Who hacked NASA in 1999 and which data he she hacked?

Could you elaborate on the 1999 NASA hacking incident? Who was the perpetrator, and what specific data were compromised? I'm particularly interested in understanding the scope and nature of the attack, as well as any potential implications or consequences it may have had for NASA's operations and data security. Your insights would be invaluable in helping me gain a more comprehensive understanding of this notable cybersecurity event.