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Q:
What was Dr. Steven Kissel role in the operation of Chandra?
A:
Dr. Kissel explains his work in the following quote.
"My role in Chandra operation, specifically design and fabrication
actually began with the Astro-D (ASCA) satellite which was the
first use of X-ray CCDs in space. Participation in this US/Japan
mission was intended to provide experience with X-ray CCDs in
order to prove their suitability as detectors for the Chandra
(then called AXAF) observatory. The great success of ASCA was
encouraging and lessons learned in that program guided design
and test strategies used in AXAF. An example of this was the
realization that a "room temperature readout" capability would
be crucial to verifying detector performance during assembly
and pre-launch activity. One of my tasks was to make sure this
capability was achieved.
One of the Chandra science instruments, the ACIS (Advanced CCD
Imaging Spectrometer) uses and array of 10 Lincoln Laboratory
fabricated CCDs. We received several hundred such devices
each of which required testing and evaluation. My role was to
fabricate testing facilities, X-ray calibration beam lines
and cooling systems for example, and to undertake the initial
testing or "screening". This evaluation determined the correct
operating parameters, voltages and clocking waveforms, that
would yield maximum performance from the subsequent detector
assembly. During this period much practical experience about
CCD operation was learned and incorporated into the higher
assembly. An example of this is the little known but quite
essential "jitter dac" trick which is used at the start of
every science observation to tame a start up dark current
instability.
The role which has had the longest lasting impact is that of
the "institutional memory of CCD operation" which basically
means that I get to try all the unusual operational techniques
before they get applied to the actual spacecraft. This activity
continues even to this date where questions about radiation
damage, high temperature bakeout and CTI suppression can only be addressed by laboratory experiments on "sibling" CCDs."
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