Up to 1,800 jobs at Kennedy Space Centre will go today, with 2,000 more expected in the coming months.
staff at the Florida centre celebrated and mourned yesterday's final space shuttle landing.
They were thrilled with the success of the last mission, which ended with Atlantis touching down before dawn. But they also traded goodbye hugs and took souvenir photos of their colleagues, knowing some of them will not be be returning next week.
The latest round of redundancies - between 1,500 and 1,800 in Florida - takes place today.
Close to 9,500 contract workers in total will have been laid off nationwide from the shuttle programme's demise.
Angie Buffaloe,wept yesterday with three colleagues who are losing their posts in her engineering office.
"I spend more time with these guys than I do with my family," said Ms Buffaloe, a 22-year space centre veteran.
"We've been through everything: divorce, sick children, grandchildren. They've been there. We've shared life together ... and now their last day is today."
The job losses involve everyone from high-ranking managers to caretaking staff. Many of the workers had spent their entire careers at Kennedy Space Centre and were inspired as children to work at the home of the moonshot launches from the Apollo era and the place that has hosted every shuttle lift-off in the past 30 years.
"For me the shuttle is my life, and it's very sad for me to see that part of my life end," said Glen Longwood, who has worked at shuttle emergency landing sites overseas.
He said he hoped to find another job within Nasa, where he has spent his entire 18-year career, but he is looking at other jobs around the country.
"I'm looking for the next adventure," he said. "It's a bridge I have to cross but I'm not sure what's on the other side."
Hundreds of other soon-to-be-redundant employees gathered with their co-workers over hot dogs, Popsicles, and ice cream at a thank-you gathering Nasa held outside Atlantis' hangar.
The space shuttle was parked at the front, offering a final close-up view of the vehicle they had worked on for years.
Tony Robertson, whose job ends today, worked on the maintenance team that cleaned the launch pad.
"It's a sad day," he said. "It's sad that the programme is done, but I'm going to go home, relax and cut the grass."
Nasa administrator Charles Bolden said the agency would try to bring back unemployed shuttle workers to help on private-sector spaceflight ventures or for Nasa's efforts to build a vehicle for an eventual mission to an asteroid or Mars. Nasa has yet to settle on a rocket design to get astronauts there.
Shuttle workers should "stick their chests out proudly to say they were a part of the most incredible era in American spaceflight," Mr Bolden said.
For those workers still employed, there will be old business to wrap up and new skills to learn.
Test director Michael Ciannilli, who has worked for 15 years on launch countdowns and landing operations will prepare the three shuttles for museum at Cape Canaveral, Los Angeles and suburban Washington and decommission buildings that had been used for the shuttle.