Wreck of the RMS Titanic research. The stern section, which had previously received relatively little attention from explorers, was specifically targeted for analysis. The microbial colonies aboard "Titanic" were also a key focus of investigation. The second expedition, from 27 May – 12 June 2004, saw the return of Robert Ballard to "Titanic" nearly 20 years after he discovered it. The expedition spent 11 days on the wreck, carrying out high-resolution mapping using video and stereoscopic still images. 2005 saw two expeditions to the "Titanic". James Cameron returned for the third and last time to film "Last Mysteries of the Titanic". Another expedition searched for
Titanic prime the prime number theorem. The first discovered titanic primes were the Mersenne primes 2−1 (with 1281 digits), and 2−1 (with 1332 digits). They were both found November 3, 1961, by Alexander Hurwitz. It is a matter of definition which one was discovered first, since the primality of 2−1 was computed first, but Hurwitz saw the computer output about 2−1 first. Samuel Yates called those who proved the primality of a titanic prime "titans". Titanic prime Titanic prime is a term coined by Samuel Yates in the 1980s, denoting a prime number of at least 1000 decimal digits. Few such primes