[There's joy in his eyes as he looks up from where he stands, trying to see if he can spot Mars on his own. It takes a couple seconds, and then his eyes come back down to watch Steve. He laughs quietly at Steve’s idle observation while running a hand through his hair.]

I think that's the understatement of the century, pal.

[He gives Steve's shoulder a hearty pat before grasping on with a squeeze.]

There’s so much to see and hardly enough time to see it all with.

[Clearly another star-gazing session needs to be arranged to satiate Bucky’s curiosity.]