title: Pioneer venus radar mapper experiment.
abstract: Altimetry and radar scattering data for Venus, obtained from 10 of the first 13 orbits of the Pioneer Venus orbiter, have disclosed what appears to be a rift valley having vertical relief of up to 7 kilometers, as well as a neighboring, gently rolling plain. Planetary oblateness appears unlikely to exceed 1/2500 and may be substantially smaller.
authors.forename: G H
authors.initials: GH
authors.lastname: Pettengill
authors.forename: P G
authors.initials: PG
authors.lastname: Ford
authors.forename: W E
authors.initials: WE
authors.lastname: Brown
authors.forename: W M
authors.initials: WM
authors.lastname: Kaula
authors.forename: C H
authors.initials: CH
authors.lastname: Keller
authors.forename: H
authors.initials: H
authors.lastname: Masursky
authors.forename: G E
authors.initials: GE
authors.lastname: McGill