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

[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.

 

[StefanBroaw]

Can the journey be completed within the lifetime of a human adult?

Assuming we have got around little problems like having an adequate form of propulsion, shielding from radiation, and avoiding deadly collisions with milligram sized dust particles.
Let's say our engines can provide constant acceleration then deceleration at 1g.

If the return journey can be done within the travellers lifetime, then will there be anyone still alive on Earth who they knew before departing?, or not so because those on Earth will have aged relatively faster than the travellers.

Have a lookt at the Janus Cosmological Model from Jean-Pierre Petit.
This is a bimetric theory of gravitation, involving negative mass particules, published in peer-reviewed journals.
According to this model can make (apparent) faster-than-light interstellar travel possible are possible for negative mass vehicules traveling on the other metric.
You will find one of the last paper in Astrophisycs and Space Sciences July 2018 : https://link.springer.com/article/10.1007/s10509-018-3365-3
A copy is available here https://www.jp-petit.org/papers/cosmo/2018-AstrophysSpaceSci.pdf

He also presented a video conference earlier this month at the Advanced Propulsion Workshop, Estes Park, Colorado, 14 September 2018.

 

[rootone]

Have a lookt at the Janus Cosmological Model from Jean-Pierre Petit.
This is a bimetric theory of gravitation, involving negative mass particules, published in peer-reviewed journals.
According to this model can make (apparent) faster-than-light interstellar travel possible are possible for negative mass vehicules traveling on the other metric.
You will find one of the last paper in Astrophisycs and Space Sciences July 2018 : https://link.springer.com/article/10.1007/s10509-018-3365-3
A copy is available here https://www.jp-petit.org/papers/cosmo/2018-AstrophysSpaceSci.pdf

He also presented a video conference earlier this month at the Advanced Propulsion Workshop, Estes Park, Colorado, 14 September 2018.

OK I will take a look, but have to say that the concept of a negative mass sounds unreasonable.
This would be like an object having a velocity of less than zero?

 

[StefanBroaw]

"Negative mass" means that the energy is also negative.
Those particules only interracts with positive mass particules through "anti-Newton" laws: negative particules repulse positive particules; negative particules attract négative particules. Theye is no "run away" effect, no paradox.

it fits with observations of the large scale structure of universe (voids of positive matter), dark matters, dark energy repulsion, the great repeller, etc.
A description in english on nasaspaceflight forum here https://forum.nasaspaceflight.com/index.php?topic=43501.0

And their last paper (sept. 2018) in quantum mechanics about negative energies and masses :
https://arxiv.org/abs/1809.05046

Definitely worth a look

 

[stefan r]

...

it fits with observations of the large scale structure of universe (voids of positive matter), dark matters, dark energy repulsion, the great repeller, etc.
...

They make a cosmology argument. I am willing to concede that in order to avoid cosmology. I suspect people in the cosmology forum would have some thoughts.

The UFO drawing in that video has some serious flaws. He models the 3 dimensional universe with a 2 dimensional sheet of paper. I am fine with that. He demonstrates cutting a hole in the paper. The 2 dimensional circle cut is a model of a 3 dimensional spherical cut. His cockpit in a flying saucer is only surrounded by a ring. The ring should be modeled by 2 pin holes in the paper not a circle in the paper.

His UFO technology warps spacetime by concentrating energy. It brings to mind the idea of a kugelblitz, micro-black hole. In order to build this flying saucer you need the technology to not only concentrate the energy but also concentrate it in a ring and also not vaporize the person inside of the ring. Building a kugelblitz is not possible with just a full Dyson sphere. You need a Dyson sphere that stores up its energy and can pulse it and can also aim that pulse into a subatomic space. This thread was looking for easy ways to get to Alpha Centauri. A kugelblitz or anything more complicated than a kugelblitz does not meet that criteria.

Where did he get the number 1,000 Tesla? That sounded like he made it up. Regardless 1000T is a strong enough magnetic field to blow apart any known materials.

A rotating black hole has a ring singularity. It is plausible that the laws of physics change inside of that ring. You can claim that an observer inside of a rotating black hole would see evidence for both positive and negative mass universes and that the distance scales are different. There is no way for the observer to escape the black hole and no way for him/her to send the information to us. Traveling to a black hole takes longer than traveling to Alpha Centuari. Building a black hole is many orders of magnitude harder than launching a colony ship to Alpha Centuari.