Yes there are good reasons for going to Mars. Greatest among them is to safeguard the species from any catestrophic impacts on Earth they would extinguish us.

No potential impact to Earth would render it less hospitable to life than Mars is. For speicies survival a set of fortified underground bunkers/mini-cities would be far more practical -- and unlike Mars, we do have the tech to do that.

The suggestion that we currently have the technology to colonize Mars is, in brief, ridiculous. No human has been move than 500 miles from Earth's surface in over four decades, and the farthest we've ever sent a human is under 250,000 miles; at its closest, Mars is 38,000,000 miles away. We do not know how to safely get a human being that distance through interplanetary space, and the first few people we try to send are quite likely to die.

That investment of blood and treasure might be worthwhile if there was something useful for humans to do when they got there, but there isn't. We'll get better scientific results by building and sending better robots.

There is no practical reason to send humans to Mars in the near-term -- say, next five centuries. Especially not when all of our resources are needed over the next century or so to put human civilization on a sustainable footing. We can probably do some useful stuff with humans in Earth orbit and maybe on Luna, but deep space is for robots.

The only justification to put humans on Mars is some vague hand-waving about "inspiration" -- i.e., it's a huge performance art project. Maybe someday humanity can afford that. But not now.

There are tons of online services already like iMaterialize and Shapeways - they do really excellent work.

They're saying that it won't break because that's not the purpose here. The description of the experiment is:

In addition to safely integrating into the Microgravity Science Glovebox (MSG), the 3D Print requirements include the production of a 3D multi-layer object(s) that generate data (operational parameters, dimensional control, mechanical properties) to enhance understanding of the 3D printing process in space. Thus, some of the prints were selected to provide information on the tensile, flexure, compressional, and torque strength of the printed materials and objects. Coupons to demonstrate tensile, flexure, and compressional strength were chosen from the American Society for Testing and Materials (ASTM) standards. Multiple copies of these coupons are planned for printing to obtain knowledge of strength variance and the implications of feedstock age. Each printed part is compared to a duplicate part printed on Earth. These parts are compared in dimensions, layer thickness, layer adhesion, relative strength, and relative flexibility. Data obtained in the comparison of Earth- and space-based printing are used to refine Earth-based 3D printing technologies for terrestrial and space-based applications.

The description is not "Print out a wrench so that crew members can change a rusty lug bolt". And yes, also from the description page, they include direct metal printing as part of their list of ultimate goals with 3d printing in space research.

3d printing has tons of applications here on Earth. However, this does not include general-case home 3d printing. Unfortunately, that's what most people here on Slashdot want to judge it by.

Indeed. 3d printing is not going to be suitable for mass production, for keeping a whole colony supplied in bulk components.** But for small specialty parts, it seems like an obvious answer to that piece of the equation. As the tech advances, it's just going to get more and more capable. I'm personally looking much forward to seeing whether a 3d printer that works based on thermal spraying would work out - then your production material choice would be almost limitless, pretty much any powder or small fibers you can think of that can be made to merge with the substrate through any custom combination of either temperature or velocity, and your balance between deposition rate and precision could be chosen just by rotating through nozzles of different sizes, none of the feed mechanism or material storage or anything. Your same printer could even paint, coat, sandblast, or pretty much any other post treatment on its own.

** Concerning not being able to use 3d printing for mass manufacturing: That is, assuming 3d printing as we think of it today, printing a voxel at a time. However, if you made a custom programmable 3d *molder*, where it forms a cavity of a programmable shape, that could be a different story - then you're approaching true mass production potential. Custom programmable stamping tools and other manufacturing processes could also be developed.

A lot of the slashdot crowd still thinks of 3d printers in terms of Makerbots and the like, the low end consumer-level home 3d printers. They really have no clue what professional level hardware can achieve. They'd be singing a different tune had they ever ordered 3d-printed parts from a professional 3d printing service.

How much dedicated time does the gas station take to make the gasoline? ;-)

Realistically I would assume the solar array would use a storage battery so you don't need to generate the power at the instant the Tesla drives up.

On the other hand, 26-53 Teslas/day may be a bit of a low number. I've been at Tesla recharging stations where there are two or three Teslas parked and charging at the same time. And this was in NJ, not the west coast where there are more Teslas on the road.

On the third hand, no one drives into a supercharger with a completely depleted battery. I would wager that most people are just topping off from less than 50% charge to 90%.

On the fourth hand, a Tesla charging station doesn't have to be run completely off solar panels. Panels can supplement and take some of the base load off of the hard lines.

Germany was spending far more on their military during that time than Britain was. If Britain and France had stepped in earlier, Germany would have been totally unprepared and the war would have ended quickly. Not to mention all of the horrors of the Holocaust that would have been prevented.

If Britain and France had managed to delay the war to "prepare" even more, say a few years, the Luftwaffe would have been dominated by jets, German ballistic missiles would have been longer range and more precise, and they might even have become a nuclear power. I really don't think this is the analogy you're looking for.

By now would be surprised if they don't have at least a couple Taepodong 2s that have at least a fair chance of a successful flight. They're not impressive as far as ICBMs go, but they are ICBMs.

Propaganda campaign by who? I think Singer needs to check his haughtiness at the door:

the ability to steal gossipy emails from a not-so-great protected computer network is not the same thing as being able to carry out physical, 9/11-style attacks in 18,000 locations simultaneously. I can't believe I'm saying this. I can't believe I have to say this."

Except, of course, for the fact that the prime suspect is the hand-picked hacker squad of the Hollywood-obsessed leader of a nuclear armed state with ICBMs, whose family's Hollywood obsession has gone to such extremes in the past as kidnapping filmmakers and forcing at them at gunpoint to make movies for them. I can't believe I'm saying this. I can't believe I have to say this.

Well, at least Russians won't freeze to death this winter. They can use wheelbarrows full of rubles to insulate their homes. ;)

That's not all that different from how he got started with Tesla. He had no intention of starting a car company (he already had SpaceX), he just wanted AC Propulsion to build him a copy of their t-zero - but they had no interest, even for a small fortune. But then they pointed him to this guy named Martin Eberhard who had this wild idea to commercialize the t-zero's tech base on a Lotus Elise body and was looking for funding... and thus Tesla was born.

g++ supports it with __restrict__. And if you're writing high performance code but not having support for the features of modern compilers, you're an idiot. In appropriate situations, the performance difference for using restrict or not is huge. Array-heavy tasks like image processing often get a 2-fold or more benefit with using restrict. There's very few places in the coding word where a single keyword can raise your performance that much.

And examples of these which could plausibly be on Titan are....?

There's not much in nature that's that light.