At midnight on October 1, 2013 the US government entered the state of government shutdown where all functions deemed non-essential are suspended. This shutdown lasted 16 days.
How did this shutdown affect NASA operations?
Here is a basic rundown of the effects of the shutdown:
Besides the issues already mentioned, it's also caused some morale problems.
Unlike what user6972 claims, we did not have 'vacation'. Some were designated as essential employees, and were required to work through the shutdown. Some were sent home, but unlike with a vacation, you couldn't really go anywhere as you might be called back at any time.
In my case, I was designated as essential-on-call. This meant that I was required to check in daily to see if there were any emergencies that I needed to respond to, and in one case, I had to actually go into the office to correct a problem that I couldn't deal with remotely.
This has also resulted in some significant morale issues, as we kept getting conflicting reports from our contract management about what we were or weren't allowed to do remotely. As our task is staffed by personnel who work for three different companies, everyone got different information; even within the same task, some people's duties were considered essential, others not.
Now we're sitting in a waiting game -- only the civil servants were paid for their time off. Those of us that are contracts are still waiting to hear months later if we're going to have to burn through weeks of leave to make up our time, or if the government's going to pay us for the time. We've been told that it depends on the terms of the contract, and that each contract will have to be evaluated separately.
The long-term affects won't be known for some time ... and that is, how many people decide to leave NASA and federal work in general so that they don't have to go through this again?