The Midcourse Space Experiment satellite was launched in 1996 into an 898-km altitude, near sun-synchronous orbit. A principal sensor on board the satellite is the Space-Based Visible (SBV) sensor, a visible-band electro-optical camera designed at Lincoln Laboratory to perform the first technical and functional demonstration of space-based space surveillance. The principal task of the SBV sensor is to gather metric and photometric information on a variety of resident space objects (RSO). In 1997, after the successful technologydemonstration phase of the mission, the SBV sensor was transitioned to a Contributing Sensor in the Space-Surveillance Network. Since April 1998, upon completion of the transition and testing phase, the SBV sensor has responded to daily tasking requests from the 1st Command and Control Squadron, in Cheyenne Mountain, in support of routine RSO catalog maintenance.

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An Analytic theory for the evolution of high altitx3.e satellite orbits is developed in this rote. The distinctive feature of the theory lies in the dc*ĩble averaging of the differential equaticns-onoe over the period of the orbit , and secondly over the period of the ucon. This technique is called "intern~diate averaging" to distinguish it fran the conventional &*ibly averaged theories , and to deIx)te the tine scales inherent in the averaging technique.

Analysis of orbital debris data collected by the Haystack radar have shown an anomalously high concentration of debris between the altitudes of 800 and 1000 km. Indications from the Haystack data are that the debris range in size from 8 mm to 2 cm and that they are spherical in shape. Previous work by NASA researchers has shown the likely origin to be the leaking of liquid coolant from the nuclear power sources of a now defunct Soviet spacebased series of ocean surveillance satellites. We report on a project at Massachusetts Institute of Technology's Lincoln Laboratory to detect, track, and characterize a small sample of the anomalous debris using ground-based radars and telescopes. Our goal was to provide evidence supporting or refuting the NASA conclusions. We have determined that the size, shape, density, and surface properties of the debris are consistent with the hypothesis that it is liquid, eutectic sodium-potassium coolant like that used in the Soviet satellites. The techniques used to detect and track the debris are discussed. The radar and optical data used to characterize the debris are also presented. Nomenclature A= projected area of object, m 2 a = radius of spherical radar target, m C d = ballistic coef cient F drag = atmospheric drag force acting on an orbiting object I 1 .I 2 / = intensity of light polarized in the plane parallel (perpendicular) to the plane of incidence k = complex index of refraction (attenuation coef cient) M = mass of object subjected to atmospheric drag, g M1= astronomical V-band visual magnitude corrected to a range of 1000 km n = real index of refraction r = re ectivity (albedo) S d = thermospheric density scale factor for debris object S 0 = thermospheric density scale factor for radar calibration sphere V s = velocity of an object relative to the atmospheric velocity V sun = astronomical V-band visual magnitude of the sun (¡26.8) = wavelength, m ½ true .½ model / = true (modeled) thermospheric density ¾ = radar cross section of spherical target, dBsm, dB relative to a square meter 8 = phase function Á = phase angle (sun-object-observer angle), deg or rad