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In operation, there were two events I was told in confidence by current and former employees that I would rather not disclose publicly. Without going into speci

In operation, there were two events I was told in confidence by current and former employees that I would rather not disclose publicly. Without going into specifics, they both related to operational deficiencies in launch systems (hardware in one instance, software in another) that were not disclosed to NASA prior to launch. This hits me particularly hard as this is not an industry where you ask forgiveness rather than permission. I was involved in situations with a separate contractor where we diagnosed technical problems days before a launch that in all likelihood would not have affected any other systems. We still went to NASA, admitted our faults, and provided an analysis of the situation and mitigating steps we would take in order to get their blessing. They worked with us and we didn't disrupt the launch schedule, but we were fully prepared to if that was what it took. For the design aspects, I admit it isn't my forte and I'm taking the word of other engineers who may have their own biases. In short, the use of many small engines used together (e.g. Falcon Heavy using 27 Merlin-1Ds and MCT using 9 Raptors) makes a lot of people who have been doing this for much longer than I very uncomfortable. This is especially true given that they are planning on launching Falcon Heavy missions so soon without having tested the cores operating together extensively (to my knowledge, at least). I'm sorry if this comes off as overly aggressive or biased. I do really think that reusability, automation, and low cost are important goals to work towards. I also even think that SpaceX is making some of the greatest strides in the industry. But I'm very uncomfortable with the company that seems (at least to me) to be disregarding established knowledge that was gained through the hardships of an earlier era.

kiba 10y ago
The way you make reliable rockets is to manufacture more of them and build more reliable system for manufacturing, or so that's the argument.
- thelambentonion 10y ago
  Agreed, with the caveat that you can make more reliable rocket _components_ that way, and you can use those components to assemble a more reliable system from them. No matter how reliable your individual components are, the added complexity from using many of them together in an already complex system is an area of concern. As a small example: the Falcon 9 has 9 Merlin 1-D engines pulling from shared RP-1/LOx on the first stage. Combustion instability in any one of the engines can induce a 'pogo oscillation' in the fuel lines that can stress the structure of the spacecraft. More engines means a higher risk of instability inducing such an event and damaging the spacecraft. Afaik, no one really has a generalized solution for dealing with pogo oscillations but many (including SpaceX) have ad-hoc solutions for specific rocket designs. The wrinkle here is that the Falcon Heavy is going to not only have 3 Falcon 9 cores, these cores will also be cross-supplying fuel/oxidizer to each other (i.e. the left and right cores will feed the center engines before separating). Even small changes in rocket design can bring underlying issues to light [0], and ad-hoc solutions, by definition, shouldn't be expected to solve them across the board. [0] Anecdotal again, I know, but: I was speaking with a solid rocket engineer a little while back who had helped diagnose a combustion instability. The root cause ended up being that the aluminum pellets embedded into the oxidizer were shaped such that they could clump together and create small bursts of excess thrust under certain conditions. This excess thrust had happened in just such a way that it created a standing wave inside the combustion chamber which vibrated the entire structure during flight. Other designs didn't have this problem (e.g. slightly different lengths of the combustion chamber, slightly different ratios of fuel/oxidizer).
perseusprime11 10y ago
I fully respect your argument and where you are coming from. Thank you. As an engineer, I fully support Elon Musk's approach. Space in general is unreliable and there are thousands and thousands of moving parts in space travel and the payloads they carry. A simple error or fault in any of these parts can create unpredictable outcomes. Remember the Apollo missions?Columbia space shuttle disaster? So, to me it seems perfectly acceptable to focus on reducing the costs of these missions to the point where these missions become cheaper, some fail - we learn, and ultimately failures won't matter much because we cut the costs down by tenth or even twentieth. If we move at the pace of the current industry, it will take 500 years to out a man on Mars. Obviously I am exaggerating but you see my point. Let them try something new, fail but learn and ultimately speed has to matter because humanity has ambitions and Universe is friggin big.
- tajen 10y ago
  We still need to account for the carbon emissions of such an explosion. A complete carbon study would include how much GHG we save thanks to the satellite we pace, how much we encourage emitting more GHG by making rockets ten times cheaper and encouraging satellite, how much energy we require to generate that weight of H2, how emissions of a normal launch at high altitude compare to ground-level emissions (hint: GHG from rockets are around 9x more harmful than the same weight of a Boeing 747's kerosen), and how frequently we have explosions that lead to no satellite launched and pollution. Whether SpaceX is actually advancing humanity is the real question here. But it seems the aircraft industry is much worse (3-5% of global warming). https://www.reddit.com/r/spacex/comments/4c9ts4/what_are_the_environmental_effects_of_rocket/ https://www.reddit.com/r/spacex/comments/4c9ts4/what_are_the... The best way to know would be to introduce a tax on GHG and let the markets decide which activities lose their affordability, instead of each of us trying to make a GHG calculation of our own activities.
  - perseusprime11 10y ago
    Good points. One thing to note is that not every failure will or should lead to an explosion.
jlmorton 10y ago
Just to be clear: you believe SpaceX has "a blatant disregard for even basic elements of safety in their design and operation," and you base this on two anecdotes from friends (which you won't share), and an element of the Falcon 9 that has never caused a loss of vehicle, and is arguably a point of reliability (Falcon 9 can still complete its mission with an engine out, while most other launchers cannot).

kiba 10y ago

The way you make reliable rockets is to manufacture more of them and build more reliable system for manufacturing, or so that's the argument.

thelambentonion 10y ago
Agreed, with the caveat that you can make more reliable rocket _components_ that way, and you can use those components to assemble a more reliable system from them. No matter how reliable your individual components are, the added complexity from using many of them together in an already complex system is an area of concern. As a small example: the Falcon 9 has 9 Merlin 1-D engines pulling from shared RP-1/LOx on the first stage. Combustion instability in any one of the engines can induce a 'pogo oscillation' in the fuel lines that can stress the structure of the spacecraft. More engines means a higher risk of instability inducing such an event and damaging the spacecraft. Afaik, no one really has a generalized solution for dealing with pogo oscillations but many (including SpaceX) have ad-hoc solutions for specific rocket designs. The wrinkle here is that the Falcon Heavy is going to not only have 3 Falcon 9 cores, these cores will also be cross-supplying fuel/oxidizer to each other (i.e. the left and right cores will feed the center engines before separating). Even small changes in rocket design can bring underlying issues to light [0], and ad-hoc solutions, by definition, shouldn't be expected to solve them across the board. [0] Anecdotal again, I know, but: I was speaking with a solid rocket engineer a little while back who had helped diagnose a combustion instability. The root cause ended up being that the aluminum pellets embedded into the oxidizer were shaped such that they could clump together and create small bursts of excess thrust under certain conditions. This excess thrust had happened in just such a way that it created a standing wave inside the combustion chamber which vibrated the entire structure during flight. Other designs didn't have this problem (e.g. slightly different lengths of the combustion chamber, slightly different ratios of fuel/oxidizer).

perseusprime11 10y ago

I fully respect your argument and where you are coming from. Thank you. As an engineer, I fully support Elon Musk's approach. Space in general is unreliable and there are thousands and thousands of moving parts in space travel and the payloads they carry. A simple error or fault in any of these parts can create unpredictable outcomes. Remember the Apollo missions?Columbia space shuttle disaster? So, to me it seems perfectly acceptable to focus on reducing the costs of these missions to the point where these missions become cheaper, some fail - we learn, and ultimately failures won't matter much because we cut the costs down by tenth or even twentieth. If we move at the pace of the current industry, it will take 500 years to out a man on Mars. Obviously I am exaggerating but you see my point. Let them try something new, fail but learn and ultimately speed has to matter because humanity has ambitions and Universe is friggin big.

tajen 10y ago
We still need to account for the carbon emissions of such an explosion. A complete carbon study would include how much GHG we save thanks to the satellite we pace, how much we encourage emitting more GHG by making rockets ten times cheaper and encouraging satellite, how much energy we require to generate that weight of H2, how emissions of a normal launch at high altitude compare to ground-level emissions (hint: GHG from rockets are around 9x more harmful than the same weight of a Boeing 747's kerosen), and how frequently we have explosions that lead to no satellite launched and pollution. Whether SpaceX is actually advancing humanity is the real question here. But it seems the aircraft industry is much worse (3-5% of global warming). https://www.reddit.com/r/spacex/comments/4c9ts4/what_are_the_environmental_effects_of_rocket/ https://www.reddit.com/r/spacex/comments/4c9ts4/what_are_the... The best way to know would be to introduce a tax on GHG and let the markets decide which activities lose their affordability, instead of each of us trying to make a GHG calculation of our own activities.
- perseusprime11 10y ago
  Good points. One thing to note is that not every failure will or should lead to an explosion.

jlmorton 10y ago

Just to be clear: you believe SpaceX has "a blatant disregard for even basic elements of safety in their design and operation," and you base this on two anecdotes from friends (which you won't share), and an element of the Falcon 9 that has never caused a loss of vehicle, and is arguably a point of reliability (Falcon 9 can still complete its mission with an engine out, while most other launchers cannot).