07/19/2004: "Report Number Six from NASA"

Maine Space Grant Consortium
NASA Internship Program
Aaron Keller
Summer 2004, JSC
Dr. L.E. Nyquist, Thermal Ionization Mass Spectrometry
Working Title: “Investigations of Chemical Processes on Hot Re Filaments in Relation to Ion Yield in Thermal Ionization Mass Spectrometry”
Report #6
   I began my week by creating a document summarizing all of the filament loading techniques that I have recorded so far. Up until this week each element was recorded on a separate page in a spreadsheet so placing everything onto the same page will make it easier to compare the methods used for different elements. This sheet can then be used to explore trends and relationships.
   In discussions with Dr. Nyquist regarding electrochemistry, and the complicated oxidation and reduction reactions that may be involved in ionization, we decided that it may be too ambitious to attempt to create an overall model for ionization. At best we will be able to identify relevant elemental data and record trends that point toward underlying processes. It is these trends that will prove to be useful when the project is completed later this summer. It was Dr. Nyquist’s idea that we perform experiments in the mass spectrometer with a series of elements with different ionization potentials. It should be possible to see a relationship between the ion yield and (for example) the ionization potential, the reduction potential, and perhaps the element’s electronegativity. In doing so we would establish a basis upon which to determine what filament loading technique should be used on an element that has not been investigated using the mass spectrometer before.
(click on 'more' to read more)

   On Friday Young Reese invited me to record some temperature vs. ion yield data for some very small samples of rubidium and strontium. These data are useful because when a run can be made to go ‘to exhaustion’ I can calculate the actual number of ions formed during the run. By finding the carefully calculated starting mass of atoms loaded, an absolute ion/atom ratio for the run can be found. In addition, because the amount of rubidium loaded was so small it was possible to collect data for a larger range of temperatures. In a previous attempt to gather data on rubidium the detector’s limits were reached very quickly because even just the 5 nanograms of rubidium loaded ionized so efficiently. This time only 200 picograms (200 x 10^-12 g) of rubidium were on the filament; and it still required nearly two full hours to exhaust the sample. These data for strontium and rubidium will also contribute to determining the overall energy of ionization (as discussed in a previous report).
   I had quite a few tour and lecture opportunities this week. On Tuesday senior NASA administrator Sean O’Keefe addressed students at all the NASA centers around the country via closed circuit video. Questions about the future of human spaceflight and NASA research were taken from each center. When that presentation ended I participated in a tour of the mission control center, where we visited the Apollo era mission control, the control room for the shuttle program, where a simulation was being run, and the control center for the International Space Station. It was especially interesting to see the people hard at work supporting the space station: there was a giant projection monitor showing the station’s up-to-the-second orbital location, speed and other vital statistics.
   The next day I visited the Neutral Buoyancy Lab (http://www.jsc.nasa.gov/dx/dx12/) and the Advanced Space Propulsion Lab (http://spaceflight.nasa.gov/shuttle/support/researching/aspl/index.html). The NBL is the giant ‘swimming’ pool where astronauts can train for extravehicular activities, such as repair or construction missions. The pool is 202 ft long by 102 feet wide by 40 feet deep and holds about 6.2 million gallons of water. There are mockups in the pool of parts of the space station and the space shuttle. Everything that the astronauts will manipulate, including their space suits and carefully counterweighted and floated to give each item the same tendency to float upward as to sink. This is as close as we can come to weightlessness on the surface of the Earth. The ASPL was a fascinating place where scientists and engineers are researching a method of rocket propulsion that has great promise. With traditional, chemical rockets a trip to Mars would take about ten months, one-way. With a Variable Specific Impulse Magnetoplasma Rocket (VASIMR) powered by a 12 megawatt power source this time could be cut to four months. With a 200 megawatt power source the trip could be over in as little as 39 days. The rocket uses electrically-created plasma contained by super-conducting magnets, as the source of propulsion, rather than a chemical reaction such as that used to launch the space shuttle.
   On Thursday I had a tour of another astronaut training facility. In this facility astronauts can simulate liftoff and landing of the space shuttle in a full motion flight simulator, simulate other shuttle operations, and practice the work done on the International Space Station. I had the opportunity to ‘fly’ the space shuttle simulator for one liftoff and two landings. The simulation controller was very nice and gave me some thunder and lightning for the second landing. All in all, I did fairly well and on my second landing I managed to avoid striking the runway with too much force.
Finally, on Friday, I attended a lecture by Franklin Chang-Diaz, who is an astronaut and the inventor of the VASIMR. He explained how this propulsion system works in a bit more detail than I heard on Wednesday.

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