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My question is about Mars-one's plan to send people to Mars in 2025. I want to know why it is a one-way trip and not a round-trip. People already landed on Moon in 1969 and successfully came back to earth. also NASA sent New Horizon in 2006. so the problem can't be about fuel technology. there's also no problem in escaping Earth's gravity, going to another planet, and landing successfully on Earth. so why they can't leave people on Mars and go back in 2 or 3 years later to pick them up? is the one-way trip a part of their plan or they're simply unable to make a round-trip between Earth and Mars? if so then why?

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    $\begingroup$ Hi Stephan, welcome to Space Exploration. It isn't NASA that has that plan, it is Mars One. And New Horizons will never come back to Earth, it is going to pass by Pluto in a few days. You will need to clarify your question in order for us to answer it, there are a few confusions. Nobody would be picked up from Mars by a separate trip, a mission needs to be able to return itself. Try this page too. $\endgroup$ – kim holder Jul 4 '15 at 17:27
  • $\begingroup$ Hi, I'm sorry, I've fixed the misunderstandings. now please review my question. $\endgroup$ – Stephan Jul 4 '15 at 17:40
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    $\begingroup$ "..Mars in 2025. .. why it is a one-way trip and not a round-trip. People already landed on Moon in 1969 and successfully came back to earth" The distance (or more importantly the velocity and time) for a trip Earth to Moon is a great deal less than the distance/speed difference/time between Earth and Mars. Mars also has a much higher escape velocity than the Moon does. Not really a comparable situation. $\endgroup$ – Andrew Thompson Jul 4 '15 at 17:40
  • $\begingroup$ Okay I know that, but it was about 50 years ago. so we still are using that old technology? $\endgroup$ – Stephan Jul 4 '15 at 17:42
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    $\begingroup$ "Okay I know that, but it was about 50 years ago. so we still are using that old technology?" What's magical about technology that makes everything easier? Does a liter of kerosene (or liquid hydrogen etc) release more energy from combustion now just because we're got better computers? Does having better knowledge of how to use materials, ala composites, suddenly make Mars vastly closer to us? $\endgroup$ – NPSF3000 Jul 5 '15 at 22:40
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To fully answer your question requires giving you an enormous amount of background information.

The best explanation I have seen of this for the layman is astronaut Dr. Stan Love's presentation on why it is hard to go to Mars. Watch, be entertained, and learn.

Some highlights (these are not my points, they are his, so it is fruitless to argue them with me):

  • Delta V for lunar mission = 42K mph, for Mars mission 48K mph. DeltaV is not the problem
  • It took the Saturn V to launch 6 tons on a roundtrip lunar mission. A Mars mission would probably take 100 tons, or 25 Saturn Vs.
  • We don't know how to keep the crew alive, healthy, and sane for the duration of the mission.
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  • $\begingroup$ Thanks, so I have a final question. are the spacecrafts on the Interstellar movie real? I've read some docs about that I want to make sure. those spacecrafts seemed to do well on planets with high gravity rates. they also had problems with fuel to return to Earth from Saturn but that's not the goal for humans..least for now. $\endgroup$ – Stephan Jul 4 '15 at 18:06
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    $\begingroup$ @Stephan that is a separate question, you can ask a new one if you want. Short answer is no way, they were super advanced, and also not at all realistic even for a super advanced ship. But in very general terms, the more you can be clear and specific in a question, and especially if you have done a bit of homework and show willingness to do more, you will get much more attention given to your questions. So i'd say that is a good question, but try to shape it a bit more, okay? These questions stay here for everyone in the future who wants to know about the same thing, we work hard on quality. $\endgroup$ – kim holder Jul 4 '15 at 18:11
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    $\begingroup$ "It took the Saturn V to launch 6 tons on a roundtrip lunar mission. A Mars mission would probably take 100 tons, or 25 Saturn Vs." If one could lift 6 ton, it would take 17 (16&2/3) to lift 100 tons. Still 17 to 1 ratio (more than used in all the Apollo Missions!), but not the 25 to 1 ratio stated. $\endgroup$ – Andrew Thompson Jul 4 '15 at 18:28
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    $\begingroup$ @OrganicMarble My apologies for connecting it to you. The odd thing is, I even recall reading the caveat / alternate accreditation before writing that, yet I forgot it so quickly. Nonetheless it make me suspicious of the competence of the narration in that event. You'd think it was something easily enough checked by anyone involved in the process of making the film.. (I don't have enough bandwidth to actually watch videos, unfortunately.) $\endgroup$ – Andrew Thompson Jul 5 '15 at 11:55
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    $\begingroup$ The mission duration is the real nasty part. A fuel-efficient trip to Mars and back is a 32-month journey, over 100 times longer than the Apollo missions. So more than 100 times the radiation exposure, and assuming a recycling life support system, 100 times longer for a much more complex system to remain up and running without critical breakdowns. $\endgroup$ – Russell Borogove Jul 6 '15 at 0:09

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