Results from the Atmospheric Neutral Density Experiment Risk Reduction Mission

Abstract

The Atmospheric Neutral Density Experiment (ANDE) Risk Reduction flight was launched on Dec 9, 2006 and deployed into orbit by the Space Shuttle Discovery on December 21, 2006. The primary mission objective is to test the deployment mechanism from the Shuttle for the ANDE flight in mid 2009. Scientific objectives of the ANDE risk reduction flight include: monitor total neutral density along the orbit for improved orbit determination of resident space objects, monitor the spin rate and orientation of the spacecraft, and provide a test object for polarimetry studies. Each of the two ANDE missions consists of two spherical spacecraft fitted with retro-reflectors for satellite laser ranging (SLR). The ANDE risk reduction mission spacecraft each contain a small lightweight payload designed to determine the spin rate and orientation of the spacecraft from on-orbit measurements and from ground based observations. The follow-on ANDE mission scheduled for launch in 2009 will consist of two spherical spacecraft also fitted with retro-reflectors for SLR. One of these spacecraft will also carry instrumentation to measure the in-situ atmospheric density, composition and winds. Atmospheric densities derived from observations of the ANDERR spacecraft will be presented and compared to atmospheric models and other data sources. A methodology to improve prediction accuracy by augmenting predictions produced with radar observations with combination radar and satellite laser ranging observations will be presented. This paper presents a mission overview and emphasis will be placed on the scientific results from the risk reduction mission and a brief overview of the follow-on mission.