Yesterday was the 48th anniversary of the loss of three astronauts on the launch pad, in preparation for the Apollo missions. A child of the space age, I remember it particularly well, because it occurred the day before my twelth birthday. A little over nineteen years later, on my actual birthday, Challenger was lost. I recollected it on the sixteenth anniversary of the event.

Today is the twenty-ninth anniversary of that tragedy, and while I commemorate it, I also celebrate the completion of my sixtieth trip around the sun, over eight thousand miles from home. I’m in Israel to attend a conference named after Ilan Ramon, an Israeli hero who died a dozen years ago on February 1st, when Columbia disintegrated in the skies over east Texas. That anniversary coming up with Sunday, by which time I’ll be home, if all goes according to plan, to celebrate with friends and family, but also grieve for the losses. Yet as I point out in my book, such losses are inevitable, and necessary, perhaps even at a faster rate than once per generation, if we wish to accomplish much greater things than we have in space over the past six decades since my birth.