WASHINGTON, June 25 (Reuters) - RTX Corp ( RTX )

subsidiary Collins Aerospace is in talks with NASA to back out

of its contract to build new spacesuits for astronauts on the

International Space Station, setting back the agency's bid to

modernize its decades-old spacesuits, according to two people

familiar with the discussions.

The contract was part of $3.5 billion awarded to both

Collins and Axiom Space by NASA in 2022. A breakdown of the

contract was not provided at that time.

RTX and NASA did not immediately respond to requests for

comment.

Spacesuits, essentially human-shaped spacecraft, have

been a persistent development challenge for NASA, whose

astronauts 250 miles above Earth on the ISS currently rely on

spacesuits developed some four decades ago with only a few

refurbishments and updates since.

NASA has had two rare cancellations of

astronaut spacewalks

this month because of the spacesuits. The agency cited a

"spacesuit discomfort issue" that prompted the cancellation of

two astronauts' planned spacewalk on June 13.

The second attempt at the spacewalk, on Monday, was also

canceled because of a water leak.

Collins has been seen as a leader in spacesuit

development but has struggled on its current contract, the two

people said.