Encyclopedia Astronautica
HESSI


American solar satellite. One launch, 2002.02.05. HESSI, the sixth Small Explorer, was a Spectrum Astro satellite derived from the SA-200S design. It carried a rotating modulation collimator transform telescope.

The satellite rotated at 15 rpm, imaging hard X-ray flares from the Sun by reconstructing the Fourier components from the time modulation of the flux through a set of 9 grids each 9 cm in diameter. It was expected to make images with a resolution of 2 arcseconds at 40 keV energies and 36 arcseconds at 1 MeV energies. Launch delays meant HESSI missed some of the best flares at solar max.

Gross mass: 304 kg (670 lb).
First Launch: 2002.02.05.
Number: 1 .

More... - Chronology...


Associated Countries
See also
  • Pegasus Privately-funded, air-launched winged light satellite launcher. More...

Associated Launch Vehicles
  • Pegasus American air-launched orbital launch vehicle. Privately-funded, air-launched winged light satellite launcher. More...
  • Pegasus XL American air-launched orbital launch vehicle. Uprated version of Pegasus air-launched winged light satellite launcher. 4 stage vehicle consisting of 1 x L-1011 + 1 x Pegasus XL stage 1 + 1 x Orion 50XL + 1 x Orion 38. More...

Associated Manufacturers and Agencies
  • NASA American agency overseeing development of rockets and spacecraft. National Aeronautics and Space Administration, USA, USA. More...

Bibliography
  • McDowell, Jonathan, Jonathan's Space Home Page (launch records), Harvard University, 1997-present. Web Address when accessed: here.
  • McDowell, Jonathan, Jonathan's Space Report (Internet Newsletter), Harvard University, Weekly, 1989 to Present. Web Address when accessed: here.
  • NASA/GSFC Orbital Information Group Website, Web Address when accessed: here.
  • Space-Launcher.com, Orbital Report News Agency. Web Address when accessed: here.
  • NASA Report, HESSI Mission Press Kit, Web Address when accessed: here.
  • NASA Report, HESSI Fact Sheet, Web Address when accessed: here.

Associated Launch Sites
  • Mayport DZ Air-launched rocket drop zone known to have been used for 5 launches from 1993 to 2003, reaching up to 794 kilometers altitude. More...

HESSI Chronology


2002 February 5 - . 20:58 GMT - . Launch Site: Mayport DZ. Launch Pad: 29.0 N x 78.5 W. Launch Platform: L-1011. LV Family: Pegasus. Launch Vehicle: Pegasus XL. LV Configuration: Pegasus XL F31.
  • HESSI - . Payload: SA-200S. Mass: 449 kg (989 lb). Nation: USA. Agency: NASA. Manufacturer: Gilbert. Class: Astronomy. Type: Solar astronomy satellite. Spacecraft: HESSI. USAF Sat Cat: 27370 . COSPAR: 2002-004A. Apogee: 599 km (372 mi). Perigee: 574 km (356 mi). Inclination: 38.0000 deg. Period: 96.40 min. HESSI, the sixth Small Explorer, carried a rotating modulation collimator transform telescope, imaging solar flares in the hard X-ray spectrum. The launch marked the return to flight of Pegasus after the Hyper-X failure. The launch was originally to have occurred on 28 March 2001. The L-1011 launch aircraft took off at 19:29 GMT from the Cape Canaveral Skid Strip RW30/12, and headed out to the drop area at 28.0 N 78.5 W over the Atlantic. Drop of the Pegasus in the Atlantic Drop Zone at 28.0 N 78.5 W was at 20:58 GMT, with ignition 5 seconds later. The Pegasus reached orbit at 21:07 GMT. On the first pass it was confirmed that the solar panels had opened.

    The satellite rotated at 15 rpm, imaging by reconstructing the Fourier components from the time modulation of the solar x-ray flux through a set of 9 grids each 9 cm in diameter. It was expected to make images with a resolution of 2 arcseconds at 40 keV energies and 36 arcseconds at 1 MeV energies. The launch delays meant that HESSI missed some of the best flares at solar max.


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