In the Goldstone 1962 experiments, Venus was in effect divided into observation zones and the doppler effect or change in the returned signal from these zones was studied. The rate of rotation was derived from three months of sampling with this radar mapping technique. Also, the clear, sharp tone characteristic of the transmitted radar signal was altered on return from Venus into a fuzzy, indistinct sound. This effect seemed to confirm the slow retrograde rotation (as compared with the Earth) indicated by the radar mapping and frequency change method. In addition to these methods of deducing the slow rotation rate, two other phenomena seemed to verify it: a slowly fluctuating signal strength, and the apparent progression of a bright radar spot across from the center of Venus toward the outside edge. As a result, JPL scientists revised their 1961 estimate of an equal Venusian day and year consisting of 225 Earth days. The new value for Venus’ rotation rate around its axis is 230 Earth days plus or minus 40 to 50 days, and in a retrograde direction (opposite to synchronous or Sun-facing), assuming that Venus rotates on an axis perpendicular to the plane of its orbit. Thus, on Venus the Sun would appear to rise in the west and cross to the east about once each Venusian year. If the period were exactly 225 days retrograde, the stars would remain stationary in the sky and Venus would always face a given star rather than the Sun. A space traveller hovering several million miles directly above the Sun would thus see Venus as almost stopped in its rotation and possibly turning very slowly clockwise. All the other planets of our system including the Earth, rotate counterclockwise, except Uranus, whose axis is almost parallel to the plane of its orbit, making it seem to roll around the Sun on its side. The rotation direction of distant Pluto is unknown. The Goldstone experiments also studied what is known as the Faraday rotation of the plane of polarization of a radio wave. The results indicated that the ionization and magnetic field around Venus are very low. These data tend to confirm those gathered by Mariner’s experiments close to the planet. The mass of Venus was another value that had never been precisely established. The mass of planetary bodies is determined by their gravitational effect on other bodies, such as satellites. Since Venus has no known natural satellite or moon, Mariner, approaching closely enough to “feel” its gravity, would provide the first opportunity for close measurement. The distortion caused by Venus on Mariner’s trajectory as the spacecraft passed the planet enabled scientists to calculate the mass with an error probability of 0.015%. The value arrived at is 0.81485 of the mass of the Earth, which is known to be approximately 13.173 septillion (13,173,000,000,000,000,000,000,000) pounds. Thus, the mass of Venus is approximately 10.729 septillion (10,729,408,500,000,000,000,000,000) pounds.