Layoff notices went out Tuesday to 550 employees at NASA’s Jet Propulsion Laboratory in response to ongoing budgetary chaos at the legendary La Cañada Flintridge facility.

The layoffs reduced the employee headcount by more than 10% and affected teams across the institution, according to multiple sources not authorized to speak publicly.

A reorganization for remaining staffers will be announced on Wednesday.

“This week’s action, while not easy, is essential to securing JPL’s future by creating a leaner infrastructure, focusing on our core technical capabilities, maintaining fiscal discipline, and positioning us to compete in the evolving space ecosystem,” JPL Director Dave Gallagher said in a statement Monday.

The cuts were part of a reorganization that began in July, he said, and are not related to the federal government shutdown that began on Oct. 1.

JPL staffers are employed by Caltech, and none have been furloughed since the standoff between Democrats and Republicans in Congress began. But the research facility started preparing for a leaner future even before President Trump took office, and is enduring one of the most challenging stretches in its nearly 89-year history.

“The morale has been as low as anyone has seen in decades, maybe ever,” an employee spared by the layoffs said. “The uncertainty is very unsettling. … We expect more people will leave in the coming months due to continued uncertainty on the type of work that may or may not come.”

Layoffs and attrition have reduced JPL’s overall staffing by about one-third in the last two years, sources at the organization said, from roughly 6,500 to around 4,500 after this week’s reduction. JPL endured three rounds of layoffs last year alone, prompted by massive federal budget cuts for its beleaguered Mars Sample Return mission.

The Eaton fire came perilously close to the campus in January, forcing some 20% of the agency’s workforce to evacuate their homes. About 210 employees lost their homes in the fire, and dozens more were displaced for months.

Then in May, the Trump administration proposed a $6-billion cut from NASA’s $24.8-billion budget for the coming fiscal year, a 24% drop from its current allocation.

While both the House and Senate appropriations committees would largely keep the agency’s overall funding intact, their budgets reallocate money within the space agency in ways that could profoundly affect JPL’s work.

The House appropriations bill would keep NASA’s funding steady but cut about $1.3 billion from NASA’s $7.3 billion Science Mission Directorate, which funds many of the missions that JPL manages. The Senate bill, in contrast, would maintain the science program’s funding.

It’s not yet clear how the most recent layoffs will affect JPL’s work on drought, fire and climate change. No missions have yet been canceled or paused. But with no end in sight to the stalemate, JPL’s future remains in limbo.

“JPL is a national asset that has helped the United States accomplish some of the greatest feats in space and science for decades,” Rep. Judy Chu (D-Monterey Park) said. “Taken together with last year’s layoffs, this will result in an untold loss of scientific knowledge and expertise that threatens the very future of American leadership in space exploration and scientific discovery.”

Times staff writer Hayley Smith contributed to this report.