It’s been estimated that the Titan, the small, deep-sea, Titanic-spotting submersible that went missing early Sunday morning, can sustain the lives of five on-board travelers for 96 hours, or four 24-hour days.

The 23,000-pound Titan began descending around 4 am on Sunday, or roughly 53 hours ago. (It’s now 9 am eastern.) Start to finish Titanic dives last ten hours, including a 2 and 1/2 hour descent to the wreckage some 13,000 feet below.

If the five aren’t rescued by early Thursday morning, an agonizing finale awaits. The clock is ticking — at most rescuers have the remainder of today (Tuesday, 6.20) and all-day Wednesday.

This paragraph, from a N.Y. Times report, conveys the bottom line:

This also: