DALLAS (REUTERS).- Shortly after Apollo 13 astronauts reported, “Houston, we have had a problem,” Commander James Lovell jotted down handwritten calculations in hopes of guiding his crew safely home. The notebook with those calculations from the aborted 1970 NASA mission to the moon fetched $388,375 at auction on Wednesday in Dallas when it was sold to an American collector who was not identified. The notebook, the main attraction of a space memorabilia auction, was part of retired NASA commander Lovell’s personal collection of artifacts. Lovell, 83, said he had forgotten about the notebook until recently. “I was cleaning out some old stuff on a bookcase and found it,” said Lovell, who now has homes in Horseshoe Bay, Texas, and the Chicago suburb of Lake Forest. “My kids took all they wanted and I