Shuttle flight #134 out of 135 is set to launch this Friday, April 29, when Space Shuttle Endeavour will blast into space for the last time. During its last mission, the Endeavour crew will deliver a special physics instrument to the International Space Station.

The instrument, called the Alpha Magnetic Spectrometer (AMS), is designed to make detections of exotic phenomena that are not observable from the surface of the Earth, including antimatter, dark matter, strangelets, and cosmic ray counts. These are all important for testing various theories and for practical reasons.

Antimatter

Big bang theory requires that equal amounts of matter and antimatter existed in the very early history of the universe. The matter and antimatter would collide and annihilate, producing a burst of energy. The great mystery is why our galaxy and everything we observe appears to be made of matter. Actually, the great mystery is why there is any matter at all, for if there was an equal amount of antimatter, all of it should have been annihilated. Some theories propose a tiny asymmetry, with slightly more matter than antimatter, but these theories raise problems of their own. It is important to determine whether any antimatter still exists in the universe, and this is where AMS comes in. AMS is designed to be highly sensitive to antimatter detections all the way to the “edge” of the observable universe.

Dark Matter

Anyone who has been fortunate enough to view the night sky free from the glow of city lights knows that the sky appears to be awash in stars. It’s tempting to think the entire universe looks this way, but this view is misleading. Our night sky provides a local view of a particularly dense area of the universe, the inside of a galactic disk of stars. Even the lovely visage of seemingly endless galaxies in the Hubble Ultra Deep Field may tempt the viewer into thinking the universe is overflowing with galactic material. The (theoretical) reality is that the vast majority of the “stuff” of the universe can’t be seen at all. In fact, according to the latest results from WMAP, stars and gas make up less than 5% of the total stuff out there. Dark matter is theorized to make up 23% of the total stuff (with dark energy making up the biggest chunk at 72% of the total). Even though it’s supposed to be a major constituent of the universe, dark matter has never been directly detected. AMS will look for neutralinos, the leading candidate for the dark matter particle. Theory predicts that when neutralinos collide, they produce other charged particles and energy, which can be detected by AMS.

Strangelets

One of the great discoveries of particle physics was the quark, the basic building block of matter. “Normal” matter (also called baryonic matter) comprises the familiar things of existence, from people to planets to stars. Normal matter is made of two kinds of quarks, called “up” and “down” quarks, bound together in groups of three. Four other types of quarks — called charm, strange, top, and bottom — were predicted to exist and subsequently discovered in particle accelerators. Some of these quarks are known to combine into other types of hadrons, or heavy particles. One theory predicts that strange quarks may group with up and down quarks to make extremely heavy “strange matter” particles called strangelets. Theory predicts that if strange matter comes into contact with normal matter, it could convert the normal matter into strange matter. AMS is designed to make detections of these strangelets if they do in fact exist.

Cosmic Ray Counts

If we have any hope of sending a manned mission to Mars we will need an accurate measurement for the rate of cosmic rays in our solar system. Cosmic rays are charged particles accelerated to near-light speeds, and they represent a major hazard to astronauts who would be exposed to them in space long term without the protection of the Earth’s atmosphere. AMS will make accurate counts of cosmic rays in the solar system so that scientists and engineers can devise appropriate protection for Mars-bound astronauts.

Related posts:

• Last flight
• Rethinking the origin of cosmic rays
  

Recommended reading:

• NASA: Alpha Magnetic Spectrometer (AMS)
• CSM: Antimatter breakthrough could help scientists unravel Big Bang mystery

Recommended viewing:

• Texas Cosmology Center: “Dark Matter: Seeing the Invisible”
• ESA: “Catching the strange strangelets”