THURSDAY Race to Save the Planet (PBS, 8-9 p.m.): Shot on all seven continents and in some 30 countries, this 10-part series - the big item in public TV's year-long ``Operation Earth'' - offers a global view of our threatened environment, starting with a look back at man's former coexistence with nature and the disastrous shift since then. Meryl Streep is host and Roy Scheider narrator. FRIDAY Great Performances (PBS, 9-10 p.m.): Spike Lee and Debbie Allen begin this series' 18th season by hosting ``Do It A Cappella,'' a feast of close harmony sung unaccompanied by groups like Take 6 and Ladysmith Black Mambazo - who know how it should sound.
MONDAY 24th Country Music Awards (CBS, 9-11 p.m.): One long hoedown, basically - and you don't have to be a country type to enjoy it. Carried live from Nashville's Grand Ole Opry House, hosted by Reba McEntire and Randy Travis, it boasts an appealing slate of stars to announce awards and deliver songs with the zest typical of this popular annual event.
WEDNESDAY Scientific American Frontiers (PBS, 8-9): First of five magazine-style shows, aired monthly, that poke into a somewhat unexpected array of subjects. The focus - as in the opener, ``Roller Coaster Physics'' - tends to be on designs in nature and technology. It's all pulled together and made palatable by host Woody Flowers, a noted MIT scientist.
Please check local listings for all programs, especially on PBS.