[HN Gopher] NTSB report: Decryption of images from the Titan sub...
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       NTSB report: Decryption of images from the Titan submersible camera
       [pdf] (2024)
        
       Author : bmurray7jhu
       Score  : 178 points
       Date   : 2025-11-23 00:35 UTC (22 hours ago)
        
 (HTM) web link (data.ntsb.gov)
 (TXT) w3m dump (data.ntsb.gov)
        
       | bmurray7jhu wrote:
       | Report on unrecoverable SSDs:
       | 
       | https://data.ntsb.gov/Docket/Document/docBLOB?ID=19169363&Fi...
       | 
       | Full docket:
       | 
       | https://data.ntsb.gov/Docket/?NTSBNumber=DCA23FM036
        
       | dwohnitmok wrote:
       | I'm confused. Why are decryption keys in NVRAM? That seems to
       | negate the purpose of at-rest encryption if you can retrieve keys
       | from the device even after shutdown.
        
         | daemonologist wrote:
         | Well they're encrypting an SD card, so this still defends
         | against its being removed from the camera and stolen or left in
         | a bar or something.
         | 
         | But honestly from the rest of the story it sounds like the
         | camera manufacturer was selling their pressure housing moreso
         | than the off-the-shelf camera hardware inside, and was not
         | particularly concerned with whether/how the storage was
         | encrypted.
        
         | tremon wrote:
         | What would you say is the threat model that leads one to auto-
         | encrypt sdcards?
         | 
         | For a machine that needs to boot unattended, what would you do
         | with disk decryption keys?
        
           | dwohnitmok wrote:
           | > What would you say is the threat model that leads one to
           | auto-encrypt sdcards?
           | 
           | Jumping off of daemonologist's point, the most convincing
           | model I could think of is one where you are consistently
           | removing the SD Card, likely because you are swapping
           | multiple SD cards back and forth. But this still seems bad!
           | In that case your multiple SD cards all share the same
           | decryption key (or I guess less egregiously all at least
           | share the same physical vulnerability of that device's
           | nonvolatile memory).
           | 
           | > For a machine that needs to boot unattended, what would you
           | do with disk decryption keys?
           | 
           | This depends entirely on what you mean by unattended. Here's
           | some candidates:
           | 
           | 1. The machine has a network connection and you would like to
           | boot it over the network. In that case you have a small
           | unencrypted bit that handles the boot sequence and then pass
           | the decryption key over the wire, store in volatile memory,
           | and wipe on shutdown or logout.
           | 
           | 2. The machine is regularly serviced/booted by an in-person
           | operator. You give the decryption key or passphrase to the
           | operator to decrypt and boot the machine.
           | 
           | 3. The machine is meant to autonomously reboot itself due to
           | e.g. error conditions. In extreme cases when the machine
           | detects that there is a large probability of physical
           | compromise, it shuts down. In this case for the former I
           | would imagine some power supply, e.g. a backup battery, that
           | keeps the volatile memory up when rebooting and in case of
           | large probability of physical compromise there is a forced
           | shutdown and/or wipe of the volatile memory.
           | 
           | 4. An operator needs to periodically boot up the machine, but
           | the operator should not be able to access any previous data
           | the machine has recorded (data from the moment operator
           | arrives forward is assumed leaked to the operator because
           | e.g. the operator can just position their own sensor in front
           | of the machine and collect data). In that case asymmetric
           | encryption should be used and the encryption keys should be
           | stored on the machine, but the decryption keys should not,
           | effectively turning the machine into a write-only device from
           | the operator's perspective.
           | 
           | The only case I could imagine where you want the machine to
           | boot unattended and you'd keep the decryption keys in
           | nonvolatile memory on the device is if you want an operator
           | to be able to boot the device without knowledge of the
           | decryption key and also to be able to view historical data
           | previously recorded by the device. But in that case there is
           | no functional difference between that and a device that is
           | unencrypted! In both cases you boot up the device without a
           | password and voila all the data is in front of you ready to
           | be read! And indeed that's basically what happened here
           | (modulo the difficulties associated with the device being
           | damaged). And in that case encryption seems like pure
           | overhead for no real security benefit.
        
       | cbsks wrote:
       | Wow. SubC's software engineering needs some work. They thought
       | the camera's file system was unencrypted, when it was encrypted.
       | They didn't know where the keys were to decrypt it. It turned out
       | the key was written unencrypted to a UFS storage device. There
       | was a file written to /mnt/nas/Stills, which indicates that the
       | camera was to writing to a remote file system that wasn't
       | mounted.
        
         | userbinator wrote:
         | _They thought the camera's file system was unencrypted, when it
         | was encrypted._
         | 
         | Unfortunately this situation is likely to get more common in
         | the future as the "security" crowd keep pushing for encryption-
         | by-default with no regard to whether the user wants or is even
         | aware of it.
         | 
         | Encryption is always a tradeoff; it trades the possibility of
         | unauthorised access with the possibility of even the owner
         | losing access permanently. IMHO this tradeoff needs careful
         | consideration and not blind application.
        
           | jiggawatts wrote:
           | This is why I always shake my head when the Reddit armchair
           | security experts say "The data wasn't even encrypted!?
           | Amateur hour!" in response to some PII leak.
           | 
           | Sure, sure buddy, I'll encrypt all of my PII data so nobody
           | can access it... including the web application server.
           | 
           | Okay, fine, I'll decrypt it on the fly with a key in some API
           | server... now the web server had unencrypted access to it,
           | which sounds bad, but that's literally the only way that it
           | can _process_ and _serve_ the data to users in a meaningful
           | way! Now if someone hacks the web app server -- the common
           | scenario -- then the attacker has unencrypted access!
           | 
           | I can encrypt the database, but at what layer? Storage? Cloud
           | storage is already encrypted! Backups? Yeah, sure, but then
           | what happens in a disaster? Who's got the keys? Are they
           | contactable at 3am?
           | 
           | Etc, etc...
           | 
           | It's not only not as simple as ticking an "encrypted: yes"
           | checkbox, it's maximally difficult, with a very direct
           | tradeoff between accessibility and protection. The sole
           | purpose of encrypting data is to _prevent access!_
        
             | londons_explore wrote:
             | I like the approach of mega.nz...
             | 
             | Server stores encrypted blobs. Server doesn't have the
             | keys.                 Entire application is on the client,
             | and just downloads and decrypts what it needs.
             | 
             | Obviously your entire application stack needs to be
             | developed with that approach in mind, and some things like
             | 'make a hyperlink to share this' get much more complex.
        
             | Terr_ wrote:
             | Nah bro, you just gotta use homomorphic encryption! /s
             | 
             | That said, encryption at rest is still good in terms of
             | theft or mis-disposal.
        
             | dh2022 wrote:
             | Re: encrypting data that would be served via web server:
             | why would anyone bother to encrypt data meant to be shared
             | externally worldwide? It makes no sense to begin with...
        
           | UltraSane wrote:
           | This has already happened to Windows users when BitLocker
           | disk encryption is enabled by default and they do something
           | that causes the encryption key to be lost.
           | 
           | You can have the key saved in your Microsoft account.
        
             | userbinator wrote:
             | _You can have the key saved in your Microsoft account._
             | 
             | I find it very hard to believe that those who _want_ their
             | disk encrypted also want Microsoft to have the key.
        
               | UltraSane wrote:
               | Microsoft isn't going to release it without a warrant.
               | But you have to trust their security not to leak it.
        
         | londons_explore wrote:
         | > They thought the camera's file system was unencrypted, when
         | it was encrypted.
         | 
         | Willing to bet plenty of hn readers are unaware of encryption
         | going on at lower layers of the tech stack than they're aware
         | of.
         | 
         | For example most hard drives encrypt all data, even when not
         | commanded to, as a way to do 'data whitening' (ie making sure
         | there are even numbers of 0's and 1's in the data stream and
         | not some pattern which might throw off tracking.)
         | 
         | The encryption key is simply stored elsewhere in the drive - or
         | nvram or in the firmware.
         | 
         | But it means if you extract the physical magnetic surface and
         | read it with the right microscope, you might well find the data
         | encrypted with no available key.
        
           | ryan-ca wrote:
           | To my knowledge, encoding avoids runs to avoid
           | desynchronization in a way that isn't encrypted.
        
             | londons_explore wrote:
             | This used to be done, but since ~2000, disks were expected
             | to support on-device encryption, and by making encryption
             | always-on no encoding is needed.
        
             | rocqua wrote:
             | This is line coding, often used on wired connections. But
             | reading a hard drive trace isn't quite a wired connection,
             | so the trade-offs are different.
             | 
             | Most notably with line coding when using positive and
             | negative voltages it is quite important for the average
             | voltage to be zero to avoid building up a charge
             | difference. Whitening can often be used if the downside to
             | an imbalance or long runs is much lower. Notably in RF this
             | is often about avoid harmonics with a little bit of symbol
             | timing advantage thrown in.
             | 
             | Whitening doesn't really require encryption though. Weak
             | cypher streams xored into the data work fine. Even a
             | repeated 256 bit string is quite alright.
             | 
             | Whitening using any non trivial encryption key seems weird
             | to me. AES with a key equal to the current offset in ECB
             | mode already feels over-engineerd.
        
               | londons_explore wrote:
               | > Whitening using any non trivial encryption key seems
               | weird to me.
               | 
               | It's because there was an era when drives were expected
               | to be able to do 'hardware' encryption with a user
               | provided key, so reusing that hardware to also do
               | whitening even if the user didn't provide a key was very
               | convenient.
               | 
               | Plus you get all the other benefits - ie. a single scsi
               | command can 'secure erase' the whole disk in milliseconds
               | by simply changing the stored key.
        
           | themafia wrote:
           | Scrambling and encryption are two different things.
           | Scrambling is very easy to do at line rates. Encryption not
           | so much.
           | 
           | Ethernet is a good example. It has the same problem where
           | long strings of 0's or 1's can cause clock recovery problems.
           | The solution as clock rates have increased is to just run all
           | the data through a scrambler driven by a simple Linear
           | Feedback Shifter.
        
           | kasabali wrote:
           | If you're talking about SED feature, no, it isn't widespread
           | since it's regarded as an "enterprise" feature and only
           | available in minority of drives (regardless of HDD or SSD).
           | Client or OEM variants of same drives (otherwise identical)
           | lack SED option most of the time and doesn't encrypt data by
           | default.
        
             | londons_explore wrote:
             | The hardware is still there - they don't make a new asic
             | for the consumer version
        
               | kasabali wrote:
               | doesn't mean it's active.
        
               | Nextgrid wrote:
               | "Active" with those systems just means the encryption key
               | is now user-supplied instead of being stored on the
               | controller/drive. The actual encryption is always active;
               | which makes sense, if anything it means you have one less
               | configuration to test.
        
       | watersb wrote:
       | The SD card on the camera was intact but encrypted. Decrypting
       | the data required a key stored on a separate SOM board, but the
       | SOM was damaged. The investigation team delivered the SOM and SD
       | card to the camera manufacturer in Newfoundland, and they were
       | able to decrypt the card.
       | 
       | They found a couple of images, but                  No data with
       | a timestamp after May 16th was found on the camera, so it is
       | likely that none of the data recorded on the SD Card were of the
       | accident voyage or dive.
       | 
       | After all that work...
       | 
       | If you're interested in data recovery, you will enjoy reading
       | this report, about 10 pages, clearly written. The technical
       | language mentioned they didn't see a LUKS header on the card so
       | they figured it was a custom dm_crypt setup.
        
         | cloudbonsai wrote:
         | > No data with a timestamp after May 16th was found on the
         | camera, so it is likely that none of the data recorded on the
         | SD Card were of the accident voyage or dive.
         | 
         | Evidently the camera data was recorded to an external SSD card
         | in the mission computer when the accident occurred.
         | 
         | The investigation team actually managed to salvage the PC as
         | well:
         | 
         | https://data.ntsb.gov/Docket/Document/docBLOB?ID=19169363&Fi...
         | 
         | Sadly it turned into a compressed ball of metal...
        
           | djmips wrote:
           | That's a striking image! Thanks for sharing - that really
           | hits home on the pressures involved.
        
           | londons_explore wrote:
           | Pretty sure tech exists to recover data from flash memory
           | with cracked dies...
           | 
           | I guess they decided it wasn't worth pursuing.
        
             | dwohnitmok wrote:
             | > Pretty sure tech exists to recover data from flash memory
             | with cracked dies...
             | 
             | If you have anymore on this would love to see any relevant
             | materials.
        
           | yawpitch wrote:
           | You can just make out the heatsink fins of the three PCs
           | there, stacked atop (and now kind of inside) each other.
           | 
           | That truly is one of those "let God sort them out"
           | situations.
        
           | gattr wrote:
           | From the report:
           | 
           | > To conduct the CT scans, the large mass was evaluated by a
           | third-party laboratory under NTSB supervision. This facility
           | had a range of scanners with different power and energy
           | levels and could scan large masses using a rotating table,
           | avoiding the need to rotate the mass itself. Ultimately, the
           | third-party laboratory attempted to image the large mass at a
           | power as high as 320 kilovolts (kV). The scans conducted at
           | 320 kV were not powerful enough to penetrate the object, and
           | as a result, no internal structures or voids were visible,
           | and no memory devices could be identified. The NTSB evaluated
           | using another laboratory with higher power and energy CT scan
           | devices, however, there was concern that increased CT scan
           | energy could damage data stored on any surviving NVM chips.
           | Consequently, higher-energy scans were not pursued.
           | 
           | I'm no expert, but remember reading about neutron imaging
           | ([1]). I'm curious if that was deemed unfeasible, too
           | expensive, or having little chance of success? From
           | Wikipedia:
           | 
           | > X-rays are attenuated based on a material's density. Denser
           | materials will stop more X-rays. With neutrons, a material's
           | likelihood of attenuation of neutrons is not related to its
           | density. Some light materials such as boron will absorb
           | neutrons while hydrogen will generally scatter neutrons, and
           | many commonly used metals allow most neutrons to pass through
           | them.
           | 
           | [1] https://en.wikipedia.org/wiki/Neutron_imaging#Neutron_rad
           | iog...
        
       | rozab wrote:
       | What's with the entire dev board crammed in there? Is that...
       | normal? What board is it?
        
         | daemonologist wrote:
         | It appears to be a Teensy 3.2
         | 
         | The "carrier" that everything rides on within the housing is
         | clearly FDM printed as well. I assume these cameras (rated to
         | 6,000 meters) are rather low volume products.
        
           | buildbot wrote:
           | It honestly makes sense. You are paying for the pressure
           | engineering, and can take advantage of an off the shelf
           | camera system. Maybe use a special lens or filter or
           | something but why bother customizing the software/hardware of
           | the camera much.
           | 
           | They probably should still know what it's doing though...
        
           | analog31 wrote:
           | I came here to say "that's definitely a Teensy 3.2"
           | 
           | The black cable goes dangerously close to the pushbutton of
           | death. ;-)
        
         | duskwuff wrote:
         | The small board on the left is unmistakably a Teensy 3.2:
         | 
         | https://www.pjrc.com/store/teensy32.html
         | 
         | As to what it's doing in there, I have no idea.
        
           | djmips wrote:
           | Well, I'll be darned! I wonder if Paul Stoffregen knows about
           | that!
           | 
           | edit: probably? It was posted at the Teensy forum about a
           | month ago.
           | 
           | https://forum.pjrc.com/index.php?threads/the-deepest-
           | teensy....
        
         | whalesalad wrote:
         | Looks like a pi zero
        
         | quamserena wrote:
         | I have seen engineers slap Teensies on a PCB and call it a day,
         | so it's definitely normal. It's faster than having to route
         | your MCU, USB, debugger, etc. manually, so there isn't really a
         | drawback as long as it physically fits there.
        
           | 15155 wrote:
           | > It's faster than having to route your MCU
           | 
           | Common misconception. A handful of capacitors, SPI NOR flash,
           | an inductor, and a crystal is way easier to place and route
           | than a restrictive module that completely disables your
           | ability to use SWD/JTAG on an otherwise excellent MCU.
        
           | switknee wrote:
           | Yup, if it works in your testing, why bother changing it?
        
       | daemonologist wrote:
       | Previous discussion (October 17th):
       | https://news.ycombinator.com/item?id=45613898
       | 
       | Also a good video from Scott Manley: https://youtu.be/qMUjCZ7MMWQ
        
       | pseudolus wrote:
       | There's a fascinating and redacted interview with an "anonymous"
       | subject about the disaster. To say the least it's an unsuccessful
       | attempt to hide the identity of the individual:
       | 
       | "Q. So how did you get yourself started into submersible
       | operations?
       | 
       | A. Well, I'm sure you're familiar with my film Titanic. When I
       | set down the path to make that film, the first thing that I did
       | was arrange to be introduced to the head of the submersible
       | program at the P.P. Shirshov Institute in Moscow, a guy named..."
       | 
       | https://media.defense.gov/2025/Sep/17/2003800984/-1/-1/0/CG-...
        
         | vlovich123 wrote:
         | Let's hear from L Simpson. No, that's too specific. Let's hear
         | from Lisa S.
        
           | vlovich123 wrote:
           | Took me forever to find the actual quote - ChatGPT and Gemini
           | kept trying to gaslight me that it's not a real quote or that
           | Willie said it to Bart until I gave the exact quote (at which
           | point normal search engines were fine):
           | 
           | > A certain agitator, for privacy's sake, let's call her Lisa
           | S. No, that's too obvious, let's say L. Simpson.
           | 
           | Lisa the Vegetarian
        
             | edoceo wrote:
             | When I grow up I'm going to Bovine University!
        
             | maybelsyrup wrote:
             | In the future, Frinkiac [0] is your friend
             | 
             | [0] https://frinkiac.com/
        
             | monkpit wrote:
             | If you google "Lisa S L Simpson" it's the first thing that
             | comes up... why make it harder with AI?
        
               | lanyard-textile wrote:
               | ... Quite ironically, Google results are AI... :)
        
               | palmotea wrote:
               | >> Took me forever to find the actual quote - ChatGPT and
               | Gemini kept trying to gaslight me that it's not a real
               | quote or that Willie said it to Bart until I gave the
               | exact quote (at which point normal search engines were
               | fine):
               | 
               | > If you google "Lisa S L Simpson" it's the first thing
               | that comes up... why make it harder with AI?
               | 
               | Because AI is the future! His employer is probably
               | requiring him use it first for everything. Only when it
               | fails (and you can tell), may other ways to solve the
               | problem be tried.
        
               | sva_ wrote:
               | I've recently randomly seen some younger guy running a
               | basic calculation like 7*12 in chatgpt on his phone. It
               | just had me in disbelief
        
         | bmurray7jhu wrote:
         | "I think the most dangerous part of our whole operation was
         | these young software engineers puking over the railing in a
         | high sea."
        
         | cloudbonsai wrote:
         | Among the interviews, one with the former engineering director
         | was the most eye-opening for me.
         | 
         | https://data.ntsb.gov/Docket/Document/docBLOB?ID=17236880&Fi...
         | 
         | It appears that all the engineers -- system designer, material
         | engineer and structural analyst -- thought that OceanGate CEO
         | was going to kill himself:                   If you ever find
         | <name-of-the-engineer>, he's not going         to have a whole
         | lot of nice to say. He was very frustrated         with the
         | company. (...) And I understand why. He thought
         | Stockton was going to kill himself.
         | 
         | And the director himself declined to dive on Titan when asked:
         | Now, the question is, why wouldn't the engineer get inside
         | his own vehicle? It was because of what I felt -- and I have a
         | background in Navy diving in EOD operations. I knew firsthand
         | that the operations group was not the right group for that
         | role,         and I told him as much, that I don't trust
         | operations and who he         has there.
        
           | idontwantthis wrote:
           | I read that the pilot was also basically suicidal. His wife
           | had died, and he was completely fine with the danger because
           | he would die doing what he loved, and he didn't really want
           | to live anymore.
        
             | djmips wrote:
             | Wasn't the pilot Stockton Rush? His wife was alive. Who are
             | you referring to? I tried to check your claim but I
             | couldn't verify it.
        
               | nagaiaida wrote:
               | they're talking about nargeolet
               | 
               | > Wreck expert Paul-Henri "P.H." Nargeolet, who was also
               | onboard, told me he wasn't worried about what would
               | happen if the structure of the Titan itself were damaged
               | when at the bottom of the ocean. "Under that pressure,
               | you'd be dead before you knew there was a problem." He
               | said it with a smile.
               | 
               | (as recounted by Arnie Weissmann, in Travel Weekly
               | article published June 22, 2023)
        
               | idontwantthis wrote:
               | Yeah I got the roles of pilot and guide mixed
               | 
               | https://www.newyorker.com/news/a-reporter-at-large/the-
               | titan...
        
               | netsharc wrote:
               | There was only one other crew member in that vessel
               | (well, actual crew and not paper "mission specialist").
               | He was an older gentleman, and it's quite common for
               | older people to have lost their spouse. Was that so hard
               | to figure out?
        
               | djmips wrote:
               | yeah but he remarried
        
           | bambax wrote:
           | The number of stupid decisions that went in the design and
           | construction of the Titan is astonishing. One of my favorites
           | was that, after putting on the carbon fiber around the tube,
           | they would sand imperfections to make the surface perfectly
           | smooth, severing layers in the process! It shouldn't require
           | an engineering degree from MIT to recognize this as ill-
           | advised.
        
             | lazide wrote:
             | Even without that, the material is just wrong. It's strong
             | in tension, not so much compression. Tends towards sudden
             | brittle fractures. Doesn't like impacts, as it tends to
             | have issues with delaminating.
             | 
             | It's just not what you ever want as a sub hull. It's dumb.
             | 
             | And weight is not even a huge issue for a sub!
        
               | bambax wrote:
               | Yes, using carbon fiber was also a very bad decision; it
               | was known for a very long time that it was only good for
               | single-use sub, because after the first dive it was too
               | damaged to continue. In 2014, Virgin Oceanic, which had
               | similar plans with similar technology, closed shop
               | because it didn't make economic sense to build a new sub
               | for each dive.
               | 
               | But weight is absolutely an issue; the basic and tried-
               | and-true metal sphere design allows for only three
               | people. Since size and thickness grow exponentially,
               | making a sphere for more than three people becomes more
               | and more difficult. And it should also be possible to
               | lift the vehicle with a crane.
               | 
               | But if you want to carry paying passengers (like
               | Oceangate did), having only two per dive is very
               | limiting. That's why they went with a tube design, and
               | carbon fiber to limit weight. But it couldn't work, and
               | it didn't.
        
               | schiffern wrote:
               | >size and thickness grow exponentially
               | 
               | It's a [reverse] pressure vessel, so it follows pressure
               | vessel scaling. Mass scaling is linear with internal
               | volume.
        
               | FabHK wrote:
               | It's funny how "literally" often means "figuratively"
               | now, and "exponentially" means "polynomially".
        
               | bambax wrote:
               | Yep.
               | 
               | https://books.google.com/ngrams/graph?content=exponential
               | ly%...
        
               | bambax wrote:
               | Ok yes "exponentially" was hyperbolic. Mass scales
               | linearly with volume, but volume is proportional to the
               | cube of the radius (not linear).
               | 
               | Also, in practice, small imperfections can have a
               | disproportionate impact on the resistance of the sphere
               | so design codes typically apply conservative reductions
               | that can have a big impact on actual thickness
               | requirements.
        
               | wkat4242 wrote:
               | Did this thing meet any design codes though? I doubt it.
        
               | donavanm wrote:
               | I read the report when it come out. From memory, no. It
               | never had any components or certification for human
               | pressure vessels. IIRC theres no existing regs for carbon
               | fiber and it would have cost like $50M to do the design
               | and test work. They did buy some things, like the
               | viewport, from companies who _do_ certified parts, but
               | instead opted for the same design minus any test certs to
               | save money. The craft was never certified or inspected by
               | the uscg. It did have a registration for a while, but
               | they had to play find-a-new-district-sign-off shell games
               | for a while, then... just stopped bothering.
        
               | wkat4242 wrote:
               | Thanks for the detailed answer! It doesn't suprise me at
               | all.
        
               | owenversteeg wrote:
               | "Strong in tension, not compression" is a meme, and
               | obviously wrong. It is certainly stronger in tension, but
               | it is also remarkably strong in compression. That's why
               | it's used - yes, in compression - in modern passenger
               | aircraft. You don't even need to know that, though; the
               | simple fact is that the Titan had a double-digit number
               | of deep dives. If it was weak in compression it would not
               | have survived diving to 3.7 kilometers deep or even a
               | fraction of that depth _once_.
               | 
               | That said, yes, it's a difficult material to use
               | properly, and they were a bunch of cowboys slapping
               | things together. It's no surprise that they missed
               | several critical steps and created a sub doomed to fail.
               | 
               | N.b. all of this was kickstarted by James Cameron saying
               | that carbon fiber has "no strength in compression" in a
               | New York Times "science" article, which the Times printed
               | directly.
        
               | lazide wrote:
               | Aircraft fuselages are typically loaded in tension. It's
               | a key part of the design.
               | 
               | Carbon fiber compressive strength is only ~ 30-50% of
               | it's tensile strength because of the way the fibers and
               | the epoxy interact. When compressed, the carbon fibers
               | don't do as much. [https://www.sciencedirect.com/science/
               | article/abs/pii/S02638...]
               | 
               | But don't believe me, actually read a useful paper on the
               | subject.
               | 
               | In fact, it's a major factor limiting it's wider use. As
               | is it's fatigue behavior, which would probably also
               | explain why it eventually imploded!
               | 
               | I never followed James Cameron's interview, but it sounds
               | like he knows what he is talking about!
        
               | buildbot wrote:
               | Speaking of which I heavily recommend reading interview
               | the prime ancestor comment to this chain linked. It's
               | really clear he knows what he is talking about.
        
               | owenversteeg wrote:
               | James Cameron certainly knows a lot about submarines, but
               | if he says something factually incorrect then it's
               | factually incorrect, period. Carbon fiber does not have
               | "no strength in compression" and it is used in
               | compression in countless applications, for example
               | airplane wings. Again, the fact that the sub - built at
               | absurdly low cost for its size, built by a bunch of
               | cowboys that didn't know what they were doing - DID
               | survive to 3.7 km deep on several occasions is proof
               | sufficient. If CF had no compressive strength than the
               | whole thing would have failed at a tiny fraction of that
               | depth. If CF had no compressive strength then what kept
               | the sub together during the successful dives? Hopes and
               | dreams?
               | 
               | I'm not here to defend the decision to use carbon fiber,
               | and as I've said I completely agree that there are many
               | issues with using it in this application. Delamination,
               | water ingress, bonding the titanium to the carbon fiber,
               | difficulty of manufacture including varying layer
               | thickness and voids, sensitivity to impact, the list goes
               | on. But _those_ are the issues, not the compressive
               | strength.
        
               | lazide wrote:
               | Moved the goalposts again eh? While completely ignoring
               | the cites and discussion? What, were you a major
               | shareholder? Family member?
        
             | franktankbank wrote:
             | I don't like this interpretation of things. Its worthwhile
             | to experiment and try things. They were basically mentally
             | ill as a group and rejected genuine concern. Everyone wants
             | to shit on the build but it was the human relations that
             | killed it.
        
               | nativeit wrote:
               | Also, honestly, the build. That "genuine concern" they
               | ignored was that the build was critically flawed. I don't
               | think anyone here would have these takes if a small group
               | of curious engineers tried their hand at a composite
               | submersible, it was when they kept doing it after all the
               | qualified engineers had said, "This is crazy, I'm out."
               | 
               | The build was kind of dumb, and I'm hardly an engineer.
               | It's common sense. Carbon fiber composites are
               | interesting because they're strong relative to their
               | weight. Remove either of those features and they become
               | pointless.
               | 
               | Who cares if a submarine is heavy?
        
           | robot-wrangler wrote:
           | Wow! Man, an insider with these kinds of concerns isn't
           | exactly exonerating or excusing themselves with such a
           | testimony. Whistle-blowing to any relevant authority as hard
           | as possible seems like the bare minimum? And if there's no
           | governing agency to pass the responsibility over to, I think
           | you gotta quietly approach the first customer (or victim)
           | with these concerns if not a newspaper
        
         | bambax wrote:
         | Cameron did several TV interviews about the Titan, why would
         | they redact his name?
         | 
         | He didn't mince his words either; he was extremely critical of
         | the whole thing before and after the disaster.
        
           | desert_rue wrote:
           | Maybe it is policy. If you have three experts in the field
           | and you redact the details for two of the interviews taken,
           | you can't work it out that Bob was one of the two. Granted,
           | they borked the redaction here.
        
             | Nextgrid wrote:
             | Same policy that "redacted" the brand of the SD card, even
             | though anyone that would be able to do anything with that
             | information would immediately recognize it as a SanDisk.
        
       | Zak wrote:
       | > _Removed SD card. The manufacturer of the camera had requested
       | certain components of the device be redacted. Portions of this
       | image have been redacted._
       | 
       | And so it is, but anyone who has ever seen a Sandisk SD card
       | knows what they're looking at. I can even tell it's not the
       | fastest V90 speed.
       | 
       | The things companies try ineffectually to keep out of public view
       | are weird.
        
         | vayup wrote:
         | Especially when anyone can buy the product off the shelf,
         | remove the casing to see what they are trying to redact in
         | these images.
        
       | JCM9 wrote:
       | Amusing that the bits the "manufacturer asked to be redacted" in
       | the images appear to be the identifiers for common off-the-shelf
       | electronic components, including a standard memory card. Is that
       | really super secret IP?
        
         | rasz wrote:
         | It is if you are a camera manufacturer. Another example
         | https://www.cined.com/whats-inside-a-red-mini-mag-the-contro...
        
         | gosub100 wrote:
         | could be a PR / brand identity management thing. They dont want
         | their slogan to be come "The official Storage Medium of Deadly
         | Disasters".
        
       | alhirzel wrote:
       | Crazy that it's pretty much a 3D printed assembly internally, and
       | the manufacturer didn't know how it worked. No way that would
       | pass any kind of vibration test.
        
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