HEIDI (High Energy Imaging Device)

HEIDI was the acronym for High Energy Imaging Device a scientific instrument developed to study solar flares and cosmic X-ray sources, such as the Crab Nebula, through hard X-ray and gamma-ray imaging. It was developed by the NASA Goddard Space Flight Center (GSFC) with collaboration from Auburn University, the California Institute of Technology (Caltech) and the Naval Research Laboratory (NRL) among other institutions.

Balloon launched on: 6/22/1993 at 10:25 utc
Launch site: Columbia Scientific Balloon Facility, Palestine, Texas, US  
Balloon launched by: National Scientific Balloon Facility (NSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon SF3-424.37-080-NSCHR-X-ST
Balloon serial number: W29.47-2X-06
Flight identification number: 1528P
End of flight (L for landing time, W for last contact, otherwise termination time): 6/22/1993 at 19:01 utc
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): F 6 h 17 m
Landing site: 50 miles SW of Ozona, Texas, US

The balloon was launched from the National Scientific Balloon Facility in Palestine, Texas at 7:25 EDT on June 22, 1993. After an ascent phase of two and a half hours it reached a float altitude of 26 miles (42 kilometers). During the ascent, HElDI received a flare alert, and the payload was commanded successfully into the solar pointing mode for observation. When the flare failed to develop into a significant event, the payload was commanded to resume observations of the Crab Nebula. Because of erratic behavior in the pointing control system, however, observation of the Crab was discontinued, and the payload resumed viewing the sun.

The flight of HEIDI ended at 16:00 EDT on June 22 when the balloon was about 375 miles (600 kilometers) west of the launch site. It landed in an uninhabited area, suffering only minor damage.

Cold temperatures encountered during ascent affected the electronics in the pressure canister, and mechanical issues with the pointing control system hindered the acquisition of targeted data. Despite the payload featured a thermal control system designed to maintain the telescope structure and grids within a strict temperature range to ensure proper alignment, parts of the system experienced temperatures below their design thresholds, which contributed to performance limitations.

• Payload Description and Results from the First Flight of the High Energy Imaging Device (HEIDI) 32nd Aerospace Sciences Meeting & Exhibit January, 1994 - Reno, NV USA
• A balloon-borne payload for imaging hard X-rays and gamma rays from solar flares Proceedings of the AIAA International Balloon Technology Conference, 1991
• Balloon Payload to Yield Big Results with Small Budget Goddard News Vol. 36 Nº 9, September 1990, pag. 4
• HEIDI soars aloft to make images in "hard" x-rays Goddard News Vol. 40 Nº 9, September 1993, p. 2
• NASA Balloon Flights (1989-1998) in NASA Historical Data Book, Vol. VII: NASA Launch Systems, Space Transportation, Human Spaceflight, and Space Science, 1989-1998
• Quantitative characterization of the x-ray imaging capability of rotating modulation collimators with laser light Applied Optics 1996 Dec 1;35(34):6714-26