but the crew were not informed during the flight. Irwin had heart problems after retiring as an astronaut and died in 1991 of a heart attack; Scott felt that he as commander should have been informed of the biomedical readings. NASA doctors at the time theorized the heart readings were due to potassium deficiency, due to their hard work on the surface and inadequate resupply through liquids. The crew spent the next two days working on orbital science experiments, including more observations of the Moon from orbit and releasing the subsatellite. Endeavour departed lunar orbit with another burn of the SPS engine of 2minutes 21 seconds at 21:22:45 GMT on August4. The next day, during the return to Earth, Worden performed a 39-minute EVA to retrieve film cassettes from the service module's scientific instrument module (SIM) bay, with assistance from Irwin who remained at the command module's hatch. At approximately 171,000 nautical miles (197,000 mi; 317,000 km) from Earth, it was the first "deep space" EVA in history, performed at great distance from any planetary body. As of , it remains one of only three such EVAs, all performed during Apollo's J missions under similar circumstances. Later that day, the crew set a record for the longest Apollo flight to that point. On approach to Earth on August7, the service module was jettisoned, and the command module reentered the Earth's atmosphere. Although one of the three parachutes on the CM failed after deploying, likely due to damage as the spacecraft vented fuel, only two were required for a safe landing (one extra for redundancy). Upon landing in the North Pacific Ocean, the CM and crew were recovered and taken aboard the recovery ship, , after a mission lasting 12 days, 7hours, 11 minutes and 53 seconds. Assessment The mission objectives for Apollo 15 were to "perform selenological inspection, survey, and sampling of materials and surface features in a pre-selected area of the Hadley–Apennine region. Emplace and activate surface experiments. Evaluate the capability of the Apollo equipment to provide extended lunar surface stay time, increased extravehicular operations, and surface mobility. [and] Conduct inflight experiments and photographic tasks from lunar orbit." It achieved all those objectives. The mission also completed a long list of other tasks, including experiments. One of the photographic objectives, to obtain images of the gegenschein from lunar orbit, was not completed, as the camera was not pointed at