The Future of Helioseismology

NSF Senior Review Has recommended that GONG be closed one year after successful SDO/HMI commissioning unless outside funding can be found. According to current schedule, the closure would start in late 2009/early 2010 and would take 1 to 2 years. Response: –Expression of concern to NSF from community (Vote now!) –Search for outside funding (starting) –Planning the future of helioseismology (this talk)

A Tale of two committees In 2002, GONG management proposed that GONG be closed one year after the launch of SDO. The NSO/AURA Solar Observatories Council rejected the proposal, and instead recommended that GONG become a “permanent” NSO flagship facility with its own scientific staff. This was accepted by the NSO director. Now the NSF SR has re-recommended the original recommendation.

Arguments (but who cares?) Helioseismology must have at least two facilities to confirm discoveries and detect systematic errors. The upcoming Cycle 24, with widely varying predictions for its behavior now that we are beginning to have physics-based models, needs to be completely studied by helioseismology for understanding the generation of magnetic fields. Hard to fix SDO when it breaks. Helioseismology requires long consistent observations; SDO/HMI will put a break into the space observations and also change spectral lines. GONG++ can operate as a synoptic facility “forever” GONG++ has just brought online continuous magnetic field measurements of unparalleled precision and cadence.

The future EVEN WITHOUT THE SENIOR REVIEW, GONG instruments are aging and will eventually need to be replaced. SDO will not last forever. Is Solar Orbiter a comprehensive helioseismology program? What does the community want to do next? How will it be funded? It can take a long time to get the next big thing going (typically years in the US, Solar Orbiter is 30 years from concept to launch) Suggest we start to seriously plan for the post-GONG and post-SDO era now. We are willing to host a planning meeting in Tucson

Hard choices Do we need to have two large helioseismology observing systems? Is global helioseismology still relevant? Is a synoptic local helioseismology capability necessary?

Possible next steps Add a second (or more?) spectral line to GONG to improve studies of magnetic effects, atmospheric seismology, energy balance, etc. Replace current GONG with a network of 3 large- aperture, A/O-enabled ground-based instruments to access high spatial frequencies. Asteroseismology may also benefit… Do not process GONG data, but collect and archive it and analyze as needed. This reduces costs. Transition away from pure science to mixture of space weather operations and science. This would place a new set of constraints on operation of the helioseismology facilities. Plan the next space mission. Or is it too early? Other ideas??

Planning meeting? In Tucson? In spring 2007? Need broad community participation, especially from younger researchers – it’s their future.

Science Goals Probing the zonal and meridional flows in the tachocline & convection zone to understand the operation of the dynamo. What is missing from solar/stellar structure models? Why is there a large sound speed discrepancy at the tachocline? G modes? Measuring the deep internal magnetic field, esp toroidal field in tachocline -- Detecting magnetic flux tubes below the surface How deep do active regions extend? What’s up at the poles? How fast does the core rotate? Are there internal thermal variations? What can helioseismology say about abundances?