Gravity modes are the best probes to study the solar radiative zone, in particular the nuclear core and to follow its potential variability with time and latitude. Nevertheless, their amplitude is small and the solar noise particularly high in the range of frequency where they stand (below 500 μ Hz). It is why they are looked for more than 20 years and actively serached with GOLF and MDI instruments aboard SoHO which offers the best conditions of observation. Some candidates (Turck-Chièze et al. 2004) have been identified in the GOLF instrument, during the period of low solar activity thanks to an original research of multiplets corresponding to surface amplitudes of about 2mm/s. The examination of the interesting frequency range (100 to 400 μ Hz) will be pursued up to the end of the SoHO mission scheduled for 2007. Today our knowledge of the radiative zone is due to acoustic modes. Recent clear progress is due to the detection of modes less influenced by the sun activity, in the range 400-1600 μ Hz. The sound speed is determined down to 0.06 Ro with a resolution of 3%. This profile is used to improve the solar model and its deviations from a static vision. The rotation profile is now clearly established down to the limit of the core and its rigidity can only be explained by invoking a magnetic field effect. We present here GOLF-NG (Turck-Chièze et al., 2000) built by a French Spanish collaboration to improve g-mode detection. Based on the Doppler velocity method using a resonant spectrometer with a 16 channels on the sodium line, the main objective of GOLF-NG is to contribute to get an MHD picture of the Sun to better understand the influence of the Sun on earth climate, in improving the detection by a factor 10 in decreasing the solar noise thanks to a variable magnet. Consequently, the physical information will be extracted at different heights in the atmosphere. A prototype will be installed in 2005 in Tenerife. Then a spatial version will be available for taking place in one project of the ILWS mission. Turck-Chièze, S., Robillot, J.M., Dzitko, H ., Boumier, P., Decaudin, M., Gabriel, A.H., Garcia, R.A., Grec, G., Pallé, P.L., Renaud, C., Schmidt, D., 2000, ESA SP-464, 331; Turck-Chieze, S., Garcia, R.A., Couvidat, S., et al., 2004, ApJ, vol 604,