The Need for Near-Earth Multi-Spacecraft Heliospheric Measurements and an Explorer Mission to Investigate Interplanetary Structures and Transients in the Near-Earth Heliosphere.

Based on decades of single-spacecraft measurements near 1 au as well as data from heliospheric and planetary missions, multi-spacecraft simultaneous measurements in the inner heliosphere on separations of 0.05-0.2 au are required to close existing gaps in our knowledge of solar wind structures, transients, and energetic particles, especially coronal mass ejections (CMEs), stream interaction regions (SIRs), high speed solar wind streams (HSS), and energetic storm particle (ESP) events.

Magnetosheath Jet Occurrence Rate in Relation to CMEs and SIRs.

Magnetosheath jets constitute a significant coupling effect between the solar wind (SW) and the magnetosphere of the Earth. In order to investigate the effects and forecasting of these jets, we present the first-ever statistical study of the jet production during large-scale SW structures like coronal mass ejections (CMEs), stream interaction regions (SIRs) and high speed streams (HSSs). Magnetosheath data from Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft between January 2008 and December 2020 serve as measurement source for jet detection.

Magnetic Structure and Propagation of Two Interacting CMEs From the Sun to Saturn.

One of the grand challenges in heliophysics is the characterization of coronal mass ejection (CME) magnetic structure and evolution from eruption at the Sun through heliospheric propagation. At present, the main difficulties are related to the lack of direct measurements of the coronal magnetic fields and the lack of 3D in-situ measurements of the CME body in interplanetary space. Nevertheless, the evolution of a CME magnetic structure can be followed using a combination of multi-point remote-sensing observations and multi-spacecraft in-situ measurements as well as modeling.

Ion-driven instabilities in the solar wind: Wind observations of 19 March 2005.

Intervals of enhanced magnetic fluctuations have been frequently observed in the solar wind. But it remains an open question as to whether these waves are generated at the Sun and then transported outward by the solar wind or generated locally in the interplanetary medium. Magnetic field and plasma measurements from the Wind spacecraft under slow solar wind conditions on 19 March 2005 demonstrate seven events of enhanced magnetic fluctuations at spacecraft-frame frequencies somewhat above the proton cyclotron frequency and propagation approximately parallel or antiparallel to the background magnetic field .