Friday, November 1, 2002
2:00 - 4:30 pm
JPL, Conference Room 180-101
Longevity of endospores and bio-defense
Adrian Ponce, Ph.D.

(1) The anthrax attacks in 2001 have highlighted the need for new methods of detecting bioaerosols including airborne Bacillus anthracis spores. Current methods of bacterial spore (endospore) detection, such as colony counting and PCR, require trained personnel for sampling and analysis. The labor requirement obviates these methods for continuous, online endospore monitoring. Recent efforts in our lab have led to a prototype for automated monitoring of airborne endospores that combines an aerosol capture technique with endospore detection based on terbium luminescence turn-on.

(2) How long can life be stored and remain viable? Since bacterial spores (endospores) are the most durable form of life, a measurement of endospore viability lifetime (i.e., longevity) addresses this question most directly. Glacial and permafrost ice from Arctic and Antarctic regions contains embedded endospores and is up to millions of years old. We will determine the viability lifetime of bacterial spores by measuring the fraction of viable spores (i.e., spores capable of germination) as a function of depth in cores from glacial ice and permafrost. Since the depth of a sedimentary sample can be correlated to deposition time, the best fit of a decaying function (e.g., single- or multi-exponential decay) to the viability versus time data will yield the viability lifetime. The viability lifetime measurements are enabled by a novel method in which the viable fraction of endospores is determined in a sample, thus allowing normalization for varying spore densities across samples.

Friday, January 24, 2003
2:00 - 4:30 pm
JPL, Conference Room 180-101
Mathematical Modeling of Navigating Deep Space Missions
Dr. Tseng-Chan Wang

Mathematical models of spacecraft dynamics, solar system dynamics, measurement observation, and trajectory correction are used to navigate deep space missions. Several numerical techniques are employed in spacecraft trajectory integration, optimization, parameter estimation, orbit determination, trajectory correction and maneuver calculations. Two navigation examples, the Deep Space One (DS1) Comet 19P/Borrelly encounter and the orbit and landing on the asteroid 433 Eros of the Near Earth Asteroid Rendezvous (NEAR) Shoemaker spacecraft are presented to illustrate the use of mathematical modelling in deep space navigation.

Friday, March 21, 2003
2:00 - 4:30 pm
JPL, Conference Room 180-101
A Global View Of Mars: Results From The Mars Global Surveyor (MGS) Mission
Dr. Frank Palluconi, Ph.D.

Launched in 1996 Mars Global Surveyor is the first successful US mission to Mars since the spectacular Viking missions of the mid 1970s. MGS is still orbiting Mars 12 times per day, has completed over 17,000 orbits of Mars and is daily returning data from all experiments. Barring hardware failures the spacecraft carries enough fuel to allow operation until the end of this decade. The purpose of MGS is to return quantitative global measurements of Mars and in the process it has established that Mars has no global magnetic field, possesses a thick crust in the higher heavily cratered southern hemisphere, exhibits over 30 km of relief between the highest (Olympus Mons) and lowest (Hellas Basin) locations on the planet, has a surface composition in selected locations of basalt, andesite and coarse grained hematite, displays thick regularly layered sequences of sedimentary rocks in many locations, has a wide variety of dune forms from pole to pole, exhibits recent evidence of gully forming water seeps and has provided a comprehensive unbiased sampling of atmospheric behavior including detailed profiles of atmospheric temperature and pressure. These results and other measurements from the five MGS experiment with be presented.

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