Should we send interstellar probe to Alpha Centauri?

Urvabara

Should we send an interstellar (unmanned) probe to Alpha Centauri? Would it be much more expensive than a manned mission to Mars?

According to Wikipedia, velocities as high as 0.10c are possible with hydrogen bombs. That means that ~40 years flight time to the nearest star would be possible with today's technology!

There could be a Earth-like planet in the Alpha Centauri system so maybe the probe should try to go into the orbit of the planet and even land there.

How much would all this cost?

What problems there are?
I try to list here everything I know of:
1. Using hydrogen bombs in space violates the Partial Test Ban Treaty.
2. No one will use hydrogen bombs because...hey! we have these wonderful chemical rockets and flight times of hundres of thousands of years!
3. Micrometeoroids with speeds of 10% of the speed of light.
4. Very much fuel (hydrogen bombs) if the probe is to go into the orbit of the star(s)/planet.
5. No one knows the orbit of the (hypothetical) planet.
6. The probe and all its instruments should last at least 50 years without a human help.
7. Radiation.
8. Maybe the probe should have a very advanced Artificial Intelligence.

See also:

• Project Daedalus
• Project Longshot (NASA's pdf file)
• Project Orion

PS. A wise man once said: "Space, the final frontier. These are the voyages ... to explore strange new worlds. To seek out new life and new civilizations. To boldly go where no one has gone before." I do not recall who he was but I know he has done a good job in space exploration.

FredGarvin

First of all, you do know that Star Trek was a TV show that had zero to do with real exploration....right?

The big thing I see as an issue is that, even if we did get a probe there, you are still looking at a 4+ year turn around time for all data transmitted from there (assuming nothing gets lost in the trip due to whatever problems might arise).

Mech_Engineer

Considering the speculative nature of ALL of the technolgies you mentioned, it is impossible to gauge feasability, cost, or "worth."

Your quoting of Star Trek tells me you have no basis in reality as to guessing what would be possible. At this point you might as well aim for building the Enterprise, you'll get just as far, which is to say, nowhere.

Oberst Villa

OK, this is true, we will be looking at old data, but I would not see this as a big problem. Or are you concerned that we would not have any means to control the probe from earth due to the time delay ? Surely it would really need some good AI so that it can make completely autonomous decisions.

But your point reminds me of another issue: How the probe should communicate its data to us. The strength of any radio signal goes down with 1 / R^2 and the NASA guys already had to use a lot of brain power to receive the Pioneer and Voyager signals.

But if I had to guess the worst problem, I would go for the protection of the probe against impact. (Urvabara's point 3) Even a small dust grain can ruin your day when it hits you with 30000 km / s ...

Oberst Villa

Even if he could not make it fly, the Enterprise might look pretty cool in his backyard

Urvabara

Umm? The quote was just a joke. No sense of humor, eh?

At least, I am trying to list all the problems and find a solution.

Urvabara

Of course. Why else would I try to find all the problems and their solutions?

Saying that "this can't be done, because it hasn't be done before" doesn't get us anywhere and I strongly wonder why people so pessimistic even are scientists/engineers...

Of course the probe should be automatic but how much automatic/intelligent it must be, I don't know. I also wonder how much data is possible to send lightyears away: 1 bit/s? 1 kbit/s? 1 Mbit/s? 10 Mbit/s?

Urvabara

Did you read this? It's NASA's paper. I am not the only one daydreming of interstellar probes. Even NASA's intelligent engineers are daydreaming of them. Did you read the timeframe of the Project Longshot? The paper was written in 1987 and 1988 and the paper basically says "all the problems could be solved withing the next 20 to 30 years." 20 years has already passed. Longshot probe was to be built at the Space Station Alpha, at least according to the Wikipedia. ISS is the Space Station Alpha after major budget cuts. If SSA was to be still in the orbit when sending the Longshot probe, I would assume that Longshot would be constructed during the early 2000s, maybe before 2020s.

Mech_Engineer

You're asking a bunch of engineers and scientists to judge the feasability of sending the first ever interstellar probe to Alpha Centauri using experimental and/or theroetical technologies that are decades if not centuries away from being considered viable, controlled by an all-encompassing AI system that adapts to problems that can't even be forseen.

What kind of a response were you hoping for? Engineers by nature are skeptical realists.

Urvabara

Keep in mind that I am talking about unmanned probes so we don't have to worry about human lives. Of course, if the probe costs dozens of billions of dollars and the flight time is well over 50 years, it may not be very sensible to even send it.

Just my two eurocents.

DaveC426913

Nobody's saying it can't be done, they're saying it's too far in the future to consider with today's technology. i.e. it's still just science fiction.

Considering the difficulty of getting a probe to Mars (historically, a 50% failure rate), a journey that is 100 thousand times longer may be a bit ambitious.

Urvabara

That is why I try to concentrate on today's technology like hydrogen bombs (I am almost 100% sure that H-bombs work). I am not considering controlled fusion reactions, antimatter, wormholes, solar sails, laser sails or what ever, because they do not work yet. H-bombs should work. Why cannot they just try to use them? We do not need to reach the stars at the first try. If a small probe could be sent to the outer regions of the Solar system using H-bombs, it would be a major milestone.

Landing is usually the most difficult part of a probe mission. The interstellar probe probably wouldn't even land anywhere. For example, Project Daedalus is a (hypothetical) fly-by mission to the Barnard's Star.

Oberst Villa

I did not intent to insult you with my remark about building the Enterprise in your backyard, apologies if I did. There is nothing wrong with getting inspiration from SciFi. In fact, I have stolen my name (Oberst Villa) from a character in a German SciFi movie (much cooler than Startrek I must say )

I am not very impressed by statements like "could be solved within 30 years". I recently read an article about rail-gun development from the 1980s (when Reagan's SDI had renewed interest in this things). In this review a paper from the early 1940s was cited, where a german scientist had been quite optimistic about rail-gun development if only the 3rd Reich would give him enough ressources for his research. Then, again in the 1980s article, much optimism for the next decades. Now we have 2008 and the only operational rail-gun I ever saw was in an Arnold Schwarzenegger movie ! (I know some guys built various prototypes in their labs, but the predictions were about operational guns.) So much for "can be solved within x0 years".

EDIT: P.S: If you read my post #4 you can see that I have been thinking about the feasibility of your idea quite seriously.

Urvabara

No hard feelings here. I am just always optimistic when I see a real scientific paper and their proposals and timelines and then I get sad when I see that those things are still far in the future: "Is this not going to happen in my lifetime?!"

I like Star Wars, Star Trek, The Space Odyssey, but still more I like science FACT. I like to read physics texts far more than popular science books. I want to get things right and I want to know every little detail behind things. (I am almost a Master of Science in Physics, btw. :)

Yes, thank you.

Oberst Villa

Among other things this depends on the size of the antenna on the probe (larger size => more gain) and the power of the transmitter. Neither comes for free in terms of mass. My guess is that even if with a really fat transmitter/antenna you should rather think of bits than Mbits per second. If the probe would go into an orbit this would not be much of a problem - waiting, say, one additional month for the data would not hurt much.

Urvabara

If we are technically correct, there already are FIVE (5) interstellar probes:
Voyager 1
Voyager 2
New Horizons
Pioneer 10
Pioneer 11

It's just that they are too slow to get even outside the Solar system in a sensible time frame and we are losing the contact to them in the near future. Two (the Pioneers) of five are already non-functional.

Voyager 2: "Launch date August 20, 1977 (11286 days ago)." At least, it seems to be possible to build an interstellar probe that works 11286 days. :)
If the speed of the Voyager 2 would have been 0.10c, then it would be 3.1 lightyears away. Of course, it probably wouldn't be working at all because of the micrometeoroids and the radio signal's would be way too weak.

Astronuc

I saw operational railguns 20+ years ago (with muzzle velocities of 3 km/s), and the Navy is now testing one for naval artillery.

Here's a Popular Mechanics article on the BAE system delievered to the US Navy.
http://www.popularmechanics.com/tech...w/4231461.html