Project HALO Status Report

Sky Launch 2, Attempt 1 -- Balloon Launch Mishap

Held on Saturday, June 20, 1998 on a NASA barge in the Gulf of Mexico.

The following text was taken, with permission, from an article by Gene Young, HALO SL-2 Electronics Lead, which was published in the July-August 1998 issue of the Southeastern Space Supporter, newsletter of HAL5.

The HALO SL-2 Avionics

Two electronic subsystems were built to support the HALO SL-2 launch and flight.  These are described as follows:

Uplink Avionics Module

The Uplink Avionics Module contained electronics to ignite the SL-2 motor and provide power to the nitrous oxide tank heaters.  It contained redundant command receivers, decoder and control boards and lithium batteries.  It was contained in an aluminum cylinder, 12 inches in diameter, 12 inches long and weighed 16 pound.  Although the motor ignition circuitry did not get the opportunity to do its job, commands were sent while the balloon was in flight to cut the gondola loose from the balloon and pull the tear-out panel from the balloon.  The commands were sent when the balloon was still in sight and estimated to be above 20,000 feet.

These commands provided no visible results as the balloon floated farther and farther away.  It was not known until after the balloon burst and was recovered from the Gulf that the uplink commands had fired the pyros in the rope cutters, resulting in the ropes being cut partially through.  Without the weight of the rocket on the ropes, the partially cut ropes were strong enough to support the remaining weight.  To the left is a picture of the Uplink Avionics Module before the flight.  The short time that the module was in the salt waters of the Gulf, and not being able to right-away wash the corrosive salt away rendered the module useless for later use.

Rocket Avionics Module

The Rocket Avionics Module was designed to provide down-linked TV, accelerometer and GPS data, and deployment of parachutes after flight trajectory apogee.  A color TV camera looked out the side of the 7 inch by 18 inch aluminum canister that contained the flight electronics.  A 1.255 GHz transmitter was employed to send the space TV images to the ground.

Accelerometer and GPS data were fed through a MIM chip, 1200 baud modem and a 432 MHz transmitter for transmission to the ground station.  A Video Overlay board also was used to impose the GPS and accelerometer data onto the transmitted video signal, providing redundancy to down-linked data.  Lithium batteries provided the power for all the electronics.  Inverted F antennas for the 432 MHz and 1.255 GHz antennas were located on the outside surface of the canister.  A picture of the Rocket Avionics Module removed from its storage canister is shown above.

It was a terrible disappointment that the rocket did not fly to demonstrate the capability of the module but it was somewhat comforting to observe that it was still sending out data after a fall from about 20 feet to the steel surface of the barge.  The module could easily be repaired, tested and made ready to fly by the next day.

Ad Astra per Ardua -- “To the Stars by Our Own Hands”

For more information on Project HALO, contact HALO Project Manager Yohon Lo at (256) 658-2043 or via E-Mail at:

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This file was last modified on Saturday, 15-Apr-2017 13:19:43 EDT