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  1. Janus

    Artificial air on Mars

    There are nitrogen fixing plants that, with the help of bacteria, can use nitrogen directly from the air. Farmer use these in rotation with other crops to replenish nitrogen in the soil. https://en.wikipedia.org/wiki/Category:Nitrogen-fixing_crops
  2. Janus

    Artificial air on Mars

    Something to consider is this: Spacesuits generally use a low pressure pure oxygen system. If your habitat was a 1 ATM gas mixture, then every time you wanted to do anything outside in a suit, you would first have to spend a good deal of time breathing pure oxygen first in order to flush out...
  3. Janus

    Early Apollo design concept

    The plans also included a sheet for a "space-lab". I'm not sure exactly what its purpose was. Anyway, here's what it might have looked like docked to the CM/SM pair. The solar panels would be folded over the end during launch. The arms they were mounted on could rotate on the lab's axis...
  4. Janus

    Early Apollo design concept

    The same way it was finally done: The command module separates, turns around and reenters heat shield first. One difference was that it was equipped with a para-sail rather than parachutes.
  5. Janus

    Early Apollo design concept

    Thanks.
  6. Janus

    Early Apollo design concept

    In the TIL thread, I posted a link which had a number of imaged of an early proposal for the Apollo program. I thought I'd use them to do a few renders of what it might have looked like, and point out some of the major differences from the final version. First, what the craft in fully...
  7. Janus

    Ship thrust required to move out of the plane of our solar system

    The general solution is for the Delta v needed to change the inclination of a spacecraft can be found here: https://en.wikipedia.org/wiki/Orbital_inclination_change. And while the major bodies of Solar system do orbit close to the same plane, there is enough difference for between their orbital...
  8. Janus

    Artifical gravity on spaceships

    The levitation of the frog in this video is done by diamagnetism. Basically, some material are repelled by magnetic fields. These are materials we generally consider as being non-magnetic. The diamagnetic effect is very weak, so you need a strong magnetic field to cause a measurable effect...
  9. Janus

    Reverse gravity-assist, using the moons of a planet

    Assuming that you use a minimum energy transfer orbit, your probe would be moving at ~1 km per sec relative to the Sun, compared to Pluto's 4.74 km/sec Charon orbits at something like 0.2 km/sec . So even if you ignore speed picked up from falling towards Pluto, you end up with a minimum...
  10. Janus

    A rail gun as a thruster

    In this case, your reaction mass and energy source don't come from the same thing (unlike typical rocket fuel where your fuel provides both, and adding more fuel means adding both reaction mass and energy supply.) So you need an external energy source to accelerate your iron. This brings up...
  11. Janus

    Steering rockets in space by shifting CM

    Gimbaled thrust. The engines are mounted so that they can swivel. Same basic idea as yours, but done by changing the line of thrust relative to the center of mass vs. shifting the center of mass relative to the line of thrust.
  12. Janus

    General relationship between gravity and rocket design.

    To escape Mars, you would need ~2kg of fuel for every kg you want to lift, compared to ~11 kg of fuel per kg to escape the Earth ( assuming a 4.5 km/sec Ve for your rocket) However, for the same craft to land on Mars and then take off again would require 8.35 kg of fuel per kg. ( the rocket...
  13. Janus

    Hypothetical Interstellar Spacecraft

    Of course, the above equation is only accurate for values of delta v small with respect to c. The relativistic version is $$ \Delta v = c \tanh^{-1} \left (\frac{v_e}{c} \ln \left( \frac{M_i}{M_f} \right ) \right ) $$ So for example, if we had a ## v_e## of 0.2 c and a ratio of ##...
  14. Janus

    Nuclear Waste Disposal into Sun or outside Solar System?

    Orbital velocity is found by V_o = \sqrt{\frac{GM}{r}} where M is the mass you are orbiting (in this case the Sun) and r is the radius of your orbit (assuming a circular orbit) Escape velocity is found by V_e = \sqrt{\frac{2GM}{r}} Note that the only difference is the 2...
  15. Janus

    Nuclear Waste Disposal into Sun or outside Solar System?

    Granted, and I'll admit that my estimate of nearly all the orbital velocity was a bit overstated. It still works out to having to shed ~87% of the Earth's orbital velocity.
  16. Janus

    Nuclear Waste Disposal into Sun or outside Solar System?

    You use it when the rocket recrosses the Earth's orbit after having been given a boost by an inner planet. Timing. Voyager took advantage of the "grand tour" alignment. The outer planets where in an ideal position so that you could use one planet to not only boost speed but to alter your...
  17. Janus

    Nuclear Waste Disposal into Sun or outside Solar System?

    Assume that you kill just enough of the rocket's solar orbital velocity that it enters an orbit where its aphelion is at Earth orbit and its perihelion at Venus' orbit (such a transfer orbit uses the least delta v.) When the rocket reaches Venus' orbit it will have picked up speed from...
  18. Janus

    Moon astronauts physics experiment

    The golf ball incident is an interesting story. It was done by Alan Shepard during Apollo 14, and no one at NASA knew what he was planning. He secretly altered a six iron club head so that it could be attached to a lunar sample scoop handle and then smuggled it and the golf ball onboard in...
  19. Janus

    Boeing Boeing Delta 4-Heavy

    As great as the photo is, it is probably better at home in aerospace engineering, as it really doesn't have much to do with actual astronomy.
  20. Janus

    NASA Why is NASA going to Mars?

    Wow, If it had been left up to you, Columbus wouldn't have set sail until he had the equivalent of the Queen Mary at his command.
  21. Janus

    New Kind of Rocket Booster

    It's not exactly a new idea: http://www.sussex.ac.uk/press_office/bulletin/22oct99/article1.html
  22. Janus

    Why do plains, shuttles, & man made things that fly have 3 wings?

    Then there's the Beechcraft Bonanza, which used the "v" or "butterfly" tail: http://members.tripod.com/~LAMKINS/CN_BonanzaA35.jpg
  23. Janus

    Rocket escaping Earth's atmosphere

    But even traveling at 1 mph away from the Earth, you will reach escape velocity if you travel far enough, since you will eventually reach a distance where the escape velocity is 1 mph.
  24. Janus

    Rocket escaping Earth's atmosphere

    Right around 11 km/sec to totally escape, about 8 km/sec to attain orbit. Though rockets wouldn't "leave the ground" at this speed. If they tried, they would burn up from air friction. What they do is accelerate through the atmosphere, and by the time they reach these types of speeds they're...
  25. Janus

    Why do you aerospace engineers have such a hard time making spacecraft?

    It also sounds inefficient, as the rocket engines not in use at a given time just become extra dead weight that the engine in use has to lift
  26. Janus

    NASA Nasa offers reward for trash removal

    Why don't we just call Quark: http://quark.name/
  27. Janus

    NASA Hey Janus, where did you get the NASA patches from?

    Most of mine were mail order. The Viking Mission patch I picked up at a Science Fiction Convention in 1980 call "Vikingcon". It was convention run in order to raise money to keep the Mars Viking landers operating.
  28. Janus

    NASA Nasa's new and improved ANTI-MATTER space ship

    Just to propel a ship to Mars, requires 1.4e8 joules per kilogram. This includes leaving Earth, making the transfer orbit insertion, and matching velocities with Mars at the end of the Trip. If we assume that our ship's mass is equivalent to the mass of a fully fueled shuttle stting on the Pad...
  29. Janus

    Nuclear Fusion Rockets v.s Fission

    I don't know where you got your numbers from, but any rocket's top speed is only limited by how much fuel it carries. That being said, a fusion rocket theorectically is more efficient than a fission rocket and both are more efficient than the chemical rockets we presently use. By more...
  30. Janus

    NASA Nasa's new and improved ANTI-MATTER space ship

    Merely breaking Earth orbit will only put you into an independent Solar orbit. You will have to apply additional \Delta v to alter that orbit enough such that it intersects Mars' orbit.
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