SOHO Status Report - May 2007
A nominal station keeping and momentum management manoeuvre was performed on 27 February, followed by a 180° roll on 5 March. 0.0863 kg of fuel was used. The remaining hydrazine is 117 kg. The solar array degradation after 136 months of flight is 19.11%, which corresponds to 1.69% per year. Following the delivery of the final patch for automated operations by Saab Space on 11 April, the patch was successfully up-linked on 17 April. A test readiness review for the acceptance testing of the automated ground system will be held on 3 May.
Following component testing and testing with the SOHO S/C simulator, the primary operations testing will be done with the FOT closely monitoring the automated system and a second operation string in hot backup. The aim is to move to unmanned night passes after the summer.
Operations and Archiving
All SOHO instruments are nominal and science operations are progressing smoothly.
In April SOHO has run a very successful and intense campaign with Hinode. Over 30 different observing programs have been carried out addressing a large variety of solar phenomena, including explosive events, loop oscillations, MHD wave propagation, coronal hole structure, prominences, active regions structure and dynamics, and coronal heating. The SOHO/Hinode campaign will be followed by a two-week long high-cadence SOHO/STEREO campaign.
Links to the SOHO archives (including mirrors) are accessible at http://soho.esac.esa.int/data/.
Science Highlights
SOHO recently became the first solar physics mission to observe a complete mean solar cycle (11.1 years).
Using the far-UV spectrum of a solar flare observed with SUMER, scientists have for the first time made a direct measurement of the absolute Neon abundance in the solar atmosphere, without the need of a reference element. Their result has important consequences for models of the solar interior based on helioseismology measurements, as well as on the FIP bias determination of the solar upper atmosphere, solar wind, and solar energetic particles.
Solar energetic particle (SEP) events from the Sun are a major element of space weather. They can damage space missions and pose a serious hazard to humans in space. A new study based on COSTEP data demonstrates the possibility of short-term forecasting of the appearance and the intensity of SEP events by means of relativistic electrons, which arrive about an hour ahead of the more dangerous ions. The new method is already in trial operational use by NASA Johnson Space Center's Space Radiation Analysis Group for protecting astronauts onboard the International Space Station.
A new art exhibit on the Sun called "SunWorks" had its premiere opening in conjunction with the official kick-off of the International Heliophysical Year (IHY) at the UN in Vienna, Austria on 19 February. The 24 pieces in SunWorks were selected from the over 500 submissions to SOHO's SunWorks art contest that ran for 10 months in 2005/2006.
At the time of writing of this report, 2706 papers based on SOHO observations have been published in the refereed literature since launch. In 2007, 102 papers have appeared in the refereed literature so far.