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
NASA on February 20, 2020 finally admitted that the first SLS launch cannot happen in 2020, and set a new target date no earlier than April 18, 2021.
The previous target launch date in November 2020 was always a pure fantasy. NASA just held off admitting it in order to defuse any political consequences for having a program, building SLS, that will end up taking them almost two decades to complete.
This new launch date is likely the most realistic so far, since the hardware for SLS is actually finally coming together. Nonetheless, if anything at all should go wrong along the way, especially with the full static test firing of the core booster of the first stage scheduled for no earlier than August, then expect more delays, possibly lasting years.