Firwen
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Posts posted by Firwen
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Firwen: *facepalm*
I'm sorry if I was a bit offending but I'm particularly annoyed by people that try to sell nuclear power as "safe" as "inherently safe".
It is not "safe", there is a risk, but fortunately, this risk is minimised to almost null by a good engineering and by competent people.
In my opinion this kind of "propaganda" used by the nuclear industry since ever contributes to make the general public so suspicious about nuclear energy. People do not trust nuclear industry anymore, nor they believe in nuclear energy due to 60 years of extremely bad communication and lies on the topic.
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What if i told you a modern nuclear reactor *is* safe when handled properly ? Just, how is a nuclear power plant not safe ? Chernobyl ? Don't blame the reactor. Fukushima ? Shouldn't have been built there. And that's it...
They are not. All current nuclear reactor are *unsafe by nature*. All current reactors ( with the exceptions of ADS prototypes and molten core prototypes ) are over-critical and consequently can run out of control (melt or explode) if their cooling system goes down. This is a reality, period.
Now, yes they all have a bunch of security systems to avoid that, but everyone that has done a bit of engineering in his life know that if a thing *can* physically happen, it *will* happen. And it's just a matter of time before we get an other Three Miles Island, Chernobyl or Fukushima-style problem. Yes it happens due to human mistake, but fact is that it still happens anyway.... and even in "rich" modern countries.
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And lastly, the waste. Nuclear waste is actually one of the more "cool" things about nuclear energy. The quantity produced is absolutely puny, for fission products, the material actually produced as waste from the reaction, you would get (assuming the products have approximately the same density of uranium) about 1 cubic meter per year per 1000 MWe nuclear reactor assuming a 30% heat to electrical energy conversion efficiency.
Nuclear waste has nothing cool, and it would be nice to be honest in your argumentation.
Nuclear waste is the biggest problem of nuclear energy currently. It is a a problem to store, it is a problem to retreat. Some nuclear waste, like plutonium that the current generation of reactor produces, stay dangerous for period up to 200 000 years, meaning far more than the duration of any human civilisation in History.
Without even speaking of the danger that represent the spreading of such waste... nuclear proliferation, risk of "dirty" bombs for terrorist act, contamination of environments....
The main problem of nuclear energy are :
- The safety, because yes, current generation of reactor are nothing else than "The most dangerous way to boil water"
- The waste, which is today a major sources of problem for nuclear energy, and which cost an awful amount of money to retreat.
In my opinion, Nuclear energy is a domain where the research simply failed. They failed in 40 years to create production inherently safe sub-critical reactors. They failed to create nuclear reactor than can be miniaturized and used outside of the military / power plant domain for civil application. They failed to create reactor able to transmute they own waste ( and please don't talk about these sodium powered madness named sur-generator ).
Nuclear is still today, unfortunately, a beautiful concept on paper, and a terrible concept in reality.
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None of the other contenders can match the capabilities of Cargo Dragon without some development work, and therefore risk. I think Cygnus is ahead of CST-100.
Has Orbital Sciences ever talk about downmass or reentry for Cygnus ?
Up to my knowledge, nor Cygnus nor Cygnus enhanced have been design for it. They are built around a Thales Alenia aerospace pressurized module, single-block and without heat-shield or re-entry capacity.
If downmass and re-entry are a main requirement for CRS-2, that's imply a major redesign of their vehicle.
The only other two spacecraft being already designed for re-entry being the Dream Chaser and CST-100.
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China also have lots of desert areas where land is free, this is not the case in Europe, no real reason to build it underground at all.
One idea will get to get other to pay for the instrument packages, they just provide the accelerator
I can guarantee you that you can find way more than 100 km of free space in Europe ^^.
The main reason to a build particle accelerator underground is not because of the lack of space but for shielding reasons:
- Synchrotron emits a tangential synchrotron radiation that need to be shielded. This radiation can be pretty powerful in case of large accelerator. This shield comes for free underground.
- Detectors and particle accelerator are extremely sensible to electromagnetic interference. To have an idea, the LEP at CERN was suffering of a visible interference due to the action of a Swiss train 25km away.
Again, building underground gives you the shielding for free.
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Capsules are also lifting bodies, they just don't need to carry all that stuff to space and back
Capsules, excepted for the Apollo one, has as much lift and manoeuvrability that a random stone thrown from space.
It has winglets, control surfaces, landing gear, tyres, brakes, doors, hydraulic lines, reservoirs, and pumps. It also has heavy heatshield material that covers a much wider area and which is exposed to MMOD damage throughout the mission.The DMC shield is an ablative shield of the same kind of the ones used by the capsule and that has been used by the European IXV for demonstration, nothing new nor risky there.
All the others are all well-proved technology that has been around in the aerospace industry for 20 years.
The entire DMC concept is just to rely on "cheap" and proved technology: proved aerodynamics from HL-10/HL-20, simple/safe hybrid propulsion using nitrous oxide, ablative shield, composite structure made by Lockeed, RCS without hydrazine, simple landing gear with skies, etc, etc.
The main drawback of it would be its weight (11T) ....and even this seems rather reasonable compared to Progress/Soyouz (7-8T) or CST-100 (10-13T).
I have the impression that people hates the Dream Chaser just to hate the Dream Chaser. Mainly because they see the failure of the Shuttle by looking into it.
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I don't do hate. I do rational. The appeal for wings is irrational. I understand that it looks nice to Buck Rogers fans, but it's simply not the best use of upmass and esthetics shouldn't be a factor when it comes to selecting the best vehicle for the job.
The Dream chaser does not have wings, it has lift. And lift for a craft supposed to make regular atmosphere re-entry makes perfect sense.
Landing accounts only for the last few minutes of an orbital mission, yet the wings and all the associated systems (landing gear, hydraulics, larger heatshield...) take up the largest fraction of mass on the vehicle.Are the 8 SuperDraco engines + associated explosive propergol + landing legs + 2 emergency parachutes needed to the Dragon Capsule Massless ?
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Reusable. Lifting body. Hybrid engines. None of those are actual requirements for the CRS-2 mission. Actually, they are programmatic risks that are likely to score negatively in NASA's evaluation process.
I have to say that your forum-wide famous hate for the dream chaser is rather exhausting sometimes.
They are different technical choices, which obviously will give different results. That's precisely why I find them interesting.
NASA sponsors two programs. I would rather sponsors two program with radically different approach (two different launchers, two different concepts, two different propulsions) than two programs fundamentally similar:
1- The chance that the failure of one impacts the other is lower.
2- You analyse two radically different concepts in a real use case and learn out of it for later designs.
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I would say SpaceX and the Dream Chaser to have two different concepts in flight and being able to compare it.
- SpaceX for a relatively low cost capsule-based solution, already tested.
- The Dream Chaser for a reusable lifting body with hybrid engines.
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I assume linux does things more or less the same way, with some kind of install script. i dont really know what happens when i 'sudo apt-get install whatever', but i assume it does a lot of the same things that windows installers do.
It does not. Windows is the only operating system to act in this "dirty" way.
On Mac OSX, most of the programs are "self-contained". They are nothing more than a directory following some convention that you can drag-and-drop where you want ( by default in the application directory ).
Linux distributions have packaging systems. deb or rpm packages are more or less a "zip" of a list of file that are copied in predefined place. RPM/DEB can have scripting. The configuration under Linux is done "per application" via configuration file and there is no such (ugly) thing as "the registry".
Android use an hybrid system between the Linux way and the OSX way. They have a packaging system but each package is mainly "self-contain" to be isolated from the OS itself.
The concept of installation is a thing quite specific to Windows.
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Robots can do a lot already, saying that there are complex things that only humans can do is mostly an argument from ignorance. Dismissing someone by an equivalent of "that's just your oppinion" is a pretty bad behaviour in a discussion.
I apologize if I offended you. Far from being what I looked for.
I simply do not see the point to discuss manned vs unmanned space exploration again, this has been reviewed and documented countless number of times in the literature. And a simple scholar.google.com query would give you as many information as you want.
Most of the reasons are obvious. The reason we do today unmanned mission is mainly because of cost and simplicity.... NASA does not have unlimited budget and the Apollo missions and the ISS are a brilliant example of how costly human flight is.
However, a bunch of humans on Mars in a ISS-sized landed laboratory would open experiments possibilities that you would not even dream of ( bio/botanical experiments, life development under Mars gravity, Terraformation experiments, long range explorations, advanced chemical analysis.... ).
I think I'm pretty well informed on what Robots can do and can not. Simply because it's part of my job.
As cool as Robots are and as performant as they tend to be, they are not magic and they are still far from human flexibility. They are good to do simple, repetitive task, in well defined environments, in space like every-where else.
Or you should ask yourself, why we have the ISS today and why we do not have replaced everything by Robots on Earth
What we name today robots, are not robots, but mainly remote controlled un-brained "bot" trying to do pre-programmed defined job.
This has a lot of limitations. Speed of light being what it is, you will and will always have ultra-high latency in remote space operations which limit a lot what you can do and what you cannot. This is not KSP, in real world latency matter.
A Mars round-trip-time is around 20min, this is awfully long. If Curiosity has between 2012 and 2014 done only 8.4km (which is already amazing), it is mainly due to the complexity to operate with precision any unmanned probe over such high latency. Each little movement need to be verified carefully after a 20 min delay....
Without even mentioning that if space radioactivity impacts living creature already badly, it is even worst with Electronic. Any Electronic designed for space need to be specially designed, tend to be unreliable, and is millions time less powerful than common available Earth-Chinese-electronic nowadays.
Advanced AI could theoretically solve this, but they come with their own set of problems, are not adapted to today embedded systems, even less to space ones.
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I am going to repeat what I said last time this came up: there is simply no reason to send humans beyond NEO (probably even not beyond LEO). Everything farther away is best done by robots (e.g. researching planets/asteroids) or directly on earth (e.g. psychological effects of isolation or building geodomes).
And this time: please don't respond with "arguments" that are just a very convoluted version of "space is cool". Yes, it is. Doesn't justify spending craploads of money on something of little scientific value that could have been done at 1/10th the price by robots or on earth.
Again, It is your point of views and your "arguments", not the one of everyone here.
A lot of experiments today can be done only by humans due to their complexity, and only this justify human spaceflight outside of earth.
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Hmmm, I think you're being a bit cynical here, maybe I'm just a fanboy falling for his good PR, but I actually believe Musk when he says the primary goal of Space X is to colonise mars. Every time you hear the man speak about the founding of SpaceX and his companies primary goal, mars is all he ever talks aboutI may be
Or I simply get old.
I trust only facts, not promises, and specially not the ones from politicians and businessmen.
When SpaceX will fund on its own a probe or anything concrete to go there, I will start to believe in this. For now, this is just nice communication and free publicity for them.
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As for SpaceX, Elon's going to Mars. He's proven he has what it takes to do crazy wonderful things, and I think he's going to succeed in making humanity a two-planet species.
I like SpaceX and I would not like to break your dreams... but SpaceX is a company and like any other company, they are here to be profitable and make money. Making sciences progress and helping humankind are side effects for them, not primary goals.
They will really invest money and time to do a Manned Mission on Mars only if it is financially interesting to do, and currently, it's not.
Pionners manned Mars mission need to come from public funded organizations like NASA, ESA or NGO. Nobody else would accept to invest the amount of money necessary to such programs without any guarantee return on investment.
The main problem we have now, is that such organizations got funding from public, and general public do not understand nor approve such program.
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Ever heard of Project Orion?
I knew it and I got the reference.
But only Jebediah can consider replacing "flammable" propulsion by nuclear bombs as being "safer"
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Hmm...do you count nuclear bombs as non-flamable fuel? Because, (correct me if I am wrong) technically you can't burn nuclear fuel. The reaction is different. So rockets that get their propulsion from the detonation of a nuclear bomb would probably fit this criteria, yes?
This is the kind of idea that Jebediah would love.
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Some hybrid engines, like the one of the Dream Chaser use a mix of solid propellant and not-inflammable, not-toxic liquid propellant.
This is considered safer than classical liquid fuel + oxidizer.
However, they have a lower ISP than traditional liquid engines.
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You guys are right. It is almost unreadable. That's the reason why I don't like C++. It's just too easy to make a mess of a code nobody comprehends. And you have to be cautious to not accidentally do something wrong.
Nobody force you to do monkey coding in C++ ^^, C++ is perfectly readable and easy to understand done right, like any language.
@bartekkru99 If you want to start by something easy, when you can learn about the different basic concepts of programming ( recursion, loop, function, object-oriented, design pattern), try Python as language. It is a language that allow you to get result fast and appreciate what you do
Second language, try C. which will allow you to understand the low level aspect of programming: manual memory management, memory protection, pointers, etc, etc.
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Ok, I'm not daft. I know the Linux version will have problems too. Learning the new stuff is hard because my memory is awful nowadays. (I had to recheck that PPA was the acronym I wanted to use earlier.) But opperatingsystemly speaking, I Feel Free! (this is where other Linux users hit me up with some rep
)And you are right.
Using Linux is the first thing to do for anyone who wish to really understand computer sciences.
When you really start to be used to Linux/UNIX environments, you simply can not use something else:
- Linux allows you to control / understand anything in your environment: everything can be logged, removed/added, modded, modified as you want. You can know what your system do, how, why.
- Linux has a development ecosystem far more rich and friendly than Windows, almost any language compiler, popular librayr or scientific software exist under linux.
- Linux is free, you can really TRUST your desktop and stop to worry about one of your app potentially infected/vulnerable/full-of-spyware.
- Linux offers you a SHELL, and when you have understood how powerful it is, you simply can not live without it.
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XP was easy to use, and when I got the newer ones they looked completely different. They were so much more complicated and not user friendly.
You know, you have other things and way better things than Windows in this world ^^
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As I already said, you can continue any research you want as long as it is actuall research (yes, even on how to send people to mars); but so far nobody has mentioned a good reason for why we actually should go there anytime soon, except to satisfy our own ego.
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Randomly
a) Study how human beeing adapted under other planet constrains. Which is the next step after a space station....
Proceed to advanced scientific experiments that robots can not do ( deep drilling, advanced rock/material analysis, adaptation of Earth life on other planet ? )c) Study / Start terraformation to solve future potential over populations.
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XP is the greatest piece of software windows ever developed. They shouldn't have dropped support. Especially since the newer OSes are more mobile device oriented. Unless they decide to not do that...
XP is not good. He is just less worse than the following ones...
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But the really expensive and, from a scientific point, useless steps (especially: actually sending people) should not be taken. We gain nothing of value from that.
In the same way than on earth, you have actions and scientific experience that can be done only by human nowadays. And probably still for few decades.
We are talking about many billions of dollars here, something that could be better spent on either a) science, helping the poor, c) having a better life (the difference to being that this is more egoistical).That's not a valid excuse.
You have currently a lot of billions spent on things way more useless than "doing science and bring humanity for the first time of its existence on an other planet". If you want to save money to "help the poor", start from there. It has already been proved that getting humanity out of poverty is not a money problem, it is a political problem. UN reported a while ago that the amount of money needed to solve world hunger, is equivalent to one week of US military spending.
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The X Window System, a major part of the Linux Desktop, is some 29 years old. The problem is in the arrogance in thinking newer is better.
If you knew a bit XFree86, Xorgs today has almost nothing in common anymore with what it was 29 years ago, it evolved a lot. It's open source and consequently, it has evolved continuously.
You can not say the same about XP.
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an American "news" organization would never confuse a video simulation with a game
Indeed.
An American "news" organization would not do this. Fox news would probably show a video of Saturn V and present it as Falcon 9, or something similar
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Proceed to advanced scientific experiments that robots can not do ( deep drilling, advanced rock/material analysis, adaptation of Earth life on other planet ? )
Blue Origin successfully lands a rocket stage that's flown to space
in Science & Spaceflight
Posted
I have some difficulties to understand the interest of fighting to know which billionnar did what first, where none of them are pioneers. Sub-orbital flight with vertical controlled decent and precision landing are masterized at least since the 90's and has already been done with success by the [URL="https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-X"]Delta clipper[/URL] 20 years ago.
None of them are gods, [I]guys.[/I]