The announcement comes after the NASA notified of delays on Artemis 1's uncrewed flight around the Moon. The agency indicated last week that it would launch no earlier than May, but even that timeline is in doubt, Space.com reported.
"Given the time needed to develop and test the human landing system and NASA's next generation spacesuits, we estimate the date for a crewed lunar landing likely to slip to 2026 at the earliest," NASA Inspector General Paul Martin was quoted as saying during a House Space and Aeronautics Subcommittee hearing on Tuesday.
He acknowledged that the 2025 deadline that NASA is aiming for doesn't appear to be feasible.
Martin said there are challenges that need to be faced, "not the least of which would be getting the human landing system certified to operate spacesuits," along with changes in the agency's acquisition strategy that is expected to take more time in procuring key technologies "that are not mature".
These factors, he said, "often point to taking longer and [requiring] development to get there. So 2025 is not impossible, but it seems improbable."
According to William Russell, the US Government Accountability Office director of contracting and national security acquisitions, the problem is that NASA is seeking to manage "multiple risks simultaneously" while achieving a tight deadline, the report said.
Russell pointed to factors such as the seven-month delay induced by the HLS disputes, a key change in spacesuit development to pivot the work to a contractor instead of in-house work, and cost growth for the Space Launch System rocket and other key infrastructure required to support a human landing.
NASA, for its part, pointed to unanticipated issues that contributed to cost growth and schedule delays, particularly involving the coronavirus pandemic, which has created supply chain hiccups and personnel challenges due to safety protocols.
"Every bit of work that I've mentioned is possible because of the people of NASA and our private sector partners," James Free, the agency's associate administrator of the exploration systems development mission directorate, was quoted as saying.
Free did not speak directly about timelines for the Artemis 3 crew landing, but said more information on costs and timelines will be forthcoming as NASA formulates its next budget. He emphasised his approach, however, is to keep "a realistic schedule and budget", the report said.