Short form: a sci-fi RPG with Warship Gunner-esque ship customization. First, some information:

official site (http://mugen.sega.jp/); IGN profile page (http://ds.ign.com/objects/142/14253677.html); Joystiq entries (http://www.joystiq.com/tag/infinite-space) (includes interview with game director); GameTrailers profile page (http://www.gametrailers.com/game/infinite-space/10368) (includes subtitled forms of the four anime shorts)

With that out of the way, there are three tracks on the official site's player:

Track 1 (http://mugen.sega.jp/sound/bgm1.mp3) Track 2 (http://mugen.sega.jp/sound/bgm2.mp3) Track 3 (http://mugen.sega.jp/sound/bgm3.mp3)

Based on their ID3 tags - which mark them, respectively, as tracks 15, 11, and 12 - I suspect they are direct from the official soundtrack (CDJapan entry (http://www.cdjapan.co.jp/detailview.html?KEY=GNCA-7138)).