We made our way from California to Florida once again. We’ll head to Kennedy Space Center on Sunday morning. In the meantime, here’s what’s caught our attention.
THE ALPHA MAGNETIC SPECTROMETER
Even now, comfortably residing in the aft section of space shuttle Endeavour’s bay is a sixteen-ton, three-meter-square instrument that represents a laundry list of significant commitments: 16 years from drawing board to delivery; 600 scientists, engineers, and technicians from 56 institutions and 16 countries to design and build it; and $1.5B (yep, that’s billions) of cash to fund it. And that price tag doesn’t include the $500M cost of launching the instrument into space and connecting it up on its new home, the International Space Station (ISS). This extraordinary expenditure of scientific and financial capital is labeled with a descriptive moniker: Alpha Magnetic Spectrometer, commonly referred to as AMS. More precisely, this machine is AMS-02, having been preceded by a ten-day proof-of-concept flown by the STS-91 mission on the space shuttle Discovery in 1998.
So, why the big money, the multinational collaboration, and the long-term investment? The AMS is the brainchild of Nobel laureate Sam Ting, a particle physicist at MIT. The fact that the AMS will spend its working life affixed to the ISS is the result of a marriage of convenience, perhaps necessity (as it’s sometimes difficult to tease the two apart), between Dr. Ting and former NASA chief Dan Golden. In 1991, Dan Golden was desperately seeking scientific legitimacy for the ISS. At the same time, Dr. Ting was looking for the best possible spot in the world for his device to access unadulterated, so-called primary, cosmic rays. When hunting cosmic rays, it doesn’t get much better than 200 miles above the earth’s atmosphere. If you also happen to need to transfer a significant amount of data to physicists so they can analyze it, the ISS is a pretty good place to be. In fact, it not only provides support for communicating data, it also provides power and navigation. If you’re building an AMS to orbit the Earth, the ISS simplifies the project enough that it becomes much more possible.
We’ll have a future post about cosmic rays and their role in science, once the AMS is up in orbit and working. For now, suffice it to say that cosmic rays can be used to glean a significant amount of information about the universe’s past, its current makeup, and quite possibly its future evolution. In other words, if the AMS gets very lucky, it could revolutionize our understanding of the universe.
On a more workaday level, the AMS was designed to sift through the streams of cosmic rays that will pass through its multiple layers of detectors. The AMS will be looking for hints about one of the great cosmological mysteries: why the universe is predominantly comprised of matter. The logical outcome of the Big Bang Theory is that matter and antimatter should have been created in equal amounts. If this is the case, where did all of the antimatter go? The AMS hopes to find out.
Another question that the AMS will attempt to answer is perhaps an even greater mystery than the disappearance of—or our lack of ability thus far to detect—antimatter. Cosmologists, astronomers, and astrophysicists are confronted by the fact that what we can see in the universe—the visible matter in the universe—accounts for less that 5% of the matter that MUST be present in the universe if we explain it gravitationally. Simply put, from what we can observe, there simply isn’t enough matter to account for the rate at which the universe is expanding. Most current theories that attempt to explain this apparent contradiction do so by invoking dark matter and dark energy. Sam Ting and the hundreds of other scientists on the AMS project are hopeful that clues as to the nature of dark matter will be revealed by the project.
To accomplish this—to give scientists a chance to find dark matter—the AMS had to be a formidable piece of technology. At its heart is a 1250-Gauss permanent magnet that will curve the path of charged particles that make up cosmic rays. Particles that bend one way are ordinary matter, whereas those that are bent in the opposite direction are antimatter. The AMS has 300,000 data channels to transmit information about the particles passing through it. The dry run in 1998 had nearly 100M cosmic ray events in 103 hours, so they’re expecting a lot of data. We’re at the Space Coast hoping they start getting that data from space in about a week.