L5 Consortium Meeting 2014
The first L5 consortium meeting was held in Sac Peak, New Mexico in April 2010 to discuss L5 missions, especially the Earth-Affecting Solar Causes Observatory (EASCO) mission concept. The EASCO mission was studied at NASA/GSFC as a 10-instrument mission as an enhanced combination of SOHO and STEREO instruments. Since then there have been several developments in instrument and mission concepts in the US and elsewhere. We also have Solar Orbiter and Solar Probe Plus underway, so we need to think beyond these missions to address open questions in heliophysics using future missions from L5 and L4.
The SOHO and STEREO spacecraft were close to quadrature from the beginning of 2010 to the beginning of 2012, and demonstrated the importance of observations from off the Sun-Earth line. In particular, STEREO-behind and STEREO ahead were in the vicinity of Sun-Earth L5 and L4 respectively. Locating a mission at Sun-Earth L5 has several key benefits for solar physics and space weather, including: (1) off the Sun-Earth line view is critical in observing Earth-arriving parts of CMEs without the Thomson surface problem, (2) L5 coronagraphic observations can provide near-Sun true speed of CMEs, which is an important input to models that forecast Earth-arrival time of CMEs, (3) backside and frontside CMEs can be readily distinguished even without inner coronal imagers, (4) preceding CMEs in the path of Earth-affecting CMEs can be identified for a better estimate of the travel time, (5) CIRs reach the L5 point a few days before they arrive at Earth, and hence provide significant lead time before CIR arrival, (6) L5 observations can provide advance knowledge of CME and CIR source regions (coronal holes) rotating to Earth view, and (7) magnetograms obtained from L5 can improve the surface magnetic field distribution used as input to MHD models that predict the background solar wind.
The second L5 consortium meeting will take place in the Laboratory for Atmospheric and Space Physics (LASP), University of Colorado, Boulder during December 2-4, 2014 to discuss the current efforts and pathways towards an L5 mission or missions.