The nation's nuclear labs are preparing to furlough more than 20,000 employees and shutter their science experiments, except for work essential to national security, because of the ongoing government shutdown.

Starting Tuesday (Oct. 15), workers at California's Lawrence Livermore National Laboratory will ready the lab for a hard closure, said Lynda Seaver, deputy director of communications for the lab. "By the close of business on Oct. 16 we will be at minimal operations. Most employees will be on holiday Oct. 17 and Oct. 18, and then we will be at full shutdown by Oct. 21," Seaver told LiveScience.

The National Nuclear Security Administration (NSSA), part of the Department of Energy, has ordered its three nuclear laboratories, including Los Alamos National Laboratory and the Sandia National Laboratories, to be ready to shut down by Oct. 21. Los Alamos is scheduled for shutdown on Oct. 18, and Sandia on Oct. 21. Altogether, the three nuclear labs employ more than 24,000 people.

The initial lab closure lasts through Nov. 1. Safety and security staff will stay on-site, along with workers conducting research essential for national security, Seaver said.

The nation's other nuclear laboratories, which are run by private contractors, report they have enough money to stay open through November. These include Oak Ridge National Laboratory, the Idaho National Laboratory and the Pacific Northwest National Laboratory.

The Y-12 National Security Complex near Oak Ridge, Tenn., which manufactures nuclear weapons materials, began shutting down earlier this week because of the fiscal crisis.

The ongoing budget impasse has also imperiled the U.S. Antarctic research program. The National Science Foundation suspended the summer research season this week, canceling the experiments of thousands of scientists in the America and other countries. Contractors in Antarctica are being sent home.

Email Becky Oskin or follow her @beckyoskin. Follow us @livescience, Facebook & Google+. Original article on LiveScience.