RHESSI (Ramaty High-Energy Solar Spectroscopic Imager)

header rhessi RHESSI (Ramaty High Energy Solar Spectroscopic Imager)

Primary Mission Objective:

Explore the basic physics of particle acceleration and energy release in solar flares

Science Objectives

Solar:

Determine the frequency, location, and evolution of impulsive energy release in the corona
Study the acceleration of electrons, protons, and heavier ions in flares
Study the heating of plasma to tens of millions of degrees and determine its relationship to particle acceleration
Study the propagation and evolution of energetic particles in flares
Determine the relative abundances of accelerated and ambient ions in flares

Non-Solar:

Obtain images and spectra of the Crab Nebula with 2 arcsecond spatial resolution and ~1 keV spectral resolution
Detect and obtain high resolution spectra of gamma-ray bursts and cosmic and terrestrial transient sources over a large fraction of the sky
Search for cyclotron line features in gamma-ray bursts and cosmic transient sources
Obtain high resolution spectra and search for line features in steady X-ray and gamma-ray sources

Primary Observations:

Simultaneous, high resolution imaging and spectroscopy of solar flares from 3 keV X-rays to 17 MeV gamma rays with high time resolution

Expected Numbers of Flares:

Tens of thousands of microflares
Over a thousand X-ray flares with crude imaging and spectra to >100 keV
Hundreds of flares with >1000 counts per second above 20 keV, allowing spatial changes to be followed on timescales of 0.1 seconds.
Tens of flares sufficiently intense to allow the finest possible imaging spectroscopy
Up to 100 flares with the detection of gamma-ray lines
Tens of flares with detailed gamma-ray line spectroscopy and the location and extent of the source determined to ~40 arcseconds

Mission Class

Small Explorer (SMEX)

Launch

Date: February 5, 2002
Time: 3:58 PM EDT
Vehicle: Orbital Sciences Corporation (OSC) Pegasus XL
Site: L1011 aircraft takes off from Kennedy Space Center