Mars In Three Days?!

Posted by  $  allosaur 3 months, 1 week ago to Science
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The tech that could make it happen is in the link.
I find the possibility that Alpha Centauri could be reached in four years as awesome!
An earth-sized planet has been discovered there.
https://www.scientificamerican.com/ar...
SOURCE URL: https://futurism.com/mars-in-three-days-heres-the-tech-that-could-make-it-happen/


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  • Posted by  $  MikeMarotta 3 months, 1 week ago
    How do you stop? Several Heinlein stories have "torchships" with constant acceleration. At 9.8 m/s/s at the end of three days, you would be going 2,540,160 m/s which is fine and all, but then what?

    Heinlein's ships swung about so that the drive unit could counter the direction of motion. How do you do that with a solar sail?
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    • Posted by CircuitGuy 3 months, 1 week ago
      "but then what?"
      They did this in Arthur C Clarke's 2061. They spent half the trip slowing down.
      Suppose the trip to Mars is 100 million km = 10^11 m. You start slowing down 5 * 10^10 meters into the trip.
      We know x = 1/2 a*t^2. t = 1.5 days * 60 * 60 * 25 = 129600 sec. We solve for a and get a= 6 m/s^2. At peak v, we're at 0.13% of c.
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    • Posted by ProfChuck 3 months, 1 week ago
      Re: "How do you stop?" The simplest answer is to construct another laser array at Mars. If regular commerce between Mars and Earth becomes a reality then an infrastructure will be established on the red planet. This would include laser breaking and launch capability. Re reduced gravitation and low density atmosphere on Mars also makes many other technologies feasible. Studies of the Martian surface indicate that most of the elements necessary for an industrial society are present in abundance and if our theories of planetary formation are any where near correct the more rare elements are there as well. Automated mining, refining and manufacturing are likely to be high priority activities early in the Martian colonization strategy. Constructing an orbiting laser array would be an obvious part of that plan.
      I have been doing some consulting for some companies that are pursing asteroid mining and "exotic" propulsion systems. These and many more issues are receiving their close attention.
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      • Posted by scojohnson 3 months, 1 week ago
        That would drive a nuclear power-plant, for reliability, you would want a large orbital station-based approach to leverage solar and avoid the many-month planet-wide dust storms that frequent the Mars atmosphere. Realistically, we need fusion.
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        • Posted by ProfChuck 3 months, 1 week ago
          Fusion is good but antimatter is even better by a factor of several thousand. One of the companies I am consulting for has demonstrated a functioning antimatter power generator and rocket engine. Far from being science fiction this is a real system that is scheduled for space qualification within 5 years.
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          • Posted by  $  Dobrien 3 months, 1 week ago
            Hi ProfChuck,
            I am curious to know , is there a technique to harvest or obtain antimatter?
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            • Posted by ProfChuck 3 months, 1 week ago
              Currently antimatter occurs as part of the decay chain of certain radio isotopes and it can be manufactured in high energy particle accelerators. The company I am working with manufactures a radioisotope that produces positrons, the anti particle of the electron, as part of its decay process. It is similar to the process that produces the radionuclides used in medical PET (Positron Emission Tomography). With current technology the cost of antimatter production is very high, over 100 million dollars per gram! However, one gram of antimatter produces sufficient energy to propel a 100 ton space craft to Mars and back several times. Part of my consulting job is to seek lower cost ways to manufacture antimatter and store it safely.
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          • Posted by scojohnson 3 months, 1 week ago
            The technology is there, its just a little bit of science fiction yet to product the anti-matter in any level of quantity yet I would think (and sufficiently contain it in a magnetic bottle that would survive a rocket-launch).
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    • Posted by Lucky 3 months, 1 week ago
      How do you stop?
      Good question.
      The usual method is to aim for something soft.
      This could be the atmosphere of the target. But there is an enormous amount of energy to get rid of.
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      • Posted by  $  3 months, 1 week ago
        https://www.google.com/search?q=%3D+2...
        If the target is the atmosphere of that earth sized planet, I wonder how a spacecraft can even stay in a controlled orbit coming down from such a speed.
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        • Posted by  $  MikeMarotta 3 months, 1 week ago
          What do you mean by a "controlled orbit"?

          Whatever velocity you have when you arbitrarily enter the "gravitational field" of a ponderous body determines the shape of your orbit.

          If you are going really faster, you get a hyperbola and off you go.
          A little less fast and you get a parabola and off you go.

          More manageable and you have an ellipse, the axes of which are determined again by the initial velocity.

          Get that v just right and you have a circle.

          oh... one more... the one in this problem: straight line... impact.
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          • Posted by  $  3 months, 1 week ago
            Bad choice of words. I was thinking a craft attempting to decelerate from light speed by using atmosphere would have to loop an earth-sized planet many, many times.
            A pilot or better a computer would have to fly the thing. That's what I meant by a "controlled orbit" or flown loops around a world.
            Can't see this happening due to the speed of light entry speed into an atmosphere.
            Ship may just blow up. I once saw a meteor do that before it could become a full-fledged meteorite.
            That's what happens when an airplane dives straight into water at high speed. As a former water skier, I have bounced off water that felt like concrete at rare times I've skied that fast and fell.
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          • Posted by ProfChuck 3 months, 1 week ago
            Hohmann transfer orbits modified to accommodate constant thrust systems have been examined and several acceleration and breaking strategies have been identified. The celestial mechanics is a bit tricky but there is nothing that is beyond our current understanding or computational capability.
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          • Posted by  $  blarman 3 months, 1 week ago
            Gravitational attraction does not provide braking, however. It takes either reverse thrust or an atmosphere to bleed off the energy. It's all fine and good to accelerate, but one always has to consider the other end as well. That's why hyperspace travel from a sci-fi perspective is so appealing because one simply shifts from propulsion in normal space at one set of speeds to propulsion though hyperspace at huge speeds.
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            • Posted by  $  3 months, 1 week ago
              I'm suddenly thinking of all the times I've space movie entire fleets come out of that warp drive thingie.
              It never occurred to me until now that must be a lot harder to do than all the times I've seen entire fleets go into "warp drive."
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              • Posted by  $  blarman 3 months, 1 week ago
                One of the things that we take for granted as well is conservation of momentum. In Star Wars and Star Trek one pops out of hyperspace going the same speed one popped in. One thing I do appreciate in Star Wars is that they do have strictly tasked navigational computers which map a "safe" path through the galaxy to the destination so as to avoid flying through a star. This comes up in several instances. Other sci-fi genres (Dune) take a different tack and vehicles are stationary (in real space) while transiting "hyperspace". There the operative principle is not really hyperspace but space folding.

                Overall, I think your article reminded me most of a Star Trek: Deep Space 9 episode where Cisco and his son travel from Bajor to Cardassia in a solar sailer similar to this design. Now to see if we hit any tachyon bursts which warp us out into the galaxy! ;)
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                • Posted by  $  3 months, 1 week ago
                  From the Allosaurian Dictionary~
                  Science fiction: Contemporary fairy tales weaved from both speculative and silly science
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                  • Posted by  $  blarman 3 months, 1 week ago
                    Yes, some are absurd or rely on principles of "magic", but there are other sci-fi authors who were meticulous in their application of science in their stories. Star Trek: The Next Generation faded off quickly when it all disintegrated into "which new particle can we invent to save the day!"

                    Then again, the original Star Trek communicator led to the cell phone. See also (http://entertainment.howstuffworks.co...) I would also note that most good sci-fi has some basis in reality - see Star Trek V as a pointed example of the absurdity of some sci-fi, where The Martian was rigorously researched.
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                • Posted by fredtyg 3 months, 1 week ago
                  I came up with an idea to test light speed travel/ warp drive a while back. Not sure how valid this is:

                  I'm under the impression that if something accelerates in space, it would keep accelerating so long as it had thrust since there would be few forces to slow it down. How about launching a small rocket, albeit with a long term power source- nuclear or whatever. Point it in a safe direction and let it fly. With a consistent thrust, I would think it would continue to accelerate, perhaps faster than any space craft has gone before. Have equipment on it to send back data to Earth as it heads out of our solar system. It might be interesting to see how fast continuous acceleration would take it.

                  Some hazards for the craft involved: We likely couldn't control it well so it may run into a planet, asteroid or whatever. Plus, at those speeds, it could be a collision with a pea sized piece of space debris could prove catastrophic. But, hey, you have to start somewhere.
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                  • Posted by  $  blarman 3 months, 1 week ago
                    The problem there is that when you start dealing in relativistic speeds you run into Einstein's classic mass to energy conversion problem: that it starts taking exponentially more energy to move a massive object the closer you come to the speed of light. It is for that reason that even electrons only travel at speeds approximating the speed of light. Though your initial thought is good, the practicality is that the speed would eventually taper off to the point that even though you were constantly expending energy in thrust, your velocity increase would cease.

                    My own concept was a series of orbiting rings that would sequentially boost an object's speed as it passes through them similar to a rail gun. Each ring would dramatically boost the speed of the object and after three or four boosts it would be projected toward its target. Then the "ship" would only have to worry about slowing down on the other end. Oh, and not liquefying any kind of compressible/organic material like say... the pilot... ;)
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            • Posted by ProfChuck 3 months, 1 week ago
              "Gravitational attraction does not provide braking". Not quite true. A gravitational encounter is actually best understood by viewing the problem in terms of vector calculus. An incoming vehicle has a velocity and direction that is best described in terms of a vector and its first and second derivatives. The same may be said of the planetary body that it is approaching. Acceleration simply means changing velocity which can be either increased or decreased in the reference frame of the planetary body. It's all a function of the entry angle.
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              • Posted by  $  blarman 3 months, 1 week ago
                While all that is true, gravity's actions are insufficient for it to act as a brake on most bodies travelling at the speeds of a spacecraft precisely because of the vectors involved. The actual entry angle toward any planet is very small, as too steep an angle and the vehicle actually picks up speed as it plummets toward the planet's surface while too oblique and the vehicle skips right past. At the speeds of an intrastellar object (comets and asteroids) we find very few incidences where the circumstances are sufficient for unassisted capture, which is what you allude to. And these speeds in general are much slower than the velocities which would be necessary to reach the limits of the solar system within a person's lifetime let alone a star even as close as Alpha Centauri.
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                • Posted by ProfChuck 3 months, 1 week ago
                  Yes. Gravitation exchange maneuvers are actually the result of an exchange of momentum between the spacecraft and the celestial body by means of gravitational coupling. Capture of a spacecraft, at Jupiter for example, requires a combination of gravitational exchange and propulsion. With current technology neither is sufficient to do the job alone.
                  Again, current technology will not support an interstellar mission with anything other than a high velocity fly by.
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  • Posted by wiggys 3 months, 1 week ago
    interesting how concerned some are about stopping when in reality nobody is ever going to get off the ground for this excursion.
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    • Posted by  $  3 months, 1 week ago
      Gave you a point because I see your point.
      Nevertheless, there is a percentage of dreamers who invent what they dream of. Never say never.
      I've met some who live and breathe "never" to the point of denying that man ever went to the moon.
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  • Posted by  $  Suzanne43 3 months, 1 week ago
    Mars in three days. Wow! The Liberals want a place to escape from Trump. They are threatening to go to Canada and New Zealand. I've heard from a New Zealand Gulcher that they don't want them, so Mars would be a wonderful place for them. They could leave tomorrow and be there in time to miss the Trump's swearing in.
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    • Posted by CircuitGuy 3 months, 1 week ago
      It will happen eventually. But we won't escape human foibles. I am guessing at least some forms of human ignorance will follow humankind off earth and history will continue to rhyme.
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  • Posted by Owlsrayne 3 months, 1 week ago
    Using a light sail has been the design stage for some time. Back in the 1950's the young gun scientists and engineers at General Atomics came up with the Orion concept of using nuclear explosives dropped behind a vehicle using a pusher plate with pistons to get to Mars in the same amount of time. Nasa claims it was theirs but General Atomics was competing with them at that time.As far as I'm concerned Nasa steals concepts and make them their own.
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  • Posted by ProfChuck 3 months, 1 week ago
    When I worked at NASA one of the more interesting projects was interstellar mission planning.

    (http://interstellar.jpl.nasa.gov/inte... )
    (https://ntrs.nasa.gov/archive/nasa/ca...)

    The two greatest challenges were propulsion and spacecraft autonomy. We considered light sales and lasers but the technology at the time was not up to the task. More recent advances in materials science and laser systems make the concept not only feasible but doable.
    The options for Mars mission propulsion can be classified as "self contained" and "external source". Self contained would be any type of rocket where the reaction mass was contained within the vehicle and expelled to produce thrust. Chemical as well as nuclear powered ion drives would come under this category. External would include solar, laser and microwave powered systems where the photonic pressure directly provided thrust. Nuclear or solar powered ion rockets such as the VASIMR could reduce Mars mission times from months to weeks and a laser powered sail could reduce the mission time to a few days. Very impressive.
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