Initial Results From the Active Spacecraft Potential Control Onboard Magnetospheric Multiscale Mission

NASA’s magnetospheric multiscale (MMS) mission was successfully launched in March 2015. The scientific objectives of MMS are to explore and understand fundamental plasma physics processes in the earth’s magnetosphere: magnetic reconnection, particle acceleration, and turbulence. The region of scientific interest of MMS is in a tenuous plasma environment where the positive spacecraft potential may reach an equilibrium as high as several tens of volts. The active spacecraft potential control (ASPOC) instrument neutralizes the spacecraft potential by releasing the positive charge produced by indium ion emitters. While the method has successfully been applied to other spacecraft such as Cluster and Double Star, new developments in the design of the emitters and the electronics are enabling lower spacecraft potentials and higher reliability compared to previous missions. In this paper, we report the initial results from the tests of the ASPOC performance during the commissioning phase and discuss the different effects on the particle and field instruments observed at different plasma environments in the magnetosphere.

[1]  C. Russell,et al.  Study of the spacecraft potential under active control and plasma density estimates during the MMS commissioning phase , 2016 .

[2]  U. Gliese,et al.  Fast Plasma Investigation for Magnetospheric Multiscale , 2016 .

[3]  Per-Arne Lindqvist,et al.  The Axial Double Probe and Fields Signal Processing for the MMS Mission , 2016 .

[4]  Thomas E. Moore,et al.  Magnetospheric Multiscale Overview and Science Objectives , 2016 .

[5]  Wolfgang Baumjohann,et al.  The Magnetospheric Multiscale Magnetometers , 2016 .

[6]  S. Persyn,et al.  Hot Plasma Composition Analyzer for the Magnetospheric Multiscale Mission , 2016 .

[7]  S. Petrinec,et al.  Magnetospheric Multiscale Science Mission Profile and Operations , 2016 .

[8]  Wolfgang Baumjohann,et al.  The Electron Drift Instrument for MMS , 2016 .

[9]  Rumi Nakamura,et al.  Active Spacecraft Potential Control Investigation , 2016 .

[10]  P. Lindqvist,et al.  The Spin-Plane Double Probe Electric Field Instrument for MMS , 2016 .

[11]  Wolfgang Baumjohann,et al.  Deriving plasma densities in tenuous plasma regions, with the spacecraft potential under active control , 2015 .

[12]  R. Nakamura,et al.  Interdependencies Between the Actively Controlled Cluster Spacecraft Potential, Ambient Plasma, and Electric Field Measurements , 2015, IEEE Transactions on Plasma Science.

[13]  P. Lindqvist,et al.  In-flight calibration of double-probe electric field measurements on Cluster , 2014 .

[14]  M. Tajmar,et al.  Overview of Indium LMIS for the NASA-MMS Mission and its Suitability for an In-FEEP Thruster on LISA , 2011 .

[15]  I. Dandouras,et al.  Electron density estimations derived from spacecraft potential measurements on Cluster in tenuous plasma regions , 2008 .

[16]  J. Quinn,et al.  Low‐energy (order 10 eV) ion flow in the magnetotail lobes inferred from spacecraft wake observations , 2006 .