NASA questions

The Early prototype Mercury spacecraft had only two portholes, but the Mercury astronauts demanded a larger window to be installed, not only for the view but also for the orientation. The latter proved invaluable on their last mission, when instrument failure required visual orientation.

These images were assembled from data acquired over nine days in April 2012 and 13 days in October 2012. This means fires and other lighting (such as ships) could have been detected on any one day and integrated into the composite picture, despite being temporary phenomena - giving the appearance of a massive blaze.

Apollo 1 was scheduled to be the first manned mission to the Moon. On January 27, 1967, a cabin fire during a launch pad test at Cape Canaveral killed all three crew members (pictured). The ignition source was never identified, but many lethal design and construction flaws were identified after the accident. The manned phase of the project was delayed for 20 months while those problems were corrected.

Apollo 11 landing site was selected because it had been characterized as relatively flat and smooth by the automated Ranger 8 and Surveyor 5 landers.

There have been six manned U.S. landings of the Apollo program (between 1969 and 1972) and numerous unmanned landings, though no soft landings have occurred since 1976.

Saturn V sent astronauts to the Moon. Fully fueled it had a total mass of 6.5 million pounds (3,000 metric tons) and a payload capacity of 260,000 pounds (120,000 kg). Its engines were heard from 50 miles away.