ACS, the Advanced Camera for Surveys, suffered a power supply failure in January 2007, leaving two of its three cameras dark. Within two weeks, a project to repair ACS was organized, and in August 2007 NASA approved ACS-R for Hubble Space Telescope Servicing Mission 4 scheduled for October 2008. The total time from concept to launch is about half the usual time for such a mission, so it is a challenging project. But the potential payoff is great: restoration of a workhorse camera on the HST for the remainder of its mission lifetime.

May 18, 2009   ACS Repair Videos

Watch three ACS Repair-related videos on NASA's YouTube site:

EVA 3 video

Post-EVA 3 Press Conference

Behind the Scenes

May 16, 2009   SUCCESS!

The ACS-R hardware was successfully installed today and has passed its aliveness and functional tests.  The new hardware has restored the WFC channel, which is operating with lower noise than before.  It is now awaiting a detailed set of commissioning tests that are scheduled to start at the very end of May.  The ACS Repair has successfully demonstrated new technologies in satellite servicing by performing the first on-orbit board-level repair.  One implication is that the normal Integration and Test activities done on the ground cannot be fully completed because important parts of the hardware being tested are already on orbit.  In the case of ACS-R, this would be the detectors and the main part of the instrument.  Consequently, roughly 6 weeks of detailed testing is scheduled during the commissioning period to complete these activities.

The instrument-level functional tests revealed that the backpowering restoration of the HRC channel is not working, most likely because the original fault left the power bus in a shorted condition.  This was always recognized as a possible risk.  Assessment will continue.

With WFC and SBC operation, well over 80% of the scientific observations for ACS have been restored.

May 2009

With the successful launch of STS-125 on Monday, May 11, 2009, the ACS- R hardware and the astronauts who know how to use it are now safely in orbit.  As of today, Hubble is attached to the Space Shuttle Atlantis.  Tomorrow morning (Thursday, May 14) starts the activities on the HST.  The ACS-R activities are scheduled for Extravehicular Activity (EVA) Day 3, which starts late Saturday morning EDT (May 16).

Mid-October 2008

The ACS-R hardware was at the launch pad, but is now back in the clean room along with the other HST hardware as we wait for a new launch date.  The HST Operations Team is working hard understanding and recovering from the on-orbit science data computer issues, and the HST  Hardware Development Team is busy planning for launching a replacement  (spare) computer.  News on a new launch date is expected in November.

Mid-September 2008

As of September 10, 2008, the ACS-R hardware is installed in its carrier and ready to be loaded into the Shuttle cargo bay.  The LVPS-R (top) and CEB-R (bottom) each have their own module to protect them from vibration during launch.  When the astronauts go to install the hardware, they open the transport module by lifting and turning the T-handles on the top of each module.  Then the CEB-R and LVPS-R slide right out and are ready to be installed on the telescope.

August and Early September 2008

The flight hardware successfully completed thermal vacuum testing.  Some small issues were identified that will be fixed with software updates.  The hardware was shipped to KSC on September 7, 2008 to be installed in the flight carriers later that week.  The shipment by truck was advanced a few days to take advantage of good weather between hurricanes Hannah and Ike.  The team successfully completed the Pre-Ship Review on September 8, 2008.  After installation into the flight carriers, the flight hardware will be waiting for launch.  Meanwhile, the team will be preparing for the mission by updating software as necessary, and practicing the data analysis tasks that will establish that the ACS-R is working when it is installed into the instrument.  Because of the intense activity during this time, there will not be an update until October unless there is an unexpected development.

July 2008

Our team started off the month by successfully conducting a Pre-Environmental Review. This review certifies that the flight hardware works, and is built well enough to proceed to the environmental testing stage (sometimes referred to as "shake and bake"). The ACS-R hardware then passed vibration testing, and the electromagnetic interference and compatibility tests. Next up: thermal-vacuum testing, which will run 24/7 for almost the entire month of August. Meanwhile, our flight software and operations teams are busy testing and tidying up the software and procedures that will be needed to run the new hardware after it is installed in HST.

June 2008

June was a challenging and exciting month. After assembling the CEB-R with all its mechanisms, we found an electrical short that required some adjustment of the mechanical design. The LVPS-R also had its share of excitement: While reviewing paperwork, diligent team members noticed that some non-flight power modules had been inadvertently installed and had to be replaced. By month's end we had worked through these challenges, and also made preparations for the ACS-R Pre-Environmental Review. We also completed several significant integrated hardware tests this month, confirming the system-level compatibility of the hardware. Final environmental testing (checking for electromagnetic interference, and thermal-vacuum testing) starts next month.

May 2008

The flight CEB-R completed testing this month with very good results. Some design modifications were implemented to improve noise performance. Software and operations testing is near completion and will culminate in a set of integrated tests in June that will exercise the entire ground and (simulated) flight segments with the Engineering Model ACS-R hardware. Optimizations for the Flight Assembly Code for the ASIC are being investigated to address some performance aspects. Intense preparations are underway for the flight hardware environmental testing that will begin in mid-June.

April 2008

April was another milestone month for the ACS-R team. The flight prime CEB-R has been assembled and delivered to the DCL for performance testing. System-level testing continues with the engineering model hardware, demonstrating that the ground and flight software are close to flight readiness. Another set of engineering hardware will be shipped imminently to TIS for final verification of the Flight Assembly Code for the ASIC. Plans for the on-orbit commissioning and optimization of the CEB-R during SMOV have been put into place and preparations are under way.

March 2008

This was a month of significant progress for the ACS-R team.  The noise performance on the CEB-R Engineering Model 2 was shown to meet expectation in the primary video processing mode (integrator).  The secondary mode (clamp and sample) operates close to specification, and additional testing is planned to better understand its performance.  This is the first time that the entire flight-like system has been demonstrated to have the expected performance.  The flight LVPS-R unit has been successfully completed at Ball and delivered to GSFC.  Fabrication of the CEB-R flight boards is continuing.  The "oscilloscope mode" diagnostic tool that was added to the CEB-R in February has been demonstrated to work very well at Teledyne.  This tool will allow for more accurate and rapid on-orbit optimization of the CEB-R.

February 2008

The Flight Model CEB-R mechanical hardware is completed and being tested. The flight CEB-R printed circuit boards have been committed to production. The second flight LVPS-R is being assembled. The second Engineering Model of the CEB-R is being tested. The first EM is being used with the ACS hardware simulators to develop and test the flight software. Detailed planning has begun for the Servicing Mission Orbital Verification (SMOV) activities that will be used on-orbit to check out and tune the ACS-R hardware.

January 2008

Extensive testing on the first Engineering Model of the CEB-R is under way. The first of two Flight Model LVPS-R's is being completed. System-level testing of the EM CEB-R, EM LVPS-R together with the ACS hardware simulators demonstrates that the ACS-R system is functioning as expected. These tests use flight-like commanding and software, and exercise all the flight command, data, and power interfaces. Flight software and operations preparations are continuing.