NASA has temporarily stopped work on the Space Launch System and the Orion Spacecraft to be used for its forthcoming Artemis missions, which would potentially carry the next American man and the first American woman to the Moon's surface.

NASA administrator Jim Bridenstine announced on Thursday that the agency would shut down its New Orleans Michoud Assembly Facility and its Mississippi Stennis Space Center due to concerns about the spread of the novel coronavirus.

"NASA missions will have impacts, but as our teams are working to evaluate the whole picture and minimize risks, we agree that the workforce's health and safety is our highest priority," Bridenstine said.

The rocket and spacecraft agency conducted manufacturing and development activities ahead of the first Artemis flight, scheduled for no earlier than April 2021.

Bridenstine said in a statement that NASA and teams of contractors must complete an orderly shutdown that places all equipment in a safe condition before work can resume. When this is complete, on-site staff will be limited to those needed to protect life and vital infrastructure.

The closures marked the latest in a series of delays that NASA encountered in designing its next-generation rocket, called the Space Launch System, or SLS, and its Orion crew spacecraft, intended for the human moon and Mars missions.

It is a continuum of emergency preparedness that NASA has in place as guidelines for its response to the current COVID-19 outbreak, and it determines what steps the agency should take in terms of its resources and facilities at each of its physical sites based on how the outbreak unfolds.

It's a harsh blow to the Space Launch System, which has been facing a variety of delays over the years. Bridenstine told the Senate late in 2019 that the rocket was not ready in time to fulfill the expedited timetable of the Artemis mission, which is planned to take astronauts into the moon and eventually Mars.

Research on the SLS has been plagued by years of delays and nearly $2 billion in cost overruns, led by Boeing Company as the prime contractor. Faced with the coronavirus pandemic, the work stoppage came as engineers rushed to complete plans for the first all-engine ground test of the rocket this summer.

Bridenstine says the facilities where the SLS and Orion are being operated on will be guarded round the clock to ensure that it is in a secure state for suspension and ready for work to be resumed once the space program's Stage 4 is lifted.