Nibb31

It depends on the payload and on the orbit that you want. It's highly impractical to use SRBs for upper stage burns, though. You wouldn't have much control over orbital altitude, which would make it stupid to use as an operational launcher.

The largest cost in spaceflight is not the actual hardware or the propellant, it's the manpower. The salaries of those engineers and technicians who build, integrate, test, maintain, and launch that hardware, as well as the infrastructure, the administrative overhead and paperwork. By reusing hardware, you only save on the actual material cost of building the hardware. You still need to pay for all the other tasks and process that are traditionally associated with spaceflight. The actual reduction in manpower cost is minimal because instead of paying people to build the hardware, you have to pay people to refurbish and retest the reused hardware. You don't save anything on the cost of the design, test, integration, launch phases or the administrative overhead. On the other hand, hardware production costs can be minimized by increasing production capacity. Instead of mass producing expendable ones, which makes each individual item cheap, SpaceX plans to produce less, more complex rockets, which means that the individual cost of each one goes up. Reusable looks technically elegant, it might not be economically viable. At least SpaceX are trying, and we will soon know for sure if it can be a viable business model.

The mud or wood huts might disappear, but we would have found fossils of them by now. At least some evidence should exist before we start making crazy hypotheses. That's how science works. Otherwise, we might as well just speculate about teapots orbiting Saturn.

Spacecraft (even the ISS) are too small and too balanced to be tidally locked. The Moon is tidally locked to the Earth because it is large, heavy, and one side is heavier than the other.

As you can see on the diagram, there was an ascent engine cover that protruded inside the cabin, so that the nozzle came flush with the top of the descent stage. This is why you don't see it underneath the LM on the video. The cover could actually be removed so that they could attempt to fix it or bang on things if it failed to start. The ascent stage engine was primarily designed to be robust, with as less moving parts as possible, which is why they use hypergolics and helium instead of mechanical pumps, because it was the only engine in the Apollo-Saturn vehicle that would cause an unrecoverable loss of crew if it failed to fire.

Idiocracy.

Musk is a visionary, but above all he's a successful businessman. SpaceX is a commercial venture, not a space program. They will offer rides to Mars when somebody is prepared to pay for rides to Mars. As has been said, the goal of reusing first stages is to drive costs down. There are many very intelligent people who work in the Space industry, and there are reasons why none of them have gone with reusable rockets yet. I hope SpaceX succeeds, but there are still a lot of unknowns, both technical and economical. The technical problems are probably the easiest to solve, but it's going to be hard to pull off a commercially viable reusable vehicle.

It would have to be between 200 or 400km of the cost of the launch site, either in the Atlantic (for a KSC launch) or in the gulf of Mexico (of they launch from the new Texas site) which is not very practical. You would need to refurbish something like an oil rig. The infrastructure cost would negate the small savings you get from reusing the first stage.

Struts can solve your problem, but don't forget that struts create lag. For each strut, the physics engine has to work out the angular forces acting on the strut, in extension and compression, as well as the connections between each part. When you have lots of struts, this can bring your computer to its knees.

A Moon base makes sense because it is still quicker and easier to get to, which makes crew rotations and supply ships more feasible. The launch window for Mars resupply missions is every 2 years, which means that you need to send larger space craft. Heavy payloads mean that you need a powered landing, which requires more complexity, and more mass added to the payload. Many of the solutions for problems of living on the Moon are not needed for a Mars mission, but a lot are needed for the actual journey to Mars (hard vacuum, cosmic radiation). Others are needed for Mars (partial gravity, ISRU, closed-loop life support, reusable landers). The complexity of building a Moon shuttle capable of transferring between the lunar surface and back up to lunar orbit is much simpler than building a mars shuttle.

1) Detach the rest of the rocket from the command pod. 2) Delete the command pod 3) Add a new command pod 4) Reattach your rocket to the new command pod

We wouldn't know what to do with helium 3 even if we had it, because we can't produce power from fusion yet. Also, helium 3 is not "abundant"on the moon anyway. The first thing to do is to experiment ISRU. At the same time, we need to monitor biology of organisms submitted to partial gravity and cosmic radiation and to find out if we can mitigate any problems and survive long duration BEO missions. The results of those studies will tell us if it is relevant or not to pursue manned exploitation of the solar system.

It was tongue in cheek because the question makes zero sense. You would lose consciousness in a matter of seconds and die of asphyxiation. What does it matter what other symptoms are?

First get rid of those triple tanks and tricouplers. They mess up your fuel flow, and they cannot connect properly on the bottom due to the single parent-multiple children hierarchy structure of KSP rockets. Instead, use single tanks. Also remember that your first stage needs to have at least three time the thrust and weight of your second stage. If your rocket has identical first and second stages, then you are doing something wrong. Either your first stage is too small, or your second stage is too heavy. Finally, as already stated, do not use canards below the center of mass, they tilt in the opposite direction to winglets. Also anglers are only really useful at low altitudes. But if you are using them to correct stability problems at low altitudes, then something is wrong with your rocket.

You need to burn on the opposite side of the orbit that you want to change. Burn at Pe to raise or lower the Ap, burn at Ap to change the Pe. And of course, you burn prograde (accelerate) to raise your orbit (which will have the effect of making you go slower) and burn retrograde (slow down) to go lower and faster. It's all a bit counter-intuitive really, but once you understand what's happening, it becomes quite clear.

If you become immortal to live to see what Humanity becomes, then Humanity will have become something so totally different from what we are now that you wouldn't recognize us as human any more. Time, space, wealth, compassion, health, suffering, pleasure, sex, reproduction, would no longer have the same meaning when you can live forever. In other words, mortality is inherent to human nature. Remove mortality, and we are no longer human, but something completely different.

Well, speculating about anything beyond a couple of decades is pretty meaningless, and I'm pretty sure we won't get orbital solar plants in the next 40 years. There are much cheaper power sources on Earth, and I don't see any groundbreaking lowering of the cost of accelerating things to orbit. In the 60s, people were predicting moon bases, nuclear powered flying cars and what did we get? The Internet, that nobody expected. Yet it has changed our lives in a much deeper way than anything else that emerged out of the industrial revolution. The greatest changes are the ones that nobody expects.

We'd have to sterilize ourselves first. If we lived forever, this place would get crowded pretty quick... On the other hand, interstellar travel would be no big deal if you could live forever. There would be no need for FTL if time doesn't matter any more. You could just switch your conscience off during the boring parts of the journey. Oh, and if you could get uploaded into a computer, why stop at living one life? You could have unlimited clones of yourself and conquer the galaxy... In my opinion, that is pretty much where Humanity is heading. Unless we destroy ourselves first, I don't see how anything could stop that from happening.

We won't be using space to get power. An orbital solar farm is twice more efficient than a solar farm on the ground? Who cares? Just build a solar farm on the ground that is twice as big. It will still be massively cheaper, and we are not running out of sunny real estate any time soon. The sheer energy involved in building a massive power plant and accelerating it from 0 to 25000km/h will always be higher than the power output of that power plant. Also, factor in the loss of beaming that power back down to the ground, the cost of the ground stations that are going to convert that beam into electricity, and the complexity and risk involved. It's a no go.

We already discussed this in the Science Labs forums. A ballistic trajectory makes the first stage fall a few hundred kilometers from the launch site. Burning to Africa (or to Florida from a Texas launch site) would cost more propellant than to return to the launch site. Do you have any idea of the distances involved? A solution might be to build a landing pad on an oil rig 200km off the coastline. That would probably cost more than the fuel needed to for the reverse trajectory burn.

You wonder? It's been explained for decades. The Titanic had compartments separated by "watertight" walls, but those compartments didn't have watertight ceilings. As several compartments filled, the water overflowed into the next compartments.

You can get MechJeb, which is an autopilot. However, the rule of thumb method for getting to the Mun (or Minmus). Is to wait until the Mun (or Minmus) rises above the horizon when you are in Kerbin orbit. Then, just burn prograde until your orbit intersects with the Mun's (or Minmus') SOI.

I'm not too sure about that. You don't solve our problems by going to space. Space expands our boundaries, but the Earth will always be there, with the Humanity on it, and all our problems. Humanity didn't need smartphones and facebook to be more concerned by their immediate self interests rather than the wonders of the universe. Self concern is nothing new. I agree with this. We should definitely be spending more on space exploration and scientific research in general. There is no private space race without government money paying for it.

No they are not.

No it isn't. Redundacy adds weight and complexity and cost. More stuff on board = more stuff that can go wrong. There is a balance to be found between redundancy, reliability and cost. That's Engineering 101. The Apollo LM Ascent Stage engine was one of the single mission critical systems with no redundancy, which if it failed, the astronauts were lost. It would have added weight and complexity. Instead, they made it as simple and fault-proof as possible. They used hypergolics (which ignite spontaneously) to minimize moving parts, and put the engine under a cover that was accessible from inside the LM, so that if a valve got stuck, the crew could bang on things to get it to work. They could have added redundancy, but they didn't because redundancy isn't always a good thing. Instead of redundancy, they opted for robustness and simplicity. In the case of the Falcon, SpaceX engineers are not stupid and I'm pretty sure they have done the math regarding failure probabilities, but in the end, the main driver for using 9 Merlin engines is economical. Their aim is to make cheap rockets, and the cheapest engine is the one that you already have on the shelf.