He was diagnosed with Lymphoma in January of 2010 and, although he had no evidence of Lymphoma after his radiation treatments, the disease weakened him and ultimately triggered issues with arrhythmia (atrial fibrilation) that caused his death.
From The Desert Sun, October 26, 2011: George Barnum, 82, of Rancho Mirage, Calif., formerly of Desert Hot Springs passed away on October 20, 2011 in Rancho Mirage. He was born April 26, 1929 to Harry and Montie Barnum in Roseville, Ohio. George married the love of his life, Gladys, in Kankakee, Ill., on July 8, 1950, and they lived their life all around the country - spending time in Long Island, N.Y., San Antonio, Texas, Titusville, Fla., Honolulu, Hawaii, and Riverside, Calif. (among many other locations). He was an aerospace engineer and worked for McDonnell Douglas for about 35 years, and was a test conductor on the Saturn V (Apollo) program at Kennedy Space Center, helping man get to the moon. He also worked on the C-17 program in Long Beach, Calif., and served in the US Air Force and was a Freemason, a member of OES and a Shriner, as well as a supporter of his daughters and granddaughters membership in IORG. George is survived by his wife, Gladys of Rancho Mirage; daughters, Gayle (Terry) Huntling of Indio, Calif., Carmen Gonzalez of Sanford, Fla.; and Annette Koetje of Altamonte Springs, Fla.; grandchildren, Gretchen Redewill of Indio, Geoffrey Groesbeck of Indio, Genney Groesbeck of Indio, Kimberly (Daniel) Miles of Savannah, Ga., Jennifer (Billy) Alsbrooks of Orlando, Fla., Natasha Quoma of Orlando, and Tena (Dave) Anderson of Titusville. He is also survived by six great-grandsons, two great-granddaughters and two nephews, three nieces, and numerous great-nephews and nieces. He was preceded in death by his parents and his sister, Hattie Armstrong. A Celebration of Life will be held at 10:00 AM on Thursday, October 27, 2011 at Community United Methodist Church in Desert Hot Springs. In lieu of flowers, donations may be made in George's name to the Leukemia and Lymphoma Society. The family would like to express their deepest appreciation to the excellent nursing staff at Eisenhower Hospital who took such loving care of George. Rose Mortuary in Desert Hot Springs is in charge of the arrangements.