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AMS-02 patch
Alpha Magnetic Spectrometer
Alpha Magnetic Spectrometer - 02.jpg
Organization AMS Collaboration
Mission Type Cosmic Ray
Host Satellite International Space Station
Launch July 29, 2010[1]
Launch vehicle Space Shuttle Endeavour
Launch site Kennedy Space Center
Launch Pad 39A
Mission duration 3 years
Mass 14,809 lbs (6731 kg)
Max length
Power consumption 2000-2500 Watts
Webpage AMS-02 homepage
Orbital elements (ISS)
Inclination 51.6 degrees
Orbit LEO
Min altitude 341 km (184 nmi)
Max altitude 353 km (191 nmi)
Period ~91 minutes

The Alpha Magnetic Spectrometer, also designated AMS-02, is a particle physics experiment module that is to be mounted on the International Space Station. It is designed to search for various types of unusual matter by measuring cosmic rays. Its experiments will help researchers study the formation of the universe and search for evidence of dark matter and antimatter. The principal investigator is Nobel laureate particle physicist Samuel Ting. Final testing and assembly is being completed at CERN in Geneva and delivery to the Kennedy Space Center in Florida is expected in the the spring of 2010. Launch is targeted for July 29, 2010 on Space Shuttle Endeavour flight STS-134.[1][2]



The Alpha Magnetic Spectrometer was proposed in 1995, not long after the cancellation of the Superconducting Super Collider, by MIT particle physicist and Nobel laureate Samuel Ting. The proposal was accepted and Dr. Ting became the principal investigator.[3]



AMS-01 flew in space in June 1998 aboard the Space Shuttle Discovery on STS-91. It is visible near the rear of the payload bay.

An AMS prototype designated AMS-01, a simplified version of the detector, was built by the international consortium under Ting's direction and flown into space aboard the Space Shuttle Discovery on STS-91 in June 1998. Although AMS-01 did not detect any antihelium[4] it did prove that this detector concept worked in space. This shuttle mission was the last shuttle flight to the Mir Space Station. The photograph was taken from Mir.[5]

A detail view of the AMS-01 module (center) mounted in the shuttle payload bay for the STS-91 mission.


AMS-02 during integration and testing in Geneva.

After the flight of the prototype Dr. Ting began the development of full research system designated AMS-02. This development effort involved the work of 500 scientists from 56 institutions and 16 countries organized under United States Department of Energy (DOE) sponsorship. The power requirements for AMS-02 were thought to be too great for a practical independent spacecraft. So AMS-02 was designed to be installed as an external module on the International Space Station and use power from the ISS. The post Columbia plan was to deliver AMS-02 to the ISS by space shuttle in 2005 on station assembly mission UF4.1, but technical difficulties and shuttle scheduling issues have added more delays.[5]

AMS-02 is completing final integration and operational testing at CERN in Geneva, Switzerland. Operational testing includes exposure to powerful nuclear particle beams generated by the CERN particle accelerators.[6] After the completion of integration testing the unit will be sent to ESA's European Space Research and Technology Centre (ESTEC) facility in the Netherlands to undergo thermal vacuum, electromagnetic compatibility and electromagnetic interference testing. It is presently scheduled for delivery to the Kennedy Space Center in Florida, U.S.A. in the spring of 2010.[7]

Program management

Activities relating to payload integration, launch, and deployment of AMS-02 are managed by the Alpha Magnetic Spectrometer Project Office at NASA's Johnson Space Center in Houston, Texas, U.S.A.

Delivery and installation on the International Space Station

A computer generated image showing AMS-02 mounted to the ISS S3 Upper Inboard Payload Attach Site.

AMS-02 is slated to be delivered to the International Space Station as part of station assembly flight ULF6 on shuttle flight STS-134.[8] It will be removed from the shuttle cargo bay using the shuttle's robotic arm and handed off to the station's robotic arm for installation. AMS-02 will be mounted on top of the Integrated Truss Structure, on USS-02, the zenith side of the S3-element of the truss. At least one EVA will be required to complete the installation. A last minute top-off of the superfluid helium supply in the shuttle payload bay will be required before launch.[2]


  • Mass: 14,809 lbs (6731 kg)
  • Power: 2000 - 2500 watts
  • Internal data rate: 10 Gbit/s
  • Data rate to ground: 2 Mbit/s
  • Primary mission duration: 3 years[5]


In 1999, after the successful flight of AMS-01, the total cost of the AMS program was estimated to be $33 million, with AMS-02 planned for flight to the ISS in 2003.[9] After the Space Shuttle Columbia disaster in 2003, and after a number of technical difficulties with the construction of AMS-02, the cost of the program ballooned to an estimated $1.5 billion.[10]

The cost of the program was criticized heavily during the period when it appeared that it would not be flown.[3]

Module design

The detector module consists of a series of detectors that are used to determine various characteristics of the radiation and particles as they pass through. Characteristics are determined only for particles that pass through from top to bottom. Particles that enter the detector at any other angles are rejected. From top to bottom the subsystems are identified as:[11]

  • Transition radiation detector measures the velocities of the highest energy particles;
  • Upper time of flight counter, along with the lower time of flight counter, measures the velocities of lower energy particles;
  • Star tracker determines the orientation of the module in space;
  • Silicon tracker measures the coordinates of charged particles in the magnetic field;
  • Superconducting magnet bends the path of charged particles so they can be identified;
  • Anti-coincidence counter rejects stray particles that enter through the sides;
  • Lower time of flight counter, along with the upper time of flight counter, measures the velocities of lower energy particles;
  • Ring-imaging Cerenkov detector measures velocity of fast particles with extreme accuracy;
  • Electromagnetic calorimeter identifies particles by the heat produced in collisions with the detector.

Scientific goals

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.[2]


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 over AMS-01, sufficient to reach the edge of the expanding universe and resolve the issue definitively.

Dark matter

The visible matter in the universe, such as 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 ray flux could signal the presence of neutralinos or other dark matter candidates.


Six types of quark (up, down, strange, charmed, bottom and top) have been found experimentally, however all matter on Earth is made up of only two types of quarks (up and down). It is a fundamental question whether there is matter made up of three quarks (up, down and strange). 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-02 may provide a definitive answer on the existence of this extraordinary matter.

Space radiation environment

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 instruments 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.

Extended mission

Originally AMS-02 was to be returned to Earth on a shuttle flight after the primary mission and the exhaustion of its superfluid helium supply to cool the superconducting magnet solenoid. This element is too large and heavy to return after the retirement of the shuttle so now the plan is to leave the unit in place on the space station exterior and continue operations as a cosmic ray flux detector in an extended mission. The AMS-02 particle detectors will still be able to detect particles without the operation of the superconducting magnet but the system will lose most of its ability to identify them.[6]

Launch cancellation and restoration

For several years it was uncertain if AMS-02 would ever be launched because it was not manifested to fly on any of the remaining Space Shuttle flights.[12] After the 2003 Columbia disaster NASA decided to reduce shuttle flights and retire the remaining shuttles by 2010. A number of flights were removed from the remaining manifest including the flight for AMS-02.[3] In 2006 NASA studied alternative ways of delivering AMS-02 to the space station, but they all proved to be too expensive.[12]

In May 2008 a bill was proposed to launch AMS-02 to ISS on an additional shuttle flight in 2010 or 2011. [13] The bill was passed by the full House of Representatives on June 11, 2008.[14] The bill then went before the Senate Commerce, Science and Transportation Committee where it also passed.[15 ] It was then amended and passed by the full Senate on September 25, 2008, and was passed again by the House on September 27, 2008.[16 ] It was signed by President George W. Bush on October 15, 2008.[17 ] [18] The bill authorized NASA to add another space shuttle flight to the schedule before the space shuttle program is discontinued. In January 2009 NASA restored AMS-02 to the shuttle manifest and it is now scheduled to be launched on the newly authorized shuttle mission, STS-134, in July of 2010. Originally scheduled as the last shuttle flight, this mission is now scheduled to be the second to last shuttle flight of the space shuttle program.[8]

See also


  1. ^ a b NASA (2009-10-14). "NASA's Shuttle and Rocket Missions". NASA. Retrieved October 16, 2009.  
  2. ^ a b c "Alpha Magnetic Spectrometer - 02 (AMS-02)". NASA. 2009-08-21. Retrieved 2009-09-03.  
  3. ^ a b c Dennis Overbye: Long-Awaited Cosmic-Ray Detector May Be Shelved. The New York Times, April 3, 2007
  4. ^ AMS Collaboration (August 2002). "The Alpha Magnetic Spectrometer (AMS) on the International Space Station: Part I - results from the test flight on the space shuttle". Physics Reports 366 (6): 331–405. doi:10.1016/S0370-1573(02)00013-3.  
  5. ^ a b c "AMS experiment mission overview". Retrieved 2009-09-03.  
  6. ^ a b "AMS-02 Project Page". Retrieved 2009-09-03.  
  7. ^ "Waiting for the Alpha Magnetic Spectrometer". ESA News. 17 December 2009. Retrieved 2010-01-09.  
  8. ^ a b "Consolidated Launch Manifest". NASA. 2009-08-25. Retrieved 2009-09-03.  
  9. ^ Greg Clark (15 October 1999). "NASA Puts Big Bang to the Test". Retrieved 2009-09-20.  
  10. ^ a b Jeremy Hsu (2009-09-02). "Space Station Experiment to Hunt Antimatter Galaxies". Retrieved 2009-09-02.  
  11. ^ Benjamin Monreal. "The AMS Experiment". MIT. Retrieved 2009-09-03.  
  12. ^ a b Marc Kaufman (December 2, 2007). "The Device NASA Is Leaving Behind". Washington Post. Retrieved 2007-12-02.  
  13. ^ "House Bill Would Authorize Additional Shuttle Flights". Retrieved 2008-05-19.  
  14. ^ David Kestenbaum. (2008-06-10). NASA balks at Taking Physics Gear Into Space. [Radio production]. Washington, D.C.: National Public Radio. Retrieved 2008-06-10.  
  15. ^ "Senate Committee Passes Bill".  
  16. ^ "House Sends NASA Bill to President's Desk, Reaffirms Commitment to Balanced and Robust Space and Aeronautics Program".  
  17. ^ "Bush Signs NASA Authorization Act".  
  18. ^ Search Results - THOMAS (Library of Congress)

Further reading

  • Sandweiss J. 2004. Overview of strangelet searches and Alpha Magnetic Spectrometer: when will we stop searching?. J. Phys. G: Nucl. Part. Phys. 30 S51-S59. doi:10.1088/0954-3899/30/1/004

External links


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