Littler, who needs one appearance to reach the notable landmark of 450 career games, will join Rochdale while Aspinwall links up with Swinton.
Centurions Head of rugby Derek Beaumont said: “It’s a similar scenario to earlier in the season when we allowed several players to go out on loan.
“The forthcoming Reserve Team fixtures are against Academy sides where we are restricted with the number of over-age players we can field. We feel it will be far more beneficial for Stuart and Martin to play at a high level of rugby so that they will be in a position to come back to the club in a position to challenge again for a first-team jersey.
“Our Head Coach Paul Rowley has good relationships with his opposite numbers at both clubs, Ian Talbot at Rochdale and Ian Watson at Swinton and we will the loan moves will be mutually beneficial to all parties.”