A crystal microphone for measurement of the density of cosmic dust, mounted on the central frame. A proton detector for counting low-energy protons in the solar wind, also mounted on the central frame. Two Geiger-Müller (GM) tubes and an ion chamber, for measuring high-energy charged particles in interplanetary space and in the Venusian equivalent of Earth's Van Allen Belts (which were later shown not to exist). These were mounted on Mariner's long axis to avoid the magnetic fields of the control equipment as well as secondary radiation caused by cosmic rays hitting the metal structure of the spacecraft. An Anton special-purpose GM tube, for measuring lower energy radiation, particularly near Venus, also mounted away from the central frame. A three-axis fluxgate magnetometer for measuring the Sun's and Venus' magnetic fields, also mounted away from the central frame. A microwave radiometer, a diameter, deep, parabolic antenna designed to scan Venus up and down at two microwave wavelengths (19 mm and 13.5mm), slowing down and reversing when it found a hot spot. The 19 mm wavelength was for measuring the temperature of the planet's surface while the 13.5mm wavelength measured the temperature of Venus' cloudtops. The instrument was mounted just above the central frame. Two infrared optical sensors for parallel measurement of the temperature of Venus, one at 8 to 9 microns, the other at 10-10.8 microns, also mounted above the central frame.
A crystal microphone for measurement of the density of cosmic dust mounted on the central frame A proton detector for counting low-energy protons in the solar wind also mounted on the central frame Two Geiger-Müller (GM) tubes and an ion chamber for measuring high-energy charged particles in interplanetary space and in the Venusian equivalent of Earth's Van Allen Belts (which were later shown not to exist) These were mounted on Mariner's long axis to avoid the magnetic fields of the control equipment as well as secondary radiation caused by cosmic rays hitting the metal structure of the spacecraft An Anton special-purpose GM tube for measuring lower energy radiation particularly near Venus also mounted away from the central frame A three-axis fluxgate magnetometer for measuring the Sun's and Venus' magnetic fields also mounted away from the central frame A microwave radiometer a diameter deep parabolic antenna designed to scan Venus up and down at two microwave wavelengths (19 mm and 135mm) slowing down and reversing when it found a hot spot The 19 mm wavelength was for measuring the temperature of the planet's surface while the 135mm wavelength measured the temperature of Venus' cloudtops The instrument was mounted just above the central frame Two infrared optical sensors for parallel measurement of the temperature of Venus one at 8 to 9 microns the other at 10-108 microns also mounted above the central frame