Lock the doors: Remembering Columbia's final homecoming (2020)
americaspace.com
americaspace.com
https://arstechnica.com/science/2016/02/the-audacious-rescue...
It would have been barely on the brink of possible, but with huge risks of its own. Going through the exercise though reveals a lot of details of the shuttle, being in orbit, and our capabilities at the time. It's been discussed a few times over the years on HN, the biggest one being 8 years ago when it was first published [0], but seems timely along with this article.
I'm very glad though going forward that entire class of failure modes is gone for good and that particular possibility for heroics will not be needed. Side mounting the shuttle was always one of the worst design choices amongst many, many bad decisions that went into the STS. Also created one of the worst launch abort profiles of any system ever. Nobody will do that again though.
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Finally! Even Arthur C Clarke wrote in one of his novels that it was friction.
I'm also amazed that the shuttle could not be landed by remote control because of a couple switches.
A deliberate, but dubious decision. Deploying the gear before it's time is guaranteed catastrophe-- they decided it was important to not leave this under software control.
“Friction” is fine. What’s actually going on is quite complicated and several things at once, not at all reflected by a “well actually it’s this not that”.
We could teach a little course on hypersonics, but meh.
In more detail: at the shock, the conditions of the gas change over a distance on the order of a mean free path. This means that, locally, the gas is out of thermodynamic equilibrium, with fast molecules running into slow ones. The extremely high gradient of gas conditions causes extremely rapid relaxation to an equilibrium state, a process that very rapidly produces entropy.
As Mach number increases, the density jump across the shock approaches an asymptotic limit, but the heating increases without bound.
The temperature rise from the compression matches what one predicts from PV=NkT
A shock wave is unnecessary. It happens with subsonic flow, too. In fact, it's how refrigerators work.
(In ME101 Fluid Mechanics, the Prof showed how a re-entering satellite would melt even if the atmosphere was a frictionless gas.)
That's a null statement, since that holds for any (ideal) gas regardless of how it got into its current state.
If you mean, the temperature rise is the same as if it were adiabatically compressed to the density or pressure the gas has after the shock, then that is not true.
On a wing, the temperature rise is highest at the static point on the leading edge, where there is no motion of the air. The temperature declines from there back as the airflow speeds up. If friction was the source of the heat, you'd expect the temperature to be the lowest at the static point, and would increase towards the trailing edge.
BTW, how a diesel engine works is by compressing the air/fuel mixture until it heats up enough to ignite. A gas engine will sometimes "diesel" on after the ignition is turned off.
The point I am making is that gas going through a shock is a fundamentally different process than a gas being adiabatically compressed. The former causes an increase in entropy; the latter ideally does not. While a shock isn't "friction" per se, like friction there is dissipation (and at entry speeds, quite a lot of dissipation).
https://www.kimerius.com/app/download/5782475760/Calculation...
The paper does talk about heat from friction, but not at the stagnation point. It also talks about the heating of the surface being less than predicted by adiabatic compression, but that is the heating of the surface, not the heating of the air at the stagnation point.
Anyway, it's foundational supersonic fluid physics that shocks create entropy.
"Shocks are irreversible occurrences in supersonic flows (i.e. the entropy increases)." -- https://en.wikipedia.org/wiki/Shock_(fluid_dynamics)
Reentry with blunt bodies works because most of the dissipation is occurring at the shock, at some distance away from the vehicle, allowing most of the heat (that must be produced from the kinetic energy of the vehicle as it slows) to be carried away.
You are right. Isentropic compression will result in a higher temperature of the compressed fluid. This is undergraduate gasdynamics. In these supersonic flowfields with high shock strength though, the shock acts as a very dissipative compression mechanism. Behind the shock is a compressed fluid that is much hotter than it would be if compressed to the same pressure isentropically. Shocks are dissipative, like friction, but shocks and friction are not the same thing.
So unless you remove heat from a perfect compressible fluid being compressed (i.e., via a non-adiabatic process), it will always be hotter post-compression. It's just that the compression and heating that shocks effect causes much greater heating than the isentropic case.
In what we call "acreage" where the forward-facing area is limited (e.g., upper surfaces of wings and vehicle bodies), other effects, including turbulent skin friction heating, can dominate the local heating rate.
Columbia made it through almost the entire time of peak heating without a repair. This doesn't mean that a repair would be successful to get all the way to the ground, but it sure seems like it could be extended significantly longer.
So given that, would it have been impossible to space walk around the shuttle, identify missing/damaged tiles and shove some spare material in gaps? Could the shuttle crew have not carried epoxies designed for this purpose? Obviously it would be a repair that might not work, but at least give you a chance.
I think about this now as well when I see Starship tests that knock tiles off of it's heat shield just from vibrations.
Maybe it was completely impossible, but the topic is not even discussed.
Would it be possible to have an autonomous sensor on each termal tile that reports its integrity and the heat/pressure instead of relaying on inspections?
Feeling pain is obviously very useful to us, it's pretty much the primary mechanism of detecting issues, the limits and taking care of our bodies.
I suspect, maybe it can be possible to have a wireless sensors that function by RF(a nearby source that powers the sensors) or being powered by something like the heat gradient/MEMS that charges and stores energy from the movements.
Hearing people die is just not something we who live outside of war zones are accustomed to.
After Apollo they moved away from 100% O2, I think the ISS has a similar composition and pressure to terrestrial atmosphere.
[0] - https://www.popsci.com/why-did-nasa-still-use-pure-oxygen-af...
A lot of it was to replace flammable materials with less flammable ones. I think they replaced the insulation on all the wiring from PVC to fluoropolymer. Changed the design of the connections so there was no exposed bare wire. They redesigned the flight suits which were made partly of rubber.
They changed the life support to keep the partial pressure of oxygen constant. So 21% on the ground constantly adjusted to 100% as they went up. For weight reasons the command module designed 5 psi or some such. So that's what they had to do.
It's about the recovery effort for the accident debris, which is the largest ground search operation in US history.
As an organization starts to drift from its engineering origins and management gets populated with people who -- either because of increasing emphasis on management versus technical knowledge skills, and/or requirements to spend time on communicating versus building -- are making judgement calls far from the "detail level", is this problem bound to arise?
How does an organization incentivize its people and structure to keep on making the "right" calls?
*What I'm pointing out here is the terrible realization afterwards that the managers of the program were told about the potential damage to the orbiter, but actively denied requests from the engineering org to get help to image/diagnose/potentially repair the damage or come up with mitigations.
And even in promoting Mars colonization at SpaceX, where people insist that apparatus at Mars would plausibly have some useful role as a staging point for trips beyond Mars.
What are the odds people who paid for self-driving will ever get a refund?
I mean, early life for settlers in the USA also sucked.
Humans have evolved on Earth. Even the least habitable place on Earth (e.g. Antarctica) is paradise in comparison to Mars. Mars settlement using current technology is an intractable problem.
Musk is selling his vision as an aspirational goal, not something achievable in his (or any of our) lifetimes. He knows better than anyone that a planet without a magnetosphere, fertile soil or a breathable atmosphere (just to name a few) is a death trap for humanity. But he has made it his life purpose to get the ball rolling.
If we look at the goal of colonizing our solar system rationally, a far more optimal strategy is robotic colonization. Advances in AI are now making it possible to fundamentally change how manufacturing is done via robotics. Once this happens, Mars colonization becomes far more feasible. Musk knows this, hence his pivot of Tesla from cars to robotics. The idea of sending people onto a hostile planet, where they then build a colony is archaic. People will arrive once the colony is fully built and operational.
Even a self-sufficient colony in the middle of the Sahara Desert, constructed all hands-on, is out of reach.
Not holding my breath here.
It basically may be impossible. Sure, officially, no doubt they would say anyone can speak up, raise the alarm, etc. However there are usually overriding contradicting incentives. “You slipped on the schedule”, “Creating trouble and making our department look bad”, “So and so raised concerns and got passed up for promotions… that’s not happening to me, no way”.
Incredible song. I stumbled across it when I decided to try The Long Winters after hearing John Roderick on a podcast. Even after several listens it's capable of producing chills and tears, when it lines up with my mood.
John talked about making the song on Song Exploder as well; it is one of my favorite episodes. https://songexploder.net/the-long-winters
The launch and re-entry suits for the space shuttle crews were derived from the pressure suits the SR-71 and U-2 pilots wore. One pilot actually managed to survive the breakup of an SR-71 traveling at Mach 3 at 85,000 ft, although the suit was shredded when the pilot regained consciousness. The shuttle was traveling at Mach 18 at 200,000 ft when it broke up, so surviving the breakup would have been next to impossible anyhow.
I think being on Challenger would have probably been worse. When the crew cabin was found, some of the emergency air tanks that have to be activated manually were found activated. It's possible the shock of the explosion activated them, but it's also equally possible that at least some of the astronauts remained conscious through the breakup and didn't die until the cabin hit the water...
It will be interesting to see what happens when SpaceX has their first fatal incident involving e.g. NASA astronauts.
I'm of the opinion that astronauts should be allowed to take reasonably informed risks. Are they reasonably informed? How do you make sure they are?
And then the astronaut can head to the head mechanic who leads the assembly process and ask them how do they know that the screws are torqued right. They would show them the training the technicians receive, the tools they employ and the QA processes they have in place.
After that the astronaut can spot check a few areas.
Of course they won’t do all of this with all of the systems and processes, but they can do enough to satisfy themselves that the place has the right processes in place to their liking.
If the engineers don’t care about the screws, if the chief of technicians can’t find the calibration paper of the torque wrenches and if they find a passed out drunk technician behind a panel and rattling screws then the astronaut knows they are in trouble.
Astronauts are not just thrown in box and launched to space. The current practice is that an astronaut gets assigned to the project way before the spacecraft in question is ready and they participate in the engineering process. They are obviously consulted on aspects of operations and crew interfaces. They work together with the other engineers to write the manuals and checklists. Of course they can and do raise their own questions about subsystems too.
Their role is similar to test pilots because well that is what they are.
This will hopefully change as space flight becomes more routine. And then astronauts role will become more of what a pilot does. How do we make sure that pilots are reasonably informed? We can show them accident statistics, and through their training we explain the high level operation of the various subsystems of their craft and the role of various actors in flight safety. (Maintenance, ATC, management, the flight attendants, FFA)
If NASA employees are civilians, do they have any authority to do this? Was there special legislation used or something?
It isn't driven to keep the press out. If any benefit its a side benefit and I observe a metric French tonne of press is locked inside the room(s) at that point.
Robert Frost, Instructor and Flight Controller at NASA:
> If you are referring to the call from the Flight Director: “GC, Lock the doors” that is a command that initiates the contingency response to a significant incident, such as the loss of a vehicle. It begins a FREEZE, ISOLATE, AND PROTECT process. The Flight Director would follow up that statement with a call to the team to immediately pull out the contingency section of the Flight Control Operations Handbook to identify specific actions that are to be taken.
> Access to the facility becomes restricted. People that weren’t in the room at the time or aren’t essential to the next steps are not allowed access and the people in the room are restricted from leaving. Communication in and out of the room is restricted. Usage of all devices, both workstations and personal, is restricted. The team is hands-off. Nothing should be done that changes the configuration at the time of the incident. Those are the freeze and isolate steps. Next comes protect. All of the data that was in use must be captured, recorded, and preserved in a static state. Even the trash cans have to be preserved in their state. All of this is because any investigation into the incident will require all of this data.
> Once given permission, the occupants of the room may continue to capture their observations and actions in their console logs.
> It is important to keep the equipment, documentation, and people in a pristine state until it all has been preserved. We don’t want any form of contamination that could be caused by someone bringing in data that wasn’t in the room during the incident into the room or removing data. We don’t want the team’s observation and recording of those observations influenced by communication with people that weren’t there.
> All of the data will be collected and put into secure data containers and taken to a secure vault. Debriefing of the team may then be performed and once a response team has been formed and has begun their work, the Flight Director may release the team.
But how's that legal? Is there some special legislation for it? A citizen's arrest requires an actual crime being observed.
When it comes to leaving secure sites you can often be restrained to prevent you from smuggling out sensitive materials which is quite sane and necessary in a number of situations. There are also a plethora of public sites (i.e. government run) that non-enlisted citizens are barred from entering - though that is a bit of a different situation.
Go on law.cornell.edu and dig through the vast provisions of federal security officer power as it pertains to arrest, detainment, use of deadly force, etc.
They can do it.
Arrest authority:
https://www.law.cornell.edu/cfr/text/14/1203b.103
Deadly force authority:
https://www.law.cornell.edu/cfr/text/14/1203b.106
Management oversight:
(3) The arresting officer has reasonable grounds to believe that the person to be arrested has committed or is committing any felony cognizable under the laws of the United States.
Therefore, if you try to leave after being ordered to stay, during a crisis situation, without a valid reason, you should expect to be arrested and further dealt with.
What you're likely to find is an issue is that the security guards at NASA can arrest, if the links above are correct, and you're likely to fund yourself in a predicament if you try to leave and they don't want you to.
I'd imagine working at NASA, and at least some other space launch companies, especially those that provided services to government and defence agencies, come with additional conditions beyond what one might expect stacking shelves at a supermarket.
Being told "you're not free to leave" is rightfully worrying to a lot of people. There are countries where hearing that would be terrifying. What makes the US different is the rule of law, due process, and individual liberties. Asking on what authority the government has to detain you should never be karmic suicide. There are many places where asking that question is truly unthinkable, and they're not places you want to live.
That reads like complete sarcasm to me.
Anyway, like I said - to me this is on the same level as someone asking if an astronaut on the ISS is "free to leave" and how is this not a citizen's arrest and how somehow this constitutes an abuse of liberties.
This doesn't read like a serious question - more like something a very edgy 14 year old would ask and feel clever.
It covers things like assault, resisting, impeding, damage, theft, sabotage, forging, impersonation, destruction of vehicles or other property, communications, explosives, civil disorder and a dozen other categories with sub categories.
They'd easily get you on numerous federal charges if you attempted to flee.
...if they've observed you committing an offence.
How is any other job duty legal?
> Is there some special legislation for it? A citizen's arrest requires an actual crime being observed.
Being prohibited from leaving on pain of adverse employment action is not arrest, and does not require a crime. (That being said, I wouldn't be surprised if NASA did have special statutory authority for more binding orders related to spaceflight related emergency situations, not that they would be likely to need either those or even employment sanctions to secure compliance with control room staff staying put while trying to resolve an emergency incident.)
Apparently it's fashionable to make it look like HN has such a collective boner for "professional integrity" that even asking this question is treated like an insult and downvoted. Repugnant.
It's a collective boner for NASA.
It's interesting though the language you choose to use to deride the commenters explaining why the lockdown happens.
Federal civilian is still federal and is a different world from your typical civilian private sector corporation.
Yes, one or more people on the property are certain to have the power to prompt a security lock-down. They're also federal employees, not merely civilians. Someone in the chain of command can request that federal security officers secure the building/property as the scene of an ongoing crime or accident.
They also employ armed security officers that can legally kill you if you're a threat. They can definitely secure the property during a potential crime or accident.
They can use lethal force to protect evidence in the US?
Lethal force wouldn't be necessary in most circumstances to protect evidence unless the fleeing party is engaging in the use of lethal force. They can use force to protect government property, yes. Although most federal security officers aren't supposed to use firearms to attempt to disable vehicles.
How's that relevant in this thread? You think they brought down the shuttle... and they're also armed in the control room?
You confused their security aparatus as being akin to private civilian security guards at a convenience store in regards to their power to detain / arrest / use force. For some reason you clearly thought "civilian" was similar to the context of a private corporation and didn't understand what federal powers would exist in that situation and on that property.
Well someone else linked to them and they seem to be what I'm saying?
https://www.law.cornell.edu/cfr/text/14/1203b.103
> The person to be arrested has committed in the arresting officer's presence an offense
Define offense. Someone suggested it has to be criminal, but does it actually say that somewhere. Does disobeying an order to secure the room constitute an offense against NASA? Depending on the meaning of that word, it could certainly be interpreted that way, in which case arrest is a real possibility.
My guess is they'd arrest anyone who tried, and apologize later if someone proved that they shouldn't have done it. And nobody would actually be punished for the incorrect arrest.
Also, in jobs where people's lives are at stake, there are often situations where you may commit a crime by refusing to do your job properly. If a lockdown has been ordered, it's plausible that the situation is like that, and any official with police-like powers can reasonably stop anyone trying to leave. Especially if the person trying to leave is also a public official.
The actual question is “or what?” Well if you really were there and really did try to disobey that order, you’d definitely be putting your job at risk, unlikely to be breaking any laws, probably risking a physical convention with whoever kept the keys… but it comes down to why… if you really wanted to leave and had a good reason, would someone have let you? I’m guessing probably, but i really doubt you would have that reason or even tried to test the legal authority of people giving that order. Your whole job is to be in that room and something terrible happened, what circumstances would make you want to leave or test the “ you can’t make me” theory.