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.
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"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
The uncertainty of science: Engineers hope Juno’s Earth flyby yesterday will help solve a mystery seen in previous flybys by unmanned probes.
Since 1990, mission controllers at ESA and NASA have noticed that their spacecraft sometimes experience a strange variation in the amount of orbital energy they pick up from Earth during flybys, a technique routinely used to fling satellites deep into our Solar System. The unexplained variation is noticed as a tiny difference in the expected speed gained (or lost) during the passage.
The variations are extremely small: NASA’s Jupiter probe ended up just 3.9 mm/s faster than expected when it swung past Earth in December 1990. The largest variation– a boost of 13.0 mm/s – was seen with NASA’s NEAR asteroid craft in January 1998. Conversely, the differences during swingbys of NASA’s Cassini in 1999 and Messenger in 2005 were so small that they could not be confirmed.
The experts are stumped.
It is likely that these small variations are related in some way with simple engineering and not some unknown feature of gravity. Nonetheless, it remains a mystery.