Solar Probe: Why we need to send a spacecraft to the Sun and how we will do it

Colloquium: Astronomy Colloquia | March 14 | 4-5 p.m. | 1 LeConte Hall

Speaker/Performer: Justin Kasper, Harvard

Sponsor: Department of Astronomy

For centuries observers have marveled at the fine structure of the solar corona revealed during eclipses, but only in the last hundred years have we appreciated just how difficult the corona is to explain. The corona is millions of degrees hotter than the visible surface of the Sun, requiring sustained and extended heating. The corona is also unstable, leading to a highly variable supersonic solar wind that expands into interplanetary space. Arguably the most significant challenge in heliophysics is to identify the processes responsible for the observed heating and acceleration. We can distinguish between different theories using direct observations of solar wind plasma collected by spacecraft, and a recent result on heating using an experiment on the Wind spacecraft near Earth will be presented as an example. It has long been recognized that the only way to really understand the dynamics of the corona is to send an instrumented probe close to the Sun. The NASA Solar Probe Plus mission will revolutionize our understanding these questions by plunging into the corona and obtaining the first direct measurements of the plasma of the extended solar atmosphere. The probe uses a sequence of Venus gravitational assists to dive within 8.5 solar radii of the surface of the Sun, making it the first spacecraft to enter the sub-Alfvénic solar corona. The mission will be reviewed, with a focus on the design of plasma instruments capable of both making the necessary measurements and of surviving the solar encounters.

Event Contact: rhelgens@astro.berkeley.edu, 510-642-5275