NASA Report No. CR-55640

  Background

NASA commissioned this report to summarize available data on unexplained aerial observations. It reviewed radar cases and photographic evidence, urging continued study for national security reasons.¹²³⁴⁵

  Availability

The document circulated among researchers and later became accessible through the NASA Technical Reports Server.

  References

1. ntrs.nasa.gov ↩

2. ntrs.nasa.gov ↩

3. en.wikipedia.org ↩

4. space.stackexchange.com ↩

5. scribd.com ↩