Operations over Afghanistan included more real-time activities, such as communication with ground troops, increasing their bodies' oxygen requirements and the risk of nitrogen bubble formation. U-2 pilots now exercise during oxygen pre-breathing. In 2012, modifications were initiated under the Cockpit Altitude Reduction Effort (CARE), increasing the cabin pressure from 3.88 psi to 7.65 psi, a altitude equivalent. The urine collection device also was rebuilt to eliminate leakage.Nickel, Shawn, (Senior Airman). "CARE mModifications place pilots at better Elevation." Beale Air Force Base, 13 February 2012. Retrieved: 21 May 2013. Sensors Existing cameras had ground resolution down to from an altitude of , and were inadequate for the altitude. Ground resolution of was required, at a maximum payload weight of . The U-2's camera was specially designed by James G. Baker of Harvard and Richard Scott Perkin of the Perkin-Elmer Company, initially in collaboration and later separately. Initial missions were flown with the trimetrogon "A" camera, consisting of three cameras, with F/8 resolving 60 lines per mm, and the ground resolution can be inferred by calculation to be . This was followed by the "B" camera with a lens with F/10 and image motion compensation, resolving 100 lines per mm, and the ground resolution can be inferred by calculation to be . It was a panoramic camera which took pictures of an extremely large area of the earth's surface. The lens design consisted of a single aspheric singlet lens. reels of film were used, with the emulsion being coated on a polyester (PET) base that offered significantly improved dimensional stability over extremes of temperature and humidity compared to conventional cellulose acetate. In addition, the U-2 also carried a low-resolution Perkin-Elmer tracking camera using a 3-inch lens, which made continuous horizon-to-horizon photographs. This is common practice in high resolution cameras in later systems also, where the large image helps localize the small high-resolution images. The aircraft carries a variety of sensors in the nose, Q-bay (behind the cockpit, also known as the camera bay), and wing pods. The U-2 is capable of simultaneously collecting signals, imagery intelligence and air samples. Imagery intelligence sensors include either wet film photography, electro-optic, or radar imagery—the latter from the Raytheon ASARS-2 system. It can use both line-of-sight and over-horizon data links. Operational history United States Pilot selection and training Though the USAF and the Navy would eventually fly the U-2, the CIA had majority control over the