Balloon-Released Experiments in Gravitational Physics

Abstract - A 3-m-long, non-propelled cryostat released from a 40-km-high balloon is used to shield a detector free falling inside for 30 s. This facility provides opportunities for accurate experiments in gravitational physics. Among others, two experiments of particular interest are: (a) a free-fall test of the Equivalence Principle; and (b) the local mapping of the gravity field along vertical lines by means of as gravity gradiometer. In experiment (a), the differential accelerations between two test masses of different materials (e.g. aluminum and gold) is measured during free fall. The estimated accuracy in testing the Equivalence Principle in a 30-s free fall is 4 parts in 10^14 with 95% confidence level. In experiment (b), the knowledge of surface gravity anomalies can be improved with a 0.01-E gradiometer and the upward continuation gravity models validated. Copyright © 1993 Published by Elsevier Ltd.