After being in print for twenty years, the Chronological Encyclopedia of Discoveries in Space, covering everything that was learned on every single space mission in the 20th century, has finally gone out of print.
Behind The Black, c/o Robert Zimmerman
Cortaro, AZ 85652
"Useful to space buffs and generalists, comprehensive but readable, Bob Zimmerman's Encyclopedia belongs front and center on everyone's bookshelf." -- Mike Collins, Apollo 11 astronaut
"The Chronological Encylopedia of Discoveries in Space is no passionless compendium of information. Robert Zimmerman's fact-filled reports, which cover virtually every spacecraft or probe to have ventured into the heavens, relate the scientific and technical adventure of space exploration enthusiastically and with authority." -- American Scientist
Mammoth Cave is now officially longer than 400 miles.
This official announcement is a bit old, as the survey work that brought Mammoth over 400 miles was probably done during the October or December 2012 expeditions.
Update: I contacted some of my caving friends who survey in Mammoth regularly, and they have confirmed that the survey reached 400 miles during the October 2012 expedition.