It drives me bananas when people write posts like this and I see it online alll the time. Unless you care more about some corporation than your fellow consumer, NAME NAMES! There is essentially ZERO reason for a company to change practices other than bad PR, and you can't create that without naming them.
By picking the shape and trajectory, we can have quite good accuracy on where to land the debris. Pick a piece of federal desert land and there you go.
Seriously, the scenario as I understand it is: we'd park an asteroid in a high orbit
Bad assumption right from the beginning. That's a terrible waste of energy. You mine an earth-crossing asteroid. Chunks mined off an earth-crossing asteroid can be put onto an earth-intersecting trajectory with only the tiniest of delta-V (you might have to wait a long time your payloads, but no problem there). The amount of delta-V is so low (dozens to hundreds of m/s) that you wouldn't even need to use a rocket, you could just kick it off with a railgun or similar. Then you don't brake it when it gets to earth - it brakes itself by crossing through Earth's atmosphere ("aerocapture"). There are various optional things one could do with the reentry chunks to assist, such as small rockets for trajectory adjustment en-route or small high-speed chutes to keep the asteroids from completely obliterating themselves on reentry / landing (no need for a soft landing, it's fine for them to hit moving at hundreds of meters per second). Both of these would be dwarfed orders of magnitude over by the mass of the return chunk.
All you, as a mining operation, need to do is get your operation up to the asteroid. You need to be able to mine off chunks, shaped appropriately for optimal reentry, and kick them off onto an ideal reentry trajectory toward your target impact zone - potentially with the various hardware systems described as above, but in the base case, not with anything at all. You need a source of power (solar, nuclear) for mining and to kick your chunks into their Earth-intercept trajectory. And of course you have to deal with a million and one details, starting with how to mine at all in microgravity and what targets would actually have commercially viable quantities of valuable minerals.
Which is why you send as optimal of a size and shape as possible. Note that asteroids normally come in randomly and have random shapes. Humans can have a huge impact on the behavior by choosing an optimal shape and trajectory. And, as mentioned, drogue chutes could be used to further reduce the free fall velocity - not for a gentle impact, simply to keep the velocity down to a level that it won't completely obliterate itself in the atmosphere or on impact.
Yeah, but experience with gigantic hypersonic parachutes is also rather limited.
Again, it's really doubtful that there's any show stoppers here. But there's a lot that needs to be done before you can bet a whole mission on these sort of things. There's many thousands of little details that could kill the crew if they go wrong, so the odds of any one doing so must be kept to the tiniest fraction of a percent.
Except that your terminal velocity on Mars is orders of magnitude higher than on Earth. Decelerate to subsonic then fall and you'll be back supersonic in no time.
I'm sure this is possible to do, but it absolutely requires more research and testing.
How exactly would that happen? Isn't ballistic capture's main drawback that it's slower than a Hohmann transfer?
Isn't leaving crews drifting in space longer increasing one of the main challenges of a mars mission - crew survival in transit?
Which is a good reason to do a full discharge once. (Or once a year or so. Or a month, like the GP said: To calibrate the controller...)
Exceptions that prove the rule. Out of thousands of cultures, the number of premodern societies that attempted any serious, sustained exploration can be counted on one hand. And really, its doubtful that premodern migrations to the Americas were any kind of deliberate exploration effort. It was probably just nomads following the herds.
Look at this way, modern humans have been around for about a quarter of a million years. The first migrations out of Africa were only about 30,000 years ago. If exploration were really some fundamental human constant, it seems odd that we spent 90% of our time in a relatively small portion of one continent.
Actually, proto-humans migrated repeatedly out of Africa. Homo erectus, Homo antecessor, Homo neanderthalensis, and finally two waves of Homo sapiens moved out of Africa and into Eurasia. North America was colonized repeatedly by Homo sapiens, by the Amerindian, Navajo-Dene, and Inuit peoples. Migration probably is in the genes. Lineages that become widespread are harder to wipe out as a result of drought, famine, climate change, etc. so lineages with some innate tendency to disperse probably tend to survive. But it's kind of a moot point. The places they went to already had atmospheres, normal gravity, ambient temperatures, radiation shielding, abundant game and edible plants. Mars has none of that. It was simple enough to move out of Africa that a cave-man could do it, literally. It doesn't follow that because humans could and did repeatedly move from continent to continent that it's a good idea to try to colonize a cold, barren, airless wasteland millions of miles away.
Yes we can create robots that go out there and study very specific things. They are planned well in advance, do only very limited things, and frequently fail because they're not totally autonomous and adapt poorly to the unexpected.... case and point: Rosetta's Philae lander....or any number of probes that have malfunctioned or been lost. If you put a single human out there, they can fix the problem. A person can conduct hundreds of experiments where a machine is limited to a few. A person can analyze and interpret results onsite, even design new experiments. A person can build things, onsite.
It's a bullshit argument. The problem is that a robotic mission is going to cost on the order of 1% of a human mission to do the same thing. If there's a risk of the lander failing, the cheapest and easiest solution is to create two or three separate robotic probes which minimizes the chance of failure. Obviously a 100 billion dollar manned mission will be more capable than a 1 billion dollar robotic mission. But a 100 billion dollar robotic mission would be vastly more capable than a comparably expensive manned mission.
The value of NASA has never been commercial. It is a pure research area. WE are learning how to live and work in space, which is an environment so alien to us that our bodies don't even function properly. That knowledge flows into the private commerce section of our economy and slowly brings benefits that we have yet to imagine.
I keep hearing this argument, in fact I've been hearing it for around 20 years. And during that time, we've spent hundreds of billions of dollars on NASA. So it's about time to ask... where is all this spin-off technology we've been promised for the past 20 years? Most of the major innovations we've seen are either military (GPS, internet) or commercial (cellular networks, smartphones). It's hard to point to a single transformative innovation to come out of NASA recently, and historically the military has done far more to spur technological innovation than NASA. I'm not arguing that building more F-35s is the best way to spur technological innovation, but it's worth taking a hard look at where our research dollars make the biggest difference, and I think it would be hard to show that NASA is the best way to do that.
Meanwhile, the defense budget is only 1/6th of the federal budget and falling. The left got their way: America's military dominance is fading.
The defense budget is 20% of the federal budget, which is around 1/5th. America's defense budget exceeds that of the next 10 largest defense budgets *combined*. The U.S. still has unquestioned air superiority in every conflict it enters, a fleet of aircraft carriers to project that air power, ballistic missile submarines that can rain down nuclear death at a moment's notice, a rapidly growing drone army to silently hunt our enemies from the skies, electronic intelligence and cyberwarfare capabilities to spy on the whole world, and critically, the network of ships, bases, and air transport to rapidly move troops and supplies to conflict points anywhere on the globe and project that military force... America is the only remaining global military power. No one else- not China, not Russia- has that ability to project power beyond their regional sphere of influence. It's not limitless power, as shown by Iraq, Afghanistan, or even Viet Nam, but it still makes the U.S. the only remaining superpower. And if anyone's hurting the U.S. military preparedness, it's not the left, it's the generals who push for expensive toys like the F-35 instead of focusing on problems like counterinsurgency warfare.
It costs more for the fuel to de-obit platinum safely than the value of platinum
Asteroids seem to deorbit pretty effectively on a fuel budget of zero.
Your return chunks of asteroid are their own ablative. Ideally you'd give them as optimal of a reentry shape and trajectory as possible, but you wouldn't brake them, you'd just aerocapture, and then give them just enough of a drogue chute that they don't disintegrate fully on impact.
StartSSL offers completely free-of-cost certificates that are widely recognized by browsers to individuals and non-commercial sites.
Sure, as long as you don't try to change the key on your pre-heartbleed webserver. They charge money for that, as far as I understand it.
StartSSL.com gives free Class1 and is preinstalled in every modern browser
Great. And what does somebody do if they have a pre-heartbleed certificate from startssl? Last time I checked they charged to revoke a certificate, and as I understand it they won't let you issue a new certificate for a domain you already have one for. Thus, I imagine that MANY startssl sites are using potentially-compromised private keys.
... the companies pushing for more visas are NOT doing it because they're looking for the best and the brightest from around the world. They're doing it to drive the price of programming
They're also creating a self-fulfilling prophecy. The depressed prices for programmers and refusal of employers to hire Americans (for any but a few top-level jobs requiring rare or broad-ranging talents and experience), while importing H1Bs from several countries for any position short of startup principals and early-hires, has not been missed by the Millenials. The latter are, entirely rationally, avoiding computer science degree programs in droves.
There is no shortage of US computer scientists now. But if this keeps up, in another 20 years there WILL be a shortage of YOUNG US computer scientists.