SHUTTLE EXHAUST ION TURBULENCE EXPERIMENTS (SEITE)
Research Area: Spacecraft and Orbital Environments
Expedition(s): 18- 28
Principal Investigator(s): ● Paul A. Bernhardt, PhD, Naval Research Laboratory,
Washington, DC
RESEARCH OBJECTIVES
Shuttle Exhaust Ion Turbulence Experiments
(SEITE) uses space-based sensors to observe
the ionospheric turbulence from a Space
Shuttle Orbital Maneuvering System (OMS)
burn.
EARTH BENEFITS
Results will help in the interpretation of
spacecraft plumes when they are observed
from Earth.
SPACE BENEFITS
Artificially-created plasma turbulence can
disrupt military navigation and
communications using radio systems.
RESULTS
SEITE 1 and SEITE 2, conducted during STS-
127/2JA and STS-129/ULF3 respectively, provided unique measurements of highly altered,
neutral, and plasma environments that resulted from space shuttle Orbital Maneuvering
System (OMS) burns in the ionosphere. During STS-127, an OMS burn was timed so the exhaust
plume would cross the path of an Air Force satellite. The satellite, which flew through the near-
center of the exhaust cloud, measured a 50% increase in ion temperature, 10% increase in
electron density, increase in vertical neutral wind from 0 to 3.5 km/s in 6 seconds, and the
conversion of 25% of ions to CO 2 +, which was the result of the exchange of charges between
neutral CO 2 and ambient atomic ions. All of these results were consistent with predictions. Of
particular interest was the detection of electromagnetic pulses (EMPs) in the form of a fast
magnetohydrodynamic (ultra-low frequency) wave and multiple whistler (very low frequency)
waves, as well as a broad band of high-amplitude noise that followed the initial EMPs. The
source of the noise is still under investigation. The experiment was repeated during STS-129.
This time, the satellite flew through only the edge of the exhaust cloud. Like SEITE 1, an EMP
caused by the fast magnetohydrodynamic (MHD) wave was detected about 6 seconds after the
OMS ignition. Unlike SEITE 1, no whistler modes were observed. These observations were in
accordance with predictions: the fast MHD wave is the most likely mode to be detected by a
remotely located satellite, since it propagates in all directions. The whistler modes, however,
travel in a 19.5° cone around the magnetic field from the point of origin and therefore are only
detected by a satellite if it is within this cone. While the satellite in SEITE 1 was within this cone
Shuttle Exhaust Ion Turbulence Experiment
operational concept. US Department of Defense
Space Test Program image, Houston, TX.