Survey and chase: A new method of observations for the Michigan Orbital DEbris Survey Telescope (MODEST)

The Michigan Orbital DEbris Survey Telescope (MODEST) is normally used to survey the geosynchronous orbit (GEO) environment to obtain a statistical assessment of the debris population. Due to the short time that the object is in the field-of-view (usually 5 min), it is common practice to assume a circular orbit when calculating the orbit from this limited observational arc. Some objects in the GEO regime are GEO-transfer orbit (GTO) objects which are observed at their apogee or objects with varying eccentricities such as those with high area-to-mass ratios. For these objects, an assumed circular orbit (ACO) prediction would not be accurate. After MODEST was modernized in March 2005 and brought under computer control, it became possible to use the telescope in modes other than tracking at the sidereal rate. Three data runs were conducted to test the orbit determination program, the ability to transfer data effectively between site locations, and to determine if objects could be re-acquired with this method. We report in this paper our initial efforts to determine full orbits based on follow-up observations after the initial detection in survey mode. Our long-term goal is to construct a system which can detect and follow up an object in any orbit at GEO. This paper reports our first steps towards that goal. During the three data collections, only circular orbit objects were obtained. Although this allowed for testing of the process, further tests must be conducted in an effort to target GTO and high area-to-mass objects.