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.

The following publications may be useful:

Akioka et al. 2005, AdvSpcRes: The L5 mission for space weather forecasting

Simunac et al. 2009, Sol Phys: In situ observations of solar wind stream interface evolution

Webb et al. 2010, Space Research Today: Using STEREO-B as an L5 space weather pathfinder mission

Gopalswamy et al. November 2010, EASCO white paper submitted to the Solar and Space Physics Decadal Survey

Vourlidas et al. 2010, Decadal Survery White Paper: Mission to the Sun-Earth L5 Lagrangian Point: an optimal platform for Heliophysics & space weather research

Gopalswamy et al. 2011, SPIE: Eath-Affecting Solar Causes Observatory (EASCO): a mission at the Sun-Earth L5

Gopalswamy et al. 2011, J Atm. Sol. Terr. Phys,: Earth-Affecting Solar Causes Observatory (EASCO): a potential international Liwing with a Star Mission from Sun-Earth L5

Turner and Li 2011, Spc. Weath.: Using spacecraft measurements ahead of Earth in the Parker spiral to improve terrestrial space weather forecasts

Gopalswamy et al. 2013, Spc Weath.: Testing the empirical shock arrival model using quadrature observations