02/1967 - Apollo 1 fire

01/1986 - Challenger disaster (19 yrs later)

02/2003 - Columbia disaster (17 yrs later)

It's been 23 years since Columbia, and there seems to be a 20-ish year rhythm to NASA disasters where the organization learns lessons, becomes more careful... and then standards potentially slip.

"Wealthfolio does not currently support integration with online brokers or aggregators. Data must be imported from CSV files or by manually entering transactions."

Most likely translation: it affected the Google SMB sales team's Salesforce instance

Strongly recommend it (though admittedly, I don't use it often in suburbia)

Elevated CO2 in submarines absolutely impairs performance. One example: there was a guy on my boat who got migraines when CO2 got too high - he was useless. Luckily the fix is simple - just turn on another CO2 scrubber.

There's nothing special about a submarine that makes CO2 somehow different than anywhere else.

He's got more details on the whole Trojan Room Coffee Pot experience on his blog: https://quentinsf.com/coffeepot/

(Though in this case the parts were found before anyone was hurt/killed!)

It took them a while to find the right business model, but now they partner with huge brands to offer them textile customization AT SCALE, which previously was pretty much unheard of. - https://www.unmade.com/

But there are VLF antennas that Ohio-class submarines have to receive low-data-rate comms while submerged.

Any reasonable communications have to be made while at periscope depth. (Which is subtly different than "having to surface"... at PD just the thin mast is out of the water.)

Los Angeles and Virginia-class submarines are always doing something: doing exercises, transiting from one location to another, etc. And typically multiple things at once. While the boat is transiting from an exercise area to homeport, the team is doing engineering drills, or other kinds of training. Or the forward part of the boat is doing exercises with a carrier battle group while the engineering team is doing engineering drills. (There's ALWAYS engineering drills or maintenance happening.)

Fuel isn't a primary concern: a nuclear reactor is fueled for the life of the boat, so 30-ish years. That said, effective life of a reactor is something the Navy tracks closely, and depending on the life of the boat, the life left in the reactor, some boats are decommissioned as they get close to the end of their fuel life, and others get re-fueled. (And in the case of the USS San Francisco, who had recently been refueled before it hit an underwater mountain, they cut off the front half of the submarine and welded the front half of a recently-decommissioned submarine on, because the reactor and fuel was too valuable to go to waste)

> one of the primary reasons subs need to surface , in order to GPS lock

While getting a GPS position is helpful, the primary reason a submarine goes to periscope depth regularly is for communications. The Navy needs to send information to submarines and know that they'll get it and take action within a certain timeframe. That's by far the primary driver.

Passive sonar (where you just listen to acoustic energy in the water) is used by submarines and surface ships to find submarines. With both on-board and towed sonar.

Submarines don't have any sonar designed to map the sea floor, though there are tools to identify the depth below the keel at any given time. Creating proper maps of the sea floor are done by much more specialized equipment/systems/processes. https://en.wikipedia.org/wiki/National_Geospatial-Intelligen...

Also commented downthread, but sonar IS always on at all times. https://news.ycombinator.com/item?id=35780124

Honestly, I'm extraordinarily surprised that the USS San Francisco didn't sink killing everyone onboard. Have you seen the photos? https://en.wikipedia.org/wiki/USS_San_Francisco_(SSN-711)#/m...

The only reason that the submarine was able to get to the surface and stay there after this was because the damage was just on the port (left) side. Even with that luck, they were only able to stay on the surface because a piece of equipment was able to stay running for several times longer than it was designed to do.

You can read more about it in various places (like here: https://nationalinterest.org/blog/reboot/what-happens-when-s... ) but imagine being at work and suddenly getting thrown toward a wall at 20++mph. Damages and injuries everywhere, and its a miracle only one person died.

Yes, and no.

Yes- the US has maps with higher-resolution data on water depth around the world than what's commercially available.

No - those maps aren't perfect. Some areas are extraordinarily well-mapped, others are less so.

Submarine crews are trained not to check just the charts that are in use for a particular voyage, but also other charts covering the same area. (The USS San Francisco collision has no evidence of a seamount on the charts in use, but there was "discoloration" on another chart covering the same area.)

* forward-facing sonar is always being used at all times while a submarine is underway

* however, the sonar that's always used is passive, and since mountains don't move, passive sonar doesn't find them

* active sonar could theoretically be used, but the risk of communicating a submarine's position relative to the chance that you'd hit an underwater mountain is balanced strongly on the side of running silent.