1. Initial Results from the RENU2 Sounding Rocket
Meghan Harrington1, Kristina Lynch1
Marc Lessard2, Bruce Fritz2 and the RENU2 Team
1Department of Physics and Astronomy, Dartmouth College; 2University of New Hampshire, Space Science Center
Introduction
Comparing to Maxwellian
Ion Upflow Events
A Maxwell distribution function centered around zero with a thermal fluctuation in velocity is:
RENU2 (Rocket Experiment for Neutral Upwelling 2) is a multiple investigator sounding rocket campaign that was designed to transit the cusp region and study particle processes during a neutral upwelling event. The RENU2 payload made dayside observations between 200 and 600 km altitude in the polar cusp and these will be compared with measurements by the EISCAT Svalbard radars. This project aims to investigate the connection between ion outflows and neutral upwelling from the topside ionosphere and how these affect the variability of neutral particle densities. Low-Earth Orbiting satellites are affected by these regions of enhanced neutral densities which decay their orbits due to satellite drag. Dartmouth's part in this is to provide three top-hat style particle detectors designed to measure the ion distribution functions, temperature enhancements and bulk velocity moments. These measurements will assist in getting an initial assessment of the upwelling process. The following provides the initial ion results from the successful RENU2 launch. 
Anti-field aligned bins are shown with a degree field of view
Increase in upflowing ions as we enter the arc and move downward (rammed thermals)
3 particular events that are higher in energy
Upwelling indicates there is some form of heating occurring between 300 and 400 km
However, when we add in a drifting population, a sheath potential, and temperature enhancements in certain directions, we obtain a more interesting Maxwellian distribution that is a closer fit to what rockets observe in the thermosphere (Fernandes, 2015)
Not yet calculated whether populations were able to achieve outflow or drag neutrals up with them
Spin Modulation
Evidence of spin modulation when looking at perpendicular facing bins with a 39.4 field of view
Slight preference for the -90 over the 90 direction due to a mechanical blind spot
3D View of drifted, shifted Maxwellian
Simple Maxwellian
2D Slice of drifted, shifted Maxwellian
Pitch – Energy Format
Launch
Up-leg rammed thermals:
Launched from Andøya Space Center on Dec 13, 2015 at 7:34 UT
Saw Poleward Moving Auroral Forms, indicators of cusp aurora, around 7:00 UT which gave us the heating we were looking for
Counts are seen in one bin or the other at the spin rate of the rocket due to rammed plasma. The RAM should theoretically only affect the HT detector, we currently don’t understand why this effect can be seen in HM data
Proton Enhancement
Trajectory of the RENU2 flight with respect to EISCAT, sunlight and PMAFs.
HT Data
HT Model
HM Data
HM Model
Payload during integration at Wallops Flight Facility before the motors were attached
Near Apogee rammed thermals:
EISCAT was able to see an increase in:
electron density
electron heating
ion upflow
as low as 300 km in the hour prior to launch
Total counts from BEEPS detectors integrated over all pitch angles
At around a flight time of 350s there is an increase in the number of proton counts at an energy of 5 eV
Event is also seen in the PMT and ERPA but not in the DCE fields or in camera data
The payload flew 2.8 sigma east of nominal trajectory but that ended up increasing our time spent in the arc
Future Work
EISCAT radar data from before and after flight. Keogram with projected and actual trajectory overlaid.
HT Data
HM Data
HM Model
HT Model
Flight was from 7:34 to 7:46 UT
Heated Tail Upflow and Medium Energy Precipitation Events:
Data Handling
Identifying and avoiding saturated HT data in analysis (Fernandes, 2016)
Explicit modeling of rammed thermal population (using GPS input to Maxwellian model), to remove that signature from data and look for heated populations
Science Goals
Calculating bulk moments from modeled data for consideration of upflow vs outflow signatures
Use ion flow to give field-aligned motion, not visible from DCE
Ion distribution shapes will be studied together with the AC wave data for indications of wave particle interactions and transverse ion acceleration
The radar data will provide a large- and meso-scale framework for the in- situ microphysical observations
Provide ion data input to modeling team
Flight Overview
RAM Model
HM/HT
HT Data
Energy
Geometry Factor HT eV
5e-5 cm2 str HM eV
1e-3 cm2 str
BPS
HM Data
BEEPS
Tail Model
Image and line drawing (M. Widholm, UNH) of top hat detector
Data collection starts at s
Star indicates when we enter the arc near 442 s and lasting until 655 s
An apogee of 447 km was achieved at a flight time of 409 s
These v-shaped precipitation signatures also seen in CASCADES2 (Mella), indicating pitch angle dispersion of temporal precipitation features
HT Model
Precipitation Model
Acknowledgements
Additional collaborators: K. Oksavik (UNIS); M. Widholm, B. Fritz (UNH); D. Hysell, S. Powell (Cornell). This work would not have been possible without the NSROC folks from Wallops Space Flight Center and the work of Ralph Gibson, David Collins and Dwayne (Whitey) Adams from Dartmouth College. Special thanks to Philip Fernandes for all his guidance. Research funded by NASA Award NNX13AJ90G
HM Model
ITIT-25 CEDAR IT Poster Session – Tuesday, June 21, 2016