Making Humans a Multiplanetary Species [video]

I agree about the long term health effects of Mars gravity. I think with adults you'll probably see some bone density loss, similar to what happens to astronauts on long space missions. But arguably that will be offset by gravity at 39% of Earth's.

The bigger concern I have is for children that are born on Mars -- if you want to have a self-sustaining population there, you're going to be raising children there, and physical growth in a low-g environment isn't something we can test in the timeframe Musk has in mind.

I think your example actually harms your argument. The SR-71 is a nice plane, and certainly much more advanced than the Wright Flyer, but it is completely outclassed by the Saturn V. The space technology is much more complex, and much more energetic, and has far tighter tolerances, and less room for failure. You should have been making this same argument in the early sixties. Right now we do have the technology, the engines, the fuel, the deep-space communications network. We need to scale up the engines to rival the power of God Almighty, but we don't need new physics to do so.

Musk is pointing out, correctly, that this is possible with existing rocket technology -- at least the transportation. Keeping people alive once they're there is apparently somebody else's problem, but until we have the materials science for a space elevator, an obscenely heavy lift vehicle will probably have to do. Ultimately he's going to be asking a lot of people to climb on top of a monstrous Engine and hope that it explodes correctly, and I hope that his conscience is clear when that day dawns. Probably you are right that we're going to have a hell of a time keeping people alive on Mars, but we seem to have a tough time of that here as well.

This is not science fiction. There is no new physics required, just some fiendishly difficult engineering challenges. The Wright Brothers were able to build their plane because there was nothing physically stopping them. They had the scientific knowledge and the dedication, and everything else followed. Really it's not that people -- even Presidents -- haven't been talking about doing this and working on details and preliminaries for decades. This is news precisely because it's not science fiction. This time, it could actually happen.

I'd guess that maybe they have a limited supply of tankers and if they're only sending ships to Mars during a narrow window of time (due to planetary orbits), then it's helpful not to have a bunch of tankers sitting idle when they could be busy making trips back and forth from Earth to Leo.

There might be practical considerations, too, like if someone is on the ship for a couple days and then realizes that spending months on a ship or living on Mars is just not for them, they can get transferred to the next convenient ferry back to the surface.

We're probably overthinking this, though; what order the passengers, fuel, and cargo load is a pretty minor detail that could easily be revised when the plan is closer to completion.

I'd comment on the video itself if I could watch it, but local systems aren't cooperating.

That said: discussions can be about the nominal topic, or they can drift, naturally, to other areas of interest. I find the meta-topic of "where is a good place to discuss the things I'm interested in discussing" to be generally on-topic. HN isn't a bad place for that.

With the ability to collapse threads baked into the HN page design, if you're not interested in a discussion, you can simply collapse it an move on.

On which: I'm increasingly hitting long threads from the bottom, for a few reasons:

1. The top-ranked post often isn't particularly on-topic, and attracts diversions posted for visibility.

2. It's easier to tell if a thread is of little concern if you follow it from the bottom.

3. It's easier to track a conversation from bottom to top and collapse going up, than it is to backtrack back to the top and collapse that. There's a subreddit which runs the collapse bars down the side of the thread, allowing a subthread, or entire thread, to be collapsed in one go.

4. There are often downvoted or flagged items which I feel are incorrectly tagged. It's usually faster to assess if something has some merits than to see if it's solid, and I'll nudge stuff up -- even if I substantially disagree with it -- if it seems it's been overly penalised.

HN, as with other online discussions, does poorly for deep and complex posts. One standout was The Edge Question issue a few years ago. There were a handful of comments on the first few essays, but given that there were ~100 - 150 total responses, it's not the sort of thing you can digest quickly.

I've tracked down other issues of the Question and gone through it. I have to say on balance I'm fairly disappointed in the quality -- much is narrow self-promotion of research, another large set is rampant speculation. The short an humerous responses are often disarmingly refreshing. And every so often there's something quite good. Sturgeon's quality estimate though seems generous.

A solar flare or a gamma ray burst might knock out satellites and electrical equipment and damage earth's atmosphere. In the worst case, they could kill a few billion people. But Earth will still be more hospitable than Mars.

>Same reason people crossed the Atlantic, to take part in something greater than themselves.

People crossed the Atlantic because they wanted gold, or slaves, or timber, or land, or because they wanted to escape from religious persecution, or because they were slaves or prisoners transported against their will (by someone who wanted gold, or timber, or land). They received resupply, not as charity, but from companies which expected to receive gold, tobacco, timber, or other goods in return from their investment.

Colonization is driven by economics. That's why thousands live permanently in Norilsk, Yellowknife, La Rinconada,and Kalgoorlie, but nobody lives permanently at Amundsen-Scott, under the sea, or in LEO. If history is any guide, "how will this turn a profit" is the question any Mars colony needs to address if it is to have any hope of prospering.