Crew and ground comfort (combined with the specific altitude) and it was yet another microgravity mission. I can only get hand wavy about the field is not unif

Crew and ground comfort (combined with the specific altitude) and it was yet another microgravity mission. I can only get hand wavy about the field is not uniform mass concentration blah blah. Presumably deep in the decimal points, a 40 degree orbit or a 38 degree orbit has higher (although still very small) gravitational anomalies. It was a fairly common "track" for shuttle missions. Perhaps 5 or 6 missions were in the same orbit. (edited to point out this was not cut and paste from the 107 marketing materials, its from an older launch, although the orbit is identical for identical reasons. Basically they reflew a 90s era mission, STS sixty-something) "Columbia will climb to a 173-statute-mile (278-kilometer)-high orbit with a 39-degree inclination to the Earth's equator to allow the seven-member flight crew to maintain the same sleep/wake rhythms they are accustomed to on Earth and to reduce vibrational and directional forces that could affect on-board microgravity experiments."