SAMS-II will measure vibrations from vehicle acceleration, systems operations, crew movements, and thermal expansion and contraction. Multiple Remote Triaxial Sensor (RTS) systems are used to monitor individual experiments requiring direct monitoring. Each RTS is capable of measuring between 0.01 Hz to beyond 300 Hz of vibration, also known as g-jitter. The RTSs consist of two components: the RTS sensor enclosure (SE) and the RTS electronics enclosure (EE). The RTS-SE, placed as close to the experiment as possible, will translate the g-jitter into a digital signal. The RTS-EEs provides power and command signals for up to 2 RTS-SEs and receives the g-jitter data from the RTS-SEs.

The RTSs are linked together by the Interim Control Unit (ICU), which coordinates the various RTS systems being used throughout the Station. Eventually, the ICU will be replaced by a full-fledged Control Unit (CU), which will allow onboard data analysis and direct feedback and will permit crew to control the measurement parameters. The main component of the ICU is a computer. Once the ICU receives the measurements from the RTS systems, it checks the data for completeness, and the computer sends the data to the SAMS-II Ground Operations Equipment at Glenn Research Center.

Changes in acceleration and moving mechanical parts can cause small vibrations to move through the Station's structure. These disturbances occur within the frequency range of 0.01 to 300 Hz. MAMS is one of two experiments onboard that will measure and record the vibrations. The Space Acceleration Measurement System II (SAMS-II) will measure vibrations from vehicle acceleration, systems operations, and crew movements. MAMS will complement this data by recording accelerations caused by aerodynamic drag and Station movements caused by small attitude adjustments, gravity gradient, and the venting of water. These quasi-steady state accelerations occur in the frequency range below 1 Hz. MAMS consists of a low-frequency triaxial accelerometer, the Miniature Electro-Static Accelerometer (MESA), a high-frequency accelerometer, the High-Resolution Accelerometer Package (HiRAP), and associated computer, power, and signal processing subsystems contained within a Double Middeck Locker enclosure.

The MESA consists of a hollow, cylindrical flanged proofmass, two X-axis forcing electrodes, an outer cylindrical proofmass carrier with Y- and Z-axis electrodes, and control electronics enclosed in a protective case. Static electricity forces the sensor proofmass to remain centered between the electrodes. The "sensed" acceleration is proportional to the voltage needed to keep the sensor centered.

The MESA is mounted on a Bias Calibration Table Assembly (BCTA), a dual-gimbal mechanism allowing on-orbit calibration. Calibration is used to remove electronic bias from the "sensed" acceleration.

Currently MAMS is only operated during special events such as an ISS reboost, spacecraft dockings and undockings.

Related Web Sites
* Results Home Page / PIMS ISS Home Page
* NASA Glenn Research Center - SAMS
* NASA Glenn Research Center - MAMS