Space Acceleration Measurement System-II (SAMS-II) - 01.23.19

Summary | Overview | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
Space Acceleration Measurement System-II (SAMS-II) is an ongoing study of the small forces (vibrations and accelerations) on the International Space Station (ISS) resulting from the operation of hardware, crew activities, dockings and maneuvering. Results generalize the types of vibrations affecting vibration-sensitive experiments and structural life of ISS. Investigators and Structural Analysts seek to better understand the vibration environment on the ISS using SAMS-II data and assessing station loads and dynamics.
Science Results for Everyone Shaken, not stirred. That’s what happens to scientific experiments onboard the International Space Station (ISS), thanks to small forces created by vehicle and crew activities and by other experiments. Researchers used sensors to collect data on disturbances in the frequency range of 0.01 - 400 Hz and downlinked it to Glenn Research Center. Analysis of nearly 3.4 terabytes of data indicate that ISS is not meeting its goal of providing a quiescent, low-gravity environment for scientific research. Data also indicate that there is no clear reduction in disturbances during crew sleep periods. The measuring continues on an as-needed basis and data are available to the scientific community.

The following content was provided by Kevin M. McPherson, and is maintained in a database by the ISS Program Science Office.
Facility Details

OpNom: SAMS II

Facility Manager(s)
Kevin M. McPherson, NASA Glenn Research Center, Cleveland, OH, United States

Facility Representative(s)
Information Pending

Developer(s)
ZIN Technologies Incorporated, Cleveland, OH, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)

ISS Expedition Duration
March 2001 - December 2002; November 2002 - May 2003; April 2003 - September 2012; September 2013 - March 2016; March 2016 - October 2019

Expeditions Assigned
2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19/20,21/22,23/24,25/26,27/28,29/30,31/32,37/38,39/40,41/42,43/44,45/46,47/48,49/50,51/52,53/54,55/56,57/58,59/60

Previous Missions
SAMS, the precursor to SAMS-II flew on numerous shuttle flights since STS-40, including STS-107 (Columbia) which was lost in 2003. SAMS-II has been operating on ISS since Expedition 2.

Availability
Information Pending

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Facility Description

Facility Overview

Space Acceleration Measurement System-II (SAMS-II) measures accelerations caused by the vehicle, crew and equipment. For most scientific investigations, these measurements help characterize the disturbances experienced at their location of interest. The sensors are deployed in all three ISS laboratories, the U.S. Lab, Columbus and the Japanese Experiment Module (JEM). The vibratory/transient accelerations that SAMS-II was designed to measure occur in the frequency range 0.01 to 300 Hertz.
 
Vibrations permeate the space station for a variety of reasons: equipment operation, structural motion/resonance, crew movement, and thermal expansion are some typical examples.
 
SAMS-II measurements support physical science and biotechnology investigators and help characterize accelerations that influence the space station experiments. The acceleration data is available to researchers via the World Wide Web and tailored analysis is also available on request.
 
The SAMS-II measures vibrations of gross vehicle motion, systems operations, crew movements, and thermal expansion and contraction for effects on the main truss and solar array. Multiple Remote Triaxial Sensor (RTS) systems directly monitor individual experiments. Each RTS is capable of measuring between 0.01 Hz to beyond 300 Hz of vibration, which sometimes is referred to as g-jitter. The RTSs consist of two components: the RTS sensor enclosure (SE) and the RTS electronics enclosure (EE). The RTS-SE, which is placed as close to the experiment as possible, translates the g-jitter into a digital signal. The RTS-EEs provide power and command signals for up to 2 RTS-SEs and receive the g-jitter data from the RTS-SEs. The RTSs are connected via the ISS payload network to the SAMS-II Control Unit (CU), which coordinates the various RTS systems being used throughout ISS. The CU is externally mounted on ER#1 and receives power from ER#8. The main component is a Zbook laptop. The SAMS II flight system operates automatically with occasional routine maintenance via ground commanding, while SAMS-II ground systems are monitored to maintain ongoing operations for data capture, display, analysis and archival. Once the CU receives the measurements from the RTS systems, it checks the data for completeness, and then sends the data to the SAMS-II Ground Operations Equipment in the TeleScience Center (TSC) at Glenn Research Center in Cleveland, OH.
 
Sometimes even minute accelerations affect science or results. In fluid physics and crystal growth, SAMS-II detects the vibrational disturbances that can cause the microstructures to form undefined or in a disfigured way. The liquid - solid transition is known to be difficult when the amount of vibrational disturbances is high or when system resonances are happening.
 
The residual acceleration environment of an orbiting spacecraft in low-Earth orbit is a complex phenomenon. Many factors, such as experiment operation, life-support systems, crew activities, aerodynamic drag, gravity gradient, rotational effects and the vehicle structural resonance frequencies (structural modes) contribute to form the overall reduced gravity environment. Weightlessness is an ideal state, which cannot be achieved in practice because of the various sources of acceleration present in an orbiting spacecraft. SAMS-II records these acceleration disturbances caused by the ISS, its crew, and equipment. A complete understanding of the vibration environment can help researchers develop methods to minimize disturbances and allows other principal investigators to design their payloads with the vibration environment in mind.

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Operations

Facility Operations

  • The SAMS-II equipment is nominally powered continuously to support specific investigations and monitor space station structural modes and document disturbances. This data can later be analyzed and incorporated into models for predictive work. The SAMS-II flight system is ground controlled.
  • The crew installs and removes sensor heads and cables to relocate the SAMS-II sensors on payloads, as needed.
  • Crew occasionally (every six months) complete filters cleaning and change out.

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Decadal Survey Recommendations

Information Pending

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Results/More Information

One of the major goals of the ISS is to provide a quiescent low-gravity environment to perform fundamental scientific research. However, small disturbances aboard the ISS impact the overall environment in which experiments are being performed. Such small disturbances need to be measured in order to assess their potential impact on the experiments. The Space Acceleration Measurement System - II (SAMS-II) is used on board the ISS to do just that.

SAMS-II measures accelerations caused by vehicle, crew, and experiment disturbances. SAMS-II measures the vibratory/transient accelerations, which occur in the frequency range of 0.01 - 400 Hz. The sensors measure the accelerations electronically and transmit the data to the Interim Control Unit (ICU) located in the EXPRESS Rack drawer. Data is collected from all the sensors and downlinked to the TeleScience Center at Glenn Research Center. The acceleration data is processed and made available to the microgravity scientific community at Principal Investigator Microgravity Services.

SAMS-II measures vibratory acceleration disturbances in microgravity and non-microgravity modes of ISS operations. Current data indicate that ISS is not meeting its microgravity mode design requirement, and that there is no clear reduction in these disturbances during crew sleep periods (DeLombard et al. 2005).

SAMS-II has collected over 3.4 terabytes of acceleration data, much of which have been processed and analyzed to characterize the reduced gravity environment on board the ISS in order to help science teams understand the ISS environment. SAMS-II, began to have some computer difficulties at the beginning of Expedition 12 (October 2005); the harddrive was replaced at the end of Expedition 14 (April 2007) and SAMS-II functions nominally on an as-needed basis.

Results Publications

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Ground Based Results Publications

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ISS Patents

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Related Publications

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Related Websites

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Imagery

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NASA Image: ISS004E8406 - Space Acceleration Measurement System (SAMS) sensor head mounted near top of EXPRESS Rack 2 in U.S. Lab taken during Expedition 4.

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NASA Image: ISS008E11936 - Space Acceleration Measurement System-II (SAMS-II) in EXPRESS Rack 4 in U.S. Lab during Expedition 8.

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NASA Image: ISS007E06980 - Back-dropped by the blackness of space and Earth's horizon, an unmanned Progress supply vehicle approaches the International Space Station (ISS) during Expedition 7. Inset image shows microgravity acceleration data provided by the SAMS-II hardware during a Progress docking with the ISS.

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image NASA Image: ISS027E009634 - Documentation of a Space Acceleration Measurement System (SAMS) sensor installed at location LAB1S1 in the Destiny U.S. Laboratory during Expedition 27.
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NASA Image: ISS034E036832 - Expedite the Processing of Experiments to the Space Station (EXPRESS) Rack 4 (JPM1F5), in the Japanese Experiment Module (JEM) Pressurized Module (JPM). Elite-S2, Interface Management Unit (IMU), and Remote Triaxial Sensor System (FDO2 (SAMS-II) are visible. Photo taken during Expedition 34.

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NASA Image: ISS022E015852 - Frontal view of EXpedite the PRocessing of Experiments to Space Station EXPRESS Rack 4 (Rack 4, JPM/1F5) in the Japanese Experiment Module (JEM) Japanese Pressurized Module (JPM). Equipment visible in the EXPRESS Rack includes the Biotechnology Specimen Temperature Controller (BSTC) and the Gas Supply Module (GSM) support hardware for the Cellular Biotechnology Operations Support Systems (CBOSS) investigations, and the Device for the Study of Critical Liquids and Crystallization (DECLIC). Also visible is the Space Acceleration Measurement System-II (SAMS-II).

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NASA Image: ISS050E033362 - Payload On-orbit Still Shorts for Utilization and Maintenance (POSSUM) to document relocation/reconfiguration of NASA payload. Space Acceleration Measurement System-II (SAMS-II) is visible. Photo taken during Expedition 50.

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