Search NASA⌕ Search

Engineering topics

Richter, D. A.

Publications and source records attributed to Richter, D. A..

Development of a Compact, Ground-Based Ozone DIAL System

We are developing a portable, eye-safe, ground-based ozone lidar instrument specialized for ozone differential absorption lidar (DIAL) measurements in the troposphere. This prototype instrument is intended to operate at remote field sites and to serve as the basic unit for future monitoring projects requiring multi-instrument networks, such as that proposed for the Global Tropospheric Ozone Project (GTOP). GTOP is currently being formulated by a scientific panel of the International Global Atmospheric Chemistry Project to meet its goal to better understand the processes that control the global distribution of tropospheric ozone. In order for the lidar to be widely deployed in networks, it must be fairly easy to use and maintain as well as being cost-competitive with ground station launching ozone sondes which operate several times a day. To achieve these goals, emphasis is placed upon the incorporation of: (1) all-solid state transmitters which can reliably produce 20-40 mJ pulses; (2) a highly efficient, narrow-bandpass receiver; (3) dual analog and photon-counting detector channels; and (4) flexible, user-friendly control software.

Chyba, T. H.↗

Unique characterization of lunar samples by physical properties

The measurement of compressional velocity, shear velocity, static compressibility, and thermal expansion of (1) a suite of shocked rocks fron the Ries impact in Germany, (2) a suite of samples cracked by thermal cycling to high temperatures, (3) many terrestrial igneous rocks, and (4) lunar basalts, gabbroic anorthosites, and breccias, indicate that shock metamorphism is the primary cause for values of physical properties of lunar rocks being diffferent from their intrinsic values. Large scale thermal metamorphism, thermal cycling between temperatures of lunar day and night, large thermal gradients, or thermal fatigue could possibly cause minor cracking in the top few centimeters of the lunar regolith, but are probably not important mechanism for extensively changing values of physical properties of lunar rocks.-

Todd, T.↗