The launch was spectacular! There were several (too) exciting moments. The first launch attempt on 1999 July 19 was scrubbed at T-7 seconds -- approximately one second before launch commit. Weather prevented launch on the second attempt. The third attempt, on July 23, was obviously successful -- although we were to learn later of two fairly significant shuttle problems that ultimately resulted in a 6-month hiatus of STS launches.
The following weeks of Chandra activation were ``textbook". The pool betting on the number of times the Observatory would be in safe mode was never claimed, due to the effectively flawless operation of the hardware and dedication and skill of the operators on the ground.
Beginning with the first photons, an observation of a random x-ray source (now known as Leon X-1 in honor of the Chandra Telescope Scientist, Leon Van Speybroeck) when the last door (the outer contamination cover) opened on August 12, the Observatory has returned results consistent with and exceeding the high expectations we had so many years ago when the mission was first conceived. The ``point-source" quasar used for focusing the telescope, turned out to have a heretofore unknown x-ray jet. The official first light, a brief observation of the supernova remnant Cassiopeia A, showed a central compact source, never before detected.
In the midst of the euphoria, we were quickly reminded of how tricky our business is. We discovered that the telescope is unfortunately a moderately efficient reflector of low-energy protons and that the ACIS front-illuminated CCDs are particularly vulnerable to these protons, which have just the right energy to damage the buried channels. Indeed, before we totally understood what was happening, we were concerned that the instrument would lose all response and that the back-illuminated CCDs would probably follow. Now that one can both understand and reproduce the effects in the laboratory, the situation is quite different. Specifically, we have taken measures to avoid further damage, the most notable effect being a row-dependent degradation of energy resolution of the front-illuminated CCDs. The back-illuminated CCDs remain unaffected. More recently, the ACIS team has found a way to mitigate the effects of this damage and to recover at least part of the lost energy resolution.
In summary, it's been quite a year. Every image is a discovery! We are looking forward to many more over the next (hopefully) decade or more of Chandra operation. We in Project Science congratulate and thank everyone who has contributed to this magnificent Observatory.
- Martin C. Weisskopf