# What would be your vision of a better humanity?

I agree with assembling the ship in space. However, your dismissal of force or thrust required ignores present day realities. Now if we could build a space elevator, then we might be able to do something like you envisage, but that is not possible yet, and might never be.

I am not dismissing the need for energy. But the fact remains that energy is not what is limiting us in our space travel desires. The limiting factor is thrust. Because it takes such a vast amount of rocket fuel to give the thrust to lift a payload into orbit.

Once in orbit, small thrust can be enough, because there is time for long, slow acceleration. But to get out of Earth's gravity well is the real problem, and that takes thrust.

As to refuelling in the Kuiper Belt, please remember that I am envisaging the space city that decides to travel to another star system will already be somewhere in the solar system working, and that may well be the Kuiper Belt. If not, they are likely to be in some other suitable location, such as near Saturn's Rings, or some object orbiting Jupiter. Refuel and leave. From any such location, the sun's gravity will be small potatoes, and a slow steady acceleration from an ion drive engine will be sufficient.

The acceleration is related to mass times velocity of the exhaust. An ion drive engine of sufficiently advanced design should be able to generate an exhaust velocity of 0.999 C. At that velocity, the mass of the ions exiting also increases. Thus the acceleration is greater per unit of the mass of the material to be ionised. The NASA scientists who calculated a theoretical possible travel speed of 0.1 to 0.2 C no doubt took that into account.

The big thing I do not know, is how much acceleration such a vessel could generate. When I calculated 55 years to Alpha Centauri, that was based on an acceleration of 0.01 Earth gravities for 10 years, and the same for deceleration.

Also the orbital speed of the earth is not much help in trying to climb out of the sun's gravity well as it is almost exactly in the useless* tangential direction about the sun.

Escape velocity is escape velocity; it's largely independent of vector, and as long as it adds (i.e. you keep going in the same direction you get the assist from) you get a benefit from the original motion. That's why staged rockets work, and that's why we launch towards the east as near to the equator as we can - to capture the additional 1000mph or so we get from the Earth's spin. Note that that helps even when you are launching a vehicle intended to reach Earth escape velocity.

BTW, a fact not well known, is that it takes more energy to "fall" into the sun from an Earth launch than to escape from the sun to deep space!

Agreed in most cases*. It definitely takes more energy to enter a close orbit around the Sun than it does to escape it altogether when starting from the Earth. And that's why the Earth's motion helps you reach solar escape velocity; that's the same velocity that makes it hard to get to the Sun.

(* - if you are trying to fall directly _into_ the Sun it's a lot easier, since you don't have to shed all that velocity; you can hit it at any speed you like, and use other gravity wells to shape your orbit appropriately.)

I imagine a world without borders where we intelligently resolve fragmented opinions without war but with intelligence and all of humanity shares a common goal and works to make it a reality. For example discovering the secrets of the universe or improving our ability to venture into space. What are your own visions or opinions on the subject?

Such ideas could get you applauded ... in a beauty pageant. But in real life , unless you are very lucky -

You carry on the struggle to keep your faith in humans in spite of all the negative experiences, until you realize that:

The word 'naive' means someone who doesn't believe that totally selfish, greedy, cold, manipulative people exist. Let alone ..that there are A LOT of them in the world, and that the fact of your having a reasonably good life, can actually make you a target to such people.

As soon as you stop being naive in that sense, life gets a bit easier. Less confusing.

You'd have to change the fundamental attitudes of humans - the lies, the selfishness, the greediness and corruption etc. Theoretically possible, but never going to happen.

Agreed, thats why making a spaceship and finding another planet won't work.

Psychology is a relatively new science (if it can be considered that at all).
We still don't know how to 'fix' people eg extreme examples : serial killers, murderers...
So we either put them in prison or throw them away (death penalty). We treat broken mobile phones better than we treat 'bad' people but what else can we do?

I imagine a world without borders where we intelligently resolve fragmented opinions without war but with intelligence

This works in some contexts but there are still many everyday situations in which intelligent discussion and a world without borders could not be of any use.

Escape velocity is escape velocity;
Obviously true and it is vector not a scaler like speed for solar escape. I.e. if trying to escape from the sun by using help from Earth's orbital velocity is of little or no use because that direction is mainly along a tangent to a circle centered on the sun.

Your least escape from sun speed must be a radial vector from the sun. Earth's orbital speed can (and will if not removed) make your escape path a helix (or part of one) as your rocket leaves the sun instead of on a radial line, but your radial progress along that helix is made ONLY by the radial velocity component of the total velocity. It, and it alone, is providing the energy to climb out of the sun's gravity well, unless you can use a third body's gravity (like the moon as I discussed in prior footnote) to bend / "gravity assist" / some of the tangential component into radial direction so then the total radial speed is increased.

... That's why staged rockets work
No. staged rockets are used to shed some mass. ("Weight" is a poor term to use in this context as it is also decreasing for the uni-stage rocket, even when it is not burning any fuel - just coasting higher - but perhaps "weight" is better understood by the not well informed?)

With some mass shed, the 2nd stage rocket produces more acceleration than if that mass were still attached. That is why multi-stage rockets are used. It has nothing to do with maintaining or changing the direction of the velocity vector etc.
... and that's why we launch towards the east as near to the equator as we can - to capture the additional 1000mph or so we get from the Earth's spin.
Yes that earth surface rotational speed can help you escape from Sun or make it harder, depending upon when in the 24 hour day you launch, even if you always roll vertical rocket to the East.

For the equatorial 1000mph rotational speed to best / to fully aid / escape from solar system (i.e. most reduce the speed the rocket needs to provide) you should launch at approximately 6PM sun time. That is when the local Earth rotational speed of the launch pad has the greatest, radial away from the sun, speed.

To make this very clear, assume that the surface rotational speed at the equator was equal to the solar escape speed (plus 1mph). Then the rocket or just a brick would need to be tied down to not just go flying off the Earth. But only if you cut the tie to the brick at ~6PM would it head straight away from the sun and leave the solar system. In contrast, for example, if you cut the tie to the brick at midnite then its initial velocity is parallel to Earth's orbital velocity but the brick's total velocity is greater than the Earth's orbital velocity by 1000mph. Thus, at release, it will be at the perigee of a new but still bound to the sun elliptical orbit. This mainly because the sun's gravity, which is alway accelerating it towards the sun, is much more slowly decreasing, i.e. remains stronger longer as the brick travels nearly tangentially up to its new orbit's apogee.

If the brick's tie to earth were cut at noon, then it velocity direction is the same as the midnight release but equals the orbital velocity minus 1000mph. So it is not going fast enough to stay in Earth's orbit. It is at the apogee of its new orbit when released, but also has escaped from Earth.

Most readers should skip this paragraph as it concerns a complex subject: You will want to roll the 6PM launched, sun escaping, rocket 90 degrees to the East (into the dark sky) while rocket is still in the air as the 100mph rotational speed was initially directed perpendicular to the rocket axis (assuming it was standing vertically on the launch pad and not launched from some inclined rail gun). You also want to align the rocket's motor's thrust with that "free speed," but not roll too soon or quickly as you also want to climb up out of the dense lower atmosphere air. The computation of the optimum amount of roll / changing rocket attitude wrt to gravity direction / as it climbs in altitude is very complex problem, which only can be solved by trial and error computer models that include air drag as function of rocket speed and altitude (and local air temperature as the tells when supersonic shock will form, etc.).

... Note that that {1000mph) helps even when you are launching a vehicle intended to reach Earth escape velocity.
Yes, but now at what time of day you launch is not as critical. For example, the midnite launch, discussed two paragraphs earlier, is OK, perhaps even best (but I don't have time to think that speculation thru now) as it will put rocket into an elliptical sun-bound orbit but no longer bound to the Earth - i.e. rocket has escaped the Earth but not the sun.

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...{human nature} thats why making a spaceship and finding another planet won't work. ...
I strongly agree with this. I amazes me why anyone would think moving to a place where problems of simple existence (getting food, water, keeping warm but not boiling, living in an air tight encolsure for breathable air, hoping that the CO2 removal system does not fail, etc.) are added to the more common conflicts on earth is to be preferred (or even feasible).

The experiments, tried on earth, with modest number of people (a dozen or two at most) living in a partially sealed bubble with recycling of dish water and urine, trying to grow a small part of their own food (and not even producing their electricity, calling in doctors when anyone got seriously sick, etc.) have all failed in less than a year. In these bubbles, the stress levels were much less than they would be on a distant planet as the bubble occupants all knew if it went too badly, they could just open the door and go home.

SUMMARY: If humans can't solver their problems here on Earth, they sure as hell will not on distant planet X.

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I strongly agree with this. I amazes me why anyone would think moving to a place where problems of simple existence (getting food, water, keeping warm but not boiling, living in an air tight encolsure for breathable air, hoping that the CO2 removal system does not fail, etc.) are added to the more common conflicts on earth is to be preferred (or even feasible).

The experiments, tried on earth, with modest number of people (a dozen or two at most) living in a partially sealed bubble with recycling of dish water and urine, trying to grow a small part of their own food (and not even producing their electricity, calling in doctors when anyone got seriously sick, etc.) have all failed in less than a year. In these bubbles, the stress levels were much less than they would be on a distant planet as the bubble occupants all knew if it went too badly, they could just open the door and go home.

SUMMARY: If humans can't solver their problems here on Earth, they sure as hell will not on distant planet X.

You bet, things would have to be very bad at home to induce me to move even if all those problems you talked about were already resolved to every ones satisfaction. As a matter of fact she would have to be one of those one in a million woman I could never hope to have any other way, if you get my meaning. But if I was scheduled to be executed that might do it also.

All I can say is if they did get all the volunteers they wanted it would be a very interesting group to have as long time traveling companions.

Volunteers are not a problem. When it was recently suggested that the first trip to Mars should be one way, leaving the pioneers to cope with a life on Mars as best they could, but destined to die, there were almost immediately some thousands of people who tried to volunteer. Lots of people are prepared to do almost anything if it ensures them long lasting fame.

Volunteers are not a problem. When it was recently suggested that the first trip to Mars should be one way, leaving the pioneers to cope with a life on Mars as best they could, but destined to die, there were almost immediately some thousands of people who tried to volunteer. Lots of people are prepared to do almost anything if it ensures them long lasting fame.

Like I said some very interesting traveling companions.

Obviously true . . .

Agreed.

and it is vector not a scaler like speed for solar escape. I.e. if trying to escape from the sun by using help from Earth's orbital velocity is of little or no use because that direction is mainly along a tangent to a circle centered on the sun.

You just disagreed with what you said was "obviously true!" Escape velocity is escape velocity. It doesn't matter what direction it's in. In other words, if you started from a dead stop (relative to the Sun) from Earth's orbit it will require 42 km/s. It doesn't matter what direction you are pointed in, provided you don't run into anything. If you get to that speed at that distance you have reached escape velocity and will escape the Sun's gravity field without further thrusting or assistance.

Your least escape from sun speed must be a radial vector from the sun.

Nope. Escape velocity is escape velocity.

No. staged rockets are used to shed some mass.

That's part of it. The bigger part is that they shed the mass AFTER they have added a considerable amount of speed (delta-V.) Since the upper stages keep that speed, staging helps vehicles that want to accomplish a lot of delta V.

If all staging did was remove mass (i.e. the rocket staged, came to a stop and then resumed powered flight) staging would be nearly useless.

Yes, but now at what time of day you launch is not as critical. For example, the midnite launch, discussed two paragraphs earlier, is OK, perhaps even best (but I don't have time to think that speculation thru now) as it will put rocket into an elliptical sun-bound orbit but no longer bound to the Earth - i.e. rocket has escaped the Earth but not the sun.

If you think about it a second you will realize that the time of day doesn't matter at all. What matters is that the vehicle departs from Earth orbit so that it keeps the speed provided by the Earth's orbit. That means departing antegrade, or as close to it as you can manage. Going "straight out" (i.e. directly away from the Sun) loses you much of that advantage.

Orbital mechanics is not like driving; you don't point the rocket in the direction you want to go and hit the gas.

You bet, things would have to be very bad at home to induce me to move even if all those problems you talked about were already resolved to every ones satisfaction. As a matter of fact she would have to be one of those one in a million woman I could never hope to have any other way, if you get my meaning. But if I was scheduled to be executed that might do it also.

All I can say is if they did get all the volunteers they wanted it would be a very interesting group to have as long time traveling companions.
I understand what you are saying but it is actually all based on false assumptions / wrong.

For starter, assuming you are a male, you would not be eligible for the long trip to distant Planet X. No males go. You and all the other males are represented in a 10 kg liquid nitrogen sperm storage tank to reduce mass and save food.

Secondly, male or female, you are too old. All the carefully selected embryos are females and weight only a couple hundred grams - they will not eat more than a drop a day and do not start to grow at least until the ship has safely landed on Planet X. Most likely the embryos will not be allowed to grow until the very capable and intelligent solar powered robots have at least built their nursery chambers from disassembled parts of the ship - all as carefully planned say 250 years earlier on earth. We will use the same hormonal trick that mother kangaroos currently use to halt the growth of their tiny embryos until the time is right.

In case you do not know kangaroos are "born twice" - First when they leave the womb, via the vagina of course. Then they look like a small worm (2 or 3 cm long) but can and do crawl up to the pouch and enter it where they wait for their second birth. There they attach to a pouch-internal tit that mainly gives them this hormonal growth retardant and a drop of milk. There may be four of so like them in the pouch already. The oldest has probably been there for more than a year, waiting.

If something should kill his (or her) big brother, who is now big enough to leave and reenter the pouch many times a day, mother Kangaroo will select one of growth retarded little brothers (or little sisters) to start growing as dead brother's replacement.

I don't know how well the hormonal mechanism’s details are understood, perhaps well enough already to apply to human embryos to avoid large food requirements during the voyage to planet X. Probably some more research is needed before this can be done for 200 or more years to human embryos.

Having zero memories of Earth greatly reduce psychological problems - not one of the new colonists regrets having made the trip, is home sick for Earth, etc. They love their "Mother Planet X" just as their robot teachers told them to. After the fourth or fifth generation they get to open the "secrete book" (Really it is a DMD, Dense Memory Dot, with internal clock time lock, which their computers taken from the ship can read to them.) - Then learn that there is (or was) life quite like them on a distant planet the locals call "earth" and probably will try to "call home", but funding for SETI was killed 300 years earlier, early in WW IV to focus all efforts on winning the war. So with no reply they assume the book is just a fairy tale designed to try to keep them from waisting time seeking to know if some greater reason for their existence / origin exists.

Sorry. I guess you will need to keep looking for the one in a million girls/women here on earth or settle for the 1 in 100 like most men do. BTW, some of the 2nd generation women on Planet X have found that there can be advantages to getting pregnant without the use of the LN tank sperm. - If you know what I mean. Years later when the LN sperm was all gone, they erected an obelisk commemorating the first fathered child. The two spheres at the base, one on each side, are said to represent Earth and X, but that is only the official version.

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I strongly agree with this. I amazes me why anyone would think moving to a place where problems of simple existence (getting food, water, keeping warm but not boiling, living in an air tight encolsure for breathable air, hoping that the CO2 removal system does not fail, etc.) are added to the more common conflicts on earth is to be preferred (or even feasible).

The experiments, tried on earth, with modest number of people (a dozen or two at most) living in a partially sealed bubble with recycling of dish water and urine, trying to grow a small part of their own food (and not even producing their electricity, calling in doctors when anyone got seriously sick, etc.) have all failed in less than a year. In these bubbles, the stress levels were much less than they would be on a distant planet as the bubble occupants all knew if it went too badly, they could just open the door and go home.

SUMMARY: If humans can't solver their problems here on Earth, they sure as hell will not on distant planet X.
I'm not so inclined to think that living on another planet is going to be a walk in the park. The reason I support a human colony is so that IF something were to happen to the humans on Earth, complex intelligent life would be able to come back in a few generations or so and reseed planet Earth. It's crazy not to keep a small stock pile of DNA, human knowledge as well as HUMANS somewhere else, like the Moon and then Mars. JUST IN CASE the worse case scenario does play out someday.

Also, regarding Mars, I didn't think it could contain an atmosphere as it doesn't have a magnetic field - there's little we can do to change that, it will never be like an Earth even if it was sometime in the distance past.

Also, regarding Mars, I didn't think it could contain an atmosphere as it doesn't have a magnetic field - there's little we can do to change that, it will never be like an Earth even if it was sometime in the distance past.

While it is true that the lack of a magnetosphere results in atmospheric erosion, it takes millions of years. Thus if we could create a livable atmosphere within a few hundred years on Mars it would last a very long time.

to billvon:

Your post 129 is basically correct as you are using the standard definition of escape velocity, where as I was still focused on the problem firing a rocket from earth and calling the delta-V it needed to add "escape velocity" and discussing how to make that least. I made some wrong statements even then as you can use the ~30km/s earth orbital speed to allow a rocket with delta-V of only 12km/s to escape. (Fire forward along earth trajectory)

However, one does drop the first stage to make acceleration by the 2nd stage of the now reduced mass greater - that is the only reason. I have no idea why you suggested stopping the rocket after the mass was dropped. That is worse than your "useless" it is like starting all over again with a rocket of one less stage.

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While it is true that the lack of a magnetosphere results in atmospheric erosion, it takes millions of years. Thus if we could create a livable atmosphere within a few hundred years on Mars it would last a very long time.
I thought that it did more than just prevent gas from being blow away. Doesn't it protect us from radiation ... and stuff

While it is true that the lack of a magnetosphere results in atmospheric erosion, it takes millions of years. Thus if we could create a livable atmosphere within a few hundred years on Mars it would last a very long time.
A huge problem is the fact the current atmosphere is >95% CO2 and chronic exposure to 5% is fatal. (makes the blood too acidic as main cause of death, but really screws up your breathing and mind first.)

The reason you want to breath is to get rid of CO2. If in a room that is slowly having air exchanged by only Nitrogen, you will not notice that - just lose consciousness and then die. We have no urge to get O2, only to get rid of CO2.

I thought that it did more than just prevent gas from being blow away. Doesn't it protect us from radiation ... and stuff
That was my impression too. The solar wind is mainly protons and equal number of electrons for charge neutrality. Some, if not most, are deflected around the Earth and form a long tail behind the earth, which being a plasma drags the night side magnetic field out from the earth too, several Earth radii as I recall.

If Earth had no magnet field I would think it would capture more solar wind hydrogen in the high atmosphere, but probably not hold it in the atmosphere for long. Even so there would be a "steady state" with more atmospheric H2 than now.

A huge problem is the fact the current atmosphere is >95% CO2 and chronic exposure to 5% is fatal.

That's not really true. The partial pressure of CO2 on Mars is .09 psi. A partial pressure of CO2 of .15 psi will make you sleepy but won't make you sick.

Now, exposure to the lack of pressure on Mars _will_ kill you. But add enough inert gas (or oxygen) to get the pressure high enough that your blood won't boil and the CO2 wouldn't bother you too much.

But in any case, the goal shouldn't be a breathable atmosphere in the short term, it should be an atmosphere that supports plant life. A 90% CO2/10% O2 atmosphere at a pressure of around 3 psi would allow us to grow plants (for food and oxygen) and walk around with just a jacket and an oxygen mask.

We have no urge to get O2, only to get rid of CO2.

Also not true. CO2 is the primary driver but we have backup O2 sensors that drive our breathing when our blood O2 sat levels get low. (Which is why mountain climbers keep breathing but their breathing pattern is very odd.)

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Mars receives sufficient radiation to kill people exposed to it, though that would take perhaps 20 years.

The easy short term solution to a colony on Mars is to go troglodyte. Long term meaning terraforming. Humans living in caves is not a new phenomenon. Ten metres of rock overhead is enough to provide fully adequate radiation protection. Inside the caves, a breathable atmosphere could be maintained, and with a nuclear reactor for electricity, food and oxygen plants could be grown under artificial lights. More research needs to be done to design a balanced artificial ecosystem to support human life, but that should come with time.

Short excursions outside in a "mars suit" will be OK and should not result in excessive radiation exposure.

I imagine a world without borders where we intelligently resolve fragmented opinions without war but with intelligence and all of humanity shares a common goal and works to make it a reality. For example discovering the secrets of the universe or improving our ability to venture into space. What are your own visions or opinions on the subject?

Love.

Billy T said: "We have no urge to get O2, only to get rid of CO2."
... CO2 is the primary driver but we have backup O2 sensors that drive our breathing when our blood O2 sat levels get low. (Which is why mountain climbers keep breathing but their breathing pattern is very odd.)
Thus we are not in disagreement, but I don't understand your comment about Mt. climbers. Surely they too breath to get rid of CO2 and low O2 can explain many "odd behaviors" including loss of consciousness if extreme. I suspect there is a "low O2 sensor" but don't think it gives any signal to the conscious mind - nothing like the extreme need to stop holding your breath the increasing CO2 gives. While holding your breath as long as you can the CO2 concentration greatly increases (factor of 10 at least I think) but O2 decreases in lungs by less than 5% I would guess.* Much harder to notice such a small percentage change.

My comments were were based on sad event that happen at JHU/APL where there was a large (perhaps 4m diameter & 7m tall) steel "bell jar" vacuum chamber that could set on a circular base (with "O-rings") for testing satellites. (Mainly thermal test in vacuum.) It was heavy but raised with hand crank.

Two men enter the chamber to work on satellite after lunch, by cranking bell jar up less than 1.5 feet as cranking was a time consuming effort and they were not fat so could slip inside with only ~1.5 feet between bottom of the bell jar and its circular base. Unfortunately someone had turned on the dry N2 supply and slowly atmosphere in the chamber had little if any O2 still in it. Their dead bodies were discovered between 5:30 and 6PM by a car pool driver, who got tired of waiting for one of them to come to the car.

They could have left at any time, but had no urge to do so, as they could breath out their CO2. - I.e. They did not notice the absence of O2.

The urge to get rid of CO2 is so irresistibly strong that you will exhale the still quite rich in O2 air in your lungs, even when under water, just to get the CO2 out of your lungs!

* A 5% decrease in the O2 would be a 1% decrease in the total pressure in the lungs - more than a 50 story elevator ride -again just guessing.

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