Also, chemical propellant is "heavy", meaning it takes much more mass to get an equivalent kick. If you want real words, the Isp (specific impulse) is lower for chemical propellant engines than for ion engines. With all electric satellites, you can carry much less propellant, meaning you can have a satellite of comparable capability in much less mass.
Ion propulsion is heavy too. While the ISP is very impressive - ISP isn't everything, except to armchair engineers. T/W matters too, and for electric T/W isn't all that impressive... and unlike chemical engines, there's very little benefit gained as fuel is exausted as the mass of the fuel is such a small fraction of total powerplant mass. There's a reason why electric propulsion has only found niche applications.
In the case of these two satellites, the Boeing BSS-702SP platform they're built on means you can fit two on a "normal" GTO launch. That basically halves your launch costs.
At the cost of requiring four to six months (as opposed to four to six days) for the satellite to reach it's station on orbit. (TANSTAAFL.) It's also worth noting that this is only possible because during orbital transfer, the communications systems that are the reason for the satellites existence are turned off - making their substantial power supply available for the electric engines.
The Falcon 9's first stage weight is estimated to be about 25 tons when empty. That's the stage that returns to Earth (or sea) and lands.
The Falcon can return to Earth and land because there is sufficient atmospheric drag to slow it down to the point where a modest amount of delta-V will allow it land safely. On Mars, there isn't sufficient atmosphere to do so.
That's the basic problem with Mars - the gravity is too high to land propulsively, and the atmosphere is too thin to land using solely aerodynamic drag.
Plus there are other possible advantages. The 190-mile range is more than sufficient to shift emissions out of most urban areas.
Very true. And while there is an awful lot of long distance hauling... There's also an awful lot of "from the nearest [port|railhead|distribution warehouse] across the local region" hauling too. This truck would fit that niche rather nicely.
A trucker friend of mine used to have a regular route running cars from terminal in Portland to various destinations around the Puget Sound basin... Even if he ran electric from Portland to his destination and natural gas back to Portland, the 150 mile range would cut his fuel consumption 40-60% (depending on the destination).
Don't think that those people selected to go will have to sign a few documents and undergo a few mental evaluations to make sure they really understand that they will most likely die on the mission?
That's not the problem - it's whether or not those documents and processes will stand the scrutiny of a court of law. It's whether or not they will withstand the scrutiny of whoever ends up granting the launch license. (Which is something of a grey area right now, the current process isn't set up to handle 'non traditional' commercial launches - something the Google X-Prize candidates are currently encountering.) Etc... etc...
The law (AIUI, IANAL) in general does not make any objection to informed people knowingly taking more-or-less known risks, but the risks of this kind of flight don't clearly fall into that category.
He hasn't explained how he will avoid radiation overdoses. Or how he'll do what NASA doesn't know how to do (land such a large vehicle). Or how the colony's ongoing costs will be paid for. Or... well, he hasn't explained much of anything really.
Not that such lack of explanations has prevented the fanboys from declaring the mission a success in advance.
The aggressive program to Mars is from SpaceX, not NASA.
o.0 Seriously? SpaceX has produced nothing Mars related to date but hot air and stroke material for the fanboys. The only concrete result has been an increase in demand for tissue paper.
Meanwhile, NASA has actual functioning spacecraft in orbit around Mars, and actual functioning rovers on the surface of Mars. They're bending metal on the next generation, and planning the generation after that.
The ISS hasn't gone an extended period without resupply because it wasn't designed to and there's no reason to. So that's an invalid datapoint with respect to what mission duration modern technology can achieve.
Yes.. and no. No, you can't determine anything from looking at the number and rate of flights in a simple minded fashion. Yes, you can learn a great deal from examining the detailed manifests and determining if spares are being shipped at a greater-than-expected rate (or less than, or not at all). Bog standard logistics analysis that dates back the better part of a century.
Admittedly, the astronauts will be more cut off from support or bailout options than on previous missions, but that can be remedied with a conservative mission profile. For instance, have a fully-fueled and checked out return vehicle (or better yet, multiple) and contingency supplies ready to go at Mars before the astronauts even leave Earth.
Actually, that doesn't decrease the risk - it actually increases the risk due to the greater number of launch and assembly operations, the increased number of burns, the requirement to rendezvous in Mars orbit (as opposed to staying with the same vehicle), and the requirement that the vehicle operate (and operate untended) for a much longer period than a simple out-and-back spacecraft. (Etc... etc...)
A reasonable estimate will show that the risk of death associated with a trip to Mars is about the same as or less than the risk from being a smoker.
A nice bit of circular logic - any estimate that disagrees with yours is simply unreasonable.
One guy said he was only one out of two engineers in a company of ten, and that even with only ten people they had a full time photographer on staff.
The full time photographer may be a bit much (depending on what the company does), but otherwise I don't see anything wrong with the ratio. Programmers are usually pretty clueless about this, but trust me - it takes a lot more than just sitting at a keyboard slinging code to make a company run.
Bernie's "free everything" has a funding plan that pays for all of it, and doesn't grow the debt.
He has a 'plan', sure. But it's not at all clear that it won't drive us deeper in debt - because most of his funding plans revolve around raising taxes that won't take many years to trickle down to the middle class. Who won't stand one minute for it, left or right.
Only his haters imply the plan can't work, when it's about the same as everyone else's, with just a few numbers changed.
o.0 Do you even realize what you just said - or have you really drunk so deeply of the kool-aide that you've taken leave of the ability to write and comprehend simple English? (Hint: What you just said is "Only his haters question his plan, even though it's different from everyone else's".)
That's setting aside the level of reality distortion involved in classifying everyone who questions The Messiah as a "hater".
Or maybe it's just hard, especially for a country of 24.9 million people that's largely isolated from the rest of the world. That's about 1/10 the size of the Soviet Union when they launched Sputnik (about 205 million), and the Soviet Union had considerable access to western knowledge both through espionage and German rocket scientists they snapped up.
It's not the 1940's or 1950's anymore - all the know-how of those German engineers (and more) can be had by hitting Amazon. The actual experience you can't get mail order of course, but being able to get the information is a huge step up.
If you're interested in stories like this, I recommend the TV series "The Bletchley Circle". Four ex-codebreaking women reunite in 1952 to uncover a serial killer, using the same skills they used to break encrypted messages during the war.
The reality is, most of the 'codebreakers' at Bletchley Park (men and women) had no need of any particular analytical skill... Ninety percent of them just used a recipe written by the boffins or (later) operated machines that operated according to said recipe. If a readable message didn't come out, they reported that back up the chain and awaited the delivery of an updated 'recipe'.
Which is not in any way to say that it wasn't important work, only that it's rote and mechanical nature is largely unknown and the glamour and skills largely overstated.
If there was anybody left who believed that dreadnoughts were still part of the future of modern navies (Ronald Reagan was one of the last hold-outs I think) then that illusion was dispelled by Pearl Harbour, Midway and other carrier battles in the Pacific.
Others have corrected you on the Battle of the Atlantic - so, I'll tackle this one. No, only armchair experts had their illusions dispelled by those carrier battles in the Pacific. Every one of them that resulted in the loss of a battlewagon came down to one of three cases - luck, a poorly defended battlewagon, or overwhelming air power. Naval experts date the end of the battlewagon to September 9, 1943 when a flight of six Dornier Do-217's each armed with a single Fritz-X glide bomb sunk the Italian battleship Roma and seriously damaged the battleship Italia. On the 9th and 13th of that month, two light cruisers were struck with a single Fritz-X each and were put out of action for months. On the 16th, the British battleship Warspite was put out of action by a single Fritz-X for most of a year - and probably would have been sunk had the second hit square rather than nearly missing. It was the guided glide bomb, essentially a forerunner of the modern cruise missile, that ended the dreadnought era.
You don't hear about this one so much, at least not in America, because all this happened in the Med (a secondary theater for the USN) and mostly to non-American vessels.
The average age of cars on the road right now is around 11 years.
The interesting thing about the average age of cars on the road in America is that it correlates fairly strongly with the state of the economy... Good times come, the average age drops. Bad times come, the average age increases. But ever since 2008, the average has been moving in a single direction - steadily upward.
Even though I staunchly support freedom of speech, part of the first amendment in the US also means you have freedom of association. That means that a private organization can squelch whatever speech they want so long as it's within their own domain.
Um... no, Freedom of Assocation doesn't mean that. It doesn't mean anything even remotely close to that.
Because slashdot is neither a public domain, nor a domain that you control, then nothing anybody can do to you can be considered censorship.
No, Mr Pointless Pedant, it can't be strictly considered censorship. But that doesn't mean, as you try to imply, that squelching alternative viewpoints isn't happening. It most certainly is, to the point where Slashdot is practically synonymous with groupthink.
The real answer is "correlation is not causation". And here in the real world in the twenty teens economic growth is stalling and the standards of living are flattening or dropping.
Try being on a submarine. When I left the 655, I kept my underway uniforms thinking that I'd be assigned to boat again someday... that never happened, so they got stuffed in a box and forgotten. Found them on our most recent move, and thirty years after the last time I was underway they still smell of submarine.
What's a cycle of depndency actually mean to you? It seems meaningless to me.
Is English not your primary language, or are you just stupid? Words mean things, and if you don't understand what dependency means then use a dictionary.
Second, there doesn't seem to be any evidence that people stop working.
Had I claimed people stopped working, you'd have a point. But I didn't. So kindly reply to what I wrote rather than what you wish to pontificate about, or just go away.
Third, and most importantly, why is a cycle of dependency worse than the status quo?
Again, I didn't say it was. (You really need to work on your reading comprehension and learn the difference between your bias and assumptions and what people actually wrote.) I said it didn't fix the problems.
If you want to fix the problem, the money is far better spent on education and providing opportunity (teaching them to fish) rather than strictly on handouts and support as we historically have done (just giving them fish).
You can't just throw "money" at drugs, poverty, disease, hunger, and despair, and expect them to go away.
Strangely enough, you can just throw money directly into the hands of the people who suffer poverty and hunger (rather than the middle-men) and it does actually seem to work.
You're correct - it seems to work. And if I take painkillers, my back pain seems to go away. But in neither case do the actual causes go away - while handouts break the cycle of despair it replaces it with a cycle of dependency. Which is why decades of throwing money at the problems hasn't worked.
Seems like the editor was trying to do the equivalent of investigative reporting, to the degree that it amounted to original research and detail excessive for a Wikipedia page.
Seriously, if you use Wikipedia on any regular basis, one thing you discover is that the 'standards' (such as 'original research') are very unevenly applied. And most Wikipedia policies are ripe for misuse and are often used for punitive and personal reasons rather than to set and maintain a quality level. Reading the message, that seems like it's very likely the case here.
Slashdot Mirror
Ion propulsion is heavy too. While the ISP is very impressive - ISP isn't everything, except to armchair engineers. T/W matters too, and for electric T/W isn't all that impressive... and unlike chemical engines, there's very little benefit gained as fuel is exausted as the mass of the fuel is such a small fraction of total powerplant mass. There's a reason why electric propulsion has only found niche applications.
At the cost of requiring four to six months (as opposed to four to six days) for the satellite to reach it's station on orbit. (TANSTAAFL.) It's also worth noting that this is only possible because during orbital transfer, the communications systems that are the reason for the satellites existence are turned off - making their substantial power supply available for the electric engines.
The Falcon can return to Earth and land because there is sufficient atmospheric drag to slow it down to the point where a modest amount of delta-V will allow it land safely. On Mars, there isn't sufficient atmosphere to do so.
That's the basic problem with Mars - the gravity is too high to land propulsively, and the atmosphere is too thin to land using solely aerodynamic drag.
What makes you think I'm talking about the transporter? The Dragon alone is much larger than anything we've ever landed.
Very true. And while there is an awful lot of long distance hauling... There's also an awful lot of "from the nearest [port|railhead|distribution warehouse] across the local region" hauling too. This truck would fit that niche rather nicely.
A trucker friend of mine used to have a regular route running cars from terminal in Portland to various destinations around the Puget Sound basin... Even if he ran electric from Portland to his destination and natural gas back to Portland, the 150 mile range would cut his fuel consumption 40-60% (depending on the destination).
That's not the problem - it's whether or not those documents and processes will stand the scrutiny of a court of law. It's whether or not they will withstand the scrutiny of whoever ends up granting the launch license. (Which is something of a grey area right now, the current process isn't set up to handle 'non traditional' commercial launches - something the Google X-Prize candidates are currently encountering.) Etc... etc...
The law (AIUI, IANAL) in general does not make any objection to informed people knowingly taking more-or-less known risks, but the risks of this kind of flight don't clearly fall into that category.
He hasn't explained how he will avoid radiation overdoses. Or how he'll do what NASA doesn't know how to do (land such a large vehicle). Or how the colony's ongoing costs will be paid for. Or... well, he hasn't explained much of anything really.
Not that such lack of explanations has prevented the fanboys from declaring the mission a success in advance.
0.o Child, did you even read what I wrote before posting?
o.0 Seriously? SpaceX has produced nothing Mars related to date but hot air and stroke material for the fanboys. The only concrete result has been an increase in demand for tissue paper.
Meanwhile, NASA has actual functioning spacecraft in orbit around Mars, and actual functioning rovers on the surface of Mars. They're bending metal on the next generation, and planning the generation after that.
Yes.. and no. No, you can't determine anything from looking at the number and rate of flights in a simple minded fashion. Yes, you can learn a great deal from examining the detailed manifests and determining if spares are being shipped at a greater-than-expected rate (or less than, or not at all). Bog standard logistics analysis that dates back the better part of a century.
Actually, that doesn't decrease the risk - it actually increases the risk due to the greater number of launch and assembly operations, the increased number of burns, the requirement to rendezvous in Mars orbit (as opposed to staying with the same vehicle), and the requirement that the vehicle operate (and operate untended) for a much longer period than a simple out-and-back spacecraft. (Etc... etc...)
A nice bit of circular logic - any estimate that disagrees with yours is simply unreasonable.
The full time photographer may be a bit much (depending on what the company does), but otherwise I don't see anything wrong with the ratio. Programmers are usually pretty clueless about this, but trust me - it takes a lot more than just sitting at a keyboard slinging code to make a company run.
He has a 'plan', sure. But it's not at all clear that it won't drive us deeper in debt - because most of his funding plans revolve around raising taxes that won't take many years to trickle down to the middle class. Who won't stand one minute for it, left or right.
o.0 Do you even realize what you just said - or have you really drunk so deeply of the kool-aide that you've taken leave of the ability to write and comprehend simple English? (Hint: What you just said is "Only his haters question his plan, even though it's different from everyone else's".)
That's setting aside the level of reality distortion involved in classifying everyone who questions The Messiah as a "hater".
It's not the 1940's or 1950's anymore - all the know-how of those German engineers (and more) can be had by hitting Amazon. The actual experience you can't get mail order of course, but being able to get the information is a huge step up.
The reality is, most of the 'codebreakers' at Bletchley Park (men and women) had no need of any particular analytical skill... Ninety percent of them just used a recipe written by the boffins or (later) operated machines that operated according to said recipe. If a readable message didn't come out, they reported that back up the chain and awaited the delivery of an updated 'recipe'.
Which is not in any way to say that it wasn't important work, only that it's rote and mechanical nature is largely unknown and the glamour and skills largely overstated.
Others have corrected you on the Battle of the Atlantic - so, I'll tackle this one. No, only armchair experts had their illusions dispelled by those carrier battles in the Pacific. Every one of them that resulted in the loss of a battlewagon came down to one of three cases - luck, a poorly defended battlewagon, or overwhelming air power. Naval experts date the end of the battlewagon to September 9, 1943 when a flight of six Dornier Do-217's each armed with a single Fritz-X glide bomb sunk the Italian battleship Roma and seriously damaged the battleship Italia. On the 9th and 13th of that month, two light cruisers were struck with a single Fritz-X each and were put out of action for months. On the 16th, the British battleship Warspite was put out of action by a single Fritz-X for most of a year - and probably would have been sunk had the second hit square rather than nearly missing. It was the guided glide bomb, essentially a forerunner of the modern cruise missile, that ended the dreadnought era.
You don't hear about this one so much, at least not in America, because all this happened in the Med (a secondary theater for the USN) and mostly to non-American vessels.
The interesting thing about the average age of cars on the road in America is that it correlates fairly strongly with the state of the economy... Good times come, the average age drops. Bad times come, the average age increases. But ever since 2008, the average has been moving in a single direction - steadily upward.
Um... no, Freedom of Assocation doesn't mean that. It doesn't mean anything even remotely close to that.
No, Mr Pointless Pedant, it can't be strictly considered censorship. But that doesn't mean, as you try to imply, that squelching alternative viewpoints isn't happening. It most certainly is, to the point where Slashdot is practically synonymous with groupthink.
Whatever he damn well pleases.
That sounds more like the problem is creating languages that aren't general purpose than anything else.
Well... Like a submarine! :) Seriously, it's hard to describe. And each boat smells a little different.
The real answer is "correlation is not causation". And here in the real world in the twenty teens economic growth is stalling and the standards of living are flattening or dropping.
Try being on a submarine. When I left the 655, I kept my underway uniforms thinking that I'd be assigned to boat again someday... that never happened, so they got stuffed in a box and forgotten. Found them on our most recent move, and thirty years after the last time I was underway they still smell of submarine.
The folks whining that corporations should give away their software aren't interested in contributing - they're interested in handouts.
Is English not your primary language, or are you just stupid? Words mean things, and if you don't understand what dependency means then use a dictionary.
Had I claimed people stopped working, you'd have a point. But I didn't. So kindly reply to what I wrote rather than what you wish to pontificate about, or just go away.
Again, I didn't say it was. (You really need to work on your reading comprehension and learn the difference between your bias and assumptions and what people actually wrote.) I said it didn't fix the problems.
If you want to fix the problem, the money is far better spent on education and providing opportunity (teaching them to fish) rather than strictly on handouts and support as we historically have done (just giving them fish).
You're correct - it seems to work. And if I take painkillers, my back pain seems to go away. But in neither case do the actual causes go away - while handouts break the cycle of despair it replaces it with a cycle of dependency. Which is why decades of throwing money at the problems hasn't worked.
Seriously, if you use Wikipedia on any regular basis, one thing you discover is that the 'standards' (such as 'original research') are very unevenly applied. And most Wikipedia policies are ripe for misuse and are often used for punitive and personal reasons rather than to set and maintain a quality level. Reading the message, that seems like it's very likely the case here.