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Comment: Re:I think its gonna be a long long time (Score 2) 76

Well, at the point when atmosphere starts becoming a nuisance and you're forced to do a braking burn, isn't it safe to deploy some reasonably sized parachute afterwards? It's not like you're going to hit the ground with it, you just need to keep your velocity reasonably in check.

Comment: Re:Also incorrect (Score 2) 76

If you look at a Hohmann's ellipse, it would appear that you can get fairly significant shortening of the interplanetary trip by a fairly marginal increase in the Earth departure speed. The problems with it are the increased rendezvous speed at Mars (aerocapture perhaps necessary?), and the fact that it doesn't shorten the whole mission, just the trip. In other words, you get a longer stay at Mars. But that could be useful, too, it could cut down the radiation exposure a bit and maximize the mission's scientific output.

Comment: Re:I think its gonna be a long long time (Score 4, Interesting) 76

There's perhaps an even more compelling argument why the atmosphere is good for us if we intend to land on Mars AND launch again: ISRU and the Sabatier reaction could be a huge win. If you plan to spend a few months on the surface, you can generate a ton of methalox fuel using the local atmosphere and only half a ton of water. Even if you needed to bring the water with you (which would be the safe option, I guess), it would effectively double your engine's Isp! You could even produce fuel for the trans-Earth injection this way, further saving the total Martian payload you'd need to launch. Without the atmosphere, none of this would be possible.

Comment: Re:I think its gonna be a long long time (Score 2) 76

Uhhh, I think you could decelerate to subsonic velocities at the proper moment and then continue falling. If it works for the Falcon 9 first stage, under much worse conditions then in the Martian landing scenario (spacecraft mass and gravity), it should work on Mars, too. But I guess it would cost you even more fuel than purely propulsive landing on a Mars-sized body without atmosphere, which is bad enough already.

Comment: Re:I think its gonna be a long long time (Score 1) 76

Oh, BTW...quoting from the article:

"...and there's too little atmosphere to land like we do on Earth."

I wonder if those people even considered the Red Dragon approach, i.e. whether "land like we do on Earth" even includes "like we'll do in fairly close future". (Of course, if they talk about the Apollo capsule approach, THAT is not going to work.)

Comment: Re:I think its gonna be a long long time (Score 1) 76

I'm still sort of confused by that claim. I've performed some rudimentary energy calculations some time ago and I simply haven't found a way to make a purely propulsive landing NOT significantly heavier than what you need with using the atmosphere. Of course it sounds like an engineering challenge, but also like a significant payload win. We wouldn't have been able to send the MSL to Mars on anything smaller than a Delta IV Heavy if it weren't for the Martian atmosphere. To claim that we'd be better off without Martian atmosphere seems just preposterous to me. Yes, it would be "simpler", for some definitions of "simpler" - you'd also have to send twice as much payload onto an MTI trajectory.

Comment: Re:This is why we need a war (Score 1) 265

by Cederic (#48680519) Attached to: Newest Stealth Fighter's Ground Attack Sensors 10 Years Behind Older Jets'

Don't underestimate the F-35 with a US pilot. The airframe may or may not be competitive against the opposition but I suspect the training will be.

It's the combination that counts. It's why I'm not terribly concerned by the UK selling our top arms to other countries: we'll just be so much better at actually using them.

Comment: Re: Paul Graham: Let the Other 95% of Great Progra (Score 1) 519

by Cederic (#48680461) Attached to: Paul Graham: Let the Other 95% of Great Programmers In

Good universities teach you how to learn. It's a skill that isn't necessarily obvious, and isn't inherent to people that can become utterly awesome at other things if they know how to learn how to improve.

Anyway, your overall premise is clearly and demonstrably flawed. Great sports coaches are seldom as good as the people they coach, but they still help them get better.

I don't need to be able to intuitively apply knowledge and experience to know that piece of knowledge and experience in applying it are important, and I can share that wisdom with someone capable of intuitively grasping the concepts and applying them.

I like to think I'm pretty good at what I do. I do continually train myself and learn new things - and one key way of doing that is to listen to people that I can learn from. They already have the answers, and one thing I have learned is not to waste my time on solved problems.

Comment: Re:The internet has no borders (Score 1) 519

by Cederic (#48680439) Attached to: Paul Graham: Let the Other 95% of Great Programmers In

Oddly, I probably largely can. Very few (if any) countries on the planet would refuse me residency.

Many of them would require me to have a job in an in-demand field first, but that's not a massive problem.

Many wouldn't. I could just sell everything and go live there. Buy a mansion, with what my current house is worth - not because it's worth a lot, but because it's only not worth a lot locally.

Keep your boss's boss off your boss's back.

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