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Can An Old Dog Learn New Tricks?

Institute for Exploration / Ocean Exploration Trust

Can An Old Dog Learn New Tricks?

The question of an old dog learning new tricks has been the source of much debate for the greater part of human history. Whether that is true or not remains to be seen. Hercules, however, can without a doubt, learn any new trick he wants. Hercules has the ability to gain new capabilities simply by adding any number of devices and tools to use at his disposal. On this particular dive, Hercules has been given the awesome power to analyze the atomic make-up of samples through the use of an onboard mass spectrometer. This work was previously done in labs, after a sample was properly preserved and brought back to the research institution. However, with this new tool, Hercules can sample water and determine the exact atomic make-up of that liquid in situ. The temperature sensor on Hercules is surrounded by a new titanium tube. Through this tube, water samples are pumped into the pressure housing seen below where the mass spectrometer resides.

This tool was brought to Hercules by Dr. Charles Vidoudez, a post-doctoral researcher at Harvard University in Cambridge, Massachusetts. Charles is currently working on using this experience to fine tune the mass spectrometer so that it will be able to function in its installation on the University of Washington Ocean Observatories Initiative Regional Scale Nodes Observatory (http://www.interactiveoceans.washington.edu/story/Observatories). The mass spectrometer will be "sniffing" vent fluid from nearby hydrothermal vents. The goal is to fully analyze and understand every gas that is dissolved in the vent fluid. The mass spectrometer will be sampling venting fluids every six hours for an entire year. Charles is extremely excited by this project since traditionally, scientists have been very limited with the number of samples taken from the vents. Therefore, any changes in vent composition has been unknown . . . until now.

Hercules taking a mass spectrometer reading through the modified temperature sensor

The mass spectrometer has been specially designed in order to deal with several challenges with working at depth.  The first challenge is the depth and pressure the machine will be operating in. To combat this, they must place the mass spectrometer in a very expensive, highly specialize pressure housing. Since these housings are so expensive the mass spectrometer is engineered to be as small as possible. The interface with the water is also a challenge. The mass spectrometer must work in a complete vacuum, so the gases from the water must be transported at high pressure to a high vacuum. This is accomplished through the use of a very thin membrane supported by a disc of porous stainless steel. This is an area of ongoing work as they search for the perfect steel disc.  The final challenge is the length of time that the University of Washington wants to deploy the mass spectrometer for. It has to work without any maintenance for a full year. As the machine analyzes gases, the gases build up over time and the pressure in the housing slowly increases. This means that the pumps that keep the vacuum going will need to work harder to maintain the vacuum as time goes on.

The Mass Spectrometer

The mass spectrometer works through a very complicated process that involves injecting gases into an ionization chamber. This chamber is under a high vacuum and each gas is passed through a beam of electrons. As each molecule is hit by an electron it becomes an ion (a charged particle). Once charged, it reacts a certain way when influenced by magnetic and electric fields.  The mass spectrometer produces data analyzed by scientists. The ways in which molecules react differently to the electric and magnetic fields allow scientists to identify them.

A Sample Spectra