VISIONS-2: Quantifying ion outflow in the cusp

The Earth's upper atmosphere is a strong source of ions that ultimately end up in the magnetosphere, strongly affecting a range of processes, including reconnection, ring current development, energetic particle losses, and convection and transport. This flow of ions begins near the exobase, where ions are heated by electrodynamic energy and particle energy inputs, and where wave-particle interactions can begin to resonantly accelerate ions from thermal energies to escape velocities. The relative contributions of these processes remain unknown, and must be better characterized in order to model ion outflows, including their variation in response to changes in their drivers, and their effects on the magnetosphere. The recent VISIONS mission, launched from Poker Flat in February 2013, performed a new type of combined remote sensing / in situ measurements of the drivers of ion outflow associated with an auroral substorm, the characteristics of the ion outflow itself, and the mechanisms by which the ions are accelerated to reach energies greater than 10 eV, at which point they are no longer gravitationally bound. VISIONS focused on the altitude range between 300-1000 km, which is the "first step" in the chain of ion acceleration. VISIONS determined that the majority the low-altitude ion acceleration occurs in regions of intense soft precipitation, and provided important constraints on the overall fluxes and time variation of ion outflow late in the substorm expansion phase (30-45 minutes post-onset). We propose a follow-on mission, VISIONS-2, to further examine these important processes, and provide new insight into the mechanisms that drive ion outflow. VISIONS-2 will study ion outflow in Earths' magnetic cusp, a region that is known to produce the most intense ion fluxes in the entire high latitude region. VISIONS-2 will be the first mission to combine ENA imaging of cusp ion outflow with direct measurements of the drivers, including multispectral optical imaging of aurora, corresponding to regions of electron and proton precipitation, as well as direct in situ measurements of fields and particles that provide very strong constraints on the remote sensing inversion and modeling. VISIONS-2 will fly from Ny-Ålesund, Norway, in November 2018, through the magnetic cusp, to an apogee near 800 km. During the flight, it will remotely sense ion outflow and its drivers over a region approximately 1000 km in diameter, providing critical information about the patchiness and burstiness of cusp ion outflow, as well as detailed information about the mechanisms that drive this outflow, leading to a new understanding of the mechanisms that couple the magnetosphere and ionosphere, in support of future missions such as GDC, DYNAMIC, and MEDICI. More »