VincentS

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About VincentS

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  1. - Generation ship : large crew is required both for sanity and genetic diversity. Moreover, you can only select first generation, you have no choice on any of the next ones. (well, except if you go either the clone or eugenist way...). And you will need some very talented people to keep the ship working, so you'd better have a large population to select from... - ISS requires constant maintenance, and spaceships are likely to require even more and without any possibility to rotate crew member. So you have to add some redundancy, which increase ship size and complexity, which increase crew requirement, until you get both a very large ship and a very large crew, and can (barely) cope with some crew unavailability. When compared to planes, you basically have to perform what the ground team would do, but while in flight and multiple times and without any material assistance. And you have to either carry or manufacture anything that need replacement...
  2. The ship would have 3 problems to solve : withstanding heat, radiations, and escape. On the first point, my instinct is that ablative or regenerative cooling could do the trick, if mass is not a problem. If the ship is a cargo ship, cargo may be sacrificed as improvised insulation buffer. You would be losing mass fast, but that could help your TWR... I have no idea on the second point Escaping sun gravitation could be done in at least 3 different ways : - If you have TWR >> 1 and your engine can endure sun radiations and heat, burn away from the sun to the closest safe spot (far enough, or Mercury shadow, whichever you can reach first at full thrust). You could probably generate a big magnetic field to use as an improvised magnetic sail, this close to the sun there should be plenty of fast charged particles... - If you have to protect your engine from the sun, you obviously cannot turn your back on the sun, so you have to rise your apogee continuously by burning at 90° from the sun and spiral out - Even if you have TWR <=1, you may not be toast already (pun intended) : you could dive (almost) toward the sun and burn continuously prograde, with the lowest perigee you dare to attempt. You may gain enough kinetic energy to increase your apogee enough to be safe. Plus burning close to the sun would be highly effective due to Oberth effect. If you survive. This would obviously be the Kerbal way...
  3. Let's assume that you launch from your moon base and want to rendez-vous in orbit with some station or tug. Case A : equatorial base. Having target on equatorial orbit makes it easy to rendez-vous because orbital plane is already the same. You launch due east to get some free velocity from moon rotation, and have one window per target orbit. Case B : (almost) anywhere else. "Natural" orbit will have some inclination (depending on latitude), so obvious choice for target is an orbit with the same inclination. But due to moon rotation, orbit planes will match only once per month. Case C : polar base. You can reach any polar orbit you want directly from the pole (no plane change required), so once again you have one window per target orbit. Notices : - Landing at your base is almost the same as launching from your base, but in reverse. - Transfer between earth and your target orbit around the moon may require plane change too in case B and C (or waiting for the right window). In case of C, it matters only if you have some kind of station (you can always reach some polar orbit) - Plane change is possible, but for large angles it will be very inefficient. And if you have much dv to spare, why bother to rendez-vous ? take the direct approach... - You can test these scenarios on KSP
  4. Another approach to enhance photon rocket : use rocket engine nozzles. Yes, I know that photon don't expand. But what if you pump some gaz into the concentrated light beam (or even fire ice pellets into harm's way) ? You basically get some kind of thermal rocket. While in atmosphere, you could pump gaz for free. While in space, you could use unwanted junk to get some increase in TWR
  5. In a sci-fi setting with jump drive for a game or novel, I would go with the following set of rules : 1) FTL speed x local speed = c^2, both when entering and leaving FTL. Local speed is defined relative to local mass average speed (local mass contribution to the local speed decrease with distance squared) 2) FTL speed is constant during space jump. 3) FTL Trajectory is deflected only by gravity, in a way similar to light deflection close to stars but in the opposite direction. Intensity of the deflection increases according to the inverse of the FTL speed (the slower your FTL speed is, the more time you spend in the gravity field, the higher the deviation) Corollaries : a) The faster you are flying relative to the closest planet, the slower your FTL speed will be b) For planet to planet jump, local speed before and after the jump are identical c) Any attempt at high speed collision with a planet using a FTP jump is likely thwarted by trajectory deflection from the planet gravity (high speed -> low speed FTP -> high deviation)
  6. Prospective often fails, but let's try anyway. I think that Mars colonization will occur only once there is some hope for any kind of ROI. This requires that either something on Mars with a very very high value, or some very cheap interplanetary transportation system. For many commodities, the Moon could actually provide a much closer supply, with a weaker gravity well and hence a better ROI. One of the most interesting thing that you have on the Moon and not on Earth is an easy access to space. If we could make use of lunar resources in order to make building space things cheaper, it may be possible to get a positive ROI. So, in my opinion, the first step in Mars colonization would be to build and maintain some kind of tele-operated rocket and satellite plant on the Moon. It would initially use mostly ISRU and 3D printing, with critical parts being shipped from Earth. The plant would then grows in size and capabilities, while developing autonomous IA and (partial) self-replicative capabilities. Once the lunar plant is advanced enough, it can manufacture and send satellites in Earth orbit for a fraction of the current cost (but sadly, it won't be soon…), and it may generate a positive ROI in the long run. In the end, if the plant can self-replicate, lunar production capabilities may exceed Earth satellites needs. This would also drop the cost for building and sending a similar plant on Mars, which would probably be the first step in making human settling on Mars possible. TLDR; We have to build space infrastructure first : a self-replicant plant on the Moon, then on Mars. Humans will come after industrial capability is up and running, and space ticket cheap.
  7. You are obviously correct magnemoe, I was reacting to the following (emphasis is mine) : I should have quoted this the first time for clarity sake.
  8. As stated multiple times before, the flywheel trick won't work. If it worked, you could build a reactionless engine : 1) shot a pellet using a railgun at one end 2) catch the pellet using your flywheel-augmented sling. 3) rinse and repeat. (moving the pellet back to the railgun has no net effect on momentum) You gain momentum using 1) recoil, and lose no momentum when catching it at the other end 2) ; 3) has no net effect.
  9. Any KSP player will tell you that you'd want a spaceship to be : - light (the lesser dry mass, the better) - not wobbling Carrying human add a few requirements : - Efficient shielding - Artificial gravity would be good Ferrying goods : - normalized containers I'm no space engineer (except in KSP), but spherical tanks seems obvious : best volume/surface. May not apply for high pressure content. You'd probably want your containers to be assembled in a compact way, forming a stiff structure. So hexagonal-based containers fitting in honeycomb bays could be used. Main structure would be beam and struts (can be made light and rigid) Smaller ship would have living quarters surrounded by 6 containers lines, so that containers provide shielding. For bigger ships, you'd probably want artificial gravity. Easiest way to rotate the structure is to have two parts with tethers in-between : one main cargo + engines, the other with living space. When cruising, you'd rotate the whole structure. When thrusting, you'd have to kill rotation first, and shorten the tethers to bring the two parts together. Engines would be positioned on the sides, so that no exhaust can damage any part of the ship when in "compact" mode.
  10. On earth, biosphere does a pretty good job at harvesting and concentrating available resources required for human life preservation. Obviously, you can't duplicate that on Mars surface directly, and won't for a long time. So, how will we get our minerals, breathing gas and energy on Mars ? Adapting (useful) life forms to Mars surface condition looks way too hard, but I'm no biologist so who knows. I'd say, let's go with the next best thing to natural life : artificial life (i.e. robots !) The good news is that landing robots to the red planet is obviously possible. The bad news is that robots we sent so far are not very useful for building anything, not to mention an operational colony. We face many critical problems : - Piloting robots that far away is very slow. Some kind of IA is needed. We need to improve automated decision making, and/or make the colony easy to assemble, operate and maintain. We could wait for colons arrival to operate the robots, but it seems risky to send anybody before ensuring that the colony is operational (or will be) . - Sending enough robots and material in order to bootstrap the colony is huge. Basically, we need tools and materials to build and maintain a gigantic ground ISS, plus a farm complex etc.. However, we could reduce required payload by using as much local material as possible ( smelt raw martian rock may not have great mechanical properties, and will make robots bulkier, heavier and less durable. but who cares, it's free and already there ! ). We should have a robot plant sent there, and only enough robots to assemble and operate the plant, so that if any robot breaks it is replaced. But sending a robot plant raises problems of its own : - Some part are very hard to manufacture, and will have to be sent anyway. Some are small enough to be sent in great numbers : chips and various captors. Others are heavy or bulky, such as battery, power source and bearing. - Self replicating machine is not yet a thing on earth, so self-replicating machines in Martian environment is but a dream. However, in a strict sense, we don't need to replicate every part of our machine, only those we cannot send. I have a few ideas that may (or may not) help solve those problems : 1) Don't use rotating parts if you can avoid it : martian proof bearings and lubricant will probably be very hard to manufacture and assemble. Materials will be hard to come by. Many things can be done without rotating parts (I cannot thing of a single specie using rotating parts -- except humans). Maybe some pneumatic or muscle like system could bend material, and we could do much by bending and unbending things. Robots would probably have between one and six limbs (jumper or crawler for exploration, three legs walker for operating things, six legs for moving things ?) 2) Don't build for durability or efficiency. When something breaks, recover parts ( anything you cannot build has top priority ), build a new one and who cares ? Easy assembly and servicing is highly desirable here. 3) Some kind of martian rock solar smelter will probably be top priority. Design your original plans to use smelted rock whenever you can. Mechanical properties will be lame, but with low gravity you will probably be OK. 4) Having some kind of metal and/or plastic material plant would be great, and it is probably possible to achieve. It requires the ability to mine martian soil, but we want to dig for living space anyway. 5) Life support will be challenging, but reusing lander system could obviously make things possibles. So, in my idea the first Mars colony will be founded by robots. The first one would setup a solar smelter and cast required parts for other almost-complete robots and plants. Those robots will in turn complete and start the martian power and/or compressed air plant. Mining and mineral processing will be next. New robots will be created for mining, operation and maintenance until almost every chip is in use. Reinforced tunnels will be made into (almost) airtight living space using plastic and/or metal coating. Perfectly airtight seals will probably be hard to come by, (Airlocks being the most challenging) but you could probably make do using multiple imperfect airlocks in a row, if you produce the air faster than it leaks. Then, build and fill tanks with the various useful commodities you extracted (water, oxygen, nitrogen etc…). Your colony will not be auto sufficient already, because you still rely on earth shipping some components, but now the amount of parts to ship should be made reasonable enough (spare parts for various plants, chips etc…). Plants and animals ( human among them) should be next to come to the colony
  11. You could use "top guns" (pun intended) that would fire rapidly rotating slow (top) slugs. Of course, you'd have to launch those by (contra rotating) pairs in order to conserve your angular momentum. Any target hit by one (and only one) would start spinning uncontrollably and effectively be out of fight until attitude control is restored (in the best case -- additional helmet cleaning may be necessary after such a spin..). I didn't run numbers, so I'd appreciate if anybody could check if big enough angular momentum is actually achievable.
  12. According to some old French comedy, "La soupe aux choux", farting while outside would do call an UFO : http://www.dailymotion.com/video/xc3g60_le-meilleur-de-la-soupe-aux-choux_shortfilms Please report any success on this thread !
  13. If you can track the target with a telescope, firing at it sounds like similar (you only need the photons to go in the reverse direction). Although I wouldn't recommend shooting a high power laser through the telescope optics, you could probably use the same mount.
  14. I suppose that you could add induction hardware on highway (or any other power supply method that is acceptable while moving). This could solve charge time, maximum range and even tax problem (tax highway use for electric car). Battery could be made smaller, lighter and cheaper (you only need enough range to get to the highway).
  15. Gecko would be great (No fur or feather, and free "artificial gravity" effect on any wall.)