My Contributions to Science

I started my astronomical career in radio astronomy, using the facilities of the NASA Deep Space Network at Goldstone, just outside of Barstow in the southern California desert. These are the facilities I used for the papers on Uranus & Jupiter. I finished my astronomical career primarily analyzing the image data from the Spitzer Space Telescope, although in 2006 I did venture to the high ground of the The Mauna Kea Observatories, to use the Caltech Submillimeter Observatory (CSO). And in the middle of my astronomy career, I took a "break" to work on atmospheric physics and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) project. I have had an opportunity to work with top class scientists from all over the world, in both Earth & space sciences, collaborating with teams from France, Italy & Japan. When I pursued my education in physics, I could hardly have hoped for this kind of opportunity, to spend 28 years working with the Grandmasters in their fields. It was a fascinating experience, which I will document here through the bibliography of my own published research. There are no Einstein breakthroughs here, but just my contributions to the steady progress of science, such as they are.

I came to the Jet Propulsion Laboratory in January 1981, as part of the Radio Astronomy Group, which later changed its name to the Radio/Submillimeter Astronomy Group, in order to emphasize our transition into the then newly available submillimeter wavelengths. Our main thrust in those days was to use observations characteristic of thermal emission, to probe the structure of the atmospheres of the giant planets: Jupiter, Saturn, Uranus, and Neptune. A number of papers had already come out of the group, on Jupiter and Saturn, before I joined. This paper was the first one I was to work on. Our group was the first to recognize the time variability of the Uranian microwave spectrum, and the first to suggest a cause.

The other major project that I worked on was the Jupiter Patrol, a long term project of Mike Klein's that monitored the synchrotron emission from Jupiter at 2295 MHz, using the radio antennae of the Deep Space Network, for more than a full solar cycle. We were eventually able to draw direct correlations between the synchrotron emission, and the solar wind loading of the Jovian magnetosphere. This was a significant result, because we were monitoring emissions from deep within the Jovian magnetosphere. At the time, it was thought that low energy electrons from the solar wind could not diffuse into the inner magnetosphere on such short time scales as we were able to demonstrate. Scott Bolton eventually came up with a new theoretical model for electron diffusion that became his PhD thesis, and explained the observations nicely. The electrons come in the back door, diffusing through the weaker magnetic field at the tail of the magnetosphere.

By this time the Radio Astronomy Group was heavily involved in the NASA SETI project, which began to grow rapidly in 1988. In 1992, on Columbus Day the NASA SETI project made its official start, amidst fanfare and publicity. Congress cancelled the program within a year. I left the Radio Astronomy Group at about that time as the money for astronomy and astrophysics became too scarce. However, we all received NASA Group Achievement Awards for what we were able to get done. All SETI is now in private hands, mostly The SETI Institute and The Planetary Society. Most of my work centered around planning a system for storing several hundred terabytes of data, which was a far more difficult task to accomplish or pay for in the early 1990s than it is today. I also worked on observation strategies and the problem of radio frequency interference (RFI; intelligent signals of terrestrial origin, which must be filtered out before we look for intelligent signals of extraterrestrial origin).

I also had minor a minor support role in the COBE project. But one other interesting project, which unfortunately had little support, was a project we dubbed Argus. This was an attempt to monitor the Milky Way for transient sources, especially including supernova explosions, which are quite visible in the radio, but not optically, because of the heavy dust burden in the plane of the Galaxy. We collaborated with Woody Sullivan, from the Astronomy Department at the University of Washington. Despite its apparent scientific value, the program did not get funded over the long term.

After working in the radio astronomy group from 1981 to 1993, I spent a year as an assistant network administrator for the Science Computing Network, in the Earth & Space Sciences Division at JPL. It was a mixed network of mostly Sun workstations, along with Digital miniVAX, and a few Apple Macs, designed to supply computer support for the division scientists. I handled all of the system maintenance tasks and customer support for the VAX & Apple systems, and much of the maintenance for the network cables scattered around a few buildings.

Early in 1994 I joined the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) project, as a member of the Atmospheric Corrections Group, a part of the science team for the Thermal Infrared (TIR) detector on the ASTER instrument, which launched on the TERRA satellite of the Earth Observing System (EOS) on 18 December 1999. I designed the algorithms to compensate for the presence of Earth's atmosphere between the satellite and the ground. By removing the infrared signature of the atmosphere, we would then recover the infrared properties of the surface, which allows determination of both temperature and emissivity for the surface. Most of my time pre-launch was devoted to designing the algorithms to do that in an automated, data pipeline environment. After launch I took part in the vicarious calibration program, where we deployed on numerous occasions to specific targets, usually desert dry lake playas or lake surfaces, though we did once use the blacktop of the parking lot at Magic Mountain. The team would set up instruments to measure the physical & radiative properties of the target surface, and the atmosphere, coincident with the satellite overpass; I was responsible for the weather station, radiosonde (weather balloon) and solar radiometer. We would then use the data gathered in-situ to do the atmospheric compensation on ASTER TIR raw data, and compare with the results from the algorithms I had designed, to make sure they were doing what we all thought they would do. My algorithms passed the test, matching our calibration exercises within about 1%. The field work included a trip to Venice, Italy, in April 2001, where we were working with an Italian oceanography group studying the problem of Venice slowly sinking under its own weight. They were using ASTER data products, and we were there to help out with that. See my Venice page, and my ASTER page for more about my work on this project.

In January, 2002, I joined the staff of the newly created Center for Long Wavelength Astrophysics, in the Earth & Space Sciences Division at JPL (which has since been renamed as simply The Science Division). I was initially involved in setting up the software for the center, supporting JPL astronomers in proposal preparation, and simulating data from the Space Infrared Telescope Facility (SIRTF), which was then expected to launch in January 2003. SIRTF eventually launched on August 25, 2003, and was renamed the Spitzer Space Telescope, in honor of Lyman Spitzer, Jr.. It was Spitzer who, in 1947, first pointed out the value of space based telescopes.

Since then I have been more heavily involved in super-resolution enhancement of Spitzer images. Spitzer makes observations by adding up individual frames that are dithered in half-pixel increments. That means there is information about structures smaller than one pixel in the collected images, and our software will extract that information, creating images that are enhanced in resolution by about a factor of 3. The first major result of this was the discovery of an asymmetry in the debris disk around the star Fomalhaut. Our resolution enhanced imagery was able to show that the observations were consistent with models which indicate that the asymmetry is caused by a planet embedded in the debris disk. Of course, this is only an indirect indication, but an exciting result, nonetheless. The disk models were created by Elizabeth K. Holmes, who sadly passed away suddenly in her office, while working on her models. The Fomalhaut paper is dedicated to her memory. The September 2004 issue of The Astrophysical Journal Supplement Series is exclusively devoted to the Spitzer Space Telescope. Although I retired from JPL in 2008, I returned as a consultant in 2012/2013 to work on another exercise in Spitzer imagery.

Page updated and URLs checked; 2 February 2015

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