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HEXE (Balloon)

(1979 - 1983)

The High Energy X-Ray Experiment (HEXE) was built and operated in close collaboration with the Institut für Astronomie und Astrophysik der Universität Tübingen (Verweis IAAT, formerly AIT). It was used during three successful balloon campaigns (May 1980 and September 1981 launched from Texas (USA), as well as November 1982 lauched from Uberaba (Brazil)) to observe X-ray sources. HEXE was the successor of a detector also built and operated by MPE and AIT, with which the famous cyclotron line in Her X-1 has been discovered.


HEXE 1980 in Texas during tests.

Close to the center of this picture, the four detector units within the white square are visible. the two upper and the right lower unit are the Phoswhich detectors, the lower left is the Germanium detector.
Below the detectors are the electronics boxes of the detector units, the data transmission units and the electronics that aims the ballon gondola and the detectors towards celestial objects. All the electronics boxes are shielded against the extrene low temperatures in floating altitude (40 km). The detectors will also be covered by thermal isolation.
The picture was taken during a calibration setup a few days before launch when the magnetometers were calibrated within the Earth magbetic field. The magnetometers are used during flight to detrmine the attitude of the balloon gondola.
The detector units were aimed towards the observer when the picture was taken. By rotating the detector block around a horizontal axis and a vertical axis, all parts of the sky above horizon can be aimed at with the instruments.

Balloon campaign in Texas (USA) May 1980:

Transport to the launch pad

Before launch

Balloon, parachute, and gondola shortly after launch. The ballon is filled only in part because at float altitude the gas (Helium) expands and fills the whole volume.
Photo credit: H. Steinle, MPE

Statistics of the three launches

    1980   1981   1982
Place   Palestine, Texas (USA)     Palestine, Texas (USA)     Uberaba (Brasilia)  
Launch Team   NCAR   NCAR   INPE/NSFB
Seize of Balloon   0.97 Mio. m3   1.33 Mio. m3   0.97 Mio. m3
Payload Weight   1360 kg   1500 kg   1500 kg
Launch   May 9, 16:07 UT   September 28, 12:30 UT   November 25, 12:30 UT
Float Altitude   39 km   40 km   39 km
Flight Duration at Float   46 hrs   22 hrs   1 hr (hole in balloon)

A space-proof version of a section of the HEXE was operated since 1987 on board the Russian space station Mir
(Verweis Mir-HEXE) until the de-orbiting of Mir on March 23, 2001.

Related Links

link MPE balloon movie (contents description in German language only)

link Mir-HEXE

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