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Earth, Planets and Space
Fig. 7 | Earth, Planets and Space

Fig. 7

From: In situ observations of ions and magnetic field around Phobos: the mass spectrum analyzer (MSA) for the Martian Moons eXploration (MMX) mission

Fig. 7

Required observation configuration for the MSA observation 1 to measure secondary ions sputtered by the solar wind (SW) from Phobos surface, where \(\varvec{V}\), \(\varvec{B}\), and \(\varvec{E}\) indicate the velocity, and magnetic and electric fields of the SW, respectively. In the Phobos/Mars-centric Solar Ecliptic coordinate system, the direction of \(\varvec{B}\) is arbitrary, while \(\varvec{V}\) points approximately in the x direction. The secondary ions move along \(\varvec{E} = - \varvec{V} \times \varvec{B}\), because their initial energies are nearly 0. The magnetometer measures \(B\), while \(\varvec{E}\) is derived from \(\varvec{E} = - \varvec{V} \times \varvec{B}\), where \(\varvec{V}\) denote the SW velocity measured by the ion analyzer. The spacecraft and Phobos are located in the same plane whose normal vector is \(\varvec{V}\)

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