Space magnetics: The mariner V magnetometer experiment

Venus has intrigued planetary scientists for decades because of its huge contrasts to Earth, in spite of its nickname of "Earth's Twin". Its invisible upper atmosphere and space environment are also part of the larger story of Venus and its evolution. In 60s to 70s, several missions (Venera and Mariner series) explored Venus-solar wind interaction regions. They identified the basic structure of the near-Venus space environment, for example, existence of the bow shock, magnetotail, ionosphere, as well as the lack of the intrinsic magnetic field. A huge leap in knowledge about the solar wind interaction with Venus was made possible by the 14-year long mission, Pioneer Venus Orbiter (PVO), launched in 1978. More recently, ESA's probe, Venus Express (VEX), was inserted into orbit in 2006, operated for 8 years.Owing to its different orbit from that of PVO, VEX made unique measurements in the polar and terminator regions, and probed the near-Venus tail for the first time. The near-tail hosts dynamic processes that lead to plasma energization. These processes in turn lead to the loss of ionospheric ions to space, slowly eroding the Venusian atmosphere. VEX carried an ion spectrometer with a moderate mass-separation capability and the observed ratio of the escaping hydrogen and oxygen ions in the wake indicates the stoichiometric loss of water from Venus. The structure and dynamics of the induced magnetosphere depends on the prevailing solar wind conditions. VEX studied the response of the magnetospheric system on different time scales. A plethora of waves was identified by the magnetometer on VEX; some of them were not previously observed by PVO. Proton cyclotron waves were seen far upstream of the bow shock, mirror mode waves were observed in magnetosheath and whistler mode waves, possibly generated by lightning discharges were frequently seen. VEX also encouraged renewed numerical modeling efforts, including fluid-type of models and particle-fluid hybrid type of models, describing the plasma interaction on scales ranging from ion gyro radius to the entire induced magnetosphere. In this review article, we review what has been found from space physics measurements around Venus (from the solar wind down to the ionopause), with a particular emphasis on updated results since the Venus Express mission. We conclude the article by a short discussion on the remaining open scientific questions and the future of this field.

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“…3: Verigin et al (1978). 4: Connor (1968). 5: http://nssdc.gsfc.nasa.gov/nmc/ experimentDisplay.do?id=1967-060A-04.…”

Section: A Brief Overview Of Space Physics Exploration At Venusmentioning

confidence: 99%

Solar Wind Interaction and Impact on the Venus Atmosphere

et al. 2017

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“…This point was emphasised by the modelling comparisons between Earth and Mars by Dryer and Heckman (1967) who concluded that the magnetic dipole moment of Mars was about 3 × 10 12 T m 3 , close to the possible value suggested by Smith et al (1965aSmith et al ( , 1965b. The magnetometer used on this mission was the first vector helium instrument (Connor 1968) that was to lead to a series of instruments on key planetary missions for the next 40 years. The schematic of the instrument is shown in Fig.…”

Section: Marsmentioning

confidence: 54%

“…However, It was not possible to exclude the possibility of a weak intrinsic magnetic field, but the close approach allowed to establish a much lowered upper limit, less than a fraction 1/400 of that of the Earth, than was possible with Mariner 2. The magnetometer on Mariner 5 was identical to the one flown on Mariner 4; it was the first time a quantum effect instrument, a Vector Helium Magnetometer was embarked on a planetary mission (Slocum and Reilly 1963;Connor 1968). This instrument is described in more detail in Sect.…”

Section: Venusmentioning

confidence: 99%

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Planetary Magnetic Field Measurements: Missions and Instrumentation

Balogh

2010

Space Sci Rev

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The nature and diversity of the magnetic properties of the planets have been investigated by a large number of space missions over the past 50 years. It is clear that without the magnetic field measurements that have been carried out in the vicinity of all the planets, the state of their interior and their evolution since their formation would not be understood even though questions remain about how the different planetary dynamos (in six of the eight planets) work. This paper describes the motivation for making magnetic field measurements, the instrumentation that has been used and many of the missions that carried out the pioneering observations. Emphasis is given to the historically important early missions even if the results from these have been in some cases bettered by later missions.Keywords Planetary magnetism · Planetary space missions · Space magnetometers Motivation for Measuring the Magnetic Field of Planets and SatellitesThe presence or absence of a planetary scale magnetic field places a strong constraint of the state of a planet's interior. The nature of the field (dipolar, multipolar, crustal, induced or, in general, the combination of all such terms in different proportions) provides further indication of the details of the thermal evolution and current state and has been used extensively in constraining models of planetary structure. If a planet's magnetic field is dominated by dipolar and low-order multipolar terms, the presumed existence of a magnetohydrodynamic dynamo in the planet's interior is an additional, important factor in its internal dynamics.For planets in the solar system, the interaction of the planetary obstacle with the allpervasive solar wind critically influences the magnetic environment of planets. The interaction depends strongly on the nature of the magnetism of the planetary body, as well as on

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“…A comprehensive description of the instrument has been given by Connor (1968). There was an effort to reduce magnetic fields of the spacecraft by deperming it, and this 'led to a residual field of apprnoximately 8y, estimated both from terrestrial measurements and two axis estimates of the spacecraft field obtained during a short period of rolling of the spacecraft about the spacecraft-sun line shortly after launch.…”

Section: Lunar Experimentsmentioning

confidence: 99%

Magnetometers for space research

Ness¹

1970

Space Sci Rev

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Space magnetics: The mariner V magnetometer experiment

Cited by 32 publications

References 6 publications

Solar Wind Interaction and Impact on the Venus Atmosphere

Solar Wind Interaction and Impact on the Venus Atmosphere

Planetary Magnetic Field Measurements: Missions and Instrumentation

Magnetometers for space research

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