Chandra, me, and the number 23

A month or two after Chandra launched in July 1999, I was asked at a Chandra X-ray Center (CXC) senior staff meeting how long I actually expected Chandra to operate. I spontaneously responded: "23 years". Now that is a number not heard very frequently, so there were lots of quizzical looks indicating that an explanation was in order. Shortly after the launch, Pat Henry – an old friend and colleague from the 70's work on the Einstein Observatory – had written a congratulatory e-mail, noting that since I had worked on Chandra from its inception in 1976 through its launch in 1999 (23 years) that it would be appropriate if we all got to use it for 23 years. Given the nominal lifetime of 3 years based on tests and certifications for electronic components and the sizing of consumables for 5 years with 100% extra in reserve, 23 years seemed like a lofty and worthwhile target so that is how I answered at the staff meeting.

When I stepped down as Director of the CXC in April of this year, I realized that our proposal for the AXAF (mission name before Chandra) Science Center had been accepted by NASA in spring of 1991 and that I had served in the role for 23 years – so there is that number again. Belinda Wilkes has now taken over as CXC Director, but you would have to ask her whether she foresees 23 years in the position.

Now that Chandra has reached its 15th birthday, the Northrop-Grumman engineering team has analyzed the performance of all of the critical sub-systems and sees no "show-stoppers" to at least another 10 years of high quality performance for Chandra. This is rather amazing given that Chandra's high earth orbit does not allow access for servicing/repairs/upgrades, so the mission is operating with the original hardware our fantastic team (led by NASA's Marshall Space Flight Center) built and launched. Is it possible that Pat Henry actually meant to wish me 23 years of fun as CXC Director, rather than project a "mere" 23 years as the lifetime for Chandra? Or maybe, he was wishing for at least 23 years. With no other X-ray mission having Chandra's superb imaging capability and sensitivity flying or planned for the near future, we – NASA, the CXC, and the science community will gladly take as many more years of science as Chandra can deliver.

Oh, by the way did I mention that the launch in July of 1999 took place a bit after midnight on the 23rd! And now for those who don't have to look it up, it is time for me to 23 skidoo!

-Harvey Tananbaum, CXC