4. Required Theoretical and Modeling Support

During the Phase A study, at least three modeling exercises will provide important data to the mission.  These will deal with simulations of: the kinematics of the payload during descent, the spectral inversion problem and the tomographic inversion problem.  Support for these studies will come from existing research funding from sources such as NSERC.  

*** questions here:  If theoretical and modeling means not funded by CSA SPP program, does that mean the kinematic and detailed tomographic simulation should go in another section?  They are pretty central to the whole endeavor and I think they should be funded.****

*This project requires high altitude deployment of a controlled-spin parachute.  The local dynamics of the payload (attitude fluctuations) under the influence of atmospheric turbulence has not been modeled to date.  There exist statistical models for various upper atmospheric conditions, and the modelling required for NiteOwl will incorporate these to simulate the local payload dynamics during descent.

So far absorption data has been generated using expected constituents of the atmosphere and current data on the corresponding absorption bands.  Remaining to be done is the addition of noise to these data, with subsequent inversion to analyze the sensitivity of the process to random and systematic noise.  

There are variety of tomographic algorithms available for reconstruction of the ozone distribution from the column density data.  A comparison of these as well as a search for alternative techniques to bridge the gaps in the horizontal star distribution would permit the choice of optimal tomographic inversion techniques for our particular mission.

*Tomographic simulation has already been done for small sectors of the horizon having more than one star in them.  These have been useful for setting the current expected resolutions for tomographic reconstruction.  However, a more detailed simulation needs to be done.  This simulation would use the actual star distribution during actual launch windows and include the change in the star positions during the hour or so flight time.  In addition, the expected local payload dynamics from the first modelling study could be included.  This would provide a much stronger point of reference in establishing appropriateness of the top level science requirements.  

John Steele and Megan White