I mean, it's very likely that you can convert just about anything into some non-zero level of contribution.

I'm probably most-useful on software engineering, since that's where most of my expertise lies, and I'd be pretty confident that that's something that there's some need for, but even if not, I can do whatever.

With 180 days until the world ends, there's very time for training. The skillset we have available to someone is going to be the one that they're going in with, so if it's not able to leverage that skillset or something extremely adjacent to what they already know how to do, it's probably going to be using people in an unskilled capacity. But even there...shrugs If the answer is that what they need is a ditch dug for fuel lines to a new launch pad at Cape Canaveral for the vehicle for a deflector mission and they don't have the heavy equipment in place to use a machine for something and they need manual labor, then I'm driving down there with a shovel. If I'm not useful for that, because they've got people who are more-able to do that and all their slots already filled, then maybe I'm a cook's assistant to help put together food for the people who are digging that ditch.

shrugs

EDIT: My guess is that the very first few days would be spent setting up infrastructure to get more people slotted into place, like getting call centers tasked on this ("we may need to contact you if we can make use of you"), setting up contact information for volunteering, and putting together a database with names, contact information, and relevant skillset.

It's easiest to make use of volunteers, because you don't need to deal with motivation with them, and so volunteering speeds that up, but realistically, I'd expect that people who aren't volunteering are probably going to get conscripted. Like, the closest past analog we have to something like this is war, places where society is being mobilized en masse to deal with a major problem, and that's how things are handled in that situation. This is going to be an even more extreme situation, so start with what we'd do in a very severe war and then crank things up.

You'd probably have governments being the primary institution to respond, because they are already in place and don't have to be organized. I'd guess that in the US, you'd probably have all 50 states have their governors declare a state of emergency.

https://en.wikipedia.org/wiki/State_of_emergency

A state of emergency is a situation in which a government is empowered to put through policies that it would normally not be permitted to do, for the safety and protection of its citizens.[1] A government can declare such a state before, during, or after a natural disaster, civil unrest, armed conflict, medical pandemic or epidemic or other biosecurity risk.

Congress might declare war, just to make use of pre-existing set of mechanisms to grant authority while spending a minimal amount of time screwing around arguing over it. The federal government would probably make use of martial law:

https://en.wikipedia.org/wiki/Martial_law

Martial law is the replacement of civilian government by military rule and the suspension of civilian legal processes for military powers.[1][2] Martial law can continue for a specified amount of time, or indefinitely, and standard civil liberties may be suspended for as long as martial law continues.[1][3] Most often, martial law is declared in times of war or emergencies such as civil unrest and natural disasters.[4]

Like, if your resources are needed, they're getting commandeered, and if your labor is, it's being conscripted. If you think about, oh...the UK in World War II, you had like a 99% income tax (which Conservatives didn't like) or Labour accepting a Conservative prime minister being put into place for the duration (which Labour didn't like) to deal with the issue. There are a lot of people who might have taken issue with that sort of thing normally, but when you have an environment where there's some sort of overwhelmingly critical need, the rules go out the window. Well...no, they don't go out the window, but the concerns that they're designed to address become more-or-less irrelevant, since the urgent issue takes precedence over all else.

My guess is that you'd have something akin to wartime propaganda set up to get anyone who isn't already involved as motivated as possible.

Like, for just about any policy or action, the first question is going to be "which approach best solves the Big Rock In The Sky Problem?" Even if there are drawbacks or tradeoffs (like, maybe corruption is an issue, or someone suffers some kind of harm from the actions taken in the name of dealing with the Big Rock Problem), it's almost always going to be the case that you can say "we can sort things out six months from now, and, heck, even if things don't get sorted out, anything that happens that's bad during the duration of the crisis is still less bad than humanity ending".

People are talking about how they'd entertain themselves in this thread. Like, during past wars, we pulled entertainers off the civilian market to entertain the troops. In World War II, we directed fillet mignon to submarines, because submariners had particularly high risk and awful living conditions, and it was essential that they be doing their thing. My guess is that that sort of thing is likely going to happen. Like, anyone who can and is working directly on the Big Rock Problem is going to be worked as hard as possible. If you're digging that Cape Canaveral trench, you wake up, stay at work on this, don't leave, spend all day on it, go back to sleep on location, and whatever can be pulled off the rest of society to facilitate them doing their thing is going to be pulled off.

Companies with even vaguely-relevant capabilities are probably going to be redirected to solving the Big Rock Problem, because they have existing hierarchies with employees already in place, so you don't have to screw around with time ticking away while you set those up. In World War II, we had a problem with scaling up torpedo production; the people who made torpedoes didn't have a lot of expertise in scaling production up and were doing a bad job of it. That was a serious problem. In response, you had things like the American Can Company put on setting up torpedo production---they didn't know much about torpedoes, but they knew how to organize and optimize scaled production, and it's faster to retask existing hierarchies than to go make new ones. Frigidaire stopped making home appliances and made heavy machine guns. I'd expect similar things to happen; probably a lot of companies, any entity whose normal output can be spared for six months, even ones that don't obviously work in a relevant field, are going to be retasked with Big Rock Problem work.

You'd probably have people moved en masse to do labor. Like, if I need 100k people for work on a Big Rock Problem project, I'm going to pull them from wherever I need. Normal immigration laws and such, concerns about smuggling or trafficking or vetting people or people overstaying visas or whatever don't matter much in the face of the problem. Back during World War II again, while we never needed to fully activate plans, because Germany got sidetracked fighting the Soviet Union, we expected to need to fight a sustained maximum-effort trans-Atlantic war, to pull farmers onto war effort stuff, and we expected to hire huge masses of people out of Latin America to keep American farm production running. In a Big Rock Problem scenario, everyone, everywhere in the world has their ass in the fire. If there's someone, anywhere, in Nigeria or Eritrea or whatever and you can make the most use of them somewhere else in the world, whatever it takes to get them active on the problem, it's going to happen.

you make a valid point.

why wait? If we do the hard part now, we'll have six months to fuck around.

Be excellent to each other