How to complete the sequence

[wintringham]

NA+BA,CC+AB,AS+EM,DS+JI,JY+CD,?+?
What would be the missing symbols in this sequence also what do the initials stand for?

[gen2]

Neil Armstrong+Buzz Aldrin,
Charles Conrad+Alan Bean,
Alan Shepard+Edgar Mitchell,
David Scott+James Irwin,
John Young+Charles Duke,
Eugene Cernan+Harrison Schmitt
(people who have walked on the Moon)

[gen2]

Wasn't that a question in the Kinoulton Scout Group Christmas 2006 quiz?