Curiosity Mars Rover Success!

[eyeball]

Why should that be so? Only if we intended to physically keep returning!

Long before we settle other planets and asteroids in the solar system we would be capable of making something like an asteroid base move under power. With solar and/or nuclear power plus a self-sustaining environmental system a large asteroid could support a surprisingly large population. Add in even a very modest ion drive engine and there would be nothing to stop that asteroid from heading out to the nearest star.

It would take many generations but eventually they would arrive at another system, perhaps with other planets suitable for colonization. If so, some of the population might choose to become colonists and live on another world. If not, it would be no big deal. The asteroid would just keep moving on! To another star and another. For most of the people involved would likely to prefer living in that asteroid. It would be home. Earth would be only a memory, something in the history books. It would suggest harsh gravity, abusive climates and worst of all, germs! Why change the safe and clean life in an interstellar colony craft for that?

Population is easy to plan with contraceptives but even if the population grows too large, there would be no problem. Simply find another asteroid and build another colony craft! The beauty of such craft is that you take your material resources with you. An asteroid ten or more miles in diameter has a HUGE volume of mass, with LOTS of metals, minerals and perhaps even water!

Once the process has started, in a few hundreds of thousands of years Mankind would have spread out across a good portion of our galaxy. It would be a geometric progression, like doubling a penny every day.

I can see maybe keeping the colonists frozen while in transit between stars but it occurs to me the crew-members in such a ship would also need the sort of deep dedication that only a religion seems remotely capable of inspiring over such a long haul.

[eyeball]

Man, I wish I was younger!

Don't worry, be faithful. Just remember to go into the light. I'm betting it's a portal to the future where the Technological Singularity has lead to the evolution of benevolence and altruism without morality and people decide to rescue every-single human being that's ever lived, just because they can. No profit required.

Oh the humanity.

[Wild Bill]

Don't worry, be faithful. Just remember to go into the light. I'm betting it's a portal to the future where the Technological Singularity has lead to the evolution of benevolence and altruism without morality and people decide to rescue every-single human being that's ever lived, just because they can. No profit required.

Oh the humanity.

Sounds like you are a fan of Spider Robinson!

I've always found the idea of a Singularity to be a bit of a stretch but I can accept that if it were possible and cheap enough it would include everyone.

Leaves out the protection of using a "B" Ark, though.

[jbg]

I wouldn't want to live on Mars, but i'd like to visit one day lol.

Reminds me of the Thomas Swift books I used to read back in the mid-1960's as a kid. Were those popular in Canada too? Translated into your language?

[Wild Bill]

I can see maybe keeping the colonists frozen while in transit between stars but it occurs to me the crew-members in such a ship would also need the sort of deep dedication that only a religion seems remotely capable of inspiring over such a long haul.

Why? Such a craft would be their home! We're talking hollowing out asteroids up to 10 MILES in diameter! That means CITIES of people in space!

Do we need a religion to live in a city now? We are talking about hundreds, thousands, eventually uncounted millions of such cities in space. There are an infinite number of asteroid sized masses in the Universe. After you have built a few you can build as many as you want, forever!

People would be born, live and die in such cities. They not only would not care about ever returning to the Earth, likely many if not most would eventually forget there ever was an Earth! Just as most folks today have no idea of how Man may have originated in Mesapotamia. Or even that there is somewhere once called Mesapotamia!

Read the whole thread, eyeball. You are thinking WAY too small!

[eyeball]

Why? Such a craft would be their home! We're talking hollowing out asteroids up to 10 MILES in diameter! That means CITIES of people in space!

You're also apparently talking about a 10 mile wide speck providing an adequate amount of space for...not just cities but CITIES of people...what does that mean, hundreds of thousands or were you thinking millions - for thousands of years? So, what will all these people do to justify their existence and entertain themselves during all that time? How will they keep from going completely nuts in such a tiny constrained world?

Read the whole thread, eyeball. You are thinking WAY too small!

I've been here right from the beginning Bill and your thinking stills seems as big as the wide open spaces of your heart, which only get vaster the deeper into this thread we get.

[wyly]

I can't conceive of anything smaller than a asteroid being used and the problems are still significant...isolation shouldn't be an insurmountable problem, in my parents day it wasn't uncommon to find people who spent their entire lives within a 10Km distance of where they were born, they were self sufficient but life was simpler then. Even today there are societies that spend their entire lives on tiny isolated island communities.

water? limited/finite, resupply highly unlikely- food supply? crop failures are not an option there's no trucking in fresh produce from california...

technological repairs? our society has evolved into one of specialists, to support a highly sophisticated colony would require a very large population to cover all aspects of society, miners, farmers, medical, computer engineers, IT specialists, manufacturers for a huge array of domestic products from fabrics to toothpaste it's endless and mind-boggling what we take for granted in our everyday lives. We're no longer a society of simple farmer communities that can survive on our own. No wonder the enterprise had a replicator .

Galactic travel may require a small moon instead of an asteroid and a population of millions...sleeping for centuries maybe the other option but I don't know how many volunteers you're going to get for a trip for which you may never wake up from.

[Wild Bill]

I can't conceive of anything smaller than a asteroid being used and the problems are still significant...isolation shouldn't be an insurmountable problem, in my parents day it wasn't uncommon to find people who spent their entire lives within a 10Km distance of where they were born, they were self sufficient but life was simpler then. Even today there are societies that spend their entire lives on tiny isolated island communities.

water? limited/finite, resupply highly unlikely- food supply? crop failures are not an option there's no trucking in fresh produce from california...

technological repairs? our society has evolved into one of specialists, to support a highly sophisticated colony would require a very large population to cover all aspects of society, miners, farmers, medical, computer engineers, IT specialists, manufacturers for a huge array of domestic products from fabrics to toothpaste it's endless and mind-boggling what we take for granted in our everyday lives. We're no longer a society of simple farmer communities that can survive on our own. No wonder the enterprise had a replicator .

Galactic travel may require a small moon instead of an asteroid and a population of millions...sleeping for centuries maybe the other option but I don't know how many volunteers you're going to get for a trip for which you may never wake up from.

If you have raw material and enough energy you can do whatever you need or want!

As for how many people, remember we are not talking a 10 mile wide flat disc. We are talking about a big asteroid ten miles in diameter. That's 3D! Think about an apartment building that goes 10miles down into the ground and nearly the same forward, back and to the sides.

That's a lot of room!

Water and resources of course would be recycled. Most asteroids contain metals, minerals and often water. Space livers would not have only the tailings from their own digging to process. The Universe is full of other asteroids and material! Just reach out to another such asteroid and mine it for 100 years or more of supply.

A sleeper ship only makes sense if you have an end destination, like a planet to colonize. If you live in space, why spend your life sleeping?

I'm not saying it would be attractive to someone raised here on Earth. However, if you were born on a space colony and had an interesting life with lots of social interaction, useful work and enjoyable recreation you would never know what you were missing!

Or give a damn, for that matter!

Edited August 19, 2012 by Wild Bill

[wyly]

If you have raw material and enough energy you can do whatever you need or want!

As for how many people, remember we are not talking a 10 mile wide flat disc. We are talking about a big asteroid ten miles in diameter. That's 3D! Think about an apartment building that goes 10miles down into the ground and nearly the same forward, back and to the sides.

That's a lot of room!

but you can't esacpe the laws of physics/gravity and mining, you wanted to spin this asteroid for gravity, gravity wants to make everything level/collapse...you can't simply hollow out an asteroid...

Water and resources of course would be recycled. Most asteroids contain metals, minerals and often water. Space livers would not have only the tailings from their own digging to process. The Universe is full of other asteroids and material! Just reach out to another such asteroid and mine it for 100 years or more of supply.

an asteroid hurtling between stars isn't going to come across many if any other asteroids and if they did wouldn't have any practical/useful contact time as they whizz by each other.

A sleeper ship only makes sense if you have an end destination, like a planet to colonize. If you live in space, why spend your life sleeping?

they don't make any sense to me, run into one small space rock and it's all over if the cosmic radiation doesn't do them in first...

I'm not saying it would be attractive to someone raised here on Earth. However, if you were born on a space colony and had an interesting life with lots of social interaction, useful work and enjoyable recreation you would never know what you were missing!

Or give a damn, for that matter!

that part would work...there are many people who have no problems with isolation in small communities...the only difference being that even though they're isolated they can still imagine and plan leaving if they wished to, there's no such option in space, "island fever"...

[Bonam]

statistically I would say that life existing elsewhere at some time is a sure thing, other than confirming it in our own solar system there isn't any point in seeking it out...time and the enormous distances involved make a further search a waste of resources, without faster than light travel we're never leaving our solar system...

Faster than light travel is not a necessity for interstellar spacecraft. Neither is a spacecraft that can sustain generations of people indefinitely, as discussed above.

The key is time dilation. For example, a spacecraft traveling at 0.99c would take about 4.3 years, from the point of view of an observer on Earth, to reach the nearest star system. However, from the point of view of the spacecraft and any onboard observers, time would have dilated by a factor of 7, and they would have only experienced the passage of 220 days. At 0.999c, the time dilation factor would be 22, allowing journeys of over a hundred light years in only several years time from the point of view of any onboard systems and personnel.

For reference, there are 512 Sun-like (G-type) stars within 100 light years of Earth, all of which could be reached within 5 years of onboard time by a spacecraft traveling at 0.999c.

Traveling at these velocities does not violate any laws of physics, and the fundamental concepts of how to achieve these velocities are already known. For example, to accelerate 1 kg of payload to 0.99c, you would just need 3 kg of matter and 3 kg of antimatter propellant, such as hydrogen and antihydrogen. Production and storage of antihydrogen is the subject of current research at various physics laboratories, and is a technology that will almost definitely be mastered within the present century. 0.999c would require about 11 kg of antimatter.

Let's estimate the mass and energy requirements for an interstellar voyage of 5 years at 0.999c. Humans require about 1000 kg of food and water per year. Assuming a 100 person crew and 90% recycling efficiency, you would need 50 tons of consumable supplies. The humans themselves would be about 6 tons. Assuming that the spacecraft needs about 3 cubic meters of living space per crew member (the same as navy submarines), the pressurized volume of the spacecraft would be about 300 m^3. Assuming that this volume's structure is made of lightweight strong materials (aluminum-lithium alloys, carbon fiber composites, etc), and that the structure takes about 10% of the volume, you'd have 60 tons of structure. Adding in masses of various miscellaneous systems and rounding up, you'd need about a ~200 ton payload mass, which would require ~2000 tons of antimatter propellant.

Producing this amount of antimatter would require about 2*10^20 J of energy. World annual electricity production is about 1*10^20 J. Thus, if 10% of the world's electricity output could be put to producing antimatter fuel, the necessary 2000 tons of antimatter propellant for the above spacecraft could be produced in 20 years (keep in mind that world electricity production doubles about every 20 years, so in 2050, for example, the same spacecraft could be fueled in just 5 years, or, alternatively, using just 2.5% of the world's electricity budget).

The cost of electricity is ~5-10c/kWh or about 2x10^-8 $/J. So the cost of the required energy to produce the antimatter would be about $4 trillion, actually a quite modest amount by today's economic standards. The launch cost of the ~4200 ton spacecraft (in bits and pieces) from the Earth's surface to orbit would be about $20 billion using current launch methods ($5000/kg), small compared to the antimatter cost. The same would be true for the cost of the spacecraft modules themselves, which would likely be a few hundred billion.

The point of the above is simply to illustrate that manned interstellar travel is not outside the realm of physical possibility for our civilization in the foreseeable future.

Edited August 27, 2012 by Bonam

[TimG]

The point of the above is simply to illustrate that manned interstellar travel is not outside the realm of physical possibility for our civilization in the foreseeable future.

Interesting but what about navigation within the target solar system? i.e. aliens coming to our solar system could end up near Jupiter or Mars which would put them several years away from a earth at the speeds they could hope attain for short distance hopes within a solar system.

[Bonam]

Interesting but what about navigation within the target solar system? i.e. aliens coming to our solar system could end up near Jupiter or Mars which would put them several years away from a earth at the speeds they could hope attain for short distance hopes within a solar system.

If you have the described antimatter propulsion systems, you can use them just as well within a solar system as outside one. It's not like Star Trek warp drive that is banned from being used in solar systems ;p You just don't accelerate to 0.999c but just go to 0.1c instead if need to go slower for some reason.

Keep in mind, all current spacecraft maneuvers are calculated long in advance. The same would be true for interstellar trips. If a manned spacecraft was sent on an interstellar journey, it would be to some specific destination, such as in orbit of a planet for example, and the exact burns of its engines would be calculated long in advance. Also, any spacecraft traveling at a substantial fraction of the speed of light would begin its deceleration burn well before entering a target solar system.

[TimG]

Keep in mind, all current spacecraft maneuvers are calculated long in advance. The same would be true for interstellar trips.

I don't see how this is possible with current technology where we can only detect planets by measuring their effect on the star. We simply can't get the data that would allow an interstellar trip to be planned with the detail that we plan trips to mars.

[Bonam]

I don't see how this is possible with current technology where we can only detect planets by measuring their effect on the star. We simply can't get the data that would allow an interstellar trip to be planned with the detail that we plan trips to mars.

Obviously any manned mission would be preceded by a multitude of robotic ones, which would obtain all the required data.

[TimG]

Obviously any manned mission would be preceded by a multitude of robotic ones, which would obtain all the required data.

But now you are losing all of the relativistic effects because it would take a decade or more to get the data back from a single robotic mission. Several robotic missions would take generations. Edited August 27, 2012 by TimG

[Bonam]

But now you are losing all of the relativistic effects because it would take a decade or more to get the data back from a single robotic mission. Several robotic missions would take generations.

The relativistic effects still apply to the manned mission itself. They reduce the time experienced in the voyage by the human crew. Robotic missions are the staple of space exploration and will always precede humans.

Keep in mind that if the issue was just navigational data, as you mentioned, then you don't actually have to wait for the results of the robotic mission to be transmitted back to Earth, rather, the data could also be transmitted directly to the manned spacecraft... that is, it could be arriving just shortly after the robotic one.

Though, in practice, you'd probably want detailed information about a destination, such as a detailed planetary survey, to help design the mission. You'd want to know exact compositions of the atmosphere, the distribution and availability of surface and subsurface resources, classifications and analysis of any native lifeforms, data on planetary and stellar magnetic fields and space weather. And you may want to pre-position initial habitats and equipment as well. You may want a whole robotic colonization system that would build a settlement that the human mission would simply occupy once it arrived.

Sending humans on a one way trip to another star system is obviously a mammoth undertaking and would require at least several decades of careful planning and preparation. But the numbers show it is not out of the realm of possibility using currently foreseeable technology.

Edited August 27, 2012 by Bonam

[Guest Manny]

One problem with robotic missions at great distances is, once it's there it can't beam the data back to us. Well, it could but we'd have to wait up to 100 years for the data transmission to arrive. And if we were to send a command and wait for the response, 200 year round trip.

[Wild Bill]

but you can't esacpe the laws of physics/gravity and mining, you wanted to spin this asteroid for gravity, gravity wants to make everything level/collapse...you can't simply hollow out an asteroid...

Wyly, you don't need a very fast spin to "fake" a 1 g gravity at the surface of an asteroid 10 MILES in diameter! The stress on the rotating body would be mice nuts!

We live on a body that spins virtually eternally. Don't see everything collapsing every day.

You are making the problem overly complicated.

[wyly]

Wyly, you don't need a very fast spin to "fake" a 1 g gravity at the surface of an asteroid 10 MILES in diameter! The stress on the rotating body would be mice nuts!

We live on a body that spins virtually eternally. Don't see everything collapsing every day.

You are making the problem overly complicated.

a population of millions living inside of a big rock is uber-complex, there is nothing even remotely similar on this planet, mine/underground engineering on this planet is very dangerous and complex and it's done on tiny scale in comparison to what you envision and in a far more dangerous environment...

[Wild Bill]

a population of millions living inside of a big rock is uber-complex, there is nothing even remotely similar on this planet, mine/underground engineering on this planet is very dangerous and complex and it's done on tiny scale in comparison to what you envision and in a far more dangerous environment...

.

Well, if it bothers you, stay home!

Wait for the "B" Ark!

[GostHacked]

But now you are losing all of the relativistic effects because it would take a decade or more to get the data back from a single robotic mission. Several robotic missions would take generations.

If we head out to the stars, it won't be the people who leave that arrive on the far distant planet, it will be the generational offspring of the first explorers.

Two scenarios

1 - create a colony ship to sustain life for human propagation (aka offspring)

2 - cryogenics and freeze everyone until they arrive at the destination.

Or, we will have some hybrid ship set up were there is a crew that will maintain the ship while the colonists sleep. But that has problems as well. So for now we have to rely on mechanical means to explorer the stars.