Dr. Robert Whiteley (Innovative Technology Systems), Joe Yavorski (Innovative Technology Systems), Dr. Chris Jelks (Innovative Technology Systems), Wes Colburn (Innovative Technology Systems), Kent Berner (Innovative Technology Systems)
Keywords: Atmospherics, Space Weather
Abstract:
The use of modern Adaptive Optics (AO) systems allows large telescopes to approach diffraction limited seeing. This technique can improve the imaging resolution of a large telescope by more than an order of magnitude. Such a capability provides real improvement in ground-based space situational awareness (SSA) observations.
The drawback to current adaptive optics systems is that they only improve resolution over small imaging regions, sometimes as small as a few tens of arc seconds. Such small imaging regions limit the availability of suitable guide stars, which in turn limits the availability and duty cycle of an AO system. This limitation has led to the development of systems for producing artificial guide stars, which can be created along a line of sight coincident with that of the telescope. The most commonly used artificial guide stars are created by tuning a laser to the frequency of the Sodium D1/D2 line complex, and exciting sodium atoms in the Earth’s mesosphere.
The mesospheric sodium layer is exceptionally rarified, and has densities that vary diurnally, seasonally, and geographically. Our investigation centers on the use of sounding rockets to deliver substantial quantities of atomic sodium to the mesospheric layer. This direct enhancement of the sodium layer could increase the number of nights that laser-guide star AO observations could be performed, as well as increasing guide star brightness. These improvements should yield better AO wavefront correction and faster imaging frame rates. For the SSA application, these improvements will lead to more and better imaging opportunities.
We will present a basic overview of the relevant mesospheric dynamics, with emphasis on sodium dwell times and replenishment rates. We will present several possible mechanisms for delivery and deployment of atomic sodium in the mesosphere, and demonstrate the trade-offs in their use. We will present a possible concept of operation for notional delivery systems. Finally, we will discuss the cost-effectiveness of this approach in relation to the expected improvement in performance for typical laser-guide star AO systems.
Date of Conference: September 1-4. 2009
Track: Atmospherics/Space Weather