Flight Recap of EOSS-4

Launch date: January 4, 1992
Launch time: 15:58 UTC
Launch site: Eagle Crest High School
                   Aurora, Colorado  USA
Launch coordinates:  39.62383 deg NORTH
                              104.72070 deg WEST
Max Altitude: 92,000 ft.
Touchdown time: unknown (LOS 17:54 UTC)
Touchdown Distance: 51.02 Miles
Touchdown coordinates:  40.01551 deg NORTH
                                     103.90491 deg WEST

Payload Systems:

  • Humble Telescope
  • W6ORE Flight Controller
  • ATV - 426.250 MHz
  • Beacon - 147.555 MHz
  • 6 meter control of ATV pointing angle
  • Pressure Sensor used to determine altitude
  • Temperature sensors (internal and external)


  • Solar Telescope to measure the Mg II region of the UV light spectrum. "Humble Telescope". A telescope with sun sensors and a 35mm still camera to photograph sun spots. Still camera shutter enable and "picture taken" feed to the telemetry packet stream.
  • Two new separation devices.
    1. Hot wire cord cutter by Jack AA0P.
    2. Pyro cutter by Mike W5VSI


  • Scientific experiment built by students from CU, CSU and Green Mountain High School.
  • Colorado Repeater Association (CRA)

Sponsors included:

  • Alan Kiplinger of Solar Max '91
  • Sigma Chi Fraternity
  •  NASA and NOAA

Project Lead: Jack Crabtree, AA0P
Balloon Lead: Merle McCaslin, K0YUK
Launch Site Lead: Jack Crabtree, AA0P
Public Relations Lead: Marty Griffin, WA0GEH
Tracking and Recovery: Greg Burnett, K0ELM
Education Lead: Tom Isenberg, N0KSR

Flight Highlights

Net control were present and operated on 40 and 2 meters. See the 40 Meter Net Control Script for additional information about the flight.

An excellent recap was written up and distributed on the Packet BBS system by Marty Griffin.

This was the first zero pressure balloon with rip panel flight termination system EOSS flew. Two command cut down systems and an independent cut down timer were included in the payload. A new and larger parachute for the heavier payload was included.

From launch to recovery nine hours and 33 minutes passed. Recovery was made by:

  • Bob Ragain, WB4ETT
  • Dawn Ragain, N0QCW
  • Greg Burnett, K0ELM

Recovery was accomplished at night using a portable 10 meter RDF system.

WX at the launch was very windy and cold. The winds did cause problems during the launch.

During the launching process, the payload hit the ground, slid several feet and hit a snow bank hard enough to bend the telescope frame and cause damage to the still camera.

The ATV camera had limited control during the first half of the ascent, but we regained full control later. Video quality was good, but the 2 meter beacon interfered with the camera.

At 92,000 feet, the command was given to enable the still camera. The packet generated about 20 continuous messages indicating pictures were being taken; then beacon and ATV went off. It was not known until sometime later that the balloon had been released about the same time that the signals disappeared. Batteries were dead on arrival. Solar camera mechanical damage caused high current drain. The pyro release device worked well.


About Ann Trudeau's Archives