Just published: time traveler Jeff Harris's attempt to stop the space shuttle Challenger from exploding continues in the sequel to Loose Ends - "Little Differences" http://www.amazon.com/dp/B00RYEBPI6/r... 1st published as a novelette in Analog, June 1998; nominated for HOMer award for best novelette of 1998.
And, for the next few days, "Loose Ends" is on special sale for $0.99 http://www.amazon.com/dp/B00OJY02KQ/r...