Possible Clues:

• A drop in the ocean
• A drop in the ocean?
• End of many a space mission making front-page news on descent
• To NASA, it's a drop in the ocean
• The end of a long fall, in the main
• Wet feathers found on landing
• Display not operational at moment of landing
• Moment of landing a spacecraft on the sea
• Certain Apollo landing
• For NASA it's a drop in the ocean