ISS Plasma Thrust Shadow-Beacon Experiment Feb 1-3 and 8-10

International Space Station ISS with shuttle Endeavour 2011-05-23It is understood that the ISS amateur radio SpEx Shadow-Beacon experiment is planned to take place February 1-3 and 8-10. The timetable is here.

The Central Research Institute of Machine Building (TSNIIMASH) in Russia is conducting a series of space plasma experiments in order to evaluate the shape of previously observed “dead” zone, or shadowing due to the firing of an onboard arcjet plasma source.

Radio Amateurs are invited to participate in the Space plasma experiment “Shadow” onboard the International Space Station (ISS).

Integration of Electric Thrust (ET) onboard a spacecraft poses a certain set of problems including electromagnetic compatibility of ET. One matter of interest is that highly ionized exhaust plumes of ET may scatter RF-signals producing large “dead” zone for communications.

This plasma screening effect should be thoroughly studied before electric thrusters become standard onboard equipment. The investigation will help designers of future electrically propelled spacecraft to minimize the hazard of communication disruption by ET plasma plumes.

The experiment will use the ISS Amateur Radio 145.825 MHz FM AX.25 1200 bps packet radio downlink.

The amateur packet radio technology in the SpEx “Shadow” as proposed by astronaut and radio amateur Alexander Kaleri, U8MIR, uses the AX25 packets transmitted by “Master Stations” and reported by receiving amateur radio ground stations to track the effect of the plasma shadow.


SpEx Shadow sample report

The main web page for the SpEx project can be found at
This page contains a detailed description of the experiment and instructions for submitting your signal reports.
Register to join the experiment at

An example of the SpEx packets received by Mike Rupprecht, DK3WN is at

To check when the ISS is in range see the real time tracking at (top left).

UISS Packet Software

AGW Packet Engine

AGPE Installation and Setup