Some months ago IMAX theatres across the country showed an impressive forty-minute big-screen film titled “Shackleton’s Antarctic Adventure.” Co-produced by PBS station WGBH of Boston, directed by George Butler and narrated by Kevin Spacey, it used archival footage and stills, as well as modern recreations in the actual locales, to tell the gripping story of a failed 1914 expedition to traverse the Antarctic continent by foot. Their ship, the aptly-named Endurance, became trapped in the ice, and eventually the stranded crew of twenty-seven had to hazard a desperate voyage in three lifeboats to an uninhabited island. From there Shackleton and two companions ventured a further 800-mile voyage to the nearest inhabited island to secure assistance, and after miraculously reaching it, they had to trek across its uncharted interior to the whaling camp they had departed from months before.

This is obviously an extraordinary story, deserving to be told, especially since the stills and silent films taken by expedition photographer Frank Hurley remain wonderfully crisp, clear and fascinating. Nonetheless it may be that Butler is overdoing things a bit by offering a second documentary on the subject, using much of the same material as in his IMAX effort, in a more conventional format. “The Endurance: Shackleton’s Legendary Antarctic Expedition” is co-produced by the Nova series, and it’s very much the sort of thing that one finds–and enjoys–on PBS all the time. It’s more than twice the length of the earlier film, adding to the IMAX picture talking-head excerpts from interviews with descendants of expedition members and a more expansive presentation of the World War I historical context. Much of the added information is interesting, but some of it seems like padding beside the previous film; and the level of suspense is reduced by the decision to reveal the outcome of the venture almost immediately. The earlier film, moreover, contained one important segment the present one does not: a remarkable episode in which three contemporary adventurers retrace the journey which Shackleton and his two companions made across South Georgia Island to reach help. And, of course, the IMAX film provided a breathtaking sense of the locale which this more humble effort can’t match.

The verdict? If you haven’t seen “Shackleton’s Antarctic Adventure,” “The Endurance” should be enlightening and engrossing. It’s solidly crafted, decently narrated by Liam Neeson, and, despite some repetition and a few longueurs, reasonably well edited; and, of course, Hurley’s contributions are magnificent. If you have seen “Adventure,” on the other hand, you may find it a trifle redundant, or might want to wait until it’s shown on “Nova” to see it–it shouldn’t take terribly long. More troublesome is the news that plans are afoot to use the Shackleton expedition as the basis not only for a big-budget feature but for a television mini-series as well. Even when a story is as compelling as this one, it’s possible to go to the well once–or twice–too often.