Physics Lecture Series | Spring 2010

Many scientists, particularly in popular science writing, assert that the laws of nature are "fine tuned" to give rise to (human, conscious) life. Such arguments are intimately linked to the Anthropic principle, and more recently to speculative multi-verse cosmologies. I explore some problems I see with these principles.

In 1988, scientists exploring the electronic and magnetic properties of ultrathin layered magnetic metals discovered the amazing phenomenon of giant magnetoresistance (GMR). Within a few years of its discovery, IBM started incorporating GMR into designs for more sensitive computer hard drive read sensors. Today, your computer hard drive is read using the GMR phenomenon, and it has lead to leaps in computer hard drive storage capacity, as well as applications such as the IPod. This talk will give a general overview of GMR and its history from discovery to application, culminating in the award of the Nobel Prize in 2007. It is a wonderful story of how physics research can have a dramatic impact on our society.

The revolutionary discovery that the expansion of the universe is speeding up, not slowing down from gravity, means that 75% of our universe is made of a mysterious dark energy. I will trace the origin of how this discovery was made, tieing together scientific explorations from why the dinosaurs became extinct to the breakthrough from supernovae explosions a decade ago to design of a new space telescope to reveal the nature of the unknown physics ruling our universe.

In this presentation a procedure is described that responds to the strategic need to intelligently identify those objects whose removal from the earth orbit environment will produce the maximum and most immediate reduction in collision risk. The following collision rate equation is developed and presented as the basis for a procedure to prioritize the removal of orbital debris from the earth orbit environment.

Hij = (Fνij) {[(21/2)(Vc)][(Di+ Dj)/2]2 / [(4/3)(RTi3-RBi3)]

This equation was adapted from an environment model developed by Talent (1992). Utilizing elset data and size data (from multiple sources), one may use the above expression to assess the magnitude of the threat posed by each object to the rest of the environment. To illustrate, let object "1" be the largest member of the population — the calculation of H1,2 may be performed. Then, for the rest of the population, perhaps on the order of 13000 objects, the calculation is repeated for H1,3, H1,4, H1,5, H1,6, H1,7, ... H1,13000. These quantities may now be summed over any size regime or all members of the population to assess the risk associated with the largest object — index 1 — for any selected population or sub-population. The procedure can be repeated for the second largest object, the third, the fourth, etc. until done. Then all individual objects can be ranked from greatest to least — in order of relative threat to the environment. Those objects determined to pose the overall greatest threat are the objects that represent the greatest risk reduction upon their selection for removal from the environment. Thus, the information generated by this analysis will allow for the intelligent selection of debris targets for removal achieving maximum benefit per unit cost.

NASA utilizes a number of ground-based analogs for human research. Each analog offers a unique environment for assessing the human response as it relates to spaceflight. Some of the analogs that offer extended mission capabilities include the NASA Extreme Environment Mission Operations (NEEMO), Haughton-Mars Project (HMP), Antarctic research stations and the Flight Analogs Research Unit (FARU). The underwater environment of NEEMO provides a setting for simulations of partial gravity and extravehicular activity studies. Missions at HMP provide a platform for examining mission related human behavior and medical operations. Antarctic missions are well suited for studying disruptions in circadian rhythms and the effects of isolation and confinement. The FARU is funded and operated by NASA and managed by the NASA Flight Analogs Project (FAP).

The FAP manages a 10-bed hospital unit dedicated to NASA bed rest studies. Bed rest conditions are standardized to include 60 or 30 days of 6-degree head down tilt bed rest. These conditions produce physiological changes of bone, muscle and cardiovascular systems similar to those seen in spaceflight. Subjects are fed a standardized diet based on the NASA spaceflight nutritional requirements. A battery of standard measures is collected on subjects that participate in each of the many bed rest studies. These measures are multidisciplinary and allow for an integrated approach to study responses in bed rest. Standard measures are particularly important as NASA assesses candidate countermeasures for spaceflight. In summary, the unique environments offered by ground-based analogs provide critical support for testing research questions prior to spaceflight missions.

Current theories suggest that gravitational waves created during inflation in the early universe contributed to the creation of cosmological structure. As a result, identifying the behavior of these gravity waves and their corresponding power spectrums during inflation and at subsequent epochs has become an important area of study. The general solutions to these equations can become quite complex, making the task of obtaining analytical results a difficult one without simplifying assumptions. Using numerical techniques, a general solution to the birefringent gravity wave equation is explored. This form of the gravity wave equation is partly composed of a mode function that resembles the Coulomb wave equation from Quantum Mechanics, which has been explored computationally in the past. An attempt is then made to numerically solve these equations and the corresponding power spectrum for the present universe. These results can be tested by current/planned observatories such as LISA and Advanced LIGO.

The Variable Specific Impulse Magnetoplasma Rocket (VASIMR®) promises to send future astronauts to Mars in a fraction of the time that is possible today. Under development by the Ad Astra Rocket Company, significant progress has been made towards a VASIMR® flight demonstration unit designed to fly onboard the International Space Station (ISS). The ISS provides an ideal testing site for the VF-200, a VASIMR® unit that injects 200 kW of radio energy into a super-heated stream of plasma. After many years of development, the VASIMR® has reached a high level of maturity and is now being prepared for its first test in the "ultimate vacuum chamber" — the ISS. The VF-200 mission success would be a paradigm shift in space transportation and could open the entire solar system for human exploration. The behavior and characterization of the exhaust plume of the VASMIR® plasma jet will be discussed in the context of laboratory plasma physics research. Dr. Longmier will describe the progress of the VASIMR® development program from his past two years of VASIMR research experience as a University of Houston ISSO postdoctoral fellow, the current status of VASIMR®, and future Ad Astra plans in the context of human space exploration.

Discoveries of substellar objects - giant planets, brown dwarfs, and exoplanets - continue to fill in the gaps in population between stars and planets, and our gaps in knowledge regarding the formation and evolution of planets and planetary systems. I will present an introduction and overview of current research on exoplanets and brown dwarfs, and will discuss how understanding basic chemical and physical processes in their atmospheres (thermochemistry, photochemistry, cloud formation, and transport) is important for interpreting, explaining, and guiding astronomical observations.

Experimental petrology of basalts can reveal a great deal of information about the temperatures and pressures of basalt formation. For terrestrial basalts experiments on basalts from different tectonic settings can reveal information about the processes going on in each setting. However, on Mars this is problematic because of our sample set. Mars basalts consist of the SNC meteorites, which are dominantly cumulate rocks, and the basalts remotely analyzed on the surface. Here I will summarize the experimental studies on Martian rocks, and use this data to place constraints on the pressures and temperatures of basalt formation in the Martian mantle.

Martian valley networks - landscape features on Mars resembling terrestrial river networks — have long been viewed as providing the best evidence of prolonged surface water on ancient Mars. The point of scientific contention is the origin of the valleys; did they form through runoff erosion signaling precipitation and a warmer Martian climate or by groundwater sapping that allows for cold and dry climate? Bulk of arguments for and against both hypothesis relied on detailed examination of selected valley segments or individual networks, but it is a global analysis that is required to provide an answer. The only global map of valleys was drawn manually in 1990s. New, higher resolution and quality data have since become available calling for a major update to a global map of the valleys.

However, the high cost of mapping valleys manually on a global scale from high resolution images prevented the update from happening. We acquired the updated map of valley networks automatically by computer parsing of global topographic data. In order to do this we needed to develop a new method of valley delineation that was custom made for non-uniform character of Martian surface. The resultant map shows degree of dissection consistent with the notion of precipitation on early Mars, but only in the presence of an ocean located in the northern hemisphere of the planet. Thus, this work indirectly supports an exciting hypothesis that Mars once had an ocean.