Alpha Magnetic Spectrometer - 02 (AMS-02) - 11.22.16

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
Stars, planets and the molecules that make them are only about five percent of the total mass in the universe — the rest is either dark matter or dark energy, but no one has ever seen this material or been able to study it. What’s more, the Big Bang theory holds that the universe should be made of equal parts matter and antimatter, but scientists have never detected naturally occurring antimatter. The Alpha Magnetic Spectrometer - 02 looks for evidence of these mysterious substances, along with very high-energy radiation coming from distant stars that could harm crewmembers traveling to Mars.
Science Results for Everyone
The Alpha Magnetic Spectrometer (AMS-02) has collected and analyzed billions of cosmic ray events, and identified 9 million of these as electrons or positrons (antimatter). The number of high energy positons increases steadily rather than decaying, conflicting with theoretical models and indicates a yet to be identified source of positrons. Researchers also observed a plateau in the positron growth curve and need additional data to determine why. Results suggest that high-energy positrons and cosmic ray electrons may come from different and mysterious sources. Solving the origin of cosmic rays and antimatter increases understanding of our galaxy.

The following content was provided by Samuel C. Ting, Ph.D., Manuel Aguilar-Benitez, Silvie Rosier-Lees, Ph.D., Roberto Battiston, Shih-Chang Lee, Stefan Schael, Martin Pohl, and is maintained in a database by the ISS Program Science Office.
Experiment Details

OpNom: AMS

Principal Investigator(s)
Samuel C. Ting, Ph.D., Massachusetts Institute of Technology, Cambridge, MA, United States
Manuel Aguilar-Benitez, Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, Madrid, Spain
Silvie Rosier-Lees, Ph.D., Laboratoire d’Annecy-Le-Vieux de Physique des Particules and Universite de Savoie, Annecy-Le-Vieux, France
Roberto Battiston, Istituto Nazionale di Fiscica Nucleare-Sezione di Perugia and Universita di Perugia, Perugia, Italy
Shih-Chang Lee, Academia Sinica, Taipei, Taiwan
Stefan Schael, Physikalisches Institut B, Aachen, Germany
Martin Pohl, Departement de Physique, Université de , Genève, Switzerland

Information Pending

United States Department of Energy, Washington, DC, United States
United States
Massachusetts Institute of Technology, Cambridge, MA, United States
University of Maryland, Institute for Physical Science and Technology (IPST), College Park, MD, United States
Yale University, Physics Department, New Haven, CT, United States
Sezione INFN and Dipartimento di Fisica, Università degli Studi di Bologna, Bologna, Bologna, Italy
Istituto di Ricerca sulle Onde Elettromagnetiche, IROE, CNR, Firenze, Italy
Sezione INFN and Dipartimento di Fisica, Universita degli Studi di Milano-Bicocca, Milano, Italy
Sezione INFN and Dipartimento di Fisica, Universita degli Studi di Perugia, Perugia, Italy
Laboratorio SERMS, Polo Universitario di Terni, Terni, Italy
Sezione INFN and Dipartimento di Fisica, Universita degli Studi di Pisa, Pisa, Italy
Sezione INFN and Dipartimento di Fisica, Universita degli Studi di Roma 'La Sapienza', Roma, Italy
Dipartimento di Fisica, Universita degli Studi di Siena, Siena, Italy
Academia Sinica, Institute of Physics, Taipei, Taiwan
National Central University (NCU), Taipei, Taiwan
National Taiwan University (NTU), Taipei, Taiwan
Chung Shan Institute of Science and Technology (CSIST), Lungtan, Taiwan
Rheinisch-Westfälische Technische Hochschule (RWTH), I. Physikalisches Institut (B), Aachen, Germany
Karlsruhe Institut fur Technologie (KIT), Universität Karlsruhe, Karlsruhe, Germany
Departement de Physique, Université de Genève, Geneve, Switzerland
Eidgenossische Technische Hochschule Zurich (ETHZ), Zurich, Switzerland
Institute of Astrophysics of the Canary Islands (IAC), La Laguna, Spain
Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Madrid, Spain
Institut National de Physique Nucléaire et de Physique des Particules (IN2P3), France
Laboratoire d'Annecy-le-Vieux de Physique des Particules (LAPP), Annecy-Le-Vieux, France
Universite Joseph Fourier (Grenoble 1), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Grenoble, France
Université Montpellier II, Laboratoire de Physique Theorique and Astroparticules (LPTA), Montpellier, France
I. V. Kurchatov Institute of Atomic Energy, Moscow, Russia
ITEP Institute for Theoretical and Experimental Physics (ITEP), Moscow, Russia
Russian Academy of Sciences, Moscow, Russia
M.V. Lomonosov Moscow State University, Institute of Nuclear Physics, Moscow, Russia
Institute of Electrical Engineering (IEE), Beijing, China
Institute of High Energy Physics, Beijing, China
Jiao Tong University, Department of Physics, Shanghai, China
Shandong University, Tsinan, China
Southeast University, Nanjing, China
Sun Yat-Sen University, School of Physics and Engineering, Guangzhou, China
South Korea
Kyungpook National University, Daegu, South Korea
Ewha Women's University, Seoul, South Korea
Aarhus University, Institute of Physics and Astronomy, Aarhus, Denmark
Helsinki University of Technology, Metsähovi Radio Observatory, Kylmala, Finland
University of Turku, Space Research Laboratory, Turku, Finland
The Netherlands
Nationaal Lucht- en Ruimtevaartlaboratorium (NLR), Emmeloord, Netherlands
Dep. de Fisica Universidade de Coimbra, Coimbra, Portugal
Laboratorio de Instrumentacao e Fisica Experimental de Particulas (LIP), Lisbon, Portugal
Universidad Nacional Autonoma (UNAM), Instituto de Ciencias Nucleares, Mexico City, Mexico
University of Bucharest, Bucharest-Magurele, Romania, Romania
Contributing Space Agencies
National Aeronautics and Space Administration, Johnson Space Center, Houston, TX, United States
National Aeronautics and Space Administration, Goddard Space Flight Center, Greenbelt, MD, United States
National Aeronautics and Space Administration, Kennedy Space Center, Cape Canaveral, FL, United States
National Aeronautics and Space Administration, Marshall Space Flight Center, Huntsville, AL, United States
Italian Space Agency (ASI), Rome, Italy
German Aerospace Center (DLR), Cologne, Germany
European Space Agency (ESA), Noordwijk, Netherlands
European Center for Nuclear Research (CERN), Geneva, Switzerland
National Space Organization, HsinChu, Taiwan
In addition, the following Institutes/Groups made important contribution to the construction of the AMS-02 experiment:
Jacobs Sverdrup Engineering and Science Contract Group (ESCG), Houston, TX, United States
Florida State University, Tallahassee, FL, United States
Texas A&M University, Department of Physics, College Station, TX, United States
Johns Hopkins University, Baltimore, MD, United States
Aerospace Industrial Development Corporation (AIDC), Taichung, Taiwan
Max Planck Institute for Extraterrestrial Physics, Garching, Germany
Nationaal Instituut voor Subatomaire Fysica (NIKHEF), Amsterdam, Netherlands

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
National Laboratory - Department of Energy (NL-DOE)

Research Benefits
Information Pending

ISS Expedition Duration
March 2011 - March 2016; March 2016 - February 2017; March 2017 - September 2017

Expeditions Assigned

Previous Missions
The precursor to AMS-02, AMS, was flown on STS-91 in 1998. During this precursor flight, the basic technology required to perform the measurements was proven.

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Experiment Description

Research Overview

  • The Alpha Magnetic Spectrometer - 02 (AMS-02) is a high profile space-based particle physics experiment.

  • Orbiting the Earth at an altitude of 200 nautical miles attached to the International Space Station (ISS), AMS-02 will pioneer a new frontier in particle physics research.

  • As the largest and most advanced magnetic spectrometer in space, AMS-02 will collect information from cosmic sources emanating from stars and galaxies millions of light years beyond the Milky Way.


Excerpt from "Alpha Magnetic Spectrometer - A Physics Experiment on the International Space Station" by Dr. Sam Ting: The Alpha Magnetic Spectrometer (AMS-02) is a state-of-the-art particle physics detector constructed, tested and operated by an international team composed of 60 institutes from 16 countries and organized under United States Department of Energy (DOE) sponsorship. The AMS-02 will use the unique environment of space to advance knowledge of the universe and lead to the understanding of the universe's origin by searching for antimatter, dark matter and measuring cosmic rays.

Experimental evidence indicates that our Galaxy is made of matter; however, there are more than 100 hundred million galaxies in the universe and the Big Bang theory of the origin of the universe requires equal amounts of matter and antimatter. Theories that explain this apparent asymmetry violate other measurements. Whether or not there is significant antimatter is one of the fundamental questions of the origin and nature of the universe. Any observations of an antihelium nucleus would provide evidence for the existence of antimatter. In 1999, AMS-01 established a new upper limit of 10-6 for the antihelium/helium flux ratio in the universe. AMS-02 will search with a sensitivity of 10-9, an improvement of three orders of magnitude, sufficient to reach the edge of the expanding universe and resolve the issue definitively.

The visible matter in the universe (stars) adds up to less than 5 percent of the total mass that is known to exist from many other observations. The other 95 percent is dark, either dark matter (which is estimated at 20 percent of the universe by weight or dark energy, which makes up the balance). The exact nature of both still is unknown. One of the leading candidates for dark matter is the neutralino. If neutralinos exist, they should be colliding with each other and giving off an excess of charged particles that can be detected by AMS-02. Any peaks in the background positron, anti-proton, or gamma flux could signal the presence of neutralinos or other dark matter candidates.

Six types of quark (u, d, s, c, b and t) have been found experimentally, however all matter on Earth is made up of only two types of quarks (u and d). It is a fundamental question whether there is matter made up of three quarks (u, d and s). This matter is known as Strangelets. Strangelets can have extremely large mass and very small charge-to-mass ratios. It would be a totally new form of matter. AMS will provide a definitive answer on the existence of this extraordinary matter. The above three examples indicates that AMS will probe the foundations of modern physics.

Cosmic radiation is a significant obstacle to a manned space flight to Mars. Accurate measurements of the cosmic ray environment are needed to plan appropriate countermeasures. Most cosmic ray studies are done by balloon-borne satellites with flight times that are measured in days; these studies have shown significant variations. AMS-02 will be operative on the ISS for a nominal mission of 3 years, gathering an immense amount of accurate data and allowing measurements of the long term variation of the cosmic ray flux over a wide energy range, for nuclei from protons to iron. After the nominal mission, AMS-02 can continue to provide cosmic ray measurements. In addition to the understanding the radiation protection required for manned interplanetary flight, this data will allow the interstellar propagation and origins of cosmic rays to be pinned down.

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Space Applications
High-energy radiation from distant stars and galaxies rains down on Earth constantly, but Earth’s atmosphere and powerful magnetic fields guard against them. Crewmembers traveling to Mars or other destinations are not protected from these cosmic rays, which can be harmful to human health. Understanding where cosmic rays come from and how they move through space can improve safety precautions for future manned missions.

Earth Applications
Similar to particle detectors on Earth, AMS-02’s core is a massive magnet that bends incoming charged particles from space; the direction they bend reveals if their charge is positive or negative.  This data combined with other measurements of mass and energy help scientist determine exactly what kind of particle passed through the detector.  That combined data can tell physicists about their origins. Earth’s atmosphere has a large effect on these cosmic particles, so a space-based observatory is essential to help answer fundamental physics questions that are difficult to study here on Earth.  Essentially, the Universe is the ultimate particle accelerator and is far better than any accelerator scientist will ever build on the Earth.  The detector also might reveal new particles and atomic nuclei that could provide evidence of dark matter or antimatter. Antimatter has been produced in Earth laboratories, but it has been elusive in the cosmos.

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Operational Requirements and Protocols

AMS-02 will collect data 24 hours a day, 7 days a week, and 365 days a year. As long as the experiment has power provided by the ISS, the detectors will be on and measuring data at a rate of 7 Gigabits per seconds. This is equivalent to filling a 1 Gigabyte USB memory stick every second! Using sophisticated filtration and compression techniques, the advanced 600 computer processors located on AMS-02 are able to reduce the amount of data down by a factor of 3000. This data is sent from the ISS to the ground where researchers around the globe will compile and analyze data.

The AMS-02 will be launched on the Space Shuttle to the ISS on mission ULF6. AMS-02 will be mounted to the ISS S3 Upper Inboard Payload Attach Site during and extravehicular activity (EVA).

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Decadal Survey Recommendations

Information Pending

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Results/More Information

The Alpha Magnetic Spectrometer-02 (AMS-02) was installed on the International Space Station (ISS) on May 19, 2011. After 40 months of operations in space, AMS has collected 57 billion cosmic ray events. To date 41 billion have been analyzed. Of these, 9 million have been identified as electrons or positrons (an antimatter particle with the mass of an electron but a positive charge) in the energy range between 0.5 giga-electron volt (GeV) and 350 GeV. These events are used to determine the positron fraction - the ratio of positrons to the sum of electrons and positrons. Results show that below 10 GeV, the positron fraction decreased with increasing energy as predicted from events produced from cosmic ray collisions with the interstellar medium. However, the positron fraction increased steadily from 10 GeV to 250 GeV. This increase, previously recorded with less precision by instruments such as the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) and the Fermi Gamma-ray Space Telescope, conflicts with the standard theory of the positron fraction and indicates the existence of an unidentified source of positrons, such as pulsars or the annihilation of dark matter particles. A definitive indication of a dark matter signal has not yet been found. Furthermore, researchers observed an unexpected decrease in slope from 20 GeV to 250 GeV. Current measurements extend the energy range to 500 GeV, and the latest data set shows that, above ∼200 GeV, the positron fraction is no longer increasing. This behavior of the positron fraction was previously unobserved. The reason for this plateau can only be ascertained by continuing to collect data up to the tera-electron volt (TeV) region and by measuring the antiproton to proton ratio to high energies. Also, the isotropies, that is, characteristic arrival directions, versus energy among the high-energy positrons and cosmic ray electrons suggests that they may come from different sources.

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Results Publications

    Aguilar-Benitez M, Aisa D, Alpat B, Alvino A, Ambrosi G, Andeen K, Arruda MF.  Precision measurement of the helium flux in primary cosmic rays of rigidities 1.9 GV to 3 TV with the Alpha Magnetic Spectrometer on the International Space Station. Physical Review Letters. 2015 November 20; 115(21): 211101. DOI: 10.1103/PhysRevLett.115.211101. PMID: 26636836.

    Accardo L, Aguilar-Benitez M, Aisa D, Alpat B, Alvino A, Ambrosi G, Andeen K.  High statistics measurement of the positron fraction in primary cosmic rays of 0.5–500 GeV with the Alpha Magnetic Spectrometer on the International Space Station. Physical Review Letters. 2014 September 18; 113(12): 121101. DOI: 10.1103/PhysRevLett.113.121101.

    Aguilar-Benitez M, Alberti G, Alpat B, Alvino A, Ambrosi G, Andeen K, Anderhub H, Arruda MF, Azzarello P, Bachlechner A, Barao F, Baret B, Aurelien B, Barrin L, Bartoloni , Basara L, Basili A, Batalha L, Bates JR, Battiston R, Bazo J, Becker R, Becker UJ, Behlmann M, Beischer B, Berdugo J, Berges P, Bertucci B, Bigongiari G, Biland A, Bindi V, Bizzaglia S, Boella G, de Boer W, Bollweg KJ, Bolmont J, Borgia B, Borsini S, Boschini MJ, Boudoul G, Bourquin M, Brun P, Buenerd M, Burger J, Burger WJ, Cadoux F, Cai X, Capell M, Casadei D, Casaus J, Cascioli V, Castellini G, Cernuda I, Cervelli F, Chae M, Chang YH, Chen A, Chen C, Chen H, Cheng G, Chen HS, Cheng L, Chernoplyiokov N, Chikanian A, Choumilov E, Choutko V, Chung CH, Clark CS, Clavero R, Coignet G, Commichau V, Consolandi C, Contin A, Corti C, Costado Dios MT, Coste B, Crespo D, Cui Z, Dai M, Delgado C, Della Torre S, Demirkoz B, Dennett P, Derome L, Di Falco S, Diao XH, Diago A, Djambazov L, Diaz C, von Doetinchem P, Du WJ, Dubois JM, Duperay R, Duranti M, D'Urso D, Egorov A, Eline A, Eppling F, Eronen T, vanEs J, Esser H, Falvard A, Fiandrini E, Fiasson A, Finch E, Fisher P, Flood K, Foglio R, Fohey MF, Fopp S, Fouque N, Galaktionov Y, Gallilee MA, Gallin-Martel L, Gallucci G, Garcia B, Garcia J, Garcia-Lopez R, Garcia-Tabares L, Gargiulo C, Gast H, Gebauer I, Gentile S, Gervasi M, Gillard W, Giovacchini F, Girard L, Goglov P, Gong J, Goy-Henningsen C, Grandi D, Graziani M, Grechko A, Gross A, Guerri I, de la Guia C, Guo KH, Habiby M, Haino S, Hauler F, He ZH, Heil M, Heilig JA, Hermel R, Hofer H, Huang Z, Hungerford WJ, Incagli M, Ionica M, Jacholkowska A, Jang WY, Jinchi H, Jongmanns M, Journet L, Jungermann L, Karpinski W, Kim G, Kim K, Kirn T, Kossakowski R, Koulemzine A, Kounina O, Kounine A, Koutsenko V, Krafczyk M, Laudi E, Laurenti G, Lauritzen CA, Lebedev A, Lee MW, Lee S, Leluc C, Leon Vargas H, Lepareur V, Li J, Li Q, Li TX, Li W, Li Z, Lipari P, Lin CH, Liu D, Liu H, Lomtadze T, Lu Y, Lucidi S, Lubelsmeyer K, Luo JZ, Lustermann W, Lv S, Madsen J, Majka R, Malinin A, Mana C, Marin J, Martin TD, Martinez G, Masciocchi F, Masi N, Maurin D, McInturff A, McIntyre P, Menchaca-Rocha A, Meng Q, Menichelli M, Mereu I, Millinger M, Mo DC, Molina M, Mott PB, Mujunen A, Natale S, Nemeth PJ, Ni JQ, Nikonov N, Nozzoli F, Nunes P, Obermeier A, Oh S, Oliva A, Palmonari F, Palomares C, Paniccia M, Papi A, Park W, Pauluzzi M, Pauss F, Pauw A, Pedreschi E, Pensotti S, Pereira R, Perrin E, Pessina G, Pierschel G, Pilo F, Piluso A, Pizzolotto C, Plyaskin V, Pochon J, Pohl M, Poireau V, Porter SV, Pouxe J, Putze A, Quadrani L, Qi X, Rancoita PG, Rapin D, Ren Z, Ricol JS, Riihonen E, Rodriguez I, Roeser U, Rosier-Lees S, Rossi L, Rozhkov A, Rozza D, Sabellek A, Sagdeev R, Sandweiss J, Santos B, Saouter P, Sarchioni M, Schael S, Schinzel D, Schmanau M, Schwering G, Schulz von Dratzig A, Scolieri G, Seo E, Shan BS, Shi JY, Shi YM, Siedenburg T, Siedling R, Son D, Spada F, Spinella F, Steuer M, Stiff K, Sun W, Sun W, Sun XH, Tacconi M, Tang CP, Tang XW, Tang Z, Tao L, Tassan-Viol J, Ting SC, Ting S, Titus C, Tomassetti N, Toral F, Torsti J, Tsai JR, Tutt JC, Ulbricht J, Urban TJ, Vagelli V, Valente E, Vannini C, Valtonen E, Vargas Trevino M, Vaurynovich S, Vecchi M, Vergain M, Verlaat B, Vescovi C, Vialle JP, Viertel G, Volpini G, Wang D, Wang NH, Wang QL, Wang R, Wang X, Wang ZX, Wallraff W, Weng Z, Willenbrock M, Wlochal M, Wu H, Wu KY, Wu Z, Xiao WJ, Xie S, Xiong R, Xin GM, Xu NS, Xu W, Yan Q, Yang J, Yang M, Ye QH, Yi H, Yu Y, Yu Z, Zeissler S, Zhang JG, Zhang Z, Zhang M, Zhuang ZM, Zhuang H, Zhukov VE, Zichichi A, Zuccon P, Zurbach C.  First Result from the Alpha Magnetic Spectrometer on the International Space Station: Precision Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5-350 GeV. Physical Review Letters. 2013 Apr 3; 110: 141102-1 - 141102-10. DOI: 10.1103/PhysRevLett.110.141102.

    Aguilar-Benitez M, Cavasonza LA, Alpat B, Ambrosi G, Arruda MF, Attig N, Aupetit S.  Antiproton flux, antiproton-to-proton flux ratio, and properties of elementary particle fluxes in primary cosmic rays measured with the Alpha Magnetic Spectrometer on the International Space Station. Physical Review Letters. 2016 August 26; 117(9): 091103. DOI: 10.1103/PhysRevLett.117.091103. PMID: 27610839.

    Aguilar-Benitez M, Aisa D, Alvino A, Ambrosi G, Andeen K, Arruda MF.  Electron and positron fluxes in primary cosmic rays measured with the Alpha Magnetic Spectrometer on the International Space Station. Physical Review Letters. 2014 September 18; 113(12): 121102. DOI: 10.1103/PhysRevLett.113.121102.

    Aguilar-Benitez M, Aisa D, Alpat B, Alvino A, Ambrosi G, Andeen K.  Precision measurement of the (e++e-) flux in primary cosmic rays from 0.5 GeV to 1 TeV with the Alpha Magnetic Spectrometer on the International Space Station. Physical Review Letters. 2014 November 28; 113(22): 221102. DOI: 10.1103/PhysRevLett.113.221102. PMID: 25494065.

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Ground Based Results Publications

    Bergstrom L, Bringmann T, Cholis I, Hooper D, Weniger C.  New limits on dark matter annihilation from Alpha Magnetic Spectrometer cosmic ray positron data. Physical Review Letters. 2013 October 25; 111(17): 171101. DOI: 10.1103/PhysRevLett.111.171101. PMID: 24206472.

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ISS Patents

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Related Publications

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Related Websites
Alpha Magnetic Spectrometer

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AMS-02 integration activities in Geneva, Switzerland. Image courtesy of the Massachusetts Institute of Technology, Cambridge, MA.

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Computer generated image of the completed ISS with external workstations. Image courtesy of NASA.

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image AMS-02 in the payload by of STS-134/ULF6, Endeavor on March 28, 2011. Image courtesy of Michele Famiglietti.
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AMS-02 is an international collaboration of 600 physicists from 56 institutes in 16 countries led by Nobel Laureate Dr. Samuel Ting of MIT.

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image NASA Image: S134E007532 - The starboard truss of the ISS is featured in this image photographed by an STS-134 crew member while space shuttle Endeavour remains docked with the station. The newly-installed Alpha Magnetic Spectrometer-02 (AMS-02) is visible at center left.
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The AMS-02 in the space shuttle Endeavour's payload bay is featured in this image photographed by an STS-134 crew member while docked with the ISS. Shortly after this image was taken, the AMS was moved from the payload bay to the station's starboard truss. Image courtesy of NASA.

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NASA Image: S134E009289 - AMS-02 installed on the S3 truss segment next to the EXPRESS (Expedite the Processing of Experiments to Space Station) Logistics Carrier 2 (ELC2). Photo taken during STS-134/Expedition 27 joint operations.

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NASA Image: ISS035E022422

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NASA Image: ISS028E016134 - Exterior view of the ISS with the AMS-02 visible in the foreground.

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NASA Image: ISS042E341868 - Exterior view of the ISS taken during a session of Extravehicular Activity (EVA) with the AMS-02 visible in the foreground.

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NASA Image: ISS030E060466 - View of Don Pettit holding the AMS-02 Hard Drive.

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