IPHIR InterPlanetary Helioseismology by Irradiance measurements Scientific Results T. Toutain

IPHIR Instrument Helioseismology instrument aboard the 2 probes of the USSR Phobos mission to Mars. Triple sunphotometer (335,500 and 862 nm) measuring solar irradiance in the continuum. 2-axis solar sensor. Institutes and persons involved : PMOD/WRC (Davos, Switzerland) - C. Fröhlich(P.I.), Ch. Wehrli, H.J. Roth LPSP (Verrières-le-buisson ) – Boudine, J.C. Vial Space Science Department of ESA - R.M. Bonnet, V. Domingo Crimean Astrophysical Observatory - A. Bruns, V.A. Kotov, D.N. Rachkovskii Central Research Institute for Physics (Hungary) – Z. Kollath

IPHIR aboard a Phobos Probe Courtesy of C. Fröhlich, and H. Roth, Davos

IPHIR’s team of experts Courtesy of C. Fröhlich, and H. Roth, Davos

IPHIR Model Courtesy of C. Fröhlich, and H. Roth, Davos

Phobos mission The last mission undertaken by the USSR was that of Phobos - a mission involving two probes (Phobos 1 and 2) aiming at Mars. Phobos 1, launched 7 July 1988, never made it to Mars, losing contact with Earth on September 2, The problem was later found to be in a software upload problem on August 29/30 that caused the craft's attitude thrusters to power down, resulting in the craft no longer pointing to the sun and the solar arrays not charging the batteries. Phobos 2, launched 12 July 1988, reached Mars, and it gathered data on the Sun, interplanetary medium, Mars, and Phobos. However, a maneuver before the final phase of the mission to place the craft within 50 m of Phobos' surface to release two craft - a mobile "hopper' and a stationary platform - resulted in loss of communication. The mission ended when there was unsuccessful signal acquisition on March 27, The cause was traced to an on-board computer error.

Power Spectrum for First-Week of Data

IPHIR Power Spectrum of the 5-minute oscillations

5min. oscillations

Solar oscillation Stochastic Behaviour

Time-Frequency Domain Excitation of solar oscillations

Solar Oscillation Correlation

Conclusions Uninterrupted long duration observations (160 days). Oscillation parameters determined accurately. Solar oscillations are excited by the solar convection Solar oscillations might be correlated(?) Guideline for next-generation (VIRGO/SOHO) and asteroseismology (COROT). Thanks Boudine for your advices!