Space Linear Acceleration Mass Measurement Device (SLAMMD) - 01.16.19

Summary | Overview | Operations | Results | Publications | Imagery

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Science Objectives for Everyone
The Space Linear Acceleration Mass Measurement Device (SLAMMD) is able to calculate a crew member’s mass without the presence of gravity. It follows Newton's Second Law of Motion (force equals mass times acceleration), which means that when two springs generate a known force on a crew member (who is mounted on an extension arm that is pulled into the device by the springs), the resulting acceleration can be used to calculate the crew member’s mass. The device is accurate to 0.5 pounds (0.225 kg) over a range of 90 to 240 pounds (41 to 109 kg).
Science Results for Everyone
Information Pending

The following content was provided by Suzanne S. Mccollum, and is maintained in a database by the ISS Program Science Office.
Facility Details

OpNom: SLAMMD

Facility Manager(s)
Suzanne S. Mccollum, NASA Johnson Space Center, Houston, TX, United States

Facility Representative(s)
Information Pending

Developer(s)
NASA Johnson Space Center, Human Research Program, Houston, TX, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
NASA - Human Research Program (NASA-HRP)

ISS Expedition Duration
April 2005 - September 2014

Expeditions Assigned
11,12,13,14,15,16,17,18,19/20,21/22,23/24,25/26,27/28,29/30,31/32,33/34,35/36,37/38,39/40

Previous Missions
Information Pending

Availability
Information Pending

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Facility Description

Facility Overview

The SLAMMD (Space Linear Acceleration Mass Measurement Device) was launched aboard STS-114 (LF1) on July 26, 2005 and installed in the Human Research Rack (HRF)-1 rack during Expedition 11. SLAMMD measures the on-orbit mass of crewmembers by applying Newton's Second Law of Motion (force is equal to mass times acceleration).
 
This device measures mass from 90 to 240 pounds (41 to 109 kg) by using the known force generated by two springs located inside of the SLAMMD drawer. The resultant acceleration of the attached crewmember is measured and the mass is then calculated.
 
SLAMMD is intended to provide an accurate means of determining the on-orbit mass of humans between the 5th percentile Japanese female and the 95th percentile American male. SLAMMD is rack mounted in a 4 panel unit (PU) drawer and utilizes an 8 PU drawer for stowage.

The guiding principle of SLAMMD is Sir Isaac Newton's Second Law of Motion, F=ma (force is equal to mass times acceleration). Therefore, to find mass, the acceleration is divided into the force: m=F/a. For the HRF SLAMMD, the force is generated by two springs inside the SLAMMD 4 PU drawer. The acceleration used in calculating the mass is actually a calculated average acceleration with regression analysis. The acceleration is measured by a precise optical instrument that detects the position versus time trajectory of the SLAMMD guiding arm and a micro controller that collects the raw data and provides the precise timing. The final computation is performed via a portable laptop computer with SLAMMD unique software.

The force is generated by two springs inside the 4 PU SLAMMD drawer. Each spring has Vectran (a strong fiber) attached to one end which is fed around a separate pulley and back towards a central cam. The cam is attached to a centrally-located shaft that also has a flywheel and an encoder disk attached to it. The cam is designed such that, throughout the distance the springs stretch, a constant force is applied to the central shaft. This design feature is an important design feature, so that the mass can be calculated using the m=F/a equation. The large flywheel has a lanyard attached to it that is fed through a small slit on the SLAMMD front panel and is attached to a connector. During SLAMMD operation, the latch connector is joined to a latch assembly on the SLAMMD guiding arm. With the cam design and selected springs, the force pulling the guide arm assembly inward is constant at 5.25 lbs (23.3 N). For human mass calculations, the crewmember wraps his/her legs around the leg support assembly like one would for a leg curl machine, aligns the stomach against the belly pad and rests either the head or chin on the head rest.

For calibration and control calculations, a calibration arm assembly is attached to the SLAMMD guide arm. Using an 18-pound calibration mass at different lengths from the pivot point, different mass values can be simulated within the range of from 90 pounds to 240 pounds (41 to 109 kg).
 
After installation into HRF-1 rack during Expedition 11 and checkout during Expedition 12, the SLAMMD has been used in support of NASA's Biochem profile, Body Measures, Nutrition and Pro K investigations as well as ESA's SOLO investigation.

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Operations

Facility Operations

  • SLAMMD is a rack-mounted device. The crew member mounts the guiding arm assembly and pushes away from the drawer to a predetermined locking position.
  • An electromagnet is activated to stabilize the crew member in the ready position. The electromagnet comes into contact with the latch attachment plate located on the guiding arm assembly.
  • When the magnet is released the test subject is pulled forward with a low-level, constant force.

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Decadal Survey Recommendations

Information Pending

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Results/More Information

Results Publications

    Zwart SR, Launius RD, Coen GK, Morgan JL, Charles JB, Smith SM.  Body mass changes during long-duration spaceflight. Aviation, Space, and Environmental Medicine. 2014 September; 85(9): 897-904. DOI: 10.3357/ASEM.3979.2014.

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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: ISS012E12597 - NASA astronaut Bill McArthur sets-up the Space Linear Acceleration Mass Measurement Device (SLAMMD) in the Destiny Laboratory during Expedition 12. The SLAMMD Guiding Arm, Leg Restraint and Head Rest are visible attached to the Human Research Facility Rack 1 (HRF-1).

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NASA Image: ISS019E007130 - The Human Research Facility (HRF) Rack 1 in the European Laboratory in Columbus. Visible is the HRF Ultrasound,Workstation 2,and HRF Cooling Stowage Drawer and the Space Linear Acceleration Mass Measurement Device (SLAMMD). Photo  taken during Expedition 19.

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NASA Image: ISS019E017901 - Japan Aerospace Exploration Agency (JAXA) astronaut Koichi Wakata, Expedition 19 flight engineer, using the Space Linear Acceleration Mass Measurement Device(SLAMMD) hardware set up in the Columbus module. Hardware will be used for BMM (Body Mass Measurement) activities by the Expedition 19 crew.

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NASA Image: ISS020E015893 - European Space Agency (ESA) astronaut Frank De Winne, Expedition 20 flight engineer, works with the Space Linear Acceleration Mass Measurement Device (SLAMMD) in the Columbus laboratory of the International Space Station.

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