July 23, 2001 Research Subcommittee Committee on Science U.S. House of Representatives Your Honors: I am writing as a scientist who has experienced the benefits of information technology (IT) infrastructure improvements which have helped maximize the value of our scientific and educational efforts by enabling access to geographically remote scientific facilities. I lead a team of experimental astrophysicists who rely on high-speed, high-bandwidth communications with remote astronomical observatories to conduct our studies. Let me begin by describing our project, and then proceed to describe how IT is essential to our program and to give an example of a solution provided by National Science Foundation IT funding. Our project, the Nearby Supernova Factory, is an international collaboration between astrophysicists at the Department of Energy's Lawrence Berkeley National Laboratory and in France (at Laboratoire de Physique Nucleaire et de Haute Energies de Paris, Institut de Physique Nucleaire de Lyon, and Centre de Recherche Astronomique de Lyon). The aim of the collaboration is to discover nearby supernovae, and to study them in detail so that they can be used more effectively as cosmological distance indicators. At present, the relative distances to supernovae of Type Ia can be measured to an accuracy of 5%. This accuracy is exceptional by astronomy standards. In the past few years distances to Type Ia supernovae at very high redshifts have been measured. This has allowed astrophysicists to measure the rate of expansion of the Universe over the last 8 billion years (the Universe is now believed to be about 14 billion years old). Since all known matter in the Universe is pulled together by gravity, it was expected that these measurements would show that the expansion of the Universe has been slowing down. However, the Type Ia supernova measurements indicate that within the last few billion years this expected slowdown has been reversed. The cause for this reversal is presently unknown --- it may be related to Einstein's famous Cosmological Constant --- and so has been dubbed ``dark energy.'' This discovery (in which we were involved) that dark energy exists was the most important scientific discovery of 1998 according to the journal Science, and was acknowledged by a letter of congratulations from the White House. This discovery has revolutionized cosmology. Now astrophysicists want to understand the physical cause for the dark energy. This requires more precise measurements, and with large numbers of accurately measured Type Ia supernovae this should be possible. However, astrophysicists have learned over the years that very distant (and therefore old) objects can be subtly different than very nearby objects. Therefore, they are concerned that the most distant Type Ia supernovae may be slightly different than the nearby supernovae against which they must be compared for distance determination. Fortunately, the ingredients which go into a supernova explosion are fairly well known, and although computer modelers are not yet able to accurately predict the properties of supernovae in great detail, they do know something about how supernova properties change when the input ingredients are changed. Since measuring the change in the expansion rate of the Universe requires only relative distances, astrophysicists simply need to understand how supernovae will change in brightness when their input ingredients are changed. This question can be explored using nearby supernovae which have a wide range of values for these input ingredients. Such exploration is the basic goal of the Nearby Supernova Factory. The first step in studying nearby supernovae is to find them. For the studies needed, we would like to discover the supernovae as soon as possible after they explode. This requires imaging the night sky repeatedly, returning to the same fields every few nights, and then quickly processing the data. The most powerful imager for this purpose in existence is the CCD (charge-coupled device) camera built by the Jet Propulsion Laboratory (JPL). This camera delivers 100 million bytes of imaging data every 60 seconds. The new images are compared to archived images of the same field using digital image subtraction to find the light of any new supernovae. This digital image subtraction involves numerous steps to align the images and account for blurring by the Earth's atmosphere, and requires the equivalent power of 50 desktop computers to keep up with the data. Because the amount of data is so large (50 billion bytes per night), the image archive even larger (presently 8 trillion bytes and growing), and the computations so extensive, it is critical that the imaging data be transferred to a large computing center (in this case NERSC, the National Energy Research Scientific Computing Center at LBNL) as quickly as possible. Since such extensive computing facilities could not be maintained at the observatory, the only alternative to a fast data link would be to write the data to tape and ship it, at the cost of delaying supernova discoveries by several days. The JPL camera is sited at the Palomar Observatory, owned and operated by the California Institute of Technology. This observatory is in a remote location in southern California, surrounded by mountains and the Cleveland National Forest. Although (sadly) the lights of San Diego and Los Angeles can be seen from Palomar at night, the high-speed internet connections available in these cities do not come anywhere close to Palomar. Therefore, a custom-built high-speed data transmission capability was required to achieve our program goals. No commercial alternatives were available which could handle our data volume, but fortunately for us the NSF-funded High Performance Wireless Research & Education Network (HPWREN) came to the rescue. Establishing a remote high-speed wireless internet connection to Palomar turned out to be a very laborious undertaking for HPWREN, as everything from FCC regulations to drilling mounting poles in solid granite had to be tackled. HPWREN was unflagging in overcoming these obstacles. The wireless internet, which uses modest radio dishes (8 ft in diameter) equipped with TCP/IP compliant radio transceivers, has been in operation for 2 weeks now, and our collaboration is exceptionally pleased with the results to date. We expect supernova discoveries to begin pouring out very soon, once our software is tweaked to handle the new data. It is important to note that this modest investment (an incremental system cost added of about $30,000) now allows new and exciting science to be obtained from the multi-million dollar facilities at Palomar Observatory. Undergraduate and graduate students from the University of California at Berkeley are now working with the data, learning scientific methods and obtaining data for their theses. Eventually the supernova discoveries from Palomar Observatory will be used to direct follow-up observations of several telescopes located on remote mountain tops all over the world. High-speed data links developed at these remote sites over the last few years will play a key role here as well by allowing remote control of the telescopes and even remote monitoring of the mountaintop weather. These follow-up observations will in turn help to solve one of the most mysterious and fundamental properties of our universe --- the nature of dark energy. Ours is but one example of the scientific advances made possible by cutting-edge information technology, especially in remote locations where no commercial alternatives for accessing scientific facilities exist. Sincerely, Dr. Greg Aldering Staff Scientist & Nearby Supernova Factory project leader Lawrence Berkeley National Laboratory One Cyclotron Rd. MS 50/232 Berkeley, CA 94720