International Explosives Safety Symposium
San Diego, California, August 2018
Siting Assessment for Sounding Rocket Missions
Jon Chrostowski & Ron Lambert; ACTA Inc.;
2790 Skypark Drive: Suite 310, Torrance, CA. 90505
Keywords:
Keywords: explosives safety siting, solid rocket motors, sympathetic detonation
ABSTRACT
This paper documents the development of explosives safety analyses to support site plans for pre-launch operations
involving multi-stage sounding rockets. During ground processing, rocket stages are transported, tested and mated
together prior to launch and an Explosives Safety Site Plan (ESSP) that evaluates Quantity-Distance requirements
must be developed and approved. This paper focuses on estimating the Net Explosive Weight (NEW) associated with
sounding rockets that may include multiple Hazard Division (HD) propellants. The paper shows comparisons between
NEW based on DoD Explosives Standards (DoD 6055.09-M) mixing rules and NEW based on shock and gas physics
analyses that account for actual propellant material properties as well as the dimensions/geometry of the motor stages.
INTRODUCTION
The U.S. sounding rocket program has been active for 50+ years (over 700 launches) using a variety of rocket
configurations/stages/sizes. Prior to launch, a multi-stage sounding rocket motors is transported, processed, tested
and integrated prior to mating it with the payload. Because sounding rocket stages may utilize different types of
propellant to provide thrust and control, an explosives safety site plan (ESSP) is required to provide assurance that
related workers and unrelated personnel are not exposed to undue hazards and risks. Typically, the ESSP is developed
using DoD Explosives Safety Standard, DoD 6055.09-M [1] to determine safe separation distances based on Quantity-
Distance (QD) tables depending on an Exposed Site’s (ES’s) exposure type (e.g., Intermagazine, Intraline, Public
Transportation, Inhabited Building).
For multi-stage sounding rockets that use different Hazard Division (HD) propellants in close proximity to HD 1.1
(mass detonating) material, DoD 6055.09-M mixing rules state that the Net Explosive Weight (NEW) is the sum of
all HD’s and shall be considered HD 1.1 “unless technical justification is provided to reduce the amount”. The mixing
rule requirement can be restrictive, prevent operations and require mitigation (e.g., reduce explosives quantity, change
proposed operations, move exposed personnel, harden structures). To demonstrate this issue, we use a generic two-
stage sounding rocket.
GENERIC SOUNDING ROCKET
Figure 1 shows a generic two-stage sounding rocket configuration assembled for a proposed launch; note that a
payload (instrument package) is attached to the front end of the Stage 2 motor. Assume the Stage 1 solid propellant
rocket motor has a hazard classification of HD 1.3 (mass fire) with two small spin motors attached at its top end for
spin-stabilization that are classified as HD 1.1 (mass detonation hazard). Assume that the generic Stage 2 solid
propellant rocket motor is also classified as HD 1.3. Table 1 shows a breakdown of propellant weights and the
associated hazard divisions for the generic sounding rocket.
