R. A. Stoneback

Ground and Space-Based Measurement of Rocket Engine Burns in the Ionosphere

On-orbit firings of both liquid and solid rocket motors provide localized disturbances to the plasma in the upper atmosphere. Large amounts of energy are deposited to ionosphere in the form of expanding exhaust vapors which change the composition and flow velocity. Charge exchange between the neutral exhaust molecules and the background ions (mainly O+) yields energetic ion beams. The rapidly moving pickup ions excite plasma instabilities and yield optical emissions after dissociative recombination with ambient electrons. Line-of-sight techniques for remote measurements rocket burn effects include direct observation of plume optical emissions with ground and satellite cameras, and plume scatter with UHF and higher frequency radars. Long range detection with HF radars is possible if the burns occur in the dense part of the ionosphere. The exhaust vapors initiate plasma turbulence in the ionosphere that can scatter HF radar waves launched from ground transmitters. Solid rocket motors provide particulates that become charged in the ionosphere and may excite dusty plasma instabilities. Hypersonic exhaust flow impacting the ionospheric plasma launches a low-frequency, electromagnetic pulse that is detectable using satellites with electric field booms. If the exhaust cloud itself passes over a satellite, in situ detectors measure increased ion-acoustic wave turbulence, enhanced neutral and plasma densities, elevated ion temperatures, and magnetic field perturbations. All of these techniques can be used for long range observations of plumes in the ionosphere. To demonstrate such long range measurements, several experiments were conducted by the Naval Research Laboratory including the Charged Aerosol Release Experiment, the Shuttle Ionospheric Modification with Pulsed Localized Exhaust experiments, and the Shuttle Exhaust Ionospheric Turbulence Experiments.

Vertical ExB drifts from radar and C/NOFS observations in the Indian and Indonesian sectors: Consistency of observations and model

In this paper, we analyze vertical ExB drifts obtained from the Doppler shifts of the daytime 150 km radar echoes from two radar stations located off the magnetic equator, namely, Gadanki in India and Kototabang in Indonesia, and compare those with corresponding Coupled Ion Neutral Dynamics Investigation (CINDI) observations onboard the C/NOFS satellite and the Scherliess-Fejer model in an effort to understand to what extent the low-latitude vertical ExB drifts of the 150 km region represent the F region vertical ExB drifts. The radar observations were made during 9–16 LT in January, June, July, and December 2009. A detailed comparison reveals that vertical ExB drifts observed by the radars at both locations agree well with those of CINDI and differ remarkably from those of the model. Importantly, the model and observed drifts show large disagreement when the observed drifts are either large or downward. Further, while the CINDI as well as the radar observations from the two longitudes are found to agree with each other on the average, they differ remarkably on several occasions when compared on a one-to-one basis. The observed difference in detail is due to measurements made in different volumes linked with latitudinal and/or longitudinal differences and underlines the role of neutral dynamics linked with tides and gravity waves in the two longitude sectors on the respective vertical ExB drifts. The results presented here are the first of their kind and are expected to have wider applications in furthering our understanding on fine-scale longitudinal variabilities in the ionosphere in general and ionospheric electrodynamics in the Indian and Indonesian sectors in particular.

Daytime ionospheric equatorial vertical drifts during the 2008–2009 extreme solar minimum

One of the most interesting observations made by the Communication/Navigation Outage Forecasting System (C/NOFS) satellite mission was the detection of average equatorial ionospheric vertical drifts that largely differed from model predictions. C/NOFS measurements showed, in particular, downward drifts in the afternoon sector, and upward drifts around local midnight hours during the 2008 and 2009 extreme solar minimum. The unexpected behavior of the drifts has important implications for ionospheric modeling and suggests the necessity for a better understanding of the low-latitude electrodynamics. We used ground-based radar measurements to quantify the seasonal and solar flux variability of daytime equatorial drifts at lower altitudes (∼150 km) than those probed by C/NOFS (above ∼400 km). We found that average vertical drifts at 150 km altitude are in good agreement with model predictions of F region drifts and did not show the signatures of an enhanced semidiurnal pattern, as seen by C/NOFS. Comparison of the 150 km echo drifts with model predictions also shows that the increase (decrease) with height of the vertical drifts in the morning (afternoon) hours is a regular feature of the equatorial ionosphere. It occurred in all seasons and solar flux conditions between 2001 and 2011.

PYSAT: Python Satellite Data Analysis Toolkit: PYSAT

R. A. Stoneback, W. B. Hanson Center for Space Sciences, 800 W. Campbell Rd. WT 15, Richardson, TX 75080, USA. (rstoneba@utdallas.edu) A. G. Burrell, W. B. Hanson Center for Space Sciences, 800 W. Campbell Rd. WT 15, Richardson, TX 75080, USA. J. Klenzing, Space Weather Lab / Code 674, Goddard Space Flight Center, Greenbelt, MD, USA M. D. Depew, W. B. Hanson Center for Space Sciences, 800 W. Campbell Rd. WT 15, Richardson, TX 75080, USA.

Daytime zonal drifts in the ionospheric 150 km and E regions estimated using EAR observations

Multi-beam observations of the 150-km echoes made using the Equatorial Atmosphere Radar (EAR), located at Kototabang, Indonesia provide unique opportunity to study both vertical and zonal ExB plasma drifts in the equatorial ionosphere. In this paper, we focus on estimating daytime zonal drifts at the 150 km (140-160 km) and E (100-110 km) regions using multi-beam observations of 150-km- and E-region echoes made using the EAR and study the daytime zonal drifts covering all seasons, not studied before from Kototabang. Zonal drifts in the 150-km and E regions are found to be westward and mostly below -80 m s-1 and -60 m s-1, respectively. While the zonal drifts in the 150-km and E regions do not go hand in hand on a case by case basis, the seasonal mean drifts in the two height regions are found to be in good agreement with each other. Zonal drifts at the 150 km region show seasonal variations with three maxima peaking around May, September and January. The zonal drifts at the 150 km region are found to be smaller than the F region drifts obtained from CINDI onboard C/NOFS by about 25 m s-1 consistent with the height variations of F region zonal drifts observed by the Jicamarca radar. These results constitute the first comprehensive study of zonal drifts at the 150 km and E regions from Kototabang, Indonesia and the results are discussed in the light of current understanding on the low latitude electrodynamics and coupling.

Trimetric Imaging of the Martian Ionosphere Using a CubeSat Constellation

* Professor, Physics and ECE, 3507 Cullen Blvd.,#617/PHYS 5005, Associate Fellow. † Professor, Electrical and Computer Engineering, Engineering 2, W330 / H4005. ‡ Professor, Electrical and Computer Engineering, Engineering 2, W318 / H4005. § Professor, Physics, 3507 Cullen Blvd.,#617/PHYS 5005. ** Research Associate III, LASP, 3665 Discovery Drive, Campus Box 590. †† Associate Professor, Electrical Engineering, 1320 Beal Ave. ‡‡ Assistant Research Scientist, 1320 Beal Ave., FXB, Member. §§ Professor, Space Sciences and Engineering, Space Research Building, 2455 Hayward St. *** Assistant Professor, Aerospace Engineering, 607A HR Bright Bldg., 3141 TAMU, Member ††† Associate Professor, Atmospheric Sciences, 3150 TAMU, ‡‡‡ Regents Professor, Aerospace Engineering, 701 HR Bright Bldg., 3141 TAMU, Fellow §§§ Professor, Physics, 800 W. Campbell Rd. MS/WT 15 **** Assistant Professor, 800 W. Campbell Rd. MS/WT 15 †††† Assistant Professor, Mechanical Engineering, Macdonald Engineering Building Room 270 ‡‡‡‡ Chief Technology Officer, 133 Center st., Unit A, Member. §§§§ Associate Professor, Astronomy, 725 Commonwealth Ave. D ow nl oa de d by U N IV E R SI T Y O F M IC H IG A N o n A pr il 9, 2 01 8 | h ttp :// ar c. ai aa .o rg | D O I: 1 0. 25 14 /6 .2 01 752 52 AIAA SPACE and Astronautics Forum and Exposition 12 14 Sep 2017, Orlando, FL 10.2514/6.2017-5252

THE DIPOLE IMPEDANCE OF AN APERTURE

The dipole impedance of an aperture in a plane conductor is obtained by modifying the general network formulation of electromagnetic apertures presented by Mautz and Harrington. The derived dipole impedances are combined in parallel to form an efiective circuit description of low frequency aperture difiraction. Power transmitted into the aperture by an incident wave is determined by incorporating standard techniques for the transfer of wave power at an impedance mismatch. This transmitted power is divided into forward and backward scattered flelds based upon the behavior of image currents surrounding the aperture, leading to a peak in forward scattered power above unity, consistent with known aperture behavior. The presented aperture circuit maintains an excellent correspondence with measurements of radiated power for an aperture excited by high energy electrons and with the numerically calculated impedance of a circular aperture using the flnite element method.