ACS (Advanced Camera for Surveys) Repair
Repairing one of Hubble's most important instruments
In 2006 I was called to investigate an anomaly with
ACS, and we realized during the course of the investigation that the
instrument was damaged and would not function again unless a repair was
made. A problem in the power supply caused a loss of the
instrument, and we decided to repair the instrument in space by
removing the cover and changing out some circuit boards.
completely new set of imaging electronics was needed, and we used
Rockwell's SIDECAR ASIC as the main readout electronics for the ACS
detector. My role on this project was to design the FPGA that
interfaces the SIDECAR to the existing electronics on Hubble.
This item became internally known as the "Translator FPGA".
was the ACS instrument before its launch. This image shot in our
large SSDIF cleanroom. The red circle shows the location of the
CCD Electronics Box (CEB) that we would replace by removing all its
circuit boards and replace with a new module with new electronics.
first operation to access the CEB boards is to cut the grid that
protects the cover of the box. This was done with this innovative
plate that fits over the grid, and has small screw-actuated cutters
that cut the legs of the grid. These screws are rotated by the Pistol
Grip Tool (PGT). As the screws are turned, sharp cutters protrude
to cut the grid.
new boards are packaged into this module called the Replacement CEB, or
the CEB-R. The angle missing from the top cover is to avoid a
beam inside Hubble that may have interfered with the installation.
of an astronaut practicing the removal of the old boards from the CEB.
Shot inside the SSDIF cleanroom on our High Fidelity Mechanical
two FPGAs that I designed and that translate the data from the SIDECAR
to the Hubble computers is shown in this red circle. The code was
written in VHDL.
is Mike Massimino inside his training suit doing the install of the
CEB-R. This is shot inside the Neutral Bouyance Laboratory pool.
This is most of the ACS Repair team. Photo shot in Building 29 at NASA/GSFC.
After travel to the Kennedy Space Center, some members of the team stood in front of the launch pad to spell out:
A (me), C (Kathleen), S (Erin), -R (Kevin).
The moment that the old ACS board was pulled out of the instrument. Operation performed in space.
The repair was very successful, and most of ACS was restored to operation.
I had the privilege of being invited to the "First Light" event for the repaired ACS instrument.
This took place at the Space Telescope Science Institute.
Formerly embargoed first light image (taken 6/13/2009).
interesting historical point is that the data interface from the
SIDECAR into Hubble has some unused data slots. I had the liberty
of deciding what to put into these 'fill' locations. Taking an
idea from a previous project, I decided to fill with the hex data byte
"EC", which is 236 (decimal). This is of course my initials.
As documented in the CEB-R Translator FPGA Design Description Document
(HST-SW-010269), it causes ACS to periodically send my name into the
Hubble Science Data Handling Computer, and then down to the ground data
Excerpt from the Translator FPGA Description Document.