Predicting NROL-21 's fall: When and How.

Here is a different kind of debris. Aviation Week reports that an NRO spacecraft is uncontrollably descending into the atmosphere "at a rate of about 2,310 feet per day, according to Canadian analyst Ted Molczan." The reporter seems to be saying that the Columbia fateful reentry radar and recovery data are aiding in the analysis of the potential for accidents with the debris of that satellite. I am a little bit skeptical on several counts. When people tried to evaluate when a small disco ball would reenter the atmosphere, few guessed the right time and day it eventually happened. Also, when I last looked into it, most of the modeling that used specific small scale experiments did not seem to have some real predictive capability. It seems that this conclusion was also reached by some of the SCM folks who eventually did a new kind of statistical study on this very problem for the French Space Agency. Finally, the two photos below show before and after photographs of our camera that was on-board the Columbia Space Shuttle. It is in aluminum and even though the fusion temperature of Aluminum is 600 C, well below the temperature felt outside of the craft on reentry, the base plate was nearly intact on impact (our camera was outside). The rest melted away except for the optical component in Invar.