By Andy Pasztor

NASA has extended to the end of April from the end of February its deadline for awarding key contracts for landers intended to take astronauts back to the moon.

The delay, which surprised some industry officials, will give President Biden's incoming National Aeronautics and Space Administration appointees more time to evaluate the three competing teams and according to NASA, "seamlessly transition" from current agreements to the next phase of the program.

But the move also is the clearest sign yet that the Biden administration is likely to shake up and slow down plans that currently call for taking U.S. crews back to the lunar surface as early as 2024. That aggressive timetable had been considered moot by many industry and government officials, even before NASA's latest action made it more unlikely.

The change allows contractors to continue design and development efforts. In April, NASA awarded a total of more than $960 million to separate teams headed by closely held Blue Origin Federation LLC, Elon Musk's Space Exploration Technologies Corp. and the Dynetics unit of Leidos Holdings Inc. to begin work on proposed lunar landers. The delayed awards are intended to be follow-on contracts to further refine and test designs.

Without mentioning the 2024 lunar landing deadline set by President Donald Trump, NASA said in a post on its website it "is committed to establishing a sustained lunar presence, and this procurement action is consistent" with that commitment.

Before Friday's announcement, at least two of the three teams were expected to move to the next stage of developing spacecraft, according to industry officials. But when new NASA leadership takes over, that strategy could change, according to industry officials following the issue.

The new leadership team also will have to firm up other elements of NASA's overall human exploration plans for the moon, called Artemis. Despite pushing ahead with the landers and a mammoth rocket to transport them along with astronauts into lunar orbit, NASA's previous leaders hadn't determined the precise role of a proposed multibillion-dollar orbiting platform, called the lunar gateway, in the initial landing missions. NASA's top outside safety advisory panel has warned the agency needs to better coordinate and oversee different portions of the Artemis initiative, or it risks overlooking potential hazards to future crews.

Another complication is uncertainty surrounding the deep-space rocket, called the Space Launch System or SLS, slated to carry the landers into space. Boeing Co. is the prime contractor on the program and is responsible for producing the core and related avionics systems.

A Securities and Exchange Commission document filed earlier this week by Aerojet Rocketdyne Holdings Inc., a major SLS subcontractor, reveals deep industry misgivings about the future timetable for SLS flights. The document indicates Aerojet Rocketdyne's board recently sharply scaled back revenue projections, reduced likely SLS launch tempo and acknowledged growing uncertainty about overall prospects for NASA's lunar initiative.

NASA has announced what amounts to at least a similar two-month delay for repeating a key ground test of the SLS, which has been under development for nearly a decade but hasn't yet flown. Earlier this month, test firing of the booster's four main engines was cut short due to technical problems associated with the way the test was set up.

The agency on Friday said it plans to redo the comprehensive test as early as the end of February, making a test flight of the full rocket unlikely by late 2021, as previously anticipated. NASA also said Boeing determined the test would pose minimal risk to the booster while providing valuable data to help certify it for flight. If the second test is successful, it will take NASA at least another month to prepare the booster for shipment to the Florida launch site.

Write to Andy Pasztor at andy.pasztor@wsj.com

(END) Dow Jones Newswires

01-30-21 1324ET