SHUTTLE IONOSPHERIC MODIFICATION WITH PULSED LOCALIZED EXHAUST
EXPERIMENTS (SIMPLEX)
Research Area: Spacecraft and Orbital Environments
Expedition(s): 18- 28
Principal Investigator(s): ● Paul A. Bernhardt, PhD, Naval Research Laboratory,
Washington, DC
RESEARCH OBJECTIVES
The Shuttle Ionospheric Modification with Pulsed Localized Exhaust Experiments (SIMPLEX)
investigates plasma turbulence driven by rocket exhaust in the ionosphere using ground-based
radars.
EARTH BENEFITS
Results will help in the interpretation of spacecraft engine plumes when they are observed
from Earth.
SPACE BENEFITS
Artificially created plasma turbulence can affect
military navigation and communications using
radio systems. The plasma turbulence can also be
used to promote communications by opening
radio channels at abnormally high frequencies.
The processes by which chemical releases can
produce plasma waves are fundamental to many
applications. These processes are quantified with
the SIMPLEX measurements.
RESULTS
The effect of shuttle OMS burns on the
ionosphere at or near the equator was observed
during shuttle flights STS-86, STS-93, and STS-
122/1E. The first objective of SIMPLEX, to study
the flow of plasma into an artificially created hole
in the ionosphere, was accomplished during
shuttle mission STS-86. The hole created by the
burn recovered more quickly than was predicted
by plasma diffusion models. The second objective,
to trigger bubbles in the ionosphere, was
accomplished during STS-93, when a 10-second
burn produced a hole on the bottom side of the
equatorial layer of the ionosphere, which researchers hoped would seed an ionospheric bubble.
After the burn, an ionospheric disturbance was detected drifting eastward at 100 meters per
second. While the appearance of the disturbance after the burn was consistent with
Ground radar data collection during Orbital
Maneuvering System (OMS) burn of the space
shuttle. The radar scatter provides data on the
ionospheric interactions of the high-speed OMS
exhaust. (SIMPLEX concept image provided by
Dr. Paul A. Bernhardt, Plasma Physics Division,
Naval Research Laboratory, Washington, DC
20375)