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Old 13th February 2018, 06:52 AM   #81
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In case you couldn't tell, I find the criticism that they could have launched something useful less than compelling.

They simply could not have done better than they did. This way, they cheaply demonstrated capability and inspired probably thousands of young people to think about a career in STEM.

Rant over.
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Old 13th February 2018, 07:10 AM   #82
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Originally Posted by Octavo View Post
In case you couldn't tell, I find the criticism that they could have launched something useful less than compelling.

They simply could not have done better than they did. This way, they cheaply demonstrated capability and inspired probably thousands of young people to think about a career in STEM.

Rant over.

Yes, but can I just make an implausible suggestion based on no knowledge or experience of the processes of getting a new launch vehicle certified? Please? I could suggest something that's only viable in my mind and go on about it and put my fingers in my ears when people who do this for a living have said it's not feasible?
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Old 13th February 2018, 07:13 AM   #83
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Originally Posted by 3point14 View Post
Yes, but can I just make an implausible suggestion based on no knowledge or experience of the processes of getting a new launch vehicle certified? Please? I could suggest something that's only viable in my mind and go on about it and put my fingers in my ears when people who do this for a living have said it's not feasible?
Yes, please do. I'm sure those people won't mind entertaining yet another hare-brained LEGO rocket idea, there's no way that gets old.
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Old 13th February 2018, 07:17 AM   #84
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I have no issues with them not putting a useful payload on this particular rocket, for reasons other people have given many times.

But rocket launches in general? I wonder what lives/property/carbon has been saved by having satellites up there? Does satnav save carbon by providing efficient route planning? Tracking storms must, I'd imagine, save lives and property. Cut out the pure research projects (Mars rovers, orbiting telescopes, Rosetta-type missions etc) and save CO2 by sticking only to practical missions? Personally I'd hate to see that, but that's because I find them fascinating.

Still, what's the alternative to the current fuels?

1. StarTram type systems. A distant prospect, if that. Even if it were feasible it would be fabulously costly to construct (in money and energy), would still require substantial energy input to power it, and leaves the question of spacecraft reusability hanging. Nah, I don't think so.

2. Synthesise chemical fuel, such as methane. It would take a hefty field of solar panels and/or wind turbines to power each plant but it would be 'clean' fuel in the long term. Could that same energy be put to better use? It depends on the value of space missions, in both senses of the word as I outlined above.

3. Is there an option 3? Maybe, but it doesn't spring to my mind.

As for saving every ounce of CO2 if at all possible, well, I'm not sure I can agree. We probably all hate to see office buildings and the like burning electricity overnight because some idiots are careless about switching off lights, but how about floodlighting a beautiful building in the dark? Saving every possible ounce of CO2 - no matter what the cost in terms of the quality of our lives - doesn't strike me as the right way to tackle the problem. So I agree with those here who are saying we should go for the big sources of waste first, the areas where the big gains are to be had easily. Tackle the little ones at the same time too, sure, if it's a reasonable way of using resources.

If the B household really needed to save money it wouldn't make sense (to me) to fret about growing more veg in the back garden, it would make sense to save on the major items of expenditure. It that solved our money woes then we could just forget the hassle of weeding the radishes
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Old 13th February 2018, 07:36 AM   #85
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Originally Posted by GlennB View Post
.......3. Is there an option 3? Maybe, but it doesn't spring to my mind........
Skylon will use hydrogen. And the craft is 100% re-useable.

Currently hydrogen is produced almost exclusively from petrochemicals, but there is great potential for producing it in a number of carbon neutral ways, including using algae. Algae, BTW, have been developed which emit pure diesel with sunlight and water being the only inputs. This is obviously potential rather than existing technology, but proof-of-principle testing has happened. Before anyone tells me.......yes, hydrogen is less energy dense than kerosene.
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Old 13th February 2018, 07:41 AM   #86
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Originally Posted by MikeG View Post
Skylon will use hydrogen. And the craft is 100% re-useable.

Currently hydrogen is produced almost exclusively from petrochemicals, but there is great potential for producing it in a number of carbon neutral ways, including using algae. Algae, BTW, have been developed which emit pure diesel with sunlight and water being the only inputs. This is obviously potential rather than existing technology, but proof-of-principle testing has happened. Before anyone tells me.......yes, hydrogen is less energy dense than kerosene.
Fair enough, but I'd include that in my option 2.
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Old 13th February 2018, 07:42 AM   #87
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Originally Posted by GlennB View Post

Still, what's the alternative to the current fuels?


2. Synthesise chemical fuel, such as methane. It would take a hefty field of solar panels and/or wind turbines to power each plant but it would be 'clean' fuel in the long term. Could that same energy be put to better use? It depends on the value of space missions, in both senses of the word as I outlined above.
No doubt, it's energy-intensive. All the more reason we need to start developing space based power systems.

(yes, I'm making a circular argument. I thought it was funny though)
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Old 13th February 2018, 07:43 AM   #88
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Let's just put it this way: space launches add a negligeable amount of carbon in the system. If we get rid of petroleum-based fuel cars and power plants, then rockets, planes and boats won't matter.





End if.
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Old 13th February 2018, 07:55 AM   #89
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Originally Posted by Belz... View Post
Let's just put it this way: space launches add a negligeable amount of carbon in the system. If we get rid of petroleum-based fuel cars and power plants, then rockets, planes and boats won't matter.





End if.
This.
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Old 13th February 2018, 08:27 AM   #90
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For anybody interested there's a good summary of the issues surrounding the rail-gun, StarTram kind of thing at space.stackexchange.com Scroll down to "15" for the meaty bit. An excerpt:

"...4 Gs is the maximum we like submitting our astronauts to in a seated position, since they're not all fighter pilots in prime condition able to handle 6-8 Gs for long maneuvers.

To get the [necessary] delta-V with acceleration limited to 40m/s2 (just over 4G) would require 200 seconds, during which time you would have traveled 800,000 meters (the required length of the barrel of the railgun). 800,000 meters is just shy of 500 miles; you're talking about engineering a track from Dallas to El Paso, TX, with millimeter tolerances for deviation per kilometer of track from being perfectly straight. It would be the biggest and most expensive single civil engineering project the human race has ever undertaken; bigger by far than the current bullet train systems, bigger than the CERN supercollider, bigger than the U.S. interstate project."

... and that's before you even think about lifting the exit high enough to get into sufficiently thin atmosphere.
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Old 13th February 2018, 08:43 AM   #91
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I want to see the cranes involved in building something like that.
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Old 13th February 2018, 08:56 AM   #92
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Originally Posted by MikeG View Post
I want to see the cranes involved in building something like that.
Yes, or really excellent scaffolding? It's one of those things that is - on paper - technically possible but so impractical that it might just as well be plain impossible. This forum sees a lot of arguments over such things
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Old 13th February 2018, 09:11 AM   #93
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Originally Posted by MikeG View Post
Skylon will use hydrogen. And the craft is 100% re-useable.

Currently hydrogen is produced almost exclusively from petrochemicals, but there is great potential for producing it in a number of carbon neutral ways, including using algae. Algae, BTW, have been developed which emit pure diesel with sunlight and water being the only inputs. This is obviously potential rather than existing technology, but proof-of-principle testing has happened. Before anyone tells me.......yes, hydrogen is less energy dense than kerosene.


As an aside, the use of hydrogen fuel comes with the small advantage of reducing re-entry speeds as the vehicle has a smaller mass/volume ratio once it's out of fuel.
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Old 13th February 2018, 09:11 AM   #94
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Originally Posted by RedPillNeo View Post
Why a terrestrial car that cannot possibly be used in space?
I bet they felt stupid when they got it up there!

Elon Musk [horrified]: "Oh crap! I forgot to build the roads!"
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Old 13th February 2018, 09:16 AM   #95
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Originally Posted by 3point14 View Post
As an aside, the use of hydrogen fuel comes with the small advantage of reducing re-entry speeds as the vehicle has a smaller mass/volume ratio once it's out of fuel.
That's just a fancy way of saying it needs bigger tanks for the same amount of fuel v another
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Old 13th February 2018, 09:18 AM   #96
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Originally Posted by Octavo View Post
That's just a fancy way of saying it needs bigger tanks for the same amount of fuel v another

Well, yes, and I had to think really hard about saying it the right way around...


But... It does also reduce the need either for passive heat shielding or any active cooling upon re-entry.

Personally I think you need to add the Skylon concept to the Bristol Spaceplanes concept for maximum efficiency.
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Old 13th February 2018, 09:23 AM   #97
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I bet the Long Now Foundation could have come up with a suitable expendable "dummy" payload, given enough lead time. A copy of the top million works of world literature, micro-engraved within the stacked layers of a suitable alloy, or something like that. Always good to have an off-site backup.

Barring that. I'm cool with the roadster.
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Old 13th February 2018, 09:23 AM   #98
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My understanding of Skylon is that they need the hydrogen for a fancy intercooler when the engines are running at Mach 5+ in the earth's atmosphere.
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Old 13th February 2018, 09:30 AM   #99
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Originally Posted by Myriad View Post
I bet the Long Now Foundation could have come up with a suitable expendable "dummy" payload, given enough lead time. A copy of the top million works of world literature, micro-engraved within the stacked layers of a suitable alloy, or something like that. Always good to have an off-site backup.

Barring that. I'm cool with the roadster.
Arch contributed the foundation series on a quartz crystal storage disc if that counts?

https://www.theverge.com/tldr/2018/2...ndation-series
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Old 13th February 2018, 10:06 AM   #100
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Originally Posted by Octavo View Post
Arch contributed the foundation series on a quartz crystal storage disc if that counts?

https://www.theverge.com/tldr/2018/2...ndation-series
I'm not sure the article author has actually read the first book, never mind the others:
"
...which see mankind working to write an “Encyclopedia Galactica” to protect mankind against a coming dark age.
"
The encyclopedia was a fraud, and not Seldon's goal at all.


Stuck that in a spoiler, just in case!
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Old 13th February 2018, 10:12 AM   #101
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Originally Posted by Tolls View Post
I'm not sure the article author has actually read the first book, never mind the others:
"
...which see mankind working to write an “Encyclopedia Galactica” to protect mankind against a coming dark age.
"
The encyclopedia was a fraud, and not Seldon's goal at all.


Stuck that in a spoiler, just in case!

Do they have it confused with H2G2?
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Old 13th February 2018, 10:17 AM   #102
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Originally Posted by MikeG View Post
My understanding of Skylon is that they need the hydrogen for a fancy intercooler when the engines are running at Mach 5+ in the earth's atmosphere.
My understanding is that they use hydrogen as propellant in all phases of flight. In atmosphere, they use atmospheric oxygen as the oxidizer, like a jet. In space, they use oxidizer stored in onboard tanks, like a rocket. Best of both worlds in some ways, but fiendishly complicated in other ways due to them wanting to use the same engine for both modes.
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Old 13th February 2018, 10:29 AM   #103
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Originally Posted by theprestige View Post
My understanding is that they use hydrogen as propellant in all phases of flight.......
Yes, yes. I meant they need the hydrogen for cooling in addition to using it for fuel. Indeed, it might be what dictated their choice of fuel in the first place.
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Old 13th February 2018, 10:33 AM   #104
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I am very skeptical of Skylon. Even if it can be made to work, it seems too complex to be cost effective.

The current criticism of Musk reminds me of what I think of as Negative-but-Positive reinforcement:

1: You do something that people asked you to do (such as lower launch costs and improve re-usability).
2: You get criticized once you have actually delivered.
3: You realize that there will always be naysayers, but they don't take notice unless you actually do something.
4: Which makes you see the criticism in a more positive way, a sign that you actually really did something with significance.

In my career, I have noticed that high performing employees, those who get a lot of stuff done, are used to getting criticized for the things they get done, and start to feel a perverse sense of pride in getting yelled at or insulted ("They're really mad at me, I guess that shows I actually did something!").
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Old 13th February 2018, 10:58 AM   #105
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Originally Posted by crescent View Post
The current criticism of Musk reminds me of what I think of as Negative-but-Positive reinforcement:

1: You do something that people asked you to do (such as lower launch costs and improve re-usability).
2: You get criticized once you have actually delivered.
3: You realize that there will always be naysayers, but they don't take notice unless you actually do something.
4: Which makes you see the criticism in a more positive way, a sign that you actually really did something with significance.
I suspect there's a lot of truth in that. I also suspect that he has become pretty impervious to the criticism. The downside, maybe, is that he certainly talks total crap (imo) about future projects from time to time. Unfortunately even trying to discuss why you think it's crap gets you labelled as a 'naysayer' or 'hater'.

It's almost a love-him-or-hate him thing, with no middle ground allowed, which is a shame.
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Old 13th February 2018, 11:29 AM   #106
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Originally Posted by GlennB View Post
I suspect there's a lot of truth in that. I also suspect that he has become pretty impervious to the criticism. The downside, maybe, is that he certainly talks total crap (imo) about future projects from time to time. Unfortunately even trying to discuss why you think it's crap gets you labelled as a 'naysayer' or 'hater'.

It's almost a love-him-or-hate him thing, with no middle ground allowed, which is a shame.
The middle ground is there, people to either side of it tend to assume you're completely on the opposite side of it though. Kinda like politics these days.
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Old 13th February 2018, 11:47 AM   #107
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Originally Posted by theprestige View Post
My understanding is that they use hydrogen as propellant in all phases of flight. In atmosphere, they use atmospheric oxygen as the oxidizer, like a jet. In space, they use oxidizer stored in onboard tanks, like a rocket. Best of both worlds in some ways, but fiendishly complicated in other ways due to them wanting to use the same engine for both modes.
Aye, the fuel is carried internally, at sub-hypersonic speeds they capture air, compress and cool it to get the LOX that they need to burn the fuel. As the air thins they switch over to on-board LOX to complete the journey. The reason that they need the precooler is that the air is superheated by the compression in the intake and has to cooled rapidly to produce the LOX, but avoid freezing up.

Pluses for Skylon:
  • It can be launched from a long runway without hugely specialist launch facilities (though it will need large LOX and LH2 fuelling facilities)
  • It's a clean burner.
  • It can be launched overland (once it's through the sound barrier)
  • The precooler technology has a number of other applications (hence DARPAs interest).

Negatives for Skylon:
  • It can carry a limited payload, in terms of mass and volume.
  • It hasn't even been full scale tested yet.
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Old 13th February 2018, 11:53 AM   #108
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Originally Posted by Mikemcc View Post
[*]The precooler technology has a number of other applications (hence DARPAs interest).

I think this is where, if anywhere, the first SABRE engines will be seen, on Mach 5 military aircraft. Possibly on the A2. I don't think Skylon will ever be made in its currently envisioned form.
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Old 13th February 2018, 12:01 PM   #109
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Originally Posted by MikeG View Post
Yes, yes. I meant they need the hydrogen for cooling in addition to using it for fuel. Indeed, it might be what dictated their choice of fuel in the first place.
Might be. There is precedent. The Saturn V F1 engine had a fuel pump that...
... diverted some rocket fuel to power the pump,
... diverted some rocket fuel to lubricate the pump, and
... diverted some rocket fuel to cool the exhaust skirt.
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Old 13th February 2018, 01:28 PM   #110
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Originally Posted by theprestige View Post
Might be. There is precedent. The Saturn V F1 engine had a fuel pump that...
... diverted some rocket fuel to power the pump,
... diverted some rocket fuel to lubricate the pump, and
... diverted some rocket fuel to cool the exhaust skirt.
Common practice in aircraft, and has been for years. We use fuel to cool the electronics, hydraulic oil and pumps, among other things.
It serves several purposes. Besides keeping the vital components from overheating, it helps dissipate the waste heat, helping eliminate "hot spots" reducing the thermal signature, and it warms the fuel, increasing engine efficiency.
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Old 13th February 2018, 03:54 PM   #111
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Originally Posted by 3point14 View Post
I think this is where, if anywhere, the first SABRE engines will be seen, on Mach 5 military aircraft. Possibly on the A2. I don't think Skylon will ever be made in its currently envisioned form.
I agree, there are other launch platforms that can handle smaller payloads. To me, it's saving grace is that it can overfly land.
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Old 13th February 2018, 07:29 PM   #112
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From another thread I had someone break down the advertising costs for the Tesla stunt and the numbers are far and beyond 3 million dollars. I'll give you a summary here.

1% of population = 670 million X 100k per car = 67 trillion in possible sales (there is still a market)
Ad cost all the advertisement around the world and talk about the Tesla motors equals > 3 million (The other poster did math on it but I'm going to)
Tesla motors is losing money and needs help
https://www.cnbc.com/2017/04/05/tesl...than-ford.html
SpaceX is profitable
https://www.fool.com/investing/2017/...t-in-2017.aspx

So I'll recant on the bases of a good business decision by using SpaceX to promote Tesla motors in hopes of increasing sales there, and that the advertising for Tesla motors by the PR stunt is worth more than 3 million sending up cargo would have garnered him.

I'd preferred if he had done something for science, but I can no longer disagree that it was a good business decision, so I'll recant. Thanks for the lively discussion on the topic.
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Old 13th February 2018, 09:54 PM   #113
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Originally Posted by Coveny View Post
From another thread I had someone break down the advertising costs for the Tesla stunt and the numbers are far and beyond 3 million dollars. I'll give you a summary here.

1% of population = 670 million X 100k per car = 67 trillion in possible sales (there is still a market)
Ad cost all the advertisement around the world and talk about the Tesla motors equals > 3 million (The other poster did math on it but I'm going to)
I can't make sense of the numbers here and I can't even parse the sentence starting with "Ad cost"...
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Old 13th February 2018, 10:42 PM   #114
RecoveringYuppy
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Originally Posted by Coveny View Post
... 1% of population = 670 million
67 million, not 670. And there is also stuff in your post that isn't even wrong yet.
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Old 14th February 2018, 06:33 AM   #115
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Originally Posted by Coveny View Post
I'd preferred if he had done something for science, but I can no longer disagree that it was a good business decision, so I'll recant. Thanks for the lively discussion on the topic.

He offered a ride to lots of people, nobody wanted it.

The rocket had a fair old chance of blowing up.

Who do you think should have paid for the scientific cargo you wanted? For construction and testing?

Have you seen pre-launch testing for orbital cargo? Do you know what it involves? Do you know what it costs? Who should have paid for that?


Anything other than a vanity cargo is all but impossible without some institution being prepared to outlay an awful lot of money on something that was very likely to blow up. not many scientific institutions have so much money that they can afford to throw it away. I believe your preference for a scientific cargo is about as realistic as my preference for levitation.
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Old 14th February 2018, 06:57 AM   #116
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Originally Posted by Coveny View Post
1% of population = 670 million
75 actually.
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Old 14th February 2018, 08:01 PM   #117
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Originally Posted by Coveny View Post
http://theconversation.com/falcon-he...l-impact-91423

It's not a math issue it's a environmental consciousness issue. Some people think climate change is negligible others don't. (I'm in the former camp) As far as simple English you might want to look up something the Nirvana fallacy and Relative Privation fallacy. They might help you with your simple English issues.
I see, so if I forget to recycle an empty can, using your silly, zero sum game rationale that wouldn't have negligible impact on the environment either. You were taught fractions in elementary school were you not?
You might want to brush up on those and then look up the bolded above in a current dictionary.

Speaking of fallacies, I suggest reviewing:

Circular reasoning

False equivalence

Red Herring
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Old 14th February 2018, 08:30 PM   #118
ProBonoShill
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Originally Posted by Coveny View Post
From another thread I had someone break down the advertising costs for the Tesla stunt and the numbers are far and beyond 3 million dollars. I'll give you a summary here.

1% of population = 670 million X 100k per car = 67 trillion in possible sales (there is still a market)
Ad cost all the advertisement around the world and talk about the Tesla motors equals > 3 million (The other poster did math on it but I'm going to)
Tesla motors is losing money and needs help
https://www.cnbc.com/2017/04/05/tesl...than-ford.html
SpaceX is profitable
https://www.fool.com/investing/2017/...t-in-2017.aspx

So I'll recant on the bases of a good business decision by using SpaceX to promote Tesla motors in hopes of increasing sales there, and that the advertising for Tesla motors by the PR stunt is worth more than 3 million sending up cargo would have garnered him.

I'd preferred if he had done something for science, but I can no longer disagree that it was a good business decision, so I'll recant. Thanks for the lively discussion on the topic.
Math fail again on so many levels.

Considering the total number of worldwide vehicle sales measured in US dollars was 1.6 trillion in 2016, I think your imaginary 67 trillion dollar market might need some revision.

A+ on the hyperbole though.
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Old 14th February 2018, 08:46 PM   #119
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Originally Posted by Garrison View Post
And yet as people have pointed out SpaceX has already reduced the carbon footprint of spaceflight by reusing first stages instead of throwing them away in the oceans.



But you aren't. You are criticizing the one company doing something about making spaceflight more efficient and lowering it's Carbon footprint whilst ignoring ULA, or the Russian space agency who have a delightful habit of dropping spent boosters full of toxic chemicals all over Kazakhstan. For that matter what is 'low carbon' in spaceflight terms? Unless you have a viable alternative to chemical rockets that doesn't come with its own hidden Carbon costs you are simply holding SpaceX to a purely arbitrary standard.
"Two birds, one stone!", I suspect.
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Old 14th February 2018, 11:16 PM   #120
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What would you say if your friend Elon came up to you beforehand and said:
"Damn, I love this car! Pick us something else to send up."
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