Except that according to general relativity, gravitational _waves_ also are limited to C. As long as people confuse the current state of the system and what are basically "phase velocity" of changes in that state with the limitations of the "group veolocity", which is limited to C, we'll continue to see this sort of confusion.
> The problem is that sending people to Mars is very expensive and the billions of dollars wasted on sending people to die on an inhospitable planet could be better used for other things.
Which is what people in my youth said about the Moon landing and, frankly, has been a constant refrain against all space flight. It's difficult to know which parts of interplanetary flight and technology will pay off the most, and I'd prefer myself to pursue some of those likely byproducts first. But just a few potential benefits include the multiplication of our space capacity, enough to support zero-gee crystal and semiconductor manufacture, zero-gee electrophoresis that multiplies the sensitivity of certain types of chemical analysis, solar power from space based solar mirrors, and the migration of the most dangerous biological and nuclear research to orbital or lunar bases instead of Earth based bases.
Mars 1 seems a poorly selected political target for space development, because the obstacles are so very large they may absorb all the resources that could more quickly and effectively build a real space infrastructure. But watch, in the mantime, while many proponents of real space flight and technology manage to squeeze some funding out of the overall Mars 1 project.
> If the network infra-structure allows for POS to connect to the Internet at large
If it can't reach "the Internet at large", then it has to use modems and modem based access for credit card and debit card transactions. This is relatively slow, fragile, and expensive per transaction. Such devices are almost completely gone. Sadly, Windows XP is still commonly used on point-of-sale terminals. A typical vendor, like the one below, has _no_ Windows * based systems and supports only Windows XP and Windows 7.
> This is what happens when you have employees who think they have a god given right to surf the internet
Or when you have an employer mandate to check employee email about store policies, schedules, delivery dates, and inventory, verifying store hours for other branches, verifying alternative vendor prices for price matching, checking the weather for a customer buying exterior paint, looking up a product review or product specifications with a customer, or any of a dozen other uses. It is _embarrassing_ for a modern vendor to be unable to work with a customer checking the same information that the customer can obtain at home on their home computer, or to be unable to print out the specifications for a product that the vendor sells.
Such terminals have become quite common and are much more necessary now that customers expect one store to be able to verify inventory or reserve an item before proceeding to another physical store. If they cannot do this, they will lose the sale to an online vendor.
This especially includes video monitoring. The UK has a television tax, called the "television license fee". It's still a tax, and it's used to help fund the BBC and other government sponsored media. This tax is being skipped more and more with modern computers downloading video directly, and the DRM on British television is being evaded more and more and the broadcasts being retransmitted live, around the world. The problems of collecting the tax are compunded by home entertainment systems no longer being CRT based and easily detected by the scanning vans.
> I agree on this point. But since the proposal is for a generic design to deal with any incoming impactor, be it comet, asteroid, or even generation ship, then a design that can handle any impactor without modification is needed. There won't be time to design a modification if it is actually needed.
And this is where I would say _what!!???_ at lest if we were in person. "Any incoming impactor" includes objects of such potentially high kinetic energy, and of such unlikeliness, that we cannot even include it in any practical discussion. That includes, for example, intrastellar planetary bodies, "rogue planets". And that is where such a discussion would need need to assess, right from the start, trade-offs of likelihood of combinations of mass, velocity, and lead time to deal with it.
This was played out in the Rosetta Comet mission, which did _not_ succeed in embedding anchors in the cometary surface. Expecting a single design to handle both intra-solar-system objects, such as those from the Astroid Belt and of much smaller relative velocity to the Earth, and a cometary body that could be expected to be far, far colder and of a much larger relative velocity.
So right there, in the necessary requirements, are two profoundly distinct missions that might require two very distinct designs. Let's not limit such a discussion from the start in a single idea or technology that _must_ handle both.
It's hard work, and the pay tends to be far below the amount of work expected. Pre-school is exhausting, and grade school and high school often demand as many hours of support work, meetings, after-hours activities, and lesson preparation as hours of actual classroom teaching Many of those teachers also hung on through several deep recessions, and have reached retirement age or worked well past retirement age. And many "district" educational boards are encouraging senior teachers to retire early, so that younger, teachers with no seniority and lower hourly wages can fill those roles. Older teachers often disagree with the latest fads, and have the experience and knowledge to resist fads: middle management often finds those older teachers to be a dangerous "note of discord", and work politically to eliminate them quietly.
Please note that most of those issues occur in senior engineering roles. In IT, the sudden egress of senior tends to be much faster, and more concentrated to single companies.
Please actually look at the older generation, and revisit your own. Many younger people have _no idea_ how the technology works, much like their older peers. They have considerable hands-on familiarity with newer tools and no older habits to unlearn, but wait that same 10 years and they will be in a similar situation. I'm old enough to remember when 'C' and 'BASIC' were new and exciting. And it's a delight with my older colleagues and peers to learn new tools, and a personal delight to walk the young programmers through the same problems we had decades ago, problems they didn't realize the new tools would also have or which they ignored in testing.
I spent a very, very long week with developers and network architects arguing about the subtle disrepencies of their layouts and software and how their software works. And eventually, I took actual measurements and showed that for far less money, using the simplest tools provided the faster solution at a tiny fraction of the complexity and cost when you _actually measured things_.
This has been a consistent lesson throughout my career. People theorize and postulate endlessly with complex analysys and essentially fraudulent testcases, and don't examine it in the real world.
Just. Measure. It.
Philae did not have to apply significant force to the comet itself, especially applying consistent force as the comet itself melts, and to consistently apply force to the same side of the comet. Even if a solar sail is applied purely as a solar powered brake, the tumbling of a comet or asteroid will require that the attachment points be able to _spin_, and not to tangle the shrouds of the solar sail on the tumbling object itself. If the spin of the object has an axis on the side away from the Sun, it should be possible to attach there.
There are profound issues of how to attach robustly and avoid fracturing a comet, leaving a potentially deadly remainder still on target for Earth, if it is a porous, frozen object. I'd anticipate significatnt sublimation and thawing on even the backside if the solar sail does not reflect _away_ from the object. But the idea provides far more available thrust and control than draping coverings directly on a tumbling asteroid or comet.
I'm afraid "log jam" typically means getting a penis stuck during anal sex. Feces do not "compact" from anal sex: unless you've already got other problems. they're not that solid, and intestinal walls are somewhat elastic. They _squish_.
Until they know what the problem was, they're all at risk. If it's a maintenance mistake or bad series of parts, it could wind up applied to other aircraft and the failure only waiting to happen there, as well.
According tot he CDC at http://www.cdc.gov/reproductiv..., the unintended pregnancy rate male condoms is 18%. Whether "failures can be fixed", they're not being "fixed".
> I know people with HIV can be kept alive for a long time, but they are obviously infecting other people,
HIV can be "clinically latent" for 10 years. That is a _long_ time to be infectious but without symptoms. For someone sexually active, that is also a long time to have a single sexual partner and rely on both themselves and that partner to be sexually monogamous. And given the sexual activity of some people and of their cultures, I'm afraid the continuing though much reduced spread is not surprising.
Doctor A died of AIDS? I'd not even realized, his family apparently kept it quiet for along time. Given Isaac Asimov's reported and repeated history of sexual harassment of female fans, especially in letters such as this one (https://www.facebook.com/IndianAtheists/posts/197188677080469), it does raise some interesting questions about other possible vectors by which he may have gotten AIDS. If you dig into old letters about him, he was what we would then call "an old rogue with a twinkle in his eye" and now we'd call "a sexual harasser" and eject form a science convention, even if here were a guest-of-honor.
Also: condoms sometimes break, sometimes they slip off, and sometimes they are used incorrectly. It is much safer not to point that gun at a person, even if you're sure the safety is on and the gun unloaded.