title: Perturbations of the Orbit of the Echo Balloon.
abstract: The motion of the Project Echo communications satellite during its first 12 days clearly confirms previous predictions of the influence of solar radiation pressure. During this time, solar pressure reduced perigee height by 44 km. The approximate value of 1.1 X 101 g/cm5 has been obtained for the average air density at the 1600-km altitude of the satellite.
authors.forename: I I
authors.initials: II
authors.lastname: Shapiro
authors.forename: H M
authors.initials: HM
authors.lastname: Jones