National Aeronautics and Space Administration

A Researcher’s Guide to:

Acceleration Environment

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This International Space Station (ISS) Researcher’s Guide is published by 

the NASA ISS Program Science Office.

Authors: 

Kevin McPherson, NASA Glenn Research Center

Kenneth Hrovat, ZIN Technologies and NASA Glenn Research Center

Eric Kelly, ZIN Technologies and NASA Glenn Research Center

Jennifer Keller, ZIN Technologies and NASA Glenn Research Center

Executive Editor: Amelia Rai

Technical Editor: Neesha Hosein

Designer: Cory Duke

Cover and back cover: 

a. Front cover: The International Space Station orbits the earth. (Image credit: NASA)

b. Back cover (top): Spectrogram of SAMS measurements showing signature and features of crew 

exercise on the Velo device. (Image credit: NASA)

c. Back cover (bottom): Two-dimensional histogram of SAMS measurements in Columbus showing 

power spectral density divide above 60 Hz created by European Physiology Modules rack being on 

versus off. (Image credit: NASA)

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SAMS Sensor (SE-F02) supporting science operations near the European Drawer Rack in the Columbus Module. 

(Image credit: NASA)

Full Speed Ahead

The International Space Station (ISS) has a mass of over 900,000 pounds 

(400,000 kg), but it’s nearly weightless! This near weightlessness is due to 

its continuous state of free-fall around the Earth not considering a small 

amount of atmospheric drag. An accounting of precisely how weightless 

comes by virtue of the Microgravity Acceleration Measurement System 

(MAMS) which monitors the quasi-steady acceleration environment 24 hours 

a day, 7 days a week. 

The ISS offers a microgravity research platform for those who need to 

leverage its unique environment. The space station is over 350 feet (109 m) 

wide and has 3 separate, main laboratory modules, each roughly the size of 

a school bus. Each laboratory has a multitude of equipment, some related 

to science operations and some related to life-support. Centrifuges, fans, 

pumps, compressors, structural bending, etc. all contribute to tiny vibrations 

over a wide range of frequencies that are monitored continuously by sensors 

distributed in locations designated for support by the Space Acceleration 

Measurement System (SAMS). These SAMS measurements along with 

those from MAMS give researchers, technology developers, and structural 

analysts the information they need to do their work, whether it is principal 

investigators studying fluid or combustion behavior in microgravity, or 

analysts tracking the structural integrity of the ISS.

The Lab is Open

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1. Microgravity, or weightlessness, alters many observable phenomena 

within the physical and life sciences. Systems and processes affected by 

microgravity include surface wetting and interfacial tension, multiphase 

flow and heat transfer, multiphase system dynamics, solidification, and 

fire phenomena and combustion. Microgravity induces a vast array of 

changes in organisms ranging from bacteria to humans, including global 

alterations in gene expression and 3-D aggregation of cells into tissue-like 

architecture.

2. Extreme conditions in the ISS environment include exposure to extreme 

heat and cold cycling, ultra-vacuum, atomic oxygen, and high-energy 

radiation. Testing and qualification of materials exposed to these extreme 

conditions have provided data to enable the manufacturing of longlife, reliable components used on Earth as well as in the world’s most 

sophisticated satellite and spacecraft components.

3. Low-Earth orbit at 51 degrees inclination and at a 90-minute orbit 

affords ISS a unique vantage point with an altitude of approximately 240 

miles (400 kilometers) and an orbital path over 90 percent of the Earth’s 

population. This can provide improved spatial resolution and variable 

lighting conditions compared to the sun-synchronous orbits of typical 

Earth remote-sensing satellites.

Unique Features of the ISS 

Research Environment

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The Lab is Open 3

Unique Features of the ISS Research Environment 5

Components of Microgravity Environment 7

The Quasi-Steady Regime 8

The Vibratory Regime 9

The Transient Regime 17

Acceleration Environment Feedback Model 18

Pre-Experiment Services 18

Experiment Operations 19

Post-Experiment Feedback 19

Acceleration System Description 20

Space Acceleration Measurement System (SAMS) 20

Microgravity Acceleration Measurement System (MAMS) 21

Principal Investigator Microgravity Services (PIMS) 22

Acceleration Data Archives 25

Acceleration Environment Handbook 27

Quasi-Steady Regime Example, Progress Reboost 27

Vibratory Regime Example, Ku-Band Antenna 28

Transient Regime Example, Crew Glovebox Push-Off 28

Acceleration Measurement Availability 29

How to Request SAMS Support 30

Acceleration Support Services 33

Scientific Payloads 33

Vehicle Monitoring 33

National Laboratory 34

Perhaps You 34

Primary Plot Types 35

Descriptions 35

Where Do I Start Exploring the Space Station’s Acceleration Environment? 35

Vibration Isolation 37

Passive Vibration Isolation of the Combustion Integrated Rack (CIR) 37

Active Vibration Isolation of the Fluids Integrated Rack (FIR) 39

Time/Location “Vibration Isolation” 41

References 46

Acronyms 47

Table of Contents

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The acceleration environment of any orbiting spacecraft such as the International 

Space Station (ISS) is not truly “zero G” as sometimes assumed. This popular idiom 

applies only to the vehicle’s center of mass, a point that is not necessarily a physical 

part of the spacecraft’s structure. All the rest of the mass that comprise the vehicle 

or are otherwise attached to it will experience accelerations from a variety of sources, 

such as pumps, fans, thrusters, atmospheric drag, rotational forces and others. 

These accelerations are often referred to as disturbances in that they can introduce 

undesired effects. These disturbances are mostly transmitted mechanically through 

the vehicle structure or acoustically through the air within the habitable modules.

A prismatic view of the ISS acceleration environment reveals a broad spectrum of 

vibrational frequencies, ranging from the relatively low-magnitude, low-frequency 

portion referred to as the quasi-steady regime up through the relatively highfrequency, high-magnitude vibratory regime. Without any additional payload 

vibration isolation, the ISS acceleration spectrum ranges from on the order of much 

less than a micro-g at the low-frequency end (< 0.1 Hz) to well over 10 milli-g at the 

high-frequency end of the spectrum. With available ISS payload vibration isolation 

systems, the acceleration environment can further be reduced by up to a factor of 100 

so as to sometimes meet the ISS microgravity requirements.

Another aspect of the acceleration environment to consider is the transient regime, 

which is associated with relatively brief and relatively high-magnitude accelerations, 

such as those introduced by a vehicle docking, thruster firing, or even a crew 

push-off or crew landing. These impulsive events do not fall neatly into either 

the quasi-steady regime or the vibratory regime. When we consider its spectral 

decomposition, we see that this type of disturbance has impact over a wide portion 

of the acceleration spectrum.

Why use the label microgravity? Well, if we consider only the low-frequency, lowmagnitude accelerations, then we note that those are approximately one-millionth 

of what would be experienced at the surface of the Earth—one-millionth, hence 

the prefix “micro.” This label, of course, is oversimplified and not intended to 

completely characterize the dynamic acceleration environment of the ISS. See 

Figure 1 Microgravity Environment Components for an overview of microgravity 

environment acceleration components.

Components of 

Microgravity Environment

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The Quasi-Steady Regime

The quasi-steady regime is comprised of accelerations at the lower end of the 

spectrum (below 0.01 hertz) and with magnitudes on the order of less than a 

micro-g. These low-frequency disturbances are associated with phenomena related 

to the ISS orbital rate of about 90 minutes, and primarily are due to aerodynamic 

drag and vehicle rotation. The drag exerted on the space station comes from a thin 

atmosphere that exists even at a nominal altitude of about 200 miles. This drag 

varies as the ISS traverses a slightly elliptical orbit through the atmosphere with 

thermal variations throughout. Denser portions give rise to more drag and thus 

higher acceleration levels. In its nominal attitude (+XVV +ZLV), the aerodynamic 

drag exerted on the ISS is primarily manifested on the two axes aligned with its 

orbital trajectory. One axis is aligned with the local vertical axis (the Z-axis), and 

one axis is aligned with the velocity vector or direction of travel (the X-axis). See 

Figure 2 Space Station Analysis 

(SSA) Coordinate System for 

a depiction of this attitude 

and a description of the SSA 

coordinate system.

Gravity gradient and rotational 

effects are key factors in shaping 

the quasi-steady regime. Both 

of these factors depend on the 

location of interest relative to 

the vehicle’s center of mass. The 

gravity gradient component 

stems from the fact that 

Figure 1. Microgravity Environment Components

Figure 2. Space Station Analysis (SSA) Coordinate System

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Earth’s gravitational tug decreases according to the inverse-square law, whereby the 

lower part of the orbiting structure will get a slightly stronger tug from the Earth. 

Rotational effects come about from the attitude maintained by the ISS. In essence, 

the space station tumbles or rotates once per orbit.

The Vibratory Regime

The vibratory regime is comprised of vibrations in the acceleration spectrum above 

0.01 hertz. These vibrations result from motion of the vehicle, crew or experimentrelated equipment. The omnipresent flexing and bending of vehicle structure, 

crew sleep/wake cycles, crew exercise, turbulent airflow, and rotating/reciprocating 

machinery are some of the disturbance sources that play a role in shaping this 

vibratory regime. In general, as the vibrational frequency under consideration 

increases, the more localized the effect of these disturbances tends to be. Vehicle 

subsystems such as those needed for life support, thermal control or communications 

produce significant disturbances here. The impact of these is primarily a function of 

proximity to the disturbance source. In a similar way, experiment-related equipment 

needed to support or conduct scientific investigations on the space station can play a 

major role, particularly as disturbances to other payloads in their vicinity.

Vehicle Structural Modes

Vehicle structural modes reside at the low-frequency end of the vibratory portion 

of the acceleration spectrum. These vibrations fall within the frequency range from 

about 0.1 hertz to about 5 hertz. These vibrations arise from the excitation of natural 

frequencies associated with large components of the space station structure, such as 

the main truss, and with fundamental appendage modes, such as solar arrays. These 

structures are typically excited by relatively large magnitude, relatively brief impulsive 

events like during a reboost or by crew locomotive events like push-offs. The driving 

excitation of such events results in response vibrations as structural ringing damps 

out. Also, relatively small magnitude vibrations at just the right frequency will give 

rise to structural resonance. Structural vibrations propagate via mechanical linkage. 

While the frequency of these disturbances may be registered the same throughout the 

space station, their amplitude is a function of location. Structural mode vibrations 

tend to be low amplitude during crew sleep periods relative to crew active periods 

owing to the absence of impulsive push-off and landing events by the crew on space 

station structure.

After assembly complete, the first such structural mode of the ISS, sometimes 

referred to as “mode one” is nominally at about 0.1 hertz. During quiet periods such 

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as crew sleep, the spectral amplitude of the narrowband peak at mode one is about 

an order of magnitude less than otherwise for measurement locations in the United 

States Laboratory (USL). The color spectrogram in Figure 3 Spectrogram Showing 

Mode One with Crew Sudden Transition to Wake shows mode one as the faint, 

yellow horizontal trace at about 0.1 hertz that becomes noticeable when the crew 

wakes with a sudden transition just after Greenwich Mean Time (GMT) 06:00. 

Conversely, the color spectrogram in Figure 4 Spectrogram Showing Mode One with 

Crew Slow Transition to Sleep for that same day shows mode one along with other 

structural vibrations tapering off after GMT 21:00 with transition toward weaker 

(blue) magnitudes.

In the Japanese Experiment Module (JEM) and in the Columbus Module (COL), 

mode one is about two orders of magnitude less during quiet periods. In addition 

to mode one, there is a cluster of modes below 5 hertz that further characterize the 

vibrations of large space station structures. These are noted along with the location 

Figure 3. Spectrogram Showing Mode One with Crew Sudden Transition to Wake.

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−10

−9

−8

−7

−6

0

10

20

ugRMS 0.05

0.1

0.15

foi (Hz)

Σ PSD Magnitude [log 10(g2/Hz)]

GMT 09−January−2013, 009/hh:mm

Frequency (Hz)

Start GMT 09−January−2013, 009/00:00:00.007

from: /misc/yoda/pub/pad, pims, 11−Jan−2013,06:55:51.810

sams2, 121f03006

Span = 7.86 hours

Hanning, k = 727

Sum

.

Temp. Res. = 38.986 sec, No = 60000

∆f = 0.002 Hz, Nfft = 65536

142.0000 sa/sec (6.00 Hz)

sams2, 121f03006 at LAB1O1, ER2, Lower Z Panel:[191.54 −40.54 135.25]

00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 08:00

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

median = 0.363 ug

median = 0.098 Hz

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of the Space Acceleration Measurement System (SAMS) sensors that captured this 

persistent set of vibrations in Table 1 Partial List of Vehicle Structural Modes*.

When considering the concentration of structural modes between about 0.06 < f < 

3 hertz in aggregate, it is important to note that SAMS sensors mounted in the USL 

register root mean square (RMS) acceleration levels between about 20 and 30 ug in 

this band, while SAMS sensors mounted in the JEM and the COL register RMS 

levels closer to 40 ug. Geometry, structural dynamics and sensor location account for 

this difference.

Crew Exercise

Next in the vibratory regime, we examine crew exercise. Exercise is an important 

part of the crew’s daily routine. In addition to promoting fitness, this activity is 

geared to help prevent bone and muscle loss associated with prolonged exposure to 

microgravity. On average, each crew member is scheduled to exercise approximately 

Figure 4. Spectrogram Showing Mode One with Crew Slow Transition to Sleep.

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−8

−7

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0

10

20

ugRMS 0.05

0.1

0.15

foi (Hz)

Σ PSD Magnitude [log 10(g2/Hz)]

GMT 09−January−2013, 009/hh:mm

Frequency (Hz)

Start GMT 09−January−2013, 009/16:00:00.002

from: /misc/yoda/pub/pad, pims, 11−Jan−2013,07:01:05.063

sams2, 121f03006

Span = 7.86 hours

Hanning, k = 727

Sum

.

Temp. Res. = 38.986 sec, No = 60000

∆f = 0.002 Hz, Nfft = 65536

142.0000 sa/sec (6.00 Hz)

sams2, 121f03006 at LAB1O1, ER2, Lower Z Panel:[191.54 −40.54 135.25]

16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 00:00

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

median = 2.881 ug

median = 0.111 Hz

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two hours per day and with multiple crew 

members; many of their scheduled periods 

overlap on the daily plan. There are three basic 

types of exercise equipment that the crew can 

use including a treadmill, a cycle ergometer and 

a resistive apparatus.

The space station has one treadmill in Node 

3 referred to as “T2” and another one in the 

Service Module, which is called the Treadmill 

with Vibration Isolation and Stabilization 

(TVIS). The TVIS is suspended over an 

opening in the floor, which allows for 

movement of the treadmill into and back out 

of this opening. The vibration isolation system 

serves to minimize the transfer of exercise forces 

from the treadmill to the ISS structure. There 

are a couple of cycle ergometers on the ISS: 

the Cycle Ergometer with Vibration Isolation 

System (CEVIS) located in the USL, and the 

Veloergometer (Velo) located in the Service 

Module. These devices provide controlled 

workloads for the crew. The CEVIS is located in 

the USL where the astronauts strap themselves 

in. The CEVIS was designed to counteract crew 

motions in order to attenuate the transfer of 

its vibratory disturbances to the space station. 

The last type of exercise equipment comes in 

the form of the Advanced Resistive Exercise 

Device (ARED) located in Node 3. This is 

a resistive device that simulates gravity. The 

ARED provides the capability to do both upper- and lower-body exercises including 

squats, dead lifts, heel raises, bicep curls and bench press. This equipment has built-in 

vibration isolation as well.

In general, these exercise equipment were designed to maintain the ISS microgravity 

environment. However, factors outside of their design envelope can play a role in 

this activity having an impact on the environment. As a result, this activity can excite 

vehicle structural modes depending on the frequency of exercise movement and on 

SENSOR LOCATION

f (hertz)* ALL LAB COL JEM

0.10 x

0.18 x

0.25 x

0.28 x x

0.41 x x

0.60 x x

0.71 x x

0.83 x

0.87 x x

1.13 x

1.28 x

1.30 x x

1.62 x

1.65 x x

1.84 x x

1.95 x

1.98 x x

2.25 x

2.30 x

2.50 x

Table 1. Partial List of Vehicle Structural Modes*

* note that closely spaced modes can appear as 

a single peak in a power spectral density (PSD) 

for a given frequency resolution and that was not 

accounted for in this analysis; therefore, closely 

spaced modes may be represented as a single 

value in the table above.

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the vigor of the crew. In addition, exercise will introduce its own, unique signature 

in the vibratory regime. Typically, these signatures are manifest below about 3 hertz. 

The color spectrogram of Figure 5 Spectrogram Showing Crew Exercise Periods and 

Relative Quiet Period shows a couple of bouts of exercise between about GMT 10:00 

and 11:00 with the strongest impact (red horizontal streaks) seen below 3 hertz. 

Interesting to note in this figure also is the relative quiet crew period ending at about 

GMT 13:30 as indicated by the vertical dark blue region. This indicates most or all of 

the crew members were relatively still for the 15 minutes or so of the dark blue span.

Urine Processor Assembly (UPA)

Another noticeable, but weak, disturbance source in the vibratory regime is the 

UPA, which is part of the ISS water recovery system in Node 3. The UPA houses a 

distillation assembly centrifuge that was designed to spin at 220 rpm (3.67 hertz). 

Onboard acceleration measurements indicate that it often rotates closer to 221 

rpm (3.68 hertz). This equipment routinely operates continuously for several hours 

Figure 5. Spectrogram Showing Crew Exercise Periods and Relative Quiet Period.

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Σ PSD Magnitude [log 10(g2/Hz)]

GMT 13−December−2012, 348/hh:mm

Frequency (Hz)

Start GMT 13−December−2012, 348/08:00:00.001

from: /misc/yoda/pub/pad, pims, 17−Dec−2012,13:04:33.267

sams2, 121f03

Span = 7.97 hours

Hanning, k = 877

Sum

.

Temp. Res. = 32.768 sec, No = 16384

∆f = 0.015 Hz, Nfft = 32768

500.0000 sa/sec (200.00 Hz)

sams2, 121f03 at LAB1O1, ER2, Lower Z Panel:[191.54 −40.54 135.25]

08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00

0

1

2

3

4

5

6

7

8

9

10

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at a time and leaves a faint, yet distinct narrowband signature in the acceleration 

spectrum. The impact of this disturbance was measured by SAMS in the USL, and 

is also evident in SAMS measurements from the COL. The signature from this 

equipment, however, is much less clear in the JEM. To summarize, the UPA injects 

a weak narrowband signature at just over 3.6 hertz. This narrowband disturbance 

is most distinctive in the USL, with RMS levels of around 38 ug at the SAMS 

es06 sensor location; with RMS levels in the JEM of about 6 ug at the SAMS 

121f05 sensor location. For more information on this disturbance source see http://

pims.grc.nasa.gov/pimsdocs/public/ISS%20Handbook/hb_vib_vehicle_upa_

rev_2011_12_22.pdf. Also, use Table 2 as a reference for sensor locations on the ISS.

Ku-Band Antenna

The Ku-band antenna provides a link for payload communications between the 

ISS and ground stations throughout the world. The antenna is also referred to 

as the space-to-ground antenna and is mounted on a two-axis gimbal assembly 

to allow the dish to rotate for acquisition and line-of-sight tracking of data 

relay satellites. The vibratory signature of the Ku-band antenna is persistent and 

distributed mainly over the frequency range from about 5 hertz to about 20 hertz. 

Extended durations of auto-tracking while locked on current target satellite are 

punctuated by occasional, brief spatial acquisition iterations to lock on to the next 

target satellite and the vibratory motions associated with these functions are seen 

as twin spectral peaks at about 5.2 hertz and 7.8 hertz. Superimposed, there is a 

broad spectral hump between about 5 and 8 hertz, which gets registered to varying 

degrees throughout the ISS. The magnitude of this disturbance at any given sensor 

location is not a function of quiet versus nominal periods, like sleep versus wake, 

because this communications link is maintained around the clock; it does vary with 

Sensor RMS (ug) LAB Location

SAMS 121f08 210 COL COL1A1, ER3, Seat Track near D1

MMA 0bbd 204 JEM JPM1A3 Upper Left

SAMS 121f05 108 JEM JPM1F5, ER4, Drawer 2

SAMS 121f04 99 USL LAB1O2, ER1, Lower Z Panel

SAMS 121f03 72 USL LAB1O1, ER2, Lower Z Panel

SAMS 121f02 136 USL LAB1S2, MSG, Upper Left Seat Track

SAMS TSH es06 109 USL LAB1S4, FIR

Table 2. Ku-Band Antenna, RMS Values (5 < f < 20 hertz).

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time though. For the most part, its impact as a disturbance source is dependent on 

measurement location. Table 2 shows representative values.

For the narrowband nature of the brief acquisition handover periods, see the 

spectral peaks at 5.2 hertz, and 7.8 hertz in Figure 6 Spectrogram Showing Ku-Band 

Acquisition Signature; not seen in this figure are two more narrowband spectral peaks 

at 10.6 hertz and 13.1 hertz.

In summary, the Ku-band antenna described in this section is the dominant 

disturbance source from about 5 hertz to about 20 hertz at all acceleration sensor 

locations analyzed by the Principal Investigator Microgravity Services (PIMS) team. 

Its acceleration signature is characterized by a semi-regular pattern of frequency 

sweeps that are evident on a time scale of an orbital period. Measurements show this 

disturbance source registers loudest at the SAMS 121f08 location in the COL at 

about 210 ugRMS.

Figure 6. Spectrogram Showing Ku-Band Acquisition Signature.

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−6

Σ PSD Magnitude [log 10(g2/Hz)]

GMT 16−September−2011, 259/hh:mm

Frequency (Hz)

Start GMT 16−September−2011, 259/08:00:00.001

from: /misc/yoda/pub/pad, pims, 25−Mar−2013,12:47:10.598

sams2, 121f03

Span = 7.97 hours

Hanning, k = 877

Sum

.

Temp. Res. = 32.768 sec, No = 16384

∆f = 0.015 Hz, Nfft = 32768

500.0000 sa/sec (200.00 Hz)

sams2, 121f03 at LAB1O1, ER2, Lower Z Panel:[191.54 −40.54 135.25]

08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00

0

1

2

3

4

5

6

7

8

9

10

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Russian SKV Air Conditioner

The Russian SKV air conditioner is part of the Environmental Control and Life 

Support System. This equipment gives rise to another common vibratory disturbance 

that shows up at all sensor measurement locations. It is tightly controlled in frequency 

producing narrowband vibrations at 23.5 hertz. These vibrations were measured as 

loudest in the USL at the 121f03 and 121f04 locations at about 29 ugRMS.

SAMS Fan

There is a SAMS fan that produces a narrowband vibration at 47 hertz. This 

disturbance is only detectable at sensor locations near ER1 in the USL. At the SAMS 

121f04 location on LAB1O2, it is registered with an RMS level of about 174 ug.

General Laboratory Active Cryogenic International Space Station Experiment 

Refrigerator (GLACIER)

The GLACIER is a water-cooled freezer that provides cryogenic transportation and 

preservation of samples requiring temperatures as low as minus 160 degrees Celsius. 

Acceleration spectral analysis shows the vibratory impact of this equipment was 

focused primarily in three narrowband peaks at 60 hertz, 120 hertz, and 180 hertz. 

Since these are common operating frequencies, it is likely that some of the energy in 

these bands is attributable to other equipment as well. Acceleration measurements 

indicate the epicenter of this disturbance’s 60 hertz component is in the USL near 

ER1 (the 121f04 location on LAB1O2 at about 1027 ugRMS), and it was also loud 

near ER2 (the 121f03 location on LAB1O1 at about 911 ugRMS) and to a much 

lesser extent near the MSG (the 121f02 location at about 97 ugRMS). The other 

components shake out as follows: the 120 hertz component was loudest at 121f03 

location on LAB1O1 at about 369 ugRMS, next at 121f04 location on LAB1O2 

at about 227 ugRMS, and least so at 121f02 location on the MSG at about 102 

ugRMS. The 180 hertz component had the lowest impact with 194 ugRMS at 

121f04 location on LAB1O2, 133 ugRMS at 121f03 location on LAB1O1, and 41 

ugRMS at 121f02 location on the MSG, and it was not distinguishable at the JAXA 

MMA 0bbd sensor location on JPM1A3.

Common Cabin Air Assembly (CCAA)

The CCAA in the USL provides the capability to control the cabin air temperature, 

maintain the humidity level within desired limits and generate ventilation air flow. 

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During a normal shutdown operation of the CCAA, the inlet fan speed is reduced 

from about 5,700 RPM (about 95 hertz) to about 3,400 RPM (about 57 hertz). At 

that point, the water separator continues to operate at about 5,900 RPM (about 98 

hertz) for approximately three hours to accomplish dry-out prior to final shutdown. 

Both fans are then shut down during the transition from the port side CCAA to the 

starboard CCAA. Operation of the water separator results in the primary impact of 

this system on the microgravity environment. The water separator has a narrowband 

signature at about 98 hertz and imparts RMS levels as follows (see Table 2 for sensor 

locations): about 557 ugRMS at the 121f03 location, 397 ugRMS at the 121f02 

location, 232 ugRMS at the 121f04 location, and 39 ugRMS at the SAMS es06 

location.

Control Moment Gyroscopes (CMGs)

There are four CMGs located on the Z1 truss structure of the ISS. These rotate at 

6,600 RPM to provide angular momentum. The immutable laws of physics allow 

flight controllers to tap into inherent torque and use it as a non-propulsive means 

of attitude control for the space station. As seen by the narrow spectral peak at 

110 hertz in the figure at this link http://pims.grc.nasa.gov/plots/batch/year2013/

month01/day03/2013_01_03_00_00_00.000_121f03_pcss_roadmaps500.pdf, 

these gyros are tightly controlled in frequency and register most distinctly in the 

USL with RMS levels of about 61, 65, and 111 ugRMS at the 121f02, 121f04, and 

121f03 sensor locations, respectively.

The Transient Regime

The transient regime describes accelerations that are impulsive in nature. That is, 

brief yet relatively large amplitude accelerations that can often excite structural 

modes. These accelerations are associated with events like thruster firings for 

reboosts or attitude maneuvers, which are more globally felt and can include crew 

push-offs and landings, which tend to be more localized. An example of this type of 

disturbance is documented at this link http://pims.grc.nasa.gov/pimsdocs/public/

ISS%20Handbook/hb_vib_vehicle_progress50p_docking.pdf.

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 17 6/13/16 
18

The microgravity acceleration environment of the ISS is quite dynamic. The user 

community is diverse with concerns ranging from structural integrity of the vehicle 

to experiment resonances and sensitivities. See Figure 7 Acceleration Environment 

Feedback Model for an overview of the PIMS team interaction with the user 

community. The PIMS project supports Microgravity Research Program Office 

principal investigators in the science disciplines of biotechnology, combustion 

science, fluid physics, materials science and fundamental physics. PIMS plays an 

active role throughout the experiment life cycle with involvement and support 

during experiment planning, performance and evaluation of results.

Pre-Experiment Services

PIMS contributes to experiment teams through acceleration data analysis specific 

to their particular science. This effort is augmented by more general efforts aimed 

at educating microgravity principal investigators about reduced-gravity experiment 

platforms’ environments and about the accelerometer systems available to measure 

the environments of those platforms. This involvement with experiment teams 

during experiment planning stages results in the collection of acceleration data 

best suited for correlation with measured science data. A fundamental role of 

the PIMS project’s acceleration data support efforts is to archive and disseminate 

acceleration data. The archival of acceleration data provides investigators the means 

to determine the environment under which their experiments were conducted 

and potentially help to plan their future work. PIMS utilizes the archived data to 

support users interested in the microgravity acceleration environment by providing 

Acceleration Environment 

Feedback Model

Figure 7. Acceleration Environment Feedback Model.

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 18 6/13/16 
information about activities and sometimes about acceleration sources. The 

result of this accumulated knowledge base is an improved understanding of the 

expected environment of the various reduced gravity platforms that is passed on to 

investigator teams during the experiment planning process.

Experiment Operations

In addition to providing the proper microgravity environment education during 

experiment planning, PIMS works with investigators to design acceleration 

data displays and analysis techniques best suited for understanding potential 

relationships between measured acceleration data and the science results. A 

number of plot options, displays and analysis techniques are currently available to 

principal investigators. Distribution of the acceleration environment information 

is accomplished primarily through the Internet. The availability of the microgravity 

acceleration data in near real-time can also be employed by investigators as a tool 

for making decisions regarding when to initiate experiment operations and how 

to make adjustments from experiment run to experiment run in order to improve 

science results. This interaction during experiment operations can help lead to 

experimental success.

Post-Experiment Feedback

Post-experiment analysis and interpretation of acceleration data can be the missing 

puzzle piece for investigators trying to determine what factors either helped or 

hindered their results. Correlation with the acceleration record can help expand 

their existing knowledge base and in turn serve those who follow in their footsteps 

or toward future, follow-on investigations.

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 19 6/13/16 
20

NASA’s Glenn Research Center (GRC) is home to many key components of the 

ISS acceleration measurement and analysis program. The GRC has the longestablished goal to provide timely and readily accessible acceleration data and 

related information. Foremost in this pursuit is to capture, process and archive the 

acceleration measurements, which continuously stream from the space station. 

Furthermore, it offers analysis services for the microgravity community in general 

and with the capability to provide tailored products for scientific payloads, 

structural dynamics monitoring, and technology developers. As a means to fulfill 

its acceleration program goals, the GRC sponsors the SAMS, the Microgravity 

Acceleration Measurement System (MAMS), and the PIMS projects.

Space Acceleration Measurement System (SAMS)

SAMS has been a cornerstone in the ongoing effort to provide continuous access 

to the vibratory environment on the ISS. This system has a proven track record of 

sustained, reliable performance. It first flew in June 1991 and has flown on nearly 

every major microgravity science mission on the space shuttle. In addition, SAMS 

was used for four years aboard the Russian space station, Mir, where it measured 

accelerations in support of scientific investigations. SAMS has been onboard the 

ISS since 2001. It has streamed acceleration measurement data nearly continuously 

since then in support of principal investigators, technology developers, and the 

microgravity community at-large. Last, but certainly not least, SAMS also plays an 

integral role in daily loads and dynamics monitoring and feeds into the detailed 

analysis aimed at preserving structural integrity and possibly extending the 

longevity of the ISS as a microgravity research platform.

SAMS has the ability to instrument and measure the local vibratory regime (0.01 

< f < 300 hertz) in all three of the ISS laboratories, including throughout the USL. 

The accelerations it measures arise from vehicle activities and subsystems, experiment 

operations, crew movements, and structural dynamics. SAMS Remote Triaxial 

Sensor (RTS) systems are used primarily to monitor the local vibratory environment 

for individual experiments requiring acceleration measurement support, and for 

daily vehicle structural monitoring. Each RTS is capable of measuring acceleration 

disturbances between 0.01 hertz and 400 hertz. Each RTS consists of two 

components: the RTS sensor enclosure (SE), and the RTS electronics enclosure (EE). 

The RTS-SE, is mounted as close to the experiment as possible. There, it measures 

and translates the data into a digital signal, which gets routed to its RTS-EE. The 

RTS-EE, in turn, sends the acceleration data to the SAMS Control Unit (CU). The 

Acceleration System

Description

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 20 6/13/16 
RTS-EE also provides power and command signals for up to two attached RTS-SEs. 

See Figure 8 On-Orbit Photo of SAMS Sensor in USL during Expedition 4 for an 

on-orbit photograph of a SAMS sensor head in the USL during Expedition 4.

An additional sensor called the RTS Ethernet Standalone (RTS-ES) is available for 

acceleration measurement support. The RTS-ES is capable of making acceleration 

measurements in standalone fashion, and therefore does not require an RTS-EE for 

power or for command/data routing.

All SAMS RTSs are linked together by the CU, which coordinates the command 

and telemetry data for the various RTS systems being used throughout the ISS. All 

acceleration data obtained by each SAMS RTS are routed to the CU for downlink 

to the ground. The command and control for each RTS is accomplished through 

the CU, which has a laptop computer with a Linux operating system as its main 

component. Once the CU receives the measurements from the RTS systems, it 

checks the data for completeness, breaks the data into well-defined information 

packets, then sends those packets to the SAMS Ground Operations Equipment 

located at the Telescience Support Center at the GRC.

Microgravity Acceleration Measurement System (MAMS) 

MAMS has also played a long-standing role in providing continuous access to the 

acceleration environment on the ISS. However, in this case, the MAMS primarily 

monitors the quasi-steady acceleration regime (f < 0.01 hertz) of the space station. It 

Figure 8. On-Orbit Photo of SAMS Sensor in USL during Expedition 4.

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 21 6/13/16 
22

consists of two accelerometer subsystems: the OARE Sensor Subsystem (OSS) and 

the High-Resolution Accelerometer Package (HiRAP). The OSS is its low-frequency 

sensor, which was uniquely designed to characterize the quasi-steady environment 

of the space station for both scientific payloads and vehicle teams. The HiRAP is a 

vibratory sensor that monitors the local vibratory environment up to 100 hertz at 

the MAMS location on the ISS. MAMS is located in LAB1O2 (ER1) of the USL. 

The OSS data are typically trimmed-mean filtered to better extract the quasi-steady 

acceleration information (below 0.01 hertz) from its raw measurements. This lowmagnitude, low-frequency data is thus rendered and ready to be mapped to any 

arbitrary location on the space station using rigid-body assumptions.

The MAMS measurements serve to complement the SAMS for comprehensive 

coverage of the ISS acceleration environment. The MAMS provides global, 

quasi-steady information below 0.01 hertz, while the SAMS gives the localized 

vibratory acceleration environment nominally between 0.01 and 200 hertz. In this 

way, analysts, investigators, and researchers have access to the entire spectrum of 

disturbances that may affect what interests them.

Principal Investigator Microgravity Services (PIMS) 

The prime directive of the PIMS team is to support principal investigators who 

are conducting microgravity research on the ISS. PIMS also plays a support role 

for loads and dynamics analysis with regards to vehicle-sustaining engineering. In 

general, PIMS ongoing efforts aim to qualify, quantify, and otherwise assess and 

characterize the space station microgravity environment as it operates and evolves 

in order to capture and convey the acceleration effects on experiments, payloads, 

and structural dynamics. PIMS also responds to ad hoc user requests that typically 

include time-based or frequency-based concerns. These requests often give rise to 

specific, tailored displays and analyses of acceleration measurements and related 

data. The resulting displays and analyses are either newly developed or refined from 

existing ones and bring to front-and-center the specific concerns of researchers or 

structural dynamics analysts. PIMS then deploys the appropriate suite of resources, 

displays, and analysis tools to extract features of the acceleration environment that 

target the investigator’s concerns.

As an example, the lowest-frequency structural mode, “mode one” of the ISS 

described earlier has been monitored daily since GMT, March 9, 2012, using a 

tailored product set. These products seek to both qualify and quantify some key 

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 22 6/13/16 
vibrational features of the space station’s main truss. See Figure 9 Sample of Daily 

Products Used to Monitor Loads Events for Structural Integrity for an eight-hour 

example of these plots. This shows qualitatively a zoom-in on the low-end of the 

structural mode regime with a very fine frequency resolution spectrogram. It also 

plots features extracted from the vibratory data in the form of RMS acceleration 

versus time as the topmost subplot in that figure and the frequency of interest (foi) 

versus time shown in the subplot just above the spectrogram. Based on products like 

these, it is clear from the analysis of SAMS measurements how this lowest station 

structural mode has slowly changed over time. Its frequency has fluctuated somewhat 

around 0.1 hertz and has shown correlation with other station-related phenomena, 

such as the solar beta angle, vehicle dockings, and so on. While this “mode one” 

example highlights PIMS contributions to structural monitoring, it should be noted 

that this work serves primarily as a starting point that leads to more in-depth analysis 

by vehicle loads and dynamics engineers. It serves as a daily guide as to when the 

Figure 9. Sample of Daily Products Used to Monitor Loads Events for Structural Integrity.

−12

−11

−10

−9

−8

−7

−6

0

10

20

ugRMS 0.05

0.1

0.15

foi (Hz)

Σ PSD Magnitude [log 10(g2/Hz)]

GMT 11−October−2010, 284/hh:mm

Frequency (Hz)

Start GMT 11−October−2010, 284/00:00:00.001

from: /misc/yoda/pub/pad, pims, 06−May−2013,15:51:42.355

sams2, 121f03006

Span = 7.86 hours

Hanning, k = 727

Sum

.

Temp. Res. = 38.986 sec, No = 60000

∆f = 0.002 Hz, Nfft = 65536

142.0000 sa/sec (6.00 Hz)

sams2, 121f03006 at LAB1O1, ER2, Lower Z Panel:[191.54 −40.54 135.25]

00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 08:00

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

median = 0.695 ug

median = 0.102 Hz

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 23 6/13/16 
24

behavior of station structures are status quo or perhaps deserve a more in-depth look. 

Over the years, engineers have incorporated the wealth of vibratory measurements 

from the SAMS into their mathematical models to further identify what factors 

will govern this mode, when and under what conditions. Ultimately, the empirical 

information from SAMS has led to improvements of model estimates whereby the 

ISS program benefits with increased confidence regarding the impact of vehicle load 

events and in engineering estimates of structural life.

The JAXA sponsors and operates the MMA aboard the ISS. The MMA is dedicated 

to monitoring and characterizing the local vibratory environment in the JEM. The 

MMA does not operate continuously. It operates as needed to support science via a 

ground-commanded on/off scenario. After collecting a few days of data, the MMA 

team at JAXA uploads raw acceleration data files to an FTP server at the NASA 

GRC. The PIMS team processes these data for inclusion in the acceleration archive 

hosted by a web server at NASA’s GRC.

In addition to roadmap spectrograms and the other Web-based products that they 

produce on a daily basis, the PIMS team also creates and compiles microgravity 

handbook pages at http://pims.grc.nasa.gov/handbook. This handbook is an effort 

to educate potential users of the ISS as a microgravity platform. It highlights 

features of the microgravity environment that may be relevant to a particular 

experiment in some respect. These handbook pages also help to see where 

opportunities or pitfalls may exist. For example, if a potential user’s payload or 

experiment has a resonant frequency near 24 hertz, then the handbook page 

that describes the Russian air conditioner may be of interest. The information 

contained in these handbook pages is not comprehensive but serve more so from 

the perspective of a conversation starter. It gives future investigators an idea about 

what disturbances to expect and is intended to spark follow-up questions about how 

to use the ISS in their discipline and maybe to motivate follow-up, focused analyses.

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 24 6/13/16 
The Acceleration Measurement Program (AMP) at NASA’s GRC receives, archives, 

processes, analyzes, displays, and shares acceleration measurements from the ISS. 

The acceleration archive includes data from the SAMS and MAMS, both of which 

are sponsored by NASA. The archive also includes data from the MMA, which 

is sponsored and operated within the JEM aboard the ISS by JAXA. Like any 

good archive, the goal here is to preserve detailed records of the ISS acceleration 

environment for past, present and future platform users. Those interested in using 

the acceleration measurement data can browse starting at this link: http://pims.

grc.nasa.gov/ftp/pad. Alternatively, some processed data can be viewed starting at 

this link: http://pims.grc.nasa.gov/roadmap. This roadmap view is recommended 

as a good starting point for those interested in an overview of the ISS microgravity 

environment as it evolves over time.

The SAMS and MAMS stream data from the ISS nearly continuously, and MMA 

captures data occasionally, as needed. In the roughly 15 years between May 3, 2001 

and April 1, 2016, the archive at NASA’s GRC has grown to over 14 terabytes 

Acceleration Data Archives

Figure 10. Acceleration Data Archives.

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 25 6/13/16 
26

of ISS acceleration measurements from SAMS, MAMS and JAXA’s MMA. The 

longevity of these acceleration measurement systems pays tribute to their robust 

design plus sustaining engineering and maintenance operations allocated by NASA 

in the interest of its customers. In the roughly 131,000 hours that have transpired 

between May 3, 2001, and April 1, 2016, the SAMS and MAMS have accrued 

over 662,000 hours of acceleration measurements from multiple sensors operating 

simultaneously. See Figure 10 Acceleration Data Archives for an acceleration archive 

summary and depiction.

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 26 6/13/16 
The PIMS website makes available to the public a microgravity environment 

handbook at http://pims.grc.nasa.gov/handbook. This handbook is a compilation 

of information aimed at characterizing specific aspects or features of disturbance 

sources measured on the ISS. The main categories in this handbook are the 

acceleration regime for the given entry: quasi-steady, vibratory, or transient. These 

are further sub-categorized with respect to the disturbance source: crew-, vehicle- or 

equipment-related. Most handbook entries characterize the disturbance source of 

interest in two primary ways: qualify and quantify.

First for a handbook entry, there is typically one page dedicated to qualifying the 

effects of the disturbance source being presented. For the vibratory regime, this is 

usually a color spectrogram that shows boundaries and structure in both time and 

frequency. The third dimension on these spectrogram plots is represented by color, 

which gives a crude indication of magnitude. For the quasi-steady and transient 

regimes, this qualification is usually in the form of a three-panel, per-axis plot of 

acceleration versus time.

Secondly for an entry, there is usually a page dedicated to quantifying the effects 

of the disturbance source. This is intended to address questions like how much 

or which direction. For the vibratory regime, this quantification is usually some 

form of RMS plot versus time for a given frequency band. For the quasi-steady 

and transient regimes, some form of table or plot that depicts average or peak 

acceleration during the event of interest is the means of quantifying.

Finally, most handbook entries include unique details gleaned from analysis of 

the acceleration measurements and some handbook entries include interesting or 

ancillary information that are pertinent or related to the topic at hand. We give 

three examples in the next three subsections from among the many available on the 

Web: (1) a quasi-steady regime example of reboosts, (2) a vibratory regime example 

of the Ku-band antenna, and (3) a transient regime example of crew push-off.

Quasi-Steady Regime Example, Progress Reboost

The handbook page titled “Progress Reboost” is quite comprehensive. It provides 

analysis results from measurements made by MAMS that cover more than 60 

reboost events spanning over a decade of ISS history. The first page describes the 

primary quasi-steady effect of a reboost performed by a Russian Progress cargo 

vehicle. Recall that aerodynamic drag on the ISS leads to a gradual, inward spiral 

toward the Earth. Thus, a reboost is needed and achieved by firing thrusters in a 

Acceleration Environment 

Handbook

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 27 6/13/16 
28

direction opposite the direction of flight. As Newtonian mechanics go, the net 

result is a velocity increase in the direction of travel for the station. A reaction force 

spirals its trajectory outward to a higher altitude. Examination of this handbook 

entry shows that the salient features of a reboost are a step up in X-axis acceleration 

during the several minutes of the event. See this link: http://pims.grc.nasa.gov/

pimsdocs/public/ISS%20Handbook/hb_qs_vehicle_ProgressReboost.pdf.

Vibratory Regime Example, Ku-Band Antenna

The handbook page titled “Ku-Band Antenna” shows an interesting evolution from 

an unknown disturbance source. While the vibratory regime can be accurately 

quantified by the SAMS at up to 1,000 times per second, much of that has not 

been fully qualified. We do not always know what specific source gives way to the 

accelerations we measure at the accelerometer locations. The Ku-band antenna is 

one example of an interesting, nearly continuous vibratory disturber that eventually 

was identified as a vibratory disturbance source. For investigators with sensitivity 

or concern between about 5 hertz and 20 hertz, the Ku-band antenna is a vibratory 

disturbance source that must be considered. Its handbook entry is a good place to 

start. See this link: http://pims.grc.nasa.gov/pimsdocs/public/ISS%20Handbook/

hb_vib_vehicle_ku.pdf.

Transient Regime Example, Crew Glovebox Push-Off

The handbook page titled “Crew Glovebox Push-Off” shows the effects of crew 

push-off events. These come from the interaction between the crew and space station 

structure that yield relatively brief but large transient accelerations. Typically, these 

push-off transients are associated with crew locomotion and are accompanied to 

varying degrees by crew landing on other structure located some distance away. 

Transient events such as these tend to have two main effects on the microgravity 

environment: (1) an initial, brief acceleratory spike followed by (2) ringing excitation 

of space station structural modes. See this link: http://pims.grc.nasa.gov/pimsdocs/

public/ISS%20Handbook/hb_vib_crew_msgpushoff_rev_2003_09_02.pdf.

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 28 6/13/16 
The microgravity environment affects your science. Otherwise, you would not 

be going through the extraordinary measures that are needed to conduct your 

science on the space station; from ground-based development or pilot studies, 

station manifest, documentation, review cycles, verification, crew training, launch, 

deployment and so on through to experiment runs and, in some cases, sample 

return. Therefore, it is important to consider the effects that the microgravity 

environment will have on the phenomena you are studying. In some cases, it is 

important to consider the ancillary apparatus or mechanisms used to observe or 

gather your results and not just the underlying scientific facets of your investigation.

For example, the vibratory environment at your site might not have deleterious 

effects on the physical phenomena you are investigating, but the cantilever-mounted 

thermistor you need to gather temperatures might have a resonant frequency near a 

persistent disturbance source (e.g., a neighboring pump, fan, etc.) on the station. In 

any case, knowledge is power, so it behooves your design to develop your experiment 

and related equipment with knowledge of the microgravity environment to which 

you experiment will be exposed. In addition, during your actual science runs and 

data collection, knowledge of the microgravity environment during your critical 

time frames is important, in some cases paramount, and can lead to improved 

understanding of your results or the factors that led to those results, good or bad, 

either way. One such lesson learned came from a liquid-bridge experiment that 

happened to have a resonant frequency close to a space station structural mode. 

Investigators used this information for mitigation. They scheduled their critical runs 

during crew sleep when that structural mode tends to die down. From a microgravity 

environment user perspective, it is important to consider the spatial, temporal, and 

spectral aspects of the environment.

In spatial terms, the location and orientation of your experiment can be key 

factors. For example, proximity to the space station’s center of mass dictates 

much of the quasi-steady acceleration variations your payload will experience. 

Generally, the closer you are to the center of mass, the more quiescent the quasisteady acceleration environment. In addition, proximity to other equipment (e.g., 

an adjacent rack fan, pump, etc.) can play a major role in shaping the vibratory 

accelerations to which your payload is subjected.

In temporal terms, the daily cycles of crew sleep or occasional vehicle-related 

events might be a consideration for you. The crew typically wakes daily at 

GMT 06:00 (although that can vary), and this wake transition can clearly be 

Acceleration Measurement 

Availability

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 29 6/13/16 
30

felt in SAMS vibratory measurements. Also, the space station has a large crosssectional area, so atmospheric drag causes its orbit to decay over time. As a result, 

reboosts are scheduled to reclaim its desired altitude. See the following YouTube 

video for some clear and visible effects of a reboost http://www.youtube.com/

watch?v=8MR3daaWLXI. Other scheduled events to consider are vehicle dockings 

and extravehicular activities. A wild card in terms of scheduling is debris avoidance 

maneuvers. These are unplanned, but vital to safety.

In spectral terms, vehicle structural modes below about 5 hertz, Ku-band antenna 

motion between about 5 to 17 hertz, rotating or reciprocating equipment for 

vehicle systems or experiment operations ranging up to and above 400 hertz, are 

just some of the constituents of the wide spectrum of vibratory disturbance sources 

that comprise the vibratory regime.

The solution for acceleration measurement and support for you in all three 

laboratories of the ISS is the Acceleration Measurement Program (AMP), which 

is sponsored and managed at NASA’s GRC. The AMP offers two independent 

systems that were designed to give continuous coverage of the ISS acceleration 

environment from the low-frequency, low-magnitude quasi-steady regime up 

to the relatively high-frequency, higher-magnitude vibratory regime. The Space 

Acceleration Measurement System (SAMS) is a distributed system to measure 

the vibratory environment, while the Microgravity Acceleration Measurement 

System (MAMS) measures the quasi-steady environment on board the ISS. Both 

the SAMS and the MAMS have been operating nearly continuously since 2001. 

The acceleration measurements from these systems are a resource available to assist 

ISS users with correlating experimental results with the acceleration environment. 

In addition, the PIMS project at NASA’s GRC processes these data and can assist 

with tailored analysis or displays of the SAMS and MAMS data in support of 

principal investigators and other ISS customers upon request. Table 3 Acceleration 

Measurement Systems below shows a broad overview with system specifications.

How to Request SAMS Support

There are indirect methods to request SAMS support within the ISS program 

infrastructure. For example, you can submit an Operations Change Request (OCR) 

to the Enhanced HOSC System (EHS). However, the most direct method is to 

contact the Acceleration Measurement Program (AMP) manager at the NASA 

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 30 6/13/16 
GRC. In this way, experienced knowledge of these acceleration measurement 

systems along with logistical considerations can be directly addressed. The best 

place to start that process is to send an email to pimsops@grc.nasa.gov. Some of the 

questions to consider for making a request for SAMS support are listed here:

• Spatial: where is your payload, and where can we mount a sensor to support 

you?

• Temporal: what GMT time frame(s) do you need SAMS support?

• Spectral: what frequency range governs your sensitivity or concern?

You may not know the answers to all of these questions up front, but the more you 

bring to the discussion, the better the service that can be provided right away. In 

addition, from these fundamental questions, a tailored set of displays or analysis can 

be discussed and possibly deployed to directly support your concerns.

SAMS MAMS

RTS TSH-ES OSS HiRAP

Increment 36 

Deployment

3 triaxial sensors in USL

1 triaxial sensor in JEM

1 triaxial sensor in COL

1 triaxial in USL/FIR

1 triaxial in USL/CIR

1 triaxial sensor in USL 1 triaxial sensor in US

Description 3 orthogonal 

accelerometers, QA-3100

3 orthogonal 

accelerometers, QA-3100

MESA sensor with 

calibration table

3 orthogonal 

accelerometers, 

pendulous

Measured Quantity transient + vibratory, linear 

acceleration

transient + vibratory, linear 

acceleration

quasi-steady, linear 

acceleration

transient + vibratory

linear acceleration

Bandwidth 0.01 – 400 hertz 0.01 – 400 hertz DC – 1 hertz 10-4 – 100 hertz

Maximum Scale 1.1 g @ gain = 1

0.11 g @ gain = 10

1.1 g @ gain = 1

0.13 g @ gain = 8.5

10 – 25 mg 16 mg

Resolution 0.1 ug 0.1 ug 3 – 4.6 ng 1 ug

Dimensions (inches) 5.9x4.5x3.4 (SE)

9.1x9.3x4.7 (EE)

4.45x3.65x3.53 21.9x18.4x23.6

Weight (lbs) 2.5 (SE)

11 (EE)

1.3 117

Power (W) 2.25 (SE)

8 (EE)

4.5 @ +/- 15 VDC

7.5 @ 28 VDC

79

Data Interface Ethernet Ethernet, RS-232, USB Ethernet

Table 3. Acceleration Measurement Systems

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32

By the way, why does this section only address SAMS? What about MAMS? That 

answer comes from the nature of each system’s measurements. The SAMS is a 

distributed set of sensors intended to measure vibratory accelerations, which by 

their nature are localized. In this case, it is desirable to mount a sensor as close as 

practical to your payload in order to capture those local vibrations. On the other 

hand, the MAMS is a centralized system intended to measure the quasi-steady 

accelerations experienced onboard the ISS. By their nature, these quasi-steady 

accelerations tend to be global, not localized. At such low-frequencies in the 

quasi-steady regime, the space station can be assumed to be a rigid body. As such, 

the MAMS acceleration measurements made in the USL can be mathematically 

mapped to any arbitrary location on the ISS while accounting for gravity gradient 

and rotational effects that come with being displaced from the vehicle’s center of 

mass. You are already covered in the quasi-steady regime by MAMS as long as you 

know your location of interest.

NP-2015-11-040-JSC-Acceleration Environment-ISS-mini-book-060716.indd 32 6/13/16 
The SAMS and MAMS were designed to support a broad array of scientific 

disciplines, including those affiliated with NASA’s Physical Sciences Research 

Program. The AMP at NASA’s GRC offers analysis and measurement services for 

these scientific payload customers along with vehicle loads and dynamics analysis 

customers. In addition, NASA is committed to providing the U.S. segment of the 

ISS as a national laboratory. As a result, ongoing microgravity acceleration services 

are available to support investigators and research.

Scientific Payloads

The ceilings, walls and floors of all three laboratories of the ISS are filled with 

racks, facilities and equipment. Much of this equipment is used in direct support 

of scientific investigations led by principal investigators, who went through 

extraordinary lengths in order to conduct their experiments in a microgravity 

environment. Their primary focus, of course, is on fundamental and applied 

research in fluid physics, combustion science, materials science, fundamental 

physics or complex fluids, but at least implicitly, they are also interested in the 

acceleration environment to which their payload is subjected. After all, these 

microgravity researchers are on the ISS to take advantage of the fact that their 

experiments, along with everything else in the space station, is free falling. For these 

scientists, phenomena that are gravity-driven (such as buoyancy, convection or 

sedimentation) may be undesirable, so they exploit free fall, which mitigates those 

effects to a great extent. The details, however, are in the microgravity environment 

record and ultimately manifest in their scientific results.

Vehicle Monitoring

The International Space Station represents an ambitious international collaboration. 

It is currently the largest, best-equipped space station ever constructed. It has been 

visited and inhabited by astronauts from 14 countries. Canada, Japan, Russia, 

Belgium, Denmark, France, Germany, Italy, the Netherlands, Norway, Spain, 

Sweden, Switzerland, the United Kingdom and the United States all have a vested 

interest in its longevity and success. With an abundance of momentum, the ISS 

program at-large is interested in keeping the space station in orbit with a service 

life beyond its original plans. However, there are only so many cycles of flexing, 

bending, twisting and so on that key components of the space station can undergo 

before its structural integrity falls below acceptable levels of safety. With this in 

mind, there is a team of engineers at NASA’s JSC that does daily assessments to 

provide feedback to the program in terms of this structural integrity and a crew at 

Acceleration Support 

Services

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34

NASA’s GRC that supports that effort. Much like a seismologist on Earth, these 

engineers use SAMS measurements to monitor the vibratory environment looking 

for significant microgravity acceleration events that would have an impact on the 

structural integrity of the ISS, then further analyze the acceleration measurements 

for those events to assess their impact on the vehicle. In addition to mode one 

monitoring, see Figure 5, on page 12, Spectrogram Showing Crew Exercise Periods 

and Relative Quiet Period as another example that zooms out a bit. This gives 

structural analysts a qualitative look at, for example, the impact from crew exercise, 

with its signature visible between GMT 10:00 and 11:00 just below 3 hertz.

National Laboratory

The U.S. segment of the ISS has been designated as a national laboratory. As such, 

the science facilities and acceleration measurement systems built by NASA are 

made available to private enterprise, such as commercial entities and universities, 

to pursue their own research objectives and applications under the auspices of the 

National Lab. The overall objective is to advance science, technology, engineering 

and mathematics from a platform with a unique environment available nowhere 

on Earth.

Perhaps You

If you are interested in ISS acceleration measurement or analysis services or know 

others who might benefit, but do not fit squarely into one of the headings listed in 

this section, then send an inquiry email to pimsops@grc.nasa.gov. We might be 

able to help you.

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The ISS program offers the SAMS and the MAMS to investigators, technology 

developers and vehicle analysts as a continuous means to monitor the acceleration 

environment. Furthermore, the PIMS team is available upon request to help 

analyze these acceleration measurements and therefore help evaluate the effects of 

the dynamic microgravity environment aboard the space station on your interests. 

Section 6 earlier showed three fundamental considerations when requesting 

acceleration measurement support. Those are in terms of spatial, temporal and 

spectral aspects of the environment. This section seeks to take the next step and 

convey several ways of examining acceleration data. Some of these are from an 

exploratory perspective and others take a keenly focused viewpoint. No single 

method, however, should be regarded as the tell-all description to fully understand 

the acceleration environment and its effects. Each has strengths and weaknesses, 

but in combination or when correlated with other measurements or conditions 

these serve to help those interested to more fully understand the results of their 

experiments, technology or vehicle health.

Descriptions

For starters, it is important to recall that SAMS is intended to characterize the 

vibratory acceleration regime. Simply put, these are the relatively high-frequency, 

high-magnitude accelerations that should mostly be considered as localized to 

the sensor location. On the other hand, the MAMS is intended to characterize 

the quasi-steady acceleration regime. This is the relatively low-frequency, lowmagnitude accelerations that are global in nature. Next, it is worthwhile to consider 

the descriptions in Table 4 Acceleration Analysis and Display Formats alongside 

the information provided in Figure 1, on page 8, Microgravity Environment 

Components.

Where Do I Start Exploring the Space Station’s Acceleration 

Environment?

Roadmaps are a good place to start when exploring. For the vibratory acceleration 

regime, start navigating by date at the following link: http://pims.grc.nasa.gov/

roadmap/. Click a date on the left, then on a link for a plot on the right. These 

roadmap spectrogram products are updated daily, extend back to the early days of 

the ISS and provide a good overview starting point. For the quasi-steady regime, 

start at the following link: http://pims.grc.nasa.gov/plots/batch/Quasi-steady/. 

Primary Plot Types

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For recent data, that have not been turned into roadmaps yet, start at the following 

link: http://pims.grc.nasa.gov/plots/user/buffer/ where you will find a sequence 

of screenshots from the real-time displays maintained at NASA’s GRC Telescience 

Support Center in Cleveland, Ohio.

Finally, for near real-time data, visit http://pims.grc.nasa.gov/pims_iss_index.html

and use the menu under the “Current Real-Time” seen toward the upper left and 

see what’s shaking, so to speak, on the space station. If none of these products fit 

your need, then consider a custom request email to pimsops@grc.nasa.gov.

Name Regime(s) Notes

Power Spectral Density (PSD) versus Frequency vibratory displays distribution of power with respect to frequency

Spectrogram (PSD versus Frequency versus Time) vibratory identify structure and boundaries in time and frequency

displays power spectral density variations with time

Cumulative RMS Acceleration versus Frequency vibratory quantifies RMS contribution at and below a given frequency

Frequency Band(s) RMS Acceleration versus Time vibratory quantify RMS contribution over selected frequency band(s) 

versus time

RMS Acceleration versus One-Third Frequency Bands vibratory quantify RMS contribution over proportional frequency bands

Principal Component Spectral Analysis (PCSA) vibratory summarize magnitude and frequency excursions for key 

spectral contributors over a long period of time

results typically have finer frequency resolution and high 

PSD magnitude resolution relative to a spectrogram at the 

expense of poor temporal resolution

Acceleration versus Time vibratory

transient

quasi-steady

precise accounting of measured data with respect to time

best temporal resolution

Interval Min/Max Acceleration versus Time vibratory

quasi-steady

displays upper and lower bounds of peak-to-peak 

excursions of measured data

good display approximation for time histories on output 

devices with resolution insufficient to display all data in time 

frame of interest

Interval Average Acceleration versus Time vibratory

quasi-steady

provides a measure of net acceleration of duration greater 

than or equal to interval parameter

Interval RMS Acceleration versus Time vibratory provides a measure of effective amplitude versus time

Trimmed Mean Filtered Acceleration versus Time quasi-steady removes infrequent, large amplitude outlier data to give 

residual acceleration versus time

Quasi-Steady Mapped Acceleration versus Time quasi-steady use rigid body assumption and vehicle rates and angles to 

compute acceleration at any location attached to the vehicle

Quasi-Steady Three-Dimensional Histogram (QTH) quasi-steady summarize acceleration magnitude and direction for a 

long period of time

indication of acceleration “center-of-time” via projections onto 

three orthogonal planes

Table 4. Acceleration Analysis and Display Formats

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The ISS offers a microgravity research platform that is currently unrivaled. At 

the same time, there are many creative minds attempting to examine and study 

biological and physical phenomena that push the cutting edge of technology. 

Measurement or detection apparatus designed to peer with unprecedented precision 

inward at fundamental physics, fluids, combustion and material science or looking 

outward at distant cosmology, for example, attempting to determine the radii of 

neutron stars to within plus or minus 5 percent. For these researchers, even the 

microgravity environment provided by the ISS platform itself still perturbs their 

experiment or the equipment needed to make their measurements or observations. 

They need some form of isolation in order to attenuate the vibrations to which their 

experiment is subjected.

In general, there are two basic types of vibration isolation currently in use on the 

ISS. There is a passive type that requires no electrical power or control mechanism 

to achieve the vibration isolation. Also, there is an active type that requires both 

electrical power and a sophisticated control system to work. The table below shows 

a comparison of these two approaches.

Passive Vibration Isolation of the Combustion Integrated Rack (CIR)

The Fluids and Combustion Facility (FCF) takes on the technical challenges of 

experimenting with fluids and combustion in microgravity and provides the services 

and capabilities for conducting cutting-edge research in these disciplines. The CIR 

is part of the FCF and the only combustion research facility aboard the ISS. The 

CIR includes a combustion chamber, fuel and oxidizer control and a number of 

cameras for performing combustion experiments. The CIR is situated such that it 

can be used with the Passive Rack Isolation System (PaRIS), which provides a nonVibration Isolation

Vibration Isolation System Type Advantages Disadvantages

Passive Rack Isolation System (PaRIS) passive low cost

low maintenance

reliable

no power

isolate only higher frequencies

requires large volume

cannot mitigate payload induced vibrations

resonance versus attenuation tradeoff

Active Rack Isolation System (ARIS) active low-frequency 

performance

multiple payloads

standardized user 

interface

high maintenance

sensitive to crew contact

cannot mitigate payload induced vibrations

requires “good neighbors”

Table 5. Vibration Isolation Approaches. (The information in this table was based on a presentation given by Dr. Mark 

Whorton at a Microgravity Environment Interpretation Tutorial (MEIT) in 2004.)

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38

rigid mechanical connection 

between the CIR and 

ISS structure using eight 

spring-damper isolators and 

umbilical cables.

Analysis of SAMS 

measurements show that the 

PaRIS provides attenuation 

as a function of frequency, 

more so at higher frequencies. 

The blue trace power spectral 

densities (PSDs) plotted in 

Figure 11 Power Spectra 

Showing Passive Attenuation 

from PaRIS shows the 

magnitude roll-off with 

frequency associated with the 

SAMS sensor mounted on 

the CIR relative to the red 

trace PSDs on that same plot 

associated with a different 

SAMS sensor mounted on 

a non-isolated rack. Table 6 

gives a different view of this 

attenuation broken down 

into five frequency bands.

The reader is encouraged to refer to 

the last page of the handbook entry 

titled “Exercise PaRIS” at the following 

link to see the dramatic difference 

in acceleration magnitudes in a plot 

of acceleration vector magnitude 

versus time, http://pims.grc.nasa.gov/

pimsdocs/public/ISS%20Handbook/

hb_vib_crew_exercisecomparison.pdf. 

There you will see that the SAMS data 

(low-pass filtered at 6 hertz), shows 

Frequency Range

(hertz)

ugRMS

Non-Isolated 

Rack

PaRISIsolated CIR

SAMS 121f03 SAMS es05

0.01 - 1 13 13

1 - 2 85 41

2 - 3 69 26

3 - 4 34 10

4 - 5 15 4

Table 6. Comparison Showing PaRIS Attenuation for 

the CIR.

Figure 11. Power Spectra Showing Passive Attenuation from PaRIS.

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acceleration magnitudes 

at the non-isolated rack 

location averaged about 105 

ug during this crew exercise 

period, while the average was 

about 47 ug at the PaRISisolated CIR location. This 

example shows a quieter 

acceleration environment 

with PaRIS than otherwise 

would be achieved with a 

hard-mounted rack.

Active Vibration 

Isolation of the Fluids 

Integrated Rack (FIR)

The FIR in the FCF provides 

facilities for conducting 

microgravity fluid physics 

research on boiling, cooling, 

colloids, gels, bubbles, 

wetting and capillary action. 

The FIR is located in an 

ARIS rack. The ARIS acts 

to help isolate payloads 

that reside within the rack from disturbances that originate external to the rack. It 

employs sensors that detect rack accelerations and relative position and actuators 

that work to counter the effects of these vibrations. It does so by generating a 

reactive force between the payload 

rack and the ISS structure to which 

it is attached. The principle is similar 

to noise-cancelling headphones if you 

are familiar with those. ARIS is an 

optimized control system with multiple 

components, a sophisticated control 

algorithm and a fair bit of overhead 

and logistics to consider.

Figure 12. Power Spectra Showing Active Attenuation from ARIS.

Frequency 

Range (hertz)

GMT ugRMS

ARIS off ARIS on

0.01 - 20 02-Aug-2011 105 9

05-Aug-2011 96 12

20 - 200 02-Aug-2011 486 479

05-Aug-2011 480 469

Table 7. Comparison Showing ARIS Attenuation for the FIR.

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40

Analysis of SAMS measurements show that the ARIS also provides attenuation, but 

in this case the attenuation is more so at frequencies below 20 hertz. The blue trace 

PSDs plotted in Figure 12 Power Spectra Showing Active Attenuation from ARIS 

shows the magnitude roll-off with frequency below 20 hertz associated with the time 

span when ARIS was on relative to the red trace PSDs in that same figure associated 

with a different time span for the same SAMS sensor location on the FIR when 

ARIS was off. Table 7 gives a different view of this attenuation broken down into 

two frequency bands.

Note the large differences in acceleration RMS magnitudes below 20 hertz on 

two different days when comparing when ARIS was on versus when it was off. By 

contrast, you can see that above 20 hertz, there is not significant attenuation afforded 

by the ARIS.

Figure 13. RMS versus Time for Five Days with Blue Dots during Sleep Periods (0.01 – 0.1 hertz).

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Time/Location “Vibration Isolation”

When used as designed, both the passive and active vibration isolation systems 

aboard the ISS will deliver a quieter microgravity environment as shown in the 

examples above. However, those vibration isolation systems come with overhead, 

logistics and constraints such that not all payloads can be accommodated. For 

interested payloads that cannot be obliged in this way, knowledge is power. 

Knowledge of the microgravity environment can be leveraged to find quiet times 

and/or quiet places.

For an example of quiet time, consider the effects of crew activity. The vibratory 

impact from the crew (exercise, experiment ops, locomotion) goes away for hours 

at a time during crew sleep. If you can conduct sensitive parts of your procedure 

without need for the crew, then these are predictable times you can exploit. 

Figure 14. RMS versus Time for Five Days with Blue Dots during Sleep Periods (0.0101 – 6 hertz).

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42

Figure 13 RMS versus Time for Five Days with Blue Dots during Sleep Periods (0.01 

– 0.1 hertz) is a plot of RMS acceleration versus time for five consecutive days. The 

RMS value comes from a portion of the acceleration spectrum between 0.01 and 0.1 

hertz and clearly shows that during sleep (shown with blue dots and ending each day 

with wake at GMT 06:00), the low end of the structural mode regime gets much 

quieter. Crew motion tends to excite low-frequency vibrations in large space station 

structures, so crew sleep allows for much of those vibrations to die down.

Figure 14 RMS versus Time for Five Days with Blue Dots during Sleep Periods 

(0.0101 – 6 hertz) is a plot of RMS acceleration versus time for the same five 

consecutive days as the previous figure. The RMS value comes from a portion of 

the acceleration spectrum between 0.01 and 6 hertz and also shows similar quieting 

during sleep.

Figure 15 RMS versus Time for Five Days with Blue Dots during Sleep Periods 

(0.101 – 30 hertz) is a plot of RMS acceleration versus time for, again, the same 

Figure 15. RMS versus Time for Five Days with Blue Dots during Sleep Periods (0.101 – 30 hertz).

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five consecutive days. The RMS value comes from a portion of the acceleration 

spectrum between 0.01 and 30 hertz and does not show significant quieting during 

sleep. This portion of the acceleration spectrum is dominated by higher frequency 

disturbance sources above about 6 hertz (e.g., Ku-band antenna) that does not 

benefit from crew sleep.

Figure 16. Monitor Mode One with SAMS Sensor in USL.

Frequency 

Range (hertz)

Crew ugRMS

Mean Standard 

Deviation

Minimum Maximum

0.01 - 0.1 sleep 0.2700 0.1487 0.1231 1.6116

0.01 - 0.1 wake 1.6701 1.1483 0.1404 16.1994

0.01 - 6 sleep 13.2523 6.9151 6.5849 93.5371

0.01 - 6 wake 26.2189 11.7456 7.9301 106.8510

0.1 - 50 sleep 1155.3400 43.0793 1029.2800 1276.7200

0.1 - 50 wake 1117.6400 81.6025 936.7740 4402.2300

Table 8. Five-Day Statistical Summary Comparison of Crew Sleep to Wake (SAMS 121f04 LAB1O2).

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44

Table 8 shows results from acceleration analysis performed in support of the Cold 

Atom Laboratory sponsored by NASA’s Jet Propulsion Laboratory (JPL). The GMT 

span covered is the same five days as those shown in the previous three figures. 

These results reinforce the assertion that below about 6 hertz there is a statistically 

quieter microgravity environment owing to less excitation of structural modes 

during crew sleep. Conversely, when we consider up to 50 hertz, there is no benefit 

to crew sleep periods in this regard. Again, other higher-frequency disturbance 

sources dominate here.

This comparison of crew sleep to wake shows one way of leveraging your schedule to 

gain some respite from the vibratory impact below about 6 hertz. In an orthogonal 

sense, the location of your payload can also offset or help mitigate the impact of 

vibrations on your payload.

Consider a few locations that were simultaneously measured by SAMS sensors 

in each of the three laboratories for eight hours starting at GMT 17-Dec-2012, 

352/08:00. Comparing the spectrogram of Figure 16 Monitor Mode One with 

Figure 17. Monitor Mode One with SAMS Sensor in JEM.

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SAMS Sensor in USL to the corresponding ones from Figure 17 Monitor Mode One 

with SAMS Sensor in JEM and Figure 18 Monitor Mode One with SAMS Sensor in 

COL to see qualitatively that the SAMS sensor in the USL for the structural mode 

regime is not as harsh as those in the JEM or the COL. Table 9 below summarizes 

this with a focus strictly on the lowest mode at around 0.1 hertz.

The comparison here of the structural mode regime between the three laboratories 

says nothing about the higher-frequency environment at those locations. Different 

portions of the spectrum at different locations throughout the space station are 

subject to their vibratory neighborhood. Nevertheless, it can be seen that location can 

provide another approach to governing the acceleration environment you inhabit.

Table 9. Comparison of Mode One SAMS Measurements in All Three Laboratories.

Figure 18. Monitor Mode One with SAMS Sensor in COL.

Laboratory SAMS Sensor ugRMS

USL 121f03 1.839

JEM 121f05 3.133

COL 121f08 3.138

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46

For good background information on microgravity environment, see http://pims.

grc.nasa.gov/MMAP/PIMS_ORIG/MEIT/meit2004pdfs.html.

For more details on acceleration analysis methods, see http://pims.grc.nasa.gov/

MMAP/PIMS_ORIG/PDFs/ADAPT.pdf. 

References

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ARED Advanced Resistive Exercise Device

ARIS Active Rack Isolation System

CCAA Common Cabin Air Assembly

CEVIS Cycle Ergometer with Vibration Isolation System

CIR Combustion Integrated Rack

CMG Control Moment Gyroscope

COL Columbus Module

FCF Fluids and Combustion Facility

foi frequency of interest

GLACIER General Laboratory Active Cryogenic International Space Station 

Experiment Refrigerator

GMT Greenwich Mean Time

GRC Glenn Research Center

HiRAP High-Resolution Accelerometer Package

ICU Interim Control Unit

ISS International Space Station

JAXA Japanese Aerospace Exploration Agency

JEM Japanese Experiment Module

MAMS Microgravity Acceleration Measurement System

MEIT Microgravity Environment Interpretation Tutorial

MMA Microgravity Measurement Apparatus

PaRIS Passive Rack Isolation System

PIMS Principal Investigator Microgravity Services

PSD Power Spectral Density

RMS Root Mean Square

RTS Remote Triaxial Sensor

SAMS Space Acceleration Measurement System

SE Sensor Enclosure

SSA Space Station Analysis

TVIS Treadmill with Vibration Isolation and Stabilization

UPA Urine Processor Assembly

USL United States Laboratory

Acronyms

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48

The Complete ISS Researcher’s 

Guide Series

1. Acceleration Environment

2. Cellular Biology

3. Combustion Science

4. Earth Observations

5. Fluid Physics

6. Fruit Fly Research

7. Fundamental Physics

8. Human Research

9. Macromolecular Crystal Growth

10. Microbial Research

11. Microgravity Materials Research

12. Plant Science

13. Rodent Research

14. Space Environmental Effects

15. Technology Demonstration

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For more information...

Space Station Science

http://www.nasa.gov/iss-science

Facilities

http://www.nasa.gov/mission_pages/station/research/

facilities_category.html

ISS Interactive Reference Guide:

http://www.nasa.gov/externalflash/ISSRG/index.htm

Researchers/Opportunities

http://www.nasa.gov/mission_pages/station/research/

ops/research_information.html

ISS Research Customer Helpline

JSC-ISS-research-helpline@mail.nasa.gov

281-244-6187

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50

National Aeronautics and Space Administration

Johnson Space Center

http://www.nasa.gov/centers/johnson

www.nasa.gov

NP-2015-11-040-JSC

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