2002-004A
The High Energy Solar Spectroscopic Imager, in the SMEX series, studies particle acceleration in solar flares. Launch in 2002 by Pegasus XL after many delays.
HESSI rotates at 15rpm, imaging hard X-rays by reconstructing Fourier components from the time modulation of the flux through a set of 9 grids each 9cm in diameter. Angular resolution will be 2 arcsec at 40 keV and 36 arcsec at 1 MeV, and effective area is 100 sq cm. HESSI will also be used to image the Crab Nebula.
The first extrasolar observations were reported in April 2002. SGR 1900+14 was observed from 25 to 400 keV; an unusually bright 3-hour burst of Cygnus X-1 was detected on 2002 Feb 24. RHESSI will search for the electron/positron flash from novae; it has a much larger field of view than the Integral instruments.
Mass is 304 kg. Size is 1.1m dia 2.2m long. 5.7m span. 0.45m grid support cylinder, 9 x 9cm grids. Cylinder + box + 4 panels. Orbit 600 x 600 x 38.
Final stage is 0.97dia 1.34l and mass 202 kg.
The spacecraft was damaged when a vibration test in Mar 2000 was carried out at 20g instead of 2g
Bus is Spectrum Astro SA200S?, later Orbital Leostar-1. (or 3?)
Launch is from 28.0N 78.5W after takeoff from CCAFS Skid Strip. Drop 120km E of Palm Bay.
HESSI was renamed the (Reuven) Ramaty High-Energy Solar Spectroscopic Imager, or RHESSI, in Mar 2002. Ramaty, who died in 2001, was involved in the early stages of the project.
| RHESSI | |||
| Date | Time | Event | Orbit |
|---|---|---|---|
| 2002 Feb 5 | 1929 | T/O from Skid Strip RW30/12 | |
| 2058:12 | Drop | ||
| 2058:17 | T+0:05 St 1 burn | ||
| T+1:15 St 1 burnout | |||
| T+1:31 St 2 burn | |||
| T+2:06 Fairing sep | |||
| T+2:43 St 2 burnout | |||
| 2105:46 | T+7:34 St 3 burn 68s | ||
| 2107:00 | T+8:42 St 3 burnout | ||
| 2108:00 | T+9:42 St 3 sep | ||
Payload:
- Rotating modulation collimator transform telescope
- Ge crystal solid state spectrometer, 3 keV - 20 MeV, 1 keV res
