The shuttle program's final two missions have been delayed which will extend the shuttle program into next year. One of the reasons for this slip stems from the late delivery of one of the crucial elements of the STS-134 payload, the Alpha Magnetic Spectrometer (AMS-02), due to mechanical problems. The AMS-02 is an experiment that will be mounted to the outside of the International Space Station (ISS) and will study the formation of the universe, measure cosmic rays and seek out proof of antimatter and dark matter.
The AMS-02 was slated for delivery to NASA's Kennedy Space Center in late May. However, the delivery has been delayed due to the AMS-02 needing to have its cooling system changed out. This is one of several issues that have caused both of the remaining shuttle missions to be pushed back. Along with the delay of the AMS-02, periods of communications blackout and congested traffic heading toward the station have pushed the launch dates back with STS-134 now scheduled to take place on February 26, 2011.
"There were a lot of little issues that cropped up to delay these flights," Candrea Thomas a public affairs officer at NASA's Kennedy Space Center said during an interview. "The delay in the delivery of the AMS was just one of a number of issues that has caused the launch dates to slip."
After it was announced that ISS operations would be extended to potentially 2020 or beyond, it was decided that the AMS-02 would have its superconducting magnet swapped out with the non-superconducting variety that had flown in the AMS-01 on STS-91 aboard the space shuttle Discovery. This will significantly increase the lifespan of this instrument from an expected three years to potentially as long as 18 years. While the AMS-02 will lose some of its sensitivity, it will gain a longer functional lifespan.
After the loss of the space shuttle Columbia in 2003, the AMS-02 was not scheduled to fly. It was deemed non-essential and too expensive. The experiment was viewed this way after its cost skyrocketed to approximately $1.5 billion when problems arose with the program. However, the experiment was viewed as important enough to have the House of Representatives pass a bill regarding it which was amended and passed by the Senate in September of 2008. NASA added AMS-02 back to the manifest in 2009.
The AMS-02 will be mounted to the International Space Station's S3 truss element. From this position the instrument will scan and study the heavens, searching for antimatter. It will look for evidence of neutralino collision which should confirm the existence of dark matter. The AMS-02 will also aid research into ways to improve manned missions into deep space by providing greater insight into the nature of cosmic rays. The AMS-02 hosts a suite of instruments that will work to confirm the existence of highly-exotic forms of matter.
The layout of the AMS-02 is designed to detect characteristics specific to different types of radiation as it passes through the module. The unit contains a number of sub-systems that will measure the speed of particles containing the highest energy levels, lower energy particles, a star-tracker to orient the instrument, a filter to negate the impact of stray particles, an instrument that determines what a particle is by its heat signature and the AMS-02's magnet which will bend the particle's path so that they can be identified.
Many critics of the International Space Station program have stated that the station has not produced the science promised when the program was initiated. With the lifespan of the station extended and new instruments such as the Alpha Magnetic Spectrometer added the potential scientific rewards of the station will be greatly increased. It is therefore understandable that NASA would want to ensure that this aspect of the station which has already had a substantial down payment placed on it flies before the shuttle era draws to a close.