Goembel Instruments SCM


The Goembel Instruments Spacecraft Charge Monitor (SCM) was designed and built to monitor low level charge (~+/-30 volts) which is typically expected on the International Space Station (ISS). In fact, it is believed that such low level charge could be responsible for the death of an astronaut during an extra-vehicular activity, so it is important to monitor for such charging on craft such as the ISS [Ferguson, 2002] .

Potential Uses for the SCM Include:

The flight-ready SCM-1 has been designed and built with the assistance of NASA Phase I and II Small Business Innovative Research (SBIR) funds.

It is ready for flight today.


SCM Specifications:

Floating Potential Range

-20 to +45 volts with 0.1 volt precision.


6.5”x 3.75”x 2.75”


650 grams

Vibration Qualification level

14.5 G’s (rms) for 3 minutes each orthogonal axis

Calibrated operating temperature

-24˚C to 40˚C

Expanded operating temperature

-24˚C to +61˚C

Storage temperature

-55˚C to 105˚C


< 2Watts, 28V (unregulated)

S/C Interface

RS422 two-wire differential

Data rate

2kbits/second (raw data output)




Ferguson, Dale C., Charging of the International Space Station Due to Its High Voltage Solar Arrays, NASA Technical Report Server Document ID: 20030000606, 2002.