As the partial government shutdown continues, a notice to NASA employees showed the impossible choice faced by federal workers across the U.S.

At NASA's Johnson Space Center in Houston a sign hanging outside the bathroom asks staff to volunteer to clean the bathrooms as the center's custodial staff will no longer be funded after Friday, according to the Hill newspaper.

Employees have been forced to take unpaid leave, also known as a furlough, as NASA feels the pinch of the shutdown.

"This is our reality at the Johnson Space Center," Elizabeth Blome, a NASA employee tweeted on Thursday.

"We now have no custodial services while we work without pay to keep the International Space Station operating," she said. About 75 percent of the government remains open and funded, including the Department of Defense, following a separate spending measure passed in September.

But for the other quarter of agencies that will be affected, including NASA, many of the hundreds of thousands of employees will still be required to show up to work but will not receive paychecks until the government officially reopens.