Along with everybody else who has an interest in the human exploration of space, I watched in numb disbelief at the events unfolding in the skies over the United States this morning. My condolences go out to the families of the Columbia crew - I sincerely hope that you can take some comfort in knowing that your loved ones gave their lives for an heroic and truly noble cause.

Columbia was the first of the space shuttles to be flown up to earth orbit by Bob Young and John Crippen in the early 1980's. I found the weekends events particularly poignant - I watched that first launch as a teenager, and since then, I've always paid slightly closer attention to the STS missions whenever Columbia was scheduled to fly. I clearly remember that there was a great deal of concern on Columbias maiden flight that the thermal protection system had been damaged during the ascent to orbit, and I believe NASA even went so far as to try to assess the damage using ground based telescopes to see how many of the vital protective tiles were missing.

Obviously, the entire shuttle fleet will be grounded until the investigation into the accident is complete. The long term implications for NASA and the ISS are still unclear - some experts have already declared that it will be next to impossible for the ISS to be maintained with only the 3 remaining shuttles, Endeavour, Discovery and Atlantis. If memory serves me, Endeavour was built as a replacement for Challenger and this was only possible due to the large stock of spare parts, including an entire airframe, which NASA had available at the time. No such parts are available to build a replacement for Columbia, and there is no viable design for a replacement orbiter which is less than 10 years away from actually flying.

It saddens me to realize that my chances of seeing a human being set foot on the planet Mars in my lifetime have been reduced to almost nothing by todays events.