Next stop: space

At 6:30 a.m. on 25 August, the runway at Geneva International Airport was more crowded than usual, as dozens of airport staff and a few CERN personnel gathered as close as possible to watch the landing of one of the world's largest aircraft, a USAF (US Air Force) C5 Super Galaxy. Having left Afghanistan (where it transported provisions for the US military contingent) the day before, it had spent a few hours at a US military base in Iraq before finally landing in Geneva on a very special mission: to load AMS-02, the Alpha Magnetic Spectrometer, into its huge cargo bay.


On 25 August, after an 11 hour-long flight, the US Air Force C-5 Galaxy carrying the Alpha Magnetic Spectrometer (AMS-02) experiment landed at the Kennedy Space Centre (KSC) in Florida, US.

Weighing 7.5 tonnes and measuring 5 by 4 by 3 metres, AMS-02 is one of the most complex scientific instruments ever built for space. The experiment, assembled and tested at CERN, uses particle physics technologies but smaller and lighter (by particle physics standards) to fit into the Space Shuttle cargo bay for its voyage to the International Space Station. And luckily so, as it only just about fitted inside the C 5’s large belly and only after its lid was taken off to gain the missing 7 cm!

CERN, in collaboration with Geneva International Airport, organised a press conference followed by a visit to the aircraft, to watch the loading of the detector onto the C5 Super Galaxy, especially made available by the US Air Force. "Our job is to move anything anywhere anytime", said Donald Erbschloe, USAF chief scientist, during the press conference. "Moving this big science project on its last terrestrial voyage to the Kennedy Space Centre was a challenge we couldn't resist. The air force has relied on science since its earliest days, as to move something in the air requires a lot of technology, and science and the air force have grown up together".

AMS-02 has been built by an international collaboration involving 15 countries mainly from Europe and Asia, the largest international collaboration for a single experiment in space. "The ISS is a unique platform in space, providing the infrastructure to enable AMS-02 to search for new physics and astrophysics phenomena from primary sources millions of light years beyond our galaxy", said Nobel Laureate Professor Sam Ting, AMS-02 leader, to the 20 journalists from the international media gathered at the press conference.

Space is a vantage point from which to observe the flux of cosmic rays in which AMS-02 specializes, since the charged particles in the cosmic flux cannot make it through the atmosphere without being annihilated. With its sensitivity and a magnet 4000 times stronger than the magnetic field of the Earth, AMS-02 has a chance to observe dark matter particles directly from space by studying the details of cosmic ray distribution. For this reason it is complementary to underground experiments looking for dark matter particles that might be able to penetrate through rock, water or ice without being stopped, and to the LHC, which will produce candidate dark matter particles. But the real reason for this experiment is to look for surprises, as Roberto Battiston, deputy spokesperson of AMS-02, pointed out at the press conference. "Once you look very carefully with a very powerful detector for a long time at something that has never been observed with enough attention, you may find surprises and this is why we are doing that. We’re motivated by these theoretical models, but in reality we are looking for something new".

At 11.18 a.m. Florida time on 26 August, after an 11-hour flight, the US Air Force C-5 Galaxy plane carrying AMS-02 and some forty members of the collaboration landed on the Space Shuttle runway at the Kennedy Space Centre. "This is a major milestone for AMS-02 in its long and exciting journey that started 15 years ago", said Saoul Gonzales of the US Department of Energy. At KSC, AMS-02 will undergo a few additional tests in NASA's Space Station Processing Facility (SSPF) before being launched on board Space Shuttle Discovery on its final mission to space. The official launch date is February 2011, but the leader of the experiment is pushing NASA to get an earlier window for launch (December 2010), and the AMS-02 collaboration is working hard to make it ready for final loading onto the Space Shuttle by 15 November to maximize the chances of an earlier launch.

The installation of AMS-02 on the exterior of the Space Station, using both the shuttle and the station arms, on the right of the station's truss, or backbone, will be quite a delicate operation, and will be carried out by ESA astronaut Roberto Vittori, an Air Force colonel with a degree in physics (and a former student of Roberto Battiston). Once docked on the International Space Station, the experiment is expected to remain active for the entire lifetime of the ISS and will not return to Earth. "For the next 20 years, during the lifetime of the Space Station, there will be only one large physical science experiment, and that will be AMS-02!" and with these words Professor Ting concluded the press conference.

AMS-02 history

AMS-02’s long voyage to the Space Station started in 1994, when Professor Ting initiated the project. In 1998, a first configuration of AMS-02 flew for ten days on board Space Shuttle Discovery (STS-91), collecting nearly 100 million cosmic rays, and this successful first flight made sure that the AMS-02 collaboration could continue to work with NASA. Following the Columbia disaster in 2003, the entire space shuttle program was called into question by NASA, as was the scheduled flight for the AMS-02 final detector. In 2008, Professor Ting managed to persuade the US Congress that "after spending 100 billion dollars on the ISS, it is worth making an effort to have good science there" and last year Congress unanimously approved a bill requesting NASA to send AMS-02 into space. Last February, after a few months of test beams on the primary proton source from the SPS at CERN, AMS-02 was shipped to Nordwijk in the Netherlands, where it was placed in ESA’s thermo-vacuum room. Exhaustive tests there played an important role in the decision in June to replace the original superconducting magnet by a
permanent one with a longer life expectancy.

by Paola Catapano