Passage: On January 27, 1967, the day of the Apollo 1 fire, Armstrong was in Washington, DC with Cooper, Gordon, Lovell and Scott Carpenter for the signing of the United Nations Outer Space Treaty. The astronauts chatted with the assembled dignitaries until 18:45, when Carpenter went to the airport, and the others returned to the Georgetown Inn, where they each found messages to phone the Manned Spacecraft Center. During these calls, they learned of the deaths of Gus Grissom, Ed White and Roger Chaffee in the fire. Armstrong and the group spent the rest of the night drinking scotch and discussing what had happened.On April 5, 1967, the same day the Apollo 1 investigation released its final report, Armstrong and 17 other astronauts gathered for a meeting with Slayton. The first thing Slayton said was, "The guys who are going to fly the first lunar missions are the guys in this room." According to Cernan, only Armstrong showed no reaction to the statement. To Armstrong it came as no surprise—the room was full of veterans of Project Gemini, the only people who could fly the lunar missions. Slayton talked about the planned missions and named Armstrong to the backup crew for Apollo 9, which at that stage was planned as a medium Earth orbit test of the combined lunar module and command and service module.The crew assignment was officially announced November 20, 1967. For crewmates, Armstrong was assigned Lovell and Aldrin, from Gemini 12. After design and manufacturing delays of the lunar module (LM), Apollo 8 and 9 swapped prime and backup crews. Based on the normal crew rotation, Armstrong would command Apollo 11, with one change: Mike Collins on the Apollo 8 crew began experiencing trouble with his legs. Doctors diagnosed the problem as a bony growth between his fifth and sixth vertebrae, requiring surgery. Lovell took his place on the Apollo 8 crew, and, when Collins recovered, he joined Armstrong's crew.

Question: What did they learn about?
the deaths of Gus Grissom, Ed White and Roger Chaffee