The Solar Probe Plus Mission: Humanity’s First Visit to Our Star

Abstract

Solar Probe Plus (SPP) will be the first spacecraft to fly into the low solar corona. SPP's main science goal is to determine the structure and dynamics of the Sun's coronal magnetic field, understand how the solar corona and wind are heated and accelerated, and determine what processes accelerate energetic particles. Understanding these fundamental phenomena has been a top-priority science goal for over five decades, dating back to the 1958 Simpson Committee Report. The scale and concept of such a mission has been revised at intervals since that time, yet the core has always been a close encounter with the Sun. The mission design and the technology and engineering developments enable SPP to meet its science objectives to: (1) Trace the flow of energy that heats and accelerates the solar corona and solar wind; (2) Determine the structure and dynamics of the plasma and magnetic fields at the sources of the solar wind; and (3) Explore mechanisms that accelerate and transport energetic particles. The SPP mission was confirmed in March 2014 and is under development as a part of NASA's Living with a Star (LWS) Program. SPP is scheduled for launch in mid-2018, and will perform 24 orbits over a 7-year nominal mission duration. Seven Venus gravity assists gradually reduce SPP's perihelion from 35 solar radii (R S ) for the first orbit to <10 R S for the final three orbits. In this paper we present the science, B N.J. Fox

The density compression ratio of shock fronts associated with coronal mass ejections

“…The method holds promise for improving the extraction of quantitative information from shocks in the corona using remote sensing observations. It can readily use observations from different vantage points, including from the imagers (Howard et al, 2013;Vourlidas et al, 2016) aboard the upcoming Solar Orbiter (Müeller et al, 2013) and Solar Probe Plus (Fox et al, 2016) missions to be compared with direct in situ measurements from these missions. The technique will also greatly improve the results from any future joint coronagraphic imaging and off-limb spectroscopy of shocks (Bemporad and Mancuso, 2011;Vourlidas and Bemporad, 2012).…”

Recent progress in astrophysical plasma turbulence from solar wind observations

“…Alfvénic turbulence is thought to be captured by the incompressible magnetohydrodynamics (MHD) equations, which in fluctuating Elsasser (1950) form (omitting forcing and dissipation terms) are ∂δz ± ∂t ∓ v A ∇ δz ± + δz ∓ · ∇δz ± = −∇P, (2.1)…”

“…The following year (2018) is due to see the launch of Solar Probe Plus (Fox et al 2015) and Solar Orbiter (Müller et al 2013), which will both travel closer to the Sun than any previous spacecraft, and for which turbulence, along with the associated heating, is one of the main science goals. In particular, Solar Probe Plus will travel to within 9 Solar radii of the solar surface, and will have a comprehensive payload measuring the electromagnetic fields and particles to explore turbulence and heating within the corona for the first time.…”

Review article: Wave analysis methods for space plasma experiment

“…While many of the current spacecraft missions perform multi-point measurements -four-point tetrahedral formation flights on scales of 10 000 down to 100 km by the Cluster mission (Escoubet et al, 2001) and on a 10 km scale by the MMS mission (Burch et al, 2016), 1-D fivepoint measurements by the THEMIS mission (Angelopoulos, 2008), three-point measurements by the Swarm mission Olsen et al, 2013;Thebault et al, 2013), and two-point measurements by the Van Allen Probes (Mauk et al, 2013;Stratton et al, 2013) -the upcoming spacecraft missions are more specialized to unique observational approaches toward the understanding of turbulence processes (particularly in interplanetary space) at the cost of returning back to single spacecraft measurements. Examples are simultaneous remote sensing and in situ measurements by Solar Orbiter (Müller et al, 2013), the closest observations to the Sun by Solar Probe Plus (Fox et al, 2016), and highprecision sampling of particle velocity distribution functions, electric fields, and magnetic fields by THOR (Vaivads et al, 2016). Analysis of spatial structure or intermittency is not covered here, and will be presented in separate papers.…”