el_zorro

The corrosion from the salt water would completely ruin the engines, obviating any benefits from returning the first stage.

The utility here is not really landing on other planets, but instead the order of magnitude decrease in launch costs if they don't have to build a new first stage for every launch.

It has to do with the payload mass. If it's too massive, it won't have enough fuel to return to the launch site, so they do a landing at sea.

I'm wondering if there's been something lost in translation there, though. The word, in Western understanding, means holy war, but a more apt translation is "struggle", in the same connotation that one would struggle with a cigarette addiction or the like. Extremist groups have claimed the word for more violent connotations, but traditionally is more like a burden that one struggles against.

I just completed a degree in physics from his university, actually. I can think of a few reasons:

1. He wanted to be 100% sure about the data and not rush it, especially if it could be an error with the instruments

2. He has funding for other projects that needed to be worked on in the mean time, and didn't have a lot of time to devote to this work (this can make #1 take longer)

I'm mostly just curious about who would enforce the ban. Is there really any enforcement agency that will police the others, when they all benefit from surveillance? I just don't trust that we could ever really be sure that it's been shut down.

Mars would almost certainly require a small rocket to get to orbit, but it would be trivially sized compared to what we need on Earth. Even something as small as the Atlas rockets that brought the first Americans to space would probably be overpowered compared to Mars' small gravity well. Throw in atmospheric losses less than a hundredth of that on Earth and suddenly space becomes very accessible.

I don't think it is so much an issue of ability so much as desire. Most of the tech has been dreamed up for decades, but it needs funding and a green light (particularly the nuclear reactor, given that there were protests about even Curiosity's RTG).

Personally, I think there's a huge amount of talent just waiting for the right moment to strike, and then the whole Mars thing is going to burst right open.

I think you fundamentally misunderstand the statistics and distances involved here. Millions of civilizations? Only if you take the most optimistic of all statistical stretches. I personally think that there are at most a dozen civilizations that are within our technological range +- 10,000 years (really generous given the enormity of time) and the speed of light conspires to keep them forever beyond our reach.

Aliens do not walk among us.

The diameter actually does have an effect on where geostationary orbit is: it changes how fast the surface is spinning, and hence the orbital speed needed for a stationary orbit.

Mars spins once every 24 hours 37 minutes. If the diameter was twice as large, it would have to be moving twice as fast to maintain that length of day.

Interestingly, since you orbit faster the closer you are to the surface, a decreased diameter actually pushes geosynchronous out away from the planet. This effect is, of course, very much negated by the absence of mass. Still, two equally massive planets with the same rotational period but NOT the same diameter will have different geostationary altitudes.

Right now, SpaceX can (and does) have access to that limited market by selling off payload on current launches. It's cheaper to just bootstrap on to an existing flight than dedicating an entire rocket to a small mission. If and when the Falcon rockets become reusable, it's very difficult to imagine this series ever being competitive. SpaceX aims for launch costs of $5-7 million when they achieve reusability, putting the per-kilo cost somewhere between $540-700. At that price, these rockets will have to have a total cost of only $350k to match what SpaceX offers.

These people must either believe that SpaceX won't achieve reusability, or their rockets will. Maybe a combination of both?

I'm really curious how you think this will solve anything. Children of wealthy parents don't have to inherit anything to have advantages that most poor children could only dream of. That is, unless you somehow abolish parents using their wealth to give their kids access to better healthcare, higher-quality and healthier foods, better educations, opportunities for travel, exposure to culture, and on and on. And if you say that yes, that is what you mean and all those things are to be taken care of by the state, then you've moved beyond even the socialized policies of the Nordic countries. Not that that's a bad thing, but it would be a little disingenuous to call it capitalism.