The Sun Radio Interferometer Space Experiment (SunRISE) - Project Overview

The Sun Radio Interferometer Space Experiment (SunRISE) will reveal aspects of how Solar Energetic Particles (SEPs) are accelerated at Coronal Mass Ejections (CMEs) and how SEPs are released into interplanetary space. SunRISE is a constellation of small spacecraft operating as a radio interferometer to produce a synthetic aperture. As the first low radio frequency interferometer in space, SunRISE will provide spatially and temporally resolved observations of decametric-hectometric (DH, 0.1-23 MHz) radio bursts that cannot be observed on Earth due to ionospheric absorption. DH radio bursts are produced by electrons energized near expanding CMEs (Type II) and released by solar flares into space (Type III). A distinguishing aspect of the SunRISE mission is that the science instrument is the constellation of six small spacecraft, and the overall science is accomplished by six identical spacecraft, with well-determined positions, and significant ground processing. Each spacecraft carries an identical payload, which receives simultaneously the solar DH emissions and global navigation satellite systems (GNSS) signals. The spacecraft are independent of each other with no communications between them. The spacecraft are loosely controlled to keep them within approximately 10 km of each other at all times, staying at least 1 km apart for collision avoidance. Orbit knowledge is realized by ground-based GNSS precise orbit determination. SunRISE uses the multiple spacecraft per aperture (MSPA) capability of NASAs Deep Space Network (DSN) in order to send these recorded data to the ground. The spacecraft carry sufficient data storage that only weekly contacts are required. The SunRISE constellation is in a supersynchronous geosynchronous Earth orbit (GEO). The six SunRISE spacecraft achieve the desired orbit via a hosted rideshare, in which they are transported to the desired orbital location by a host satellite that deploys them from spring-loaded canisters at specific intervals. The SunRISE mission began Phase B (Formulation) in 2020 June, with a planned review to assess readiness to proceed to Phase C (Development) in 2021 August. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.