The sun radio space imaging experiment (SunRISE)

Radio emission from coronal mass ejections (CMEs) is a direct tracer of particle acceleration in the inner heliosphere and potential magnetic connections from the lower solar corona to the heliosphere. Energized electrons excite Lang-muir waves, which convert into radio emission at the local plasma frequency, with the most intense acceleration thought to occur within 20 RS. The capability of ground-based radio arrays to track this radio emission is limited by ionospheric absorption (ν ≳ 15 MHz) to altitudes less than about 3 RS. The state of the art for tracking such emission from space is defined by single antennas (Wind/WAVES, Stereo/SWAVES), in which the tracking is accomplished by assuming a frequency-to-density mapping; there has been some success in triangulating the emission between the spacecraft, but considerable uncertainties remain. The Sun Radio Imaging Space Experiment (SunRISE) mission concept would be a constellation of small spacecraft operating as an interferometer designed to localize and track radio emissions in the inner heliosphere. Each spacecraft would carry a receiving system for observations below 25 MHz, and SunRISE would image CMEs more than a few solar radii from the Sun.