RHESSI has completed its regular anneal procedure to recover lost energy resolution and sensitivity due to radiation damage.  The detectors were turned off on 2014 June 26 and were brought back to nominal operation on 2014 August 13.  Five of the nine detectors (1, 3, 6, 8, and 9) have electronically separate front and rear segments, and the other four detectors are currently operating unsegmented and have thresholds of ~20 keV.  Thus, hard X-ray (>~20 keV) observations have the nominal angular resolution (~2 arcsec) and spectral resolution (~1 keV), but soft X-ray (~3-20 keV) observations have a reduction in image quality.




The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) is a NASA Small Explorer Mission, launched on February 5, 2002.

RHESSI's primary mission is to explore the basic physics of particle acceleration and explosive energy release in solar flares.  This is achieved through imaging spectroscopy in X-rays and gamma-rays with fine angular and energy resolution to reveal the locations and spectra of the accelerated electrons and ions and of the hottest plasma.

Solar flares and their associated coronal mass ejections are of great scientific interest since they are so little understood. They present severe challenges to explain how the energy equivalent of billions of megatons of TNT is released in the solar atmosphere on time scales of minutes, and how so many electrons, protons and heavier ions are accelerated to such high energies. These super-energetic solar eruptive events are the most extreme drivers of space weather and present significant dangers in space and on Earth.



What is a solar flare?
How does RHESSI work?
What are the scientific objectives?
How does RHESSI make images?
RHESSI Spectroscopy