.

Do you assume a mean velocity of molecules of about zero (in the frame of the local part of the Galaxy) and a 'thermal' spread of speeds? That would be low, I imagine (?).
I don't find it surprising that the sums are not very encouraging for this idea. After all, we assume / observe that drag is very low in deep space (even within the Solar System, on the grounds that Cosmic Dust particles of microgram mass still arrive at Earth at very high velocity.

 

[russ_watters]

Thank you all for your interesting comments.
In summary, it's only feasible given as yet unknown technology and engineering.

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.

Please continue though, unimaginable technology and engineering has happenned before.

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.

 

[Vanadium 50]

In other words, not anywhere close to feasible.

Was there really any doubt? We can't get people to Mars, for heaven's sake. Alpha Centauri is 500,000 times farther away.

 

[russ_watters]

Was there really any doubt? We can't get people to Mars, for heaven's sake. Alpha Centauri is 500,000 times farther away.

Evidently, from the last few posts it seems there is.

Also, while I think the OP is stretching the definition of "feasible" literally by light-years, I think you're over-compressing it. "Can't" is too strong a word to describe the feasibility of a trip to Mars, given that plans are underway to make such a trip*. We haven't yet proven it is feasible (doable), but I doubt many scienctists/engineers doubt that it is.

*Assuming the seriousness of such plans...

 

[Chronos]

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.

 

[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%?