HERO was an X-Ray telescope and the first one aimed to obtain focused images of astronomical X-ray sources at hard X-ray energies (20-75 keV).
The key component (the hard X-ray optics) are full-shell electroformed-nickel-replicated (ENR) mirrors coated with iridium to enhance high-energy reflectivity. As the critical grazing angle for reflection varies approximately inversely with energy, these mirrors employ smaller angles than their low-energy counterparts and consequently have smaller diameters and collecting areas per shell. The mirrors have a 6 meter focal length.
To exploit the full potential of the HERO optics necessitates a balloon gondola that can provide commensurate pointing accuracy, stability, and pointing knowledge. The HERO gondola utilizes a coarse aspect system for slewing based on a differential global positioning system (GPS) and a fine inertial-mode pointing system that uses a novel day/night aspect camera system to update onboard gyroscopes. The total payload dimensions are 25 feet long, 6.5 ft wide and 16 ft high.
Balloon launched on: 5/23/2001 at 16:22 utc
Launch site: Scientific Flight Balloon Facility, Fort Sumner, (NM), US
Balloon launched by: National Scientific Balloon Facility (NSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon Raven - 39.570.000 cu ft - 0.8 Mil. - SF3-39.57-.8/.8/.8-NA
Balloon serial number: W39.57-2-23
Flight identification number: 497N
End of flight (L for landing time, W for last contact, otherwise termination time): 5/24/2001 at 12:49 utc
Balloon flight duration (d:days / h:hours / m:minutes): 24 h
Landing site: 25 miles of South King, Arizona, US
The balloon was launched by dynamic method assisted by launch vehicle on May 23, 2001.
The balloon flight spent 17 hr at a float altitude of 39 km during the day and 37 km at night.
During this flight -a test one-, the hard X-ray telescopes were pointed at the Crab Nebula, Cyg X-1, and GRS 1915+105, where they captured the First high-energy focused images of cosmic sources. This test flight confirmed the stability of the optical bench and the ability of the attitude control system to hold X-ray targets with suficient stability for extended periods of time.