The Plasma Probe is designed by me (as part of my M.S. thesis) to measure the relative plasma density in the E-region of the ionosphere during an active aurora. From inception of idea to conclusion, my thesis involved:

  • The design and implementation of the instrument.
  • Integration with other modules within the rocket.
  • Analysis of the procured plasma data.

The instrument cost a little over $60,000 and was developed as part of a $9,000,000 Horizontal E-region eXperiment (HEX-2), conducted by the Geophysical Institute (University of Alaska, Fairbanks) in collaboration with Clemson University, NASA and Poker Flat Research Range (PFRR). The Plasma Probe was successfully launched into space on a three-stage Black Brant X rocket from PFRR on February 14, 2007 (Newspaper Article). The primary focus of the HEX-2 investigation was to measure all terms in the atmospheric mass continuity equation and involved four sounding rockets carrying a multitude of instruments.

Instrument Overview

The Plasma Probe is designed to perform the following duties:

  • Measure the relative density of secondary auroral and high energy thermal electrons in plasma.
  • Measure the relative density of positively charged ions in ambient plasma.
  • Investigate the upwelling vertical wind associated with the auroral heating that may carry molecular species aloft, causing plasma depletions at trajectory altitudes near 160 km.

The instrument is chiefly composed of the following major modules:

  • Electronics:
    • Power Module: Generate all the required regulated voltages for the entire instrument.
    • Analog Modules: Houses all the analog components.
    • Digital Modules: Houses all the digital components.
  • Four segmented gold-plated collector surfaces wrapped around the rocket skin.
  • Ground Support Software (GSS) for remotely configuring and monitoring the Plasma Probe.
  • Supplimentary Hardware: NASA provided Telemetry (TM) & rocket Attitude Control System (ACS).

I have catagorized and provided a brief overview of the hardware and software that I designed for this mission below. Also, don't forget to check out a nice video of the actual launch and some photos relevent to the mission in the last tab.


HEX-2 Collaborators

GI - University of Alaska Fairbanks

Clemson University

Poker Flat Research Range, University of Alaska Fairbanks

NASA Sounding Rocket Operations Contract



Click on the required tab below to view its contents

Plasma Probe Hardware



The Plasma Probe's core elctronics are made up of two Analog Modules, two Digital Modules and one Power Module. The electronics interface with four large gold-plated surfaces that form the collector surfaces which detects the plasma particles. Figure to the right provides an electrical block diagram overview.

  • Power Module (PM): The principal function of the PM is to provide the analog and digital modules with their required voltages and currents with minimal output jitter.
  • Analog Module (AM): The AM comprises mainly the electronics that translates the densities of the plasma particlues to a voltage that can be measured and quantified.
  • Digital Module (DM): The DM houses the microcontrollers, the communication circuitry, the ADCs etc. essentially forming the brain of the entire system.
Plasma Probe Electronics Overview

Several other supporting hardware and software are required for the functioning of the Plasma Probe. The major supporting components are as follows:

  • Telemetry (TM): The TM is provided by NASA Sounding Rocket Operations Contract (NSROC) and is essentially where all the data from the Plasma Probe terminates. The TM also provides the digitization of some lower-priority analog data channels of the Plasma Probe.
  • Attitude Control System (ACS): ACS is also provided by NSROC. Apart from orienting the rocket as required, the ACS also provides the spin axis information of the daughter payload to the Plasma Probe.
  • Ground Support Software (GSS): The GSS is developed my me and is used to remotely configure and monitor the performance of the Plasma Probe.

Two pictures of the complete electronics are shown to right.There are a total of five circuit boards; two AMs, two for DM and one for PM (the Power PCB has two separate PM channels built into it). From top to bottom, the first (top most) PCB is the PM, it is followed by the DM1, then by AM1, then by DM2 and AM2,  respectively. The completed electronics is mounted into an aluminum enclosure for EMI shielding. The aluminum enclosure is then mounted on to the rocket deck plate to provide by employing conolite fiberglass, which provides thermal isolation from the heavily heated exterior skin of the rocket during flight.

The instrument’s noise resilience is extremely good and it can measure plasma currents as low as 5 nA and with 420 pA resolution.

Plasma Probe Electronics Plasma Probe Electronics

Ground Support Software


Ground Support Software (GSS)

The GSS facilitates performing the following tasks:

Configuring the multitude of options available to the Plasma Probe remotely prior to launch. This is of vital importance because once the instrument is integrated into the rocket and the rocket mounted onto the launchpad, any physical access to the instrument is a costly and time consuming affair. A total of 42 different configuration parameters have been implemented into the Plasma Probe, all of which can be remotely configured using the GSS.

Monitoring of the instrument for proper functioning. The GSS Monitoring Tool will continuously monitor the Plasma Probe's transmited data for any anomaly and will allert the user of any detected malfunction. Apart from malfunction detection, the tool is also used for continuous monitoring of all critical functions of the Plasma Probe.


GSS Configuration Tool


GSS Monitoring Tool


  GSS Confiuration Tool The GSS was developed in Microsoft Visual Studio 2005. GSS Monitoring Tool  

The software can configure almost all aspects of the Plasma Probe.


The software provides for easy monitoring and interpretation of the Plasma Probe data during the mission.



Data Analysis Software



Plasma Probe Data Analysis Software



Data Analysis Software was developed in Matlab as a standalone application (does not require Matlab to be installed on target computer) and allows for easy plotting and preliminary data analysis of the Plasma Probe data.



Mission Video & Pictures


Launch Video:

  Link to HEX-2 Rocket Launch Video  

The video is shot from a remote location and shows the launch of all four rockets along with their respective chemical trails.



Plasma Probe Wiring Harness Rocket Attitude Plot Plasma Density vs Altitude Integration

Plasma Probe Wiring Harness

Rocket Attitude Data

Plasma Density Data vs. Altitude

My laptop hard at work ;-)


Payload Vibration Test Payload Shock Test Me, Myself & Sujith Rocket Launch

Rocket Payload - Vibration Table

Rocket Payload - Shock Test

Man vs. Machine

Rocket - Launch



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