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Fixing Hubble In Honor of Frank Cepollina’s 80th Birthday Holland Ford Cepi and General George S. Patton I describe Cepi to my friends as NASA’s General George S. Patton, and that is meant as a compliment. Like Patton, when Cepi gets new directives from above, he is already either on his way, or, he has already taken the next town. Now, a short story about Cepi, Carolyn Krebs(ACS Project Manger), me, and Knickers. Missions for Ceppi Spherical Aberration After a successful launch and deployment of Hubble, my first inklings that there might be a problem was hearing people at lunch in the Institute say, “the engineers are having trouble focusing the telescope”. Soon afterward, I heard a rumor that Chris Burrows thought Hubble’s primary mirror was producing spherical aberration. I think at first the Perkin Elmer engineers were in a state of disbelief. This was, after all, the most perfect mirror ever made. But, if Chris thought it was spherical aberration, I knew we were in real trouble . So What Should NASA Do? Well, go fix it. But how? NASA planned to periodically replace old instruments with newer and more capable instruments. A replacement for WFPC I was already being built, so the spherical aberration could be (and was) corrected inside WFPC II. Genesis of the HST Strategy Panel I I had two concerns about the way NASA was proceeding. First, there were 4 axial instruments that likely were going to have to make do with aberrated images until the first servicing mission, and then be replaced My second concern was that the institute largely was out of the loop. I felt strongly that the Institute should be involved. Part of our charter was to represent the interests of all astronomers who planned on using Hubble. I didn’t think we were doing that. Convincing Giaconni At the end of every staff meeting Ricardo would ask, “is there anything else”. I raised my hand and said, “I think we should fix Hubble”. I explained that by that I meant we, the Institute, should convene a Tiger Team, that is, a group of very smart people, and see if the brainstorming could come up with a solution that would fix all instruments. This suggestion was based on my experience as FOS Instrument Scientist. On two occasions, Tiger Teams helped us solve serious problems with the FOS Digicon detectors. The third time I said this at a staff meeting, he said “do it”. One of my colleagues, Bob Brown, told Ricardo that he should lead the Tiger Team rather than me. The compromise was that we would be co-chairs. That compromise worked very well. The task was more than one person could do, and, our experiences complemented each other. The HST Strategy Panel II Rather than a Tiger Team, Bob suggested we call the group “The HST Strategy Panel’. The name was a good way of describing the importance of the task ahead of us. Lessons Learned 1 Move fast while you have NASA’s attention. Choose a diverse (optikers, engineers, astronomers, astronauts) group of the most talented people you can find. Have an open brainstorming sessions where every idea is given consideration. You can’t a priori predict who will have the best idea. So, who did we get? Panel Members What Does COSTAR Mean? Corrective Optics Space Telescope Axial Replacement COSTAR was Jim Crocker’s inspiration. Jim had three ideas, conceptually simple, but brilliant. First, we could sacrifice one of the axial instruments, the High Speed Photometer, and use that space for Costar. Second, after installation, COSTAR would extend an optical bench through the cassegrain hole in the primary, thereby providing access to the front side of the primary mirror. Third, it would deploy pairs of mirrors that would correct the spherical aberration for the three remaining axial instruments. Conceptual COSTAR M1, a spherical mirror intercepts the aberrated beam and directs it to M2. M1 M1 M2 M2, an anamorphic fourth-order asphere, has the exact inverse polishing errors of the HST primary mirror. COSTAR Schematic COSTAR Key Requirements Obviously, the “bench” had to deploy. The M2 mirrors, anamorphic fourth-order aspheres fabricated on toroidal blanks, had to have the exact inverse aberration on the primary mirror. The first 3 vendors could not make the M2 mirrors. Cepi directed us to go to Tinsely Optics, who succeeded. The M1 and M2 mirrors had to be deployed to the correct positions with a precision of ~0.1 mm. This was not easy. The deployed arms had to be stiff enough to prevent vibrations induced by moving parts in HST and other instruments. COSTAR – Start to Finish I The HST Strategy Panel’s findings and recommendations were presented to Dr. Riccardo Giacconi, Director of the Space Telescope Science Institute, on October 18, 1990. Dr. Giacconi endorsed the oral recommendations of the Panel and took the findings to NASA management. The Panel made a presentation at NASA Headquarters on October 26, 1990. In the following weeks, NASA and Ball Aerospace conducted an intensive study of the feasibility and costs of COSTAR. In December 1990, NASA Headquarters authorized the implementation of the COSTAR program to proceed. COSTAR – Start to Finish II I thought my work was done. However, Jim Crocker asked me to be the Costar Project Scientist, an offer I accepted. Ball Aerospace began design and proposal work in November, and was awarded a contract in January 1991. Costar was built from start to finish in 28 months. “On December 2, 1993 following a one-day delay for weather, Endeavour was launched.” On the 7th day of the mission, astronauts Kathy Thornton and Tom Akers removed the High Speed Photometer and installed Costar in its place. Kathy Thornton Installing COSTAR SM1 Was Very Demanding In addition to replacing WFC1 with WFC2 and replacing the High Speed Photometer with COSTAR they had the replacement tasks below. SM1 Was a Great Success FOC Before and After WFC1 and WFC2 Hubble Transformed Our Understanding of the Universe But, getting there was not an easy. On Jan 28, 1986, the Space Shuttle Challenger with a crew of seven, exploded 78 seconds after launch. The launch was the 25-th Shuttle Launch, and Challenger’s tenth launch. Before Challenger, based on a failure rate of roughly one in a hundred solid fuel powered missile launches from Van Den Berg Air Force, I put the odds for Shuttle launch failures at one fifty. In 1983, a study for the Air Force put the odds of a Shuttle loss during launch at 1 in 35. Challenger’s Crew Sadly for the crew and school teacher Crista McAuliffe, “Before the Challenger disaster, agency officials regularly asserted that the chance of disaster was 1 flight in 100,000”. Knowing the Challenger’s Commander, Dick Scoby, made Challenger very personal for me. All I can say about those particular agency officials is, “they were dammed idiots”.