Hubble Space Telescope Cameras
By Prof. Mike Disney
Wide-Field Camera 3I was picked to be a member of the ESA/NASA team to build the 'Faint Object Camera' back in 1976. I was by then a very experienced optical observer who had lived and worked in Arizona, Australia and Holland and my expertise was in detecting very faint objects such as pulsars and quasars. I helped to discover the first optical pulsar, the neutron star which blew up to to make the Crab Nebula, when I was working at the University of Arizona.
The hardest part of Hubble is building the cameras to exploit the telescope and do the best science. An ordinary camera working with just visible light won't do because up there in space Hubble collects ultraviolet and infra red radiation as well, and it does so with such enormous precision that the camera needs to be ultra sensitive and ultra-acute too. That's why such a camera, about the size of a telephone booth, can cost a hundred million dollars or more. Its performance determines the whole performance of the project.
When I came to Cardiff as professor in 77 I commuted back and forth to Holland where the Faint Object Camera was being built by the European Space Agency, which is a 15 per cent partner in Hubble.Much of the challenge comes in making optimum compromises in the camera and detector design so that the very best science is possible, and that was my chief task, designing exciting observing programs and influencing the design in such a way that they could be carried out.
Alas when the telescope was launched in 1990 we found that the telescope mirror had been wrongly polished.That was just awful. I remember banging my head against the wall in our house in Cardiff I was so upset. I then played a role in showing that the distorted images could not be recovered by clever stuff on computers so that we would have to fix the telescope. Which was done in 1993. I then led a team to image quasars for the first time . Quasars were the most distant and luminous objects in the Universe, but completely mysterious because they were just points of light when seen from the Earth. So how exciting it was in 1994 when I could see them for the first time on my computer terminal in Cardiff as images sent down from Hubble.They were huge galaxies colliding, in which the giant Black Hole at the centre of one galaxy swallowed material from the other and turned it into exotic radiation. That for me was the high point of the project because it resolved a very important question that many of us had worked on for 30 years.
In 1998 NASA selected me to work on a largely American team to work on a new and ambitious camera which would see Hubble doing even better. I was one of only two Europeans and the only Brit on it. This camera , known as Wide-Field Camera 3, is more sensitive, has a larger field of view and more perspecuity than its predecessors. Most importantly though it can see all the kinds of light up there, optical, ultraviolet and infrared. This has been an enormous challenge to get this all into one camera, and it has been nip and tuck to the very end.
My real interest astronomically these days is looking for largely invisible galaxies, to which end my team has been doing observations all over the sky using giant radio telescopes at Jodrell Bank and Parkes in Australia. We have indeed found galaxies which are virtually invisible in the optical (in one case totally invisible) but which contain vast amounts of cool hydrogen which show up in the radio. What's going on? I am hoping to use the new camera to find out by looking at the very gassiest specimen of this kind.
I am very grateful to Cardiff University for employing me to do these exciting things, which I still continue to do as an Emeritus Professor, and I have tried to share all the excitement with my students and with the ultra-enthusiastic bunch at Cardiff Astronomical Society. If you want to know more, join the society. It could change your life.