DEACON ROCKOON (Rocket-Balloon) - SUI-21

The so-called ROCKOON (Rocket-Balloon) technique enabled small rockets to reach higher altitudes by launching them from a stratospheric balloon. The balloon would ascend to approximately 70,000 feet, where the rocket was fired using an onboard timer, a pressure switch, or telecommand. This innovative method was first employed in 1952 by Dr. James Van Allen, who was working at the State University of Iowa at the time.

The primary advantage of the rockoon combination was that it allowed the rocket to bypass the denser, lower layers of the atmosphere without expending its own propulsion energy. This resulted in a higher achievable apogee. However, the technique had a limitation: once released, the balloons could not be steered, making it impossible to precisely predict the rocket's launch direction or impact area. To address this safety concern, all rockoon missions were conducted from small vessels operating in open waters. This approach offered an additional benefit, as the ships could adjust their position to create a "zero wind condition", ideal for balloon launches.

The initial rockoon launches utilized a high-performance, small rocket known as DEACON. Developed in 1947 by Allegany Ballistics Laboratory for the Navy Bureau of Ordnance, the Deacon was originally designed to carry a 50-pound instrument payload to an altitude of approximately 20 miles. The rocket had no internal controls or movable surfaces and relied on fin-based arrow stabilization at its rear. Propulsion was provided by a JATO X220 solid propellant rocket motor. The Deacon measured 12.3 feet in length, had a diameter of 6.5 inches, and featured a fin span of 38.9 inches. When launched from a balloon at an altitude of around 70,000 feet, it could achieve speeds of approximately 3,000 mph and altitudes exceeding 60 miles.

The SCIENTIFIC PAYLOAD of the rocket in this flight was a sophisticated thin-walled pulse-ionization chamber designed to measure the intensity and characteristics of heavy primary cosmic-ray nuclei at high altitudes. In the image above we can see an scheme and a picture of the device. The chamber was constructed from thin copper hemispheres, six inches in diameter, with a wall thickness of 0.010 inches to minimize interference from surrounding materials. A central electrode made of 0.025-inch Kovar wire, soldered into a precision guard ring system, facilitated accurate ion collection. The chamber was filled with ultra-pure argon gas, and counted with a polonium alpha source for absolute calibration for ionization bursts. The source emitted alpha particles through a collimating aperture, producing consistent and measurable bursts that enabled pre-flight and in-flight calibration of the system.

The payload also incorporated advanced electronics, including amplifiers which processed signals from the ionization chamber. The amplifiers produced standardized pulse shapes to facilitate telemetry and recording. A frequency-modulated telemetering system transmitted data to a ground station, where it was captured using a receiving antenna and recorded on a Brush inking oscillograph for later study. The payload included a pressure-sealed nose cone to prevent electrical corona discharge at high altitudes and used lightweight materials, such as Styrofoam supports, to minimize mass and interaction with cosmic rays.

The payload was capable of detecting ionization bursts caused by the traversal of heavy nuclei, differentiating these events from background noise and nuclear interactions. The measurements, conducted at various geomagnetic latitudes and altitudes, provided data on the spectra and behavior of heavy cosmic-ray nuclei, revealing significant information about their magnetic rigidity and absence at low momentum ranges.

Balloon launched on: 9/3/1953 at 9:53 utc
Launch site: USCGC Eastwind (WAGB 279)  
Balloon launched by: General Mills Inc.
Balloon manufacturer/size/composition: Zero Pressure Balloon General Mills -- 55 foot
Flight identification number: GMI-1028
End of flight (L for landing time, W for last contact, otherwise termination time): 9/3/1953
Landing site: Payload no recoverable

The balloon was launched on September 3th, 1953 at 9:53 utc, from the deck of the U.S Coast Guard vessel Eastwind sailing at coordinates 44º50'N - 57º13'W. The balloon reached float altitude of 73.400 ft and the rocket was fired by pressure switch activation at 10:51 utc. The rocket reached an uncertain apogee.

• Final report ANNEX IX (High Altitude Balloon Research) General Mills Inc. Mechanical division April 1954
• Low-Momentum End of the Spectra of Heavy Primary Cosmic Rays Phys. Rev. 95, 147 (1954)
• Upper Atmosphere Research Report Number 21. Summary of Upper Atmosphere Rocket Research Firings Naval Research Lab., Feb. 1954