The Alpha Magnetic Spectrometer AMS-02 cosmic-ray detector, installed aboard the International Space Station (ISS) in 2011, is preparing for a new phase of its scientific mission. More than a decade after its launch, in order to maximise the scientific return during the final operational phase of the instrument, the AMS Collaboration, led by Nobel Laureate in Physics Samuel C. C. Ting and including the Italian Space Agency (ASI) and the National Institute for Nuclear Physics (INFN), has launched the important AMS Upgrade programme to enhance the detector, which involves the installation of a new detector layer. The qualification activities for the new component, called Layer 0 (L0), were presented during the L2L Summit “From Wool to the Moon”, held on Friday 26 June 2026 at the Teatro Civico in Schio, Vicenza, on the initiative of the Science and Technology District.
“Designed to study high-energy particles originating from space, AMS-02 is contributing to defining our knowledge of cosmic rays in remarkable detail, providing new information that is helping to investigate still unresolved questions, such as the existence of primordial antimatter and the nature of dark matter”, comments Alberto Oliva, INFN researcher and national coordinator of AMS. “Now, in order to further extend the scientific capabilities of the experiment, the AMS Collaboration has designed a technological upgrade that will make it possible to maximise the remaining operational lifetime of the instrument on board the International Space Station”.
“The L0 upgrade will significantly improve the detector’s sensitivity in terms of resolution, particle-tracking efficiency and its ability to distinguish rare signals within an extremely complex background”, explains Giovanni Ambrosi, INFN researcher and Head of the Upgrade project. “AMS-02 will increase its capability to measure cosmic particles by a factor of three and will double the overall number of recorded events over the coming years, significantly improving the detector’s sensitivity in the search for antimatter and in precision measurements of cosmic rays”.
The new L0 component has recently reached a decisive milestone: it has successfully completed a rigorous programme of space qualification tests. The activities, coordinated by INFN and carried out together with CERN, MIT and NASA, included vibration tests to simulate launch conditions and thermal-vacuum cycling to reproduce the extreme environment of space. The tests were conducted with the support of ALCA Space, the Vicenza-based company that built the vacuum chamber, at the premises of Space Industries.
Having successfully passed the verification procedures that officially certified it as ready for launch, L0 has now been shipped to CERN for the final calibration activities, which involve exposure to a high-energy proton beam to ensure the highest possible measurement accuracy when operating in orbit. Once calibration has been completed, L0 will be shipped to the United States, from where it will be launched in 2027.
AMS-02 was launched from Cape Canaveral in 2011 aboard Space Shuttle Endeavour during the STS-134 mission and installed on the S3 segment of the ISS external structure by a robotic arm operated by astronauts Roberto Vittori and Drew Feustel. It is the largest particle detector ever operated in space.
Another Italian astronaut also contributed to the success of AMS-02: Luca Parmitano led one of the most complex extravehicular activity (EVA) campaigns ever carried out on the International Space Station. Between November 2019 and January 2020, as part of the Beyond mission, Parmitano and fellow astronaut Andrew Morgan conducted four spacewalks dedicated to the repair of AMS-02. In particular, the EVAs included the removal of the system’s external protective covers, the preparation and cutting of the cooling lines, the installation of new mechanical devices and, above all, the replacement of the instrument’s thermal circuit pumping system. The intervention, which had not been envisaged during the design phase of the instrument, required the development of dedicated procedures and equipment and was successfully completed, making it possible to extend the scientific operation of the experiment by many years.
Over the years, AMS-02 has collected more than 200 billion cosmic events, providing extremely precise measurements of protons, helium nuclei and other heavy nuclei, electrons and positrons. Among its most significant results are the observation of unexpected behaviour in the high-energy positron flux and extremely accurate measurements of the ratios between isotopes and rare nuclei in cosmic rays. These data have raised new questions concerning possible indirect signals of dark matter and the origin of the ultra-high-energy particles that travel through our galaxy.
Italy’s central role in the AMS mission
Italy has played a decisive role since the earliest stages of the AMS mission and continues to be a key player in the development of the L0 Upgrade. INFN, together with the Universities of Perugia, Trento, Sapienza University of Rome, Rome Tor Vergata, Milan, Pisa and Bologna, with the support of the Italian Space Agency (ASI), has made a substantial contribution both to the design and technological development of the detector and to the analysis of the scientific data collected in space. This contribution confirms the leading role of the Italian scientific community in astroparticle physics and in the major international collaborations dedicated to the exploration of the universe.
The new L0 component of AMS during testing ©INFN
