Aardsma has been out since undergoing offseason hip surgery, with a forearm injury then cropping up during his initial Minor League rehab run.
The Mariners are being cautious with their injured closer, but he appears to be getting close to where he can start another rehab assignment.
"He's feeling pretty good," manager Eric Wedge said. "He looked good. He's making progress. We're now getting to the point in time where we'll see how it's going to play out. We've been down this road before with him. I think we're getting far along enough now that we'll find out if he's going to be able to play."
Wedge said he hadn't finalized things yet with trainer Rick Griffin, but Aardsma likely would throw off the bullpen mound at least once more before any decisions are made.
Kelley, coming back from partial Tommy John surgery, isn't as far along as Aardsma after suffering his own setback when he started a Minor League stint. He threw easily from the front of the mound on Friday and said he'll move partway up the hill on Sunday. He hopes to throw a full bullpen session after next week's All-Star break.
"Right now it feels good," Kelley said. "Hopefully it keeps up. We'll work our way up the mound, work the intensity up and hopefully in a couple weeks I'll be firing full speed and will be ready for a rehab stint."
For now, both relievers are just glad to be along on the road trip, working with the team and making progress again.
"Any time I get to put my real spikes on it's a good day," Kelley said. "It's always fun, even if it's just throwing light and not even all the way up on the rubber. It's just nice to be in the bullpen and on the dirt and have the catcher down and stuff like that. It gives you a feeling that you're getting there."