Preparations for extrasolar travel

[Philosophaie]

We have put Rovers on Mars. We have made vehicles that can drive many miles without Human intevention. We have orbited and landed automously on other planets.

As Steven Hawking say not too long ago: Why cannot we begin extrasolar travel?

Traveling closer to the speed of light we could reach a close star in our childrens lifetime. The equipment would have aged a lot less due to Einstein:

deltatEarth = deltatShip / Math.Sqrt(1-vShip^2/c^2)

The Kepler and Hubble Satellites are scaning the skies. How are we preparing to send a autonomous robotic mission to a extrasolar system especially the communications and electronics?

[BMAONE23]

Unfortunately, our current technology is not suitable for extra solar travel. If you consider that the closest star outside our solar system is Proxima Centauri at 4.2ly distance.
Consider
1 hour = 60 minutes = 3600 seconds
1 day = 24 hours * 3600 seconds = 86,400 seconds
Then 86,400 seconds * 365 days = 31,536,000 seconds

Light travels 186,282.4 mi per second * 31,536,000 seconds or 5,874,601,766,400 miles in a year, that’s roughly 5.875 trillion miles. It is therefore 24,673,327,418,880 miles to the Centauri system .
Our fastest technology (the New Horizons mission to Pluto) is currently traveling, thanks to a gravity assist from Jupiter, at 47000mph
*24 hours a day is 1,128,000 miles per day
*365 days per year is 411,720,000 miles per year
At the distance to the Centauri system being 24,673,327,418,880 miles and our fastest current technology able to travel only a mere 411,720,000 miles per year it would take
59,927 years & 5 months to reach the next closest star.

[Ann]

It's easy to think that a trend that exists can be extrapolated indefinitely into the future.

In the 1930s, cars were all the rage. They were still quite new, most people still didn't own one, and the cars had been improving greatly since they were first invented.



The first self-powered road engine from 1769, built by Nicolas Joseph Cugnot from France.

In 1886, Karl Benz from Germany built the world's first gas-driven car:

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And in 1908, Henry Ford built the first T-Ford:

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But already in the 1930s, cars looked so much better:

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If cars kept improving at the rate that they had since the late 19th century, where would it all end? Surely it wouldn't be long until people flew around in their own personal flying cars?

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Well, you know... that didn't happen.

It would not have been impossible to build flying cars. I don't see why it wouldn't have been possible. But these contraptions would have been impractical and quite possibly dangerous. If you gave most families their own flying vehicle, chaos would have ensued. So it didn't happen.

It is very tempting to think that it "should" be possible to build a really fast spacecraft. After all, think how much we have learnt about space and how much our spacecraft have improved since Sputnik was sent into orbit in 1957:

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Sputnik wasn't that impressive, was it? Just compare it with the International Space Station:

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So because we have become so much better already, we should just keep becoming better, right? And since we need to travel really fast in order to visit other solar systems, we should just go ahead and build the kind of spacecraft that we need, right?

Well, no. Building an almost-as-fast-as-light spacecraft is not just impractical and dangerous, but probably impossible. There is no fuel that can accelerate a spacecraft to those speeds. You can't just "step on it". You can't just inject more fuel. And you can't build a spacecraft that won't be destroyed by travelling through not quite so empty space at such speeds. Seriously, when you are travelling at close to the speed of light, you don't want to collide with an insterstellar dust grain.

Ann

[rstevenson]

On the other hand, we might just compare automobile speeds rather than talking about that red herring flying car. We are quite capable of building a comfortable, reliable family car (not just a race car) that well exceeds 300 kph at the top-end speed. We don't do so because the roads aren't good enough, and frankly, most drivers aren't good enough either.

There's no reason to think we won't get better at making space craft. The terribly slow craft we have now are that slow because they've used up their propellant and are drifting. Ion thrusters, which we have built and used and can make bigger and better, will keep accelerating for very long periods of time (one design has been tested for 3.5 years and was not approaching failure when the test ended) and can certainly reach the nearest star in far less than 59,000 years. Estimates show a travel time in the 40-year range is quite feasible.

The Interstellar Travel article at Wikipedia gives a good run down on the possibilities.

Rob

[BMAONE23]

But the flying car is here (almost)

The little 8 prop M-200 reminds me of

[Chris Peterson]

As Steven Hawking say not too long ago: Why cannot we begin extrasolar travel?

Mainly, because it is very hard to justify. It would require a huge and expensive engineering effort, dwarfing even such massive ventures at the Apollo program. In an era of extremely limited scientific funding resources, it would divert money from countless projects with major short and medium range returns, and replace them with a very high risk project with a limited potential to return significant new science.

Perhaps the time will come to send probes to nearby stars, but we aren't there yet. We don't have the technology, and we don't have the societal maturity.

[BMAONE23]

If you round the speed to 50000 then double it to 100,000mph, 24 hours per day would be 2,400,000 miles per day or 87,600,000 miles per year or 28,165.89 years to get there
If you traveled at 1,000,000 mph it would take 2,816.5 years to get there
If you traveled at 10,000,000 mph it would take 281.6 years to get there
If you traveled at 100,000,000 mph it would take 28.16 years to get there
But to get there and back you would need to carry/produce enough fuel to accelerate you to 100 million mph 4 times over.
Once to attain 100,000,000mph
Once to decelerate to orbital speed
And twice again for the return trip
Something like an ION drive could work if the ship were nuclear for electricity to produce the ions and the engines were large enough to produce a constant 1G thrust
Of course there is that pesky micrometeoroid problem while traveling at 100,000,000 mph

[rstevenson]

Of course there is that pesky micrometeoroid problem while traveling at 100,000,000 mph

"Shields up!"

Rob

[owlice]

"Shields up!"

And watch out for speed traps!

[Beyond]

And Klingons and Romulans and........

[BMAONE23]

Also consider that at 100,000,000mph you are traveling at 146,670,578fps (feet per second) or 27,778.5 miles per second which is 14% the speed of light.
To be effective and block any particle within a second of impact, the shield would need to be either immense or energy intensive

[rstevenson]

"Everything that can be invented has been invented."
-- Charles H. Duell, Commissioner, U.S. Office of Patents, 1899

Rob

[Chris Peterson]

"Everything that can be invented has been invented."
-- Charles H. Duell, Commissioner, U.S. Office of Patents, 1899

Urban legend. Duell never said this, and neither did anybody else whose opinion on the matter might be worth considering.

[geckzilla]

Just think about how the micrometeorites feel when they smack into your annoying spaceship.

[rstevenson]

"Everything that can be invented has been invented."
-- Charles H. Duell, Commissioner, U.S. Office of Patents, 1899

Urban legend. Duell never said this, and neither did anybody else whose opinion on the matter might be worth considering.

Thanks Chris. I actually checked a couple of sites which list mis-quotes and didn't find it, so I thought it was safe.

I was simply looking for a humerous way to indicate that what looks like reasonable restrictions now might seem a little quaint in a few decades time.

Rob

[Chris Peterson]

I was simply looking for a humerous way to indicate that what looks like reasonable restrictions now might seem a little quaint in a few decades time.

Sure, the point was clear, even if the quote is mythological.

Still, I'd wager that it will be more than a "few decades" before most of the technical problems associated with interstellar probes become quaint. Not so much because they are technically hard, but because I don't see the slightest suggestion of interest in undertaking such a vast public project, nor the slightest hint that it might develop anytime soon.

[Orca]

In all likelihood, each new attempt to send a probe to another star would at some point pass the earlier ones - assuming that the time between launches would result in improved propulsion technology.

Ion or plasma engines might work if you could keep them running for a very, very long time. Perhaps a combination of technologies might be the ticket; Earth-based lasers could provide an extra push for the initial build up of speed. But again, for any attempts in the near future the folks that launch the thing certainly won't be around for the results!

[Ann]

Traveling fast in space is probably not very healthy. Take a look at red giant star Mira, here seen in ultraviolet light:

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That's some tail Mira leaves behind, isn't it? Gas shed by Mira collides with the interstellar medium and is ionized by it, making it glow in UV light. The tail is 13 light-years long and has been released over the past 30,000 years. Please note the bow shock, too!

So how fast does Mira move through space to cause such a collision with the interstellar medium and such a super-long glowing tail? http://www.galex.caltech.edu/newsroom/glx2007-04r.html writes:

Compared to other red giants, Mira is traveling unusually fast, possibly due to gravitational boosts from other passing stars over time. It now plows along at 130 kilometers per second, or 291,000 miles per hour.

291,000 miles per hour is not nearly as fast as the spacecraft that some people hope to send to Alpha Centauri to reach that star in about 40 years. How would our spacecraft feel after colliding with the interstellar medium at 100,000,000 miles per hour for forty years? Would its instruments still be working, so that it could do any observations when it reached its target?

Ann

[rstevenson]

How would our spacecraft feel after colliding with the interstellar medium at 100,000,000 miles per hour for forty years? Would its instruments still be working, so that it could do any observations when it reached its target?

That's why, for a long time, the Bussard Ram Jet seemed such a hopeful possibility. It would scoop up that interstellar medium and use it for fuel. Alas, recent calculations indicate that it would either not get enough fuel to help, or it would not be able to generate enough force to overcome the drag caused by scooping up the fuel. But perhaps something like its proposed magnetic fields would be useful deflectors at least. (Are magnetic fields causing the bow shock in front of that star?)

Yes, sending interstellar probes is fraught with difficulty, but someday we'll figure out a way to do it. We can start learning how fairly soon by using the best ion engine we can build now and sending it out of the solar system with orders to return data until it can't anymore, or until it runs out of fuel. Nothing like trying something to clarify the problems. This first step is not a terribly expensive thing to try, and would return valuable scientific data. After all, look at what we've learned from our old, slow drifting technology as it nears the outer reaches of the Solar System.

Rob

[Beyond]

One thing to consider also is that we are dealing with sub-light speeds. What happens if somehow we are able to travel at faster then light speed??
Would it turn out to be similar to when the sound barrier was a BIG obstacle to flying? And then when it was possible to fly faster than sound everything smoothed out? And that also happened at mach2 & 3, i think.
So, could it be possible that at faster than light speeds, a spaceship would just 'pass through' everything like light passes through glass here on Earth?

[rstevenson]

Beyond, you might want to read The Physics of Star Trek.

Rob

[Beyond]

Beyond, you might want to read The Physics of Star Trek.

Rob

Rob, i might want to, but will i ever get to? :: The book, that is. Wikipedia doesn't seem to have much to say about what is in the book-The Physics of Star Trek. Although it was a bit surprising to find out how the Star Trek transporters came into being.

[rstevenson]

Basically the book analyses in terms of Physics (as we understand it now) what it would require to have some of the devices they depend on in Star Trek -- devices like transporters and warp drives and such. The conclusion is that there is not enough energy in the universe to do some of the things they take for granted. I mentioned that book in response to your suggestion about going faster than light. It ain't gonna happen, unless someone makes a huge, paradigm-shifting breakthrough in our knowledge of the universe.

Rob

[Orca]

I think we are going to have to accept that living creatures such as ourselves are pinned to the solar systems we evolved in. If intelligent life exists besides us it is far away and probably won't exist in the same narrow period as our civilization (assuming roughly random distribution across a whole lot of 4D space). These other life forms are also no doubt confined to their home systems in the same way we are. I have a hunch that we live in an enormous, cold, lonely universe like the one portrayed in the movie Contact but with no way of ever connecting with other intelligent life.






"How depressing! Who let that guy in?"

[rstevenson]

... I have a hunch that we live in an enormous, cold, lonely universe like the one portrayed in the movie Contact but with no way of ever connecting with other intelligent life.

In that case, we'll just have to learn how to be intelligent ourselves.

Rob