The Moon or Mars:

Discussion in 'Astronomy, Exobiology, & Cosmology' started by paddoboy, May 20, 2015.

  1. orcot Valued Senior Member

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    Robots are most definitly affected by radiation [link]
    for example the 2003 mars rover only had 128MB ram memory whilst a run of the mill 2006 playstation 3 has 2X256MB ram.
    Sure but tele-operation can be achieved much sooner. Also for Insurance reasons it's from a legal view easier to have a human in control so you have someone to blame if something goes wrong.
    because we're human it's a easy answer but people never had any problem to find someone to trek over antartica or climb a really tall mountain that should be considered a punishment if you think abouth it, yet people do this things and are proud of it.

    That is naive whisfull thinking if that would be true, the rich and powerfull would take care of the climate and put inmense research in longevity. We don't each and everyone of us tries to get their little slice of happyness that in itself isn't bad but multiply that with 6 billion and it quickly becomes a disaster.

    And more I hope.

    the real important development is space flight at the moment is the development of cheaper rockets (like space x,) and more exotic thinks like the skylon plane. If things were cheaper we could do more.
     
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  3. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Five years and two months to reach this point, with fastest rocket ever launched. Any with humans inside would be much slower.

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    New Horizons (APLJHU designed and made) was launched 19 Jan 2006.

    It traveled 19.64 AU in 38 months or average speed of 0.517 AU/month. It will arrive at Pluto mid July 2015 or 4 years 4 months from date position shown Or 40 months with 12.69 AU to go. I.e. average speed declined to 0.317 AU/month.

    From Pluto on out into space it will be going much slower still - Climbing away from that great mass we call the sun, ain't easy. Unless you are quite dumb, you can understand that many dozens of generation would live and die on way to a star with fastest ever rocket, even if human space craft could achieve the speed of the fastest un-manned craft ever launched. If you say, not true, as we will continue to accelerate, I ask: where does the energy for that come from? Especially if speed gets up near C where mass is being increased (and acceleration decreased, with constant thrust). And I also ask: What is the exhaust? I. e. it gets same momentum as the space craft gains.
    Voyager 1 is farer than any other man-man thing from Earth. It got speed boost from Saturn which New Horizon could not do as that threw Voyage 1 out of the plane of the ecliptic. - As shown below. If you want to go to particular object like Pluto or the nearest star getting significant speed boost from a planet on the way is essentially impossible.
    Space traveling Dreamers simply are not realistic about the distance to any star and the energy requirements to get their in a few human generations.

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    Last edited by a moderator: May 28, 2015
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  5. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Only if the "life boat" for humanity does NOT need resupply of ANYTHING from earth.

    Because Earth's customers for their products don't want to pay at least 20 times more than for the same thing made on Earth.
     
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  7. cosmictraveler Be kind to yourself always. Valued Senior Member

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    Then allow those with all the money build their own space business and not take money from the taxpayers. No one is preventing them from going.There's already over a million pieces of crap floating in space today that we have already sent up there to do work for us. Now you want to create more debris and junk up there? We can't clean up the crap in space now, funny no one thought of doing that before they started the satellite programs, so how are they going to clean up millions of more pieces of crap if more things are sent up there?
     
  8. billvon Valued Senior Member

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    Agreed. It will take a while to get to that level of self sufficiency - which is one reason we should start sooner rather than later.
    It is very, very cheap to drop things. And one thing we know for sure - as time goes on, and ores are depleted, things will get more expensive here.
     
  9. billvon Valued Senior Member

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    Agreed. Taxpayers should fund exploration, science and infrastructure - and private companies should then build their own businesses.
    So you want to put industries on Earth instead and add crap to the air? Too much space debris never gave anyone emphysema, or lung cancer, or mercury poisoning.
     
  10. cosmictraveler Be kind to yourself always. Valued Senior Member

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    The satellites they put up will only create more space debris unless someone starts to make a world wide way of retrieving nonworking satellites to bring them back to Earth safely. More trash in space isn't the way to go IMO.
     
  11. billvon Valued Senior Member

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    Better than more pollution on Earth.

    But, just as people finally realized we shouldn't pollute the Earth, we now know we shouldn't pollute orbit, either. And we are making changes to ensure that. For example, rather than explosive bolts and retainer bands (which are discarded upon reaching orbit) the SpaceX Falcon 9 uses latches and pusher arms to release its payload.
     
  12. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I don't understand what you mean by "drop." For example, do your know that to "drop" something into the sun takes much more energy than to send to Pluto?
     
  13. billvon Valued Senior Member

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    Dropping things from Earth orbit is very cheap. The atmosphere provides 99.99% of the braking energy needed. And if what you want is rugged (metals, simple structures) a parachute will take care of the final .01%.
     
  14. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Agreed. The big energy cost is getting the thing you "drop" into Earth's exact oribit, say from an asteroid in an elliptical orbit about the sun that is some times more than 1AU from the sun and some times considerable less than 1AU. Just getting something from the moon is costly and it is in essentially the same orbit about the sun as earth is.

    Few realize that if both Earth and moon's orbit are accurately plotted as large as possible on 8.5 by 11 inch sheet of paper, using a common lead pencil, there is complete overlap - not the slightest separation between the two drawn orbits. The energy difference from moon to earth orbit is trivial compare to the energy difference between that asteroid's orbit to moon or to earth's orbit. I.e. the suggestion of mining asteroids is a "scientific con-game" on the ignorant investors.
     
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  15. paddoboy Valued Senior Member

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    And yet many intelligent people continue to work towards those ends.

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    “It isn’t all over; everything has not been invented; the human adventure is just beginning.”
    Gene Roddenberry
     
  16. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Which end do you refer to: Humans going to a star OR getting wealth from ignorant investors in "asteroid mining."
    You quote me from my posts 82 and 91. Do you think there is any error in either? That is why I say what I did.

    BTW I got curious about Gliese 445. Here is interesting fact about its encounter with Voyager 1:

    So the fastest ever space craft will travel 3.45 light years in 40,000 years or go less than 0.000,0863 light years per year. Gliese445 is tiny red dwarf.

    As it goes (17.6-3.45) in 40,000 years it may be near earth in 49,753 years from now and little bit cooler. Perhaps a tungeten based platform could sit on its surface and with insulation on top of that have a surface cool enough for "humans" (much more intelligent robots, actually) to live on? They would have limited electric energy possible (for all reasonable periods of interest). I. e. converted thermal energy with very high Carnot limit via radiative cooling to deep space. The limit is due to need to keep their "cold sink" from getting hot. It would be very hard (probably impossible) to make a transfer to its high speed passing trajectory of anything.

    The chance of any real humans being alive on earth 49,753 years from now, is very near zero. Bill Gates* thinks our greatest near term risk is a rapidly-spreading highly-contagious, lethal virus and I agree. People cross national boarders 80 times more now than during the "Spanish Flu." My wag, is we will be history in 1/9 of that time - before 7,000 years more have past and much less than even that unless mankind gets serious about his effects on the environmental conditions of earth - our Habitat.
    * Read more & watch his video at:http://www.vox.com/2015/5/27/8660249/gates-flu-pandemic or just read his text quoted below image.

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    “The Ebola epidemic showed me that we’re not ready for a serious epidemic, an epidemic that would be more infectious and would spread faster than Ebola did. This is the greatest risk of a huge tragedy,” Gates said, claiming that a serious epidemic could kill more than 10 million people a year."
     
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  17. paddoboy Valued Senior Member

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    In time, we'll go to the stars, despite your continued pessimism.
    And your inference that investors in Asteroid mining are ignorant is your own ignorant opinion. Many far more intelligent than you apparently disagree.
    I'm sure all the intelligent folk at NASA, ESA, Roscosmos, are also well aware of the difficulties involved, and are at this very moment working to overcome them.
     
  18. paddoboy Valued Senior Member

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    http://arxiv.org/abs/1108.4767

    Abstract:
    Recently, Near Earth Objects (NEOs) have been attracting great attention, and thousands of NEOs have been found to date. This paper examines the NEOs' orbital dynamics using the framework of an accurate solar system model and a Sun-Earth-NEO three-body system when the NEOs are close to Earth to search for NEOs with low-energy orbits. It is possible for such an NEO to be temporarily captured by Earth; its orbit would thereby be changed and it would become an Earth-orbiting object after a small increase in its velocity. From the point of view of the Sun-Earth-NEO restricted three-body system, it is possible for an NEO whose Jacobian constant is slightly lower than C1 and higher than C3 to be temporarily captured by Earth. When such an NEO approaches Earth, it is possible to change its orbit energy to close up the zero velocity surface of the three-body system at point L1 and make the NEO become a small satellite of the Earth. Some such NEOs were found; the best example only required a 410m/s increase in velocity.


    Conclusions:
    In this paper, we examined Near Earth Objects’ orbital dynamics using the framework of an accurate solar system model and the Sun-Earth-NEO three-body system to search for low-energy NEOs that may be temporarily captured by the Earth or might be able to orbit the Earth after the exertion of a small velocity increment. The results showed that none of the more six thousand NEOs were naturally captured, but we did find some NEOs that would be captured by the Earth after exerting a small velocity change (less than 1km/s) while close to the Earth. These NEOs are prime candidates for short sampling missions conducted by spacecraft.
     
  19. paddoboy Valued Senior Member

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    http://www.nss.org/settlement/asteroids/capture.html

    http://www.nasa.gov/sites/default/files/files/IAC-14-D2_8-A5_4_1-Moore.pdf

    Abstract
    NASA is developing concepts for the Asteroid Redirect Mission (ARM), which would use a robotic spacecraft to capture a small near-Earth asteroid, or remove a boulder from the surface of a larger asteroid, and redirect it into a stable orbit around the moon. Astronauts launched aboard the Orion crew capsule and the Space Launch System rocket would rendezvous with the captured asteroid mass in lunar orbit, and collect samples for return to Earth. This mission will advance critical technologies needed for human exploration in cis-lunar space and beyond. The ARM could also demonstrate the initial capabilities for defending our planet against the threat of catastrophic asteroid impacts. NASA projects are maturing the technologies for enabling the ARM, which include high-power solar electric propulsion, asteroid capture systems, optical sensors for asteroid rendezvous and characterization, advanced space suits and EVA tools, and the utilization of asteroid resources. Many of the technologies being developed for the ARM may also have commercial applications such as satellite servicing and asteroid mining.

    CONCLUSION:
    The ARM will be a milestone in human history. For the first time, we will be able to rearrange a small piece of the solar system that has been circling the sun for billions of years and use it to increase our prosperity and security. Just as we have learned to modify our terrestrial environment and harness the Earth’s resources, we are now beginning to transform our neighborhood in space for our purposes. Who knows where this may lead us in the far future? It has been hypothesized that an advanced technological civilization could rearrange their solar system to construct a Dyson Sphere that completely encompasses their star to capture all of its energy output (
     
  20. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Facts, like: "The fastest ever space craft goes less than 0.000,0863 light year each year." are not pessimistic or optimistic - They are just facts you don't like.

    What star would you like to visit? Lets assume a huge by comparison space craft (with all the food water etc., some growing and some recycling) could go twice that fast, due to "progress." How many generations later does any one arrive there and what do they do then? How many centuries before we can launch it? Are you sure humans will not be extinct first - unstoppable* and lethal global warming and/or viruses etc. will not happen first? How can you be sure?

    * We may have already past the "tipping point" with CH4's self-accelerating release. Its half life in the atmosphere is now increasing 0.3 year each year as it is now lowering the concentration of the OH- radical that mainly removes it.
     
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  21. cosmictraveler Be kind to yourself always. Valued Senior Member

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    We need to understand where we will go to by first sending robot spacecraft to destinations that seem the most suitable and that will take time to do. Once we know where we will go then preparations can be made to do so. But first let us find a place that will at least sustain human life or somewhere humans have a chance of survival.
     
  22. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    paddoboy I wonder about the "high-power solar electric propulsion" you mention in last paragraph of post 96.

    Surely the energy in the exhaust can not even equal the energy absorbed from the sun. Also note that both the energy and momentum increase linearly with the photon frequency. For example, if frequency is doubled then only twice as many photons can be in the exhaust. Or saying this another way, the energy and momentum of the photons absorbed by the sun can not be increased, only some losses. From that I think a "solar sail" is better than absorbing solar photons as it reflects them and that doubles their momentum compared to absorbing them.
    Any system that throws out particles instead of photons is vastly less efficient in energy and I think in momentum producible with same energy, but not sure of this second part. Plus you need to have the mass on board you will throw out at launch. Catching hydrogen molecule in the way of space craft motion and throwing them out as stationary in space exhaust is least energy in the exhaust but zero momentum increase. Also, note most of them are ionized even though very cold. If going fast thru a field of ions, that can be a big health problem as well as a static charging of the ship; so you probably need to maintain a magnetic field to deflect them.

    Do you have a link giving more information about "high-power solar electric propulsion"? My first thoughts about it tend to indicate it is a big loser.
     
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  23. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    23,198
    Any even wags as to how long that will take? How much hotter will continued release of CO2 make the earth surface by then?
     

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