Each of our Antarctic stations support many science programs. Some science is limited to the summer season but there are many programs that run all year, and thus require the support of the wintering team.
I’II be honest and declare that when I first heard of cosmic rays I immediately had visions of Disneyland and the galactic adventures of Buzz Lightyear. I stopped short of screaming “To infinity, and beyond!” — you must admit it does sound very Disney-ish, right? Alas, it is not from Tomorrowland or Walt’s imagination, it is real and it’s right here at Mawson.
I must also declare I have ‘borrowed’ much of this article from a number of sources including the Bureau of Meteorology website and our very own Australian Antarctic Division website. I should also confess in researching cosmic rays, and before writing this article, I assessed all of the material and gleefully plagiarised with the intent of re-writing it in ‘lay’ terms so it would make easier reading for you — respectfully of course. But that is not the case. I’m afraid I quickly discovered that all things CosRay were way over my head. What follows is pretty much a compilation of every report I could find and every website I visited. My only hope is you come out the other end a little better for the experience?
The CosRay project is the study of cosmic rays in space. It first commenced at Mawson in 1955 and has been almost continuous ever since. And whilst it now works away in the background autonomously and thus not requiring any direct input from the wintering team, it is quite fascinating and well worthy of its own article.
In the summer of 2008/09 the monitoring and data collection of cosmic rays (and a few other sciences) were mostly automated, mainly through the additional expansion of station networking and replacement of data acquisition systems. That said, no specific science personnel are employed at CosRay during the winter leaving the observatory equipment to be managed by the two Bureau of Meteorology staff we have on station. Of course they receive additional support from communications, electrical and other trades if need be.
The current CosRay building and vault system was constructed in 1971 and its exterior is unfortunately now looking a little worse for wear, as can be seen by the large number of heavy gauge guy wires. The building is very exposed to the katabatic winds because of its location at the very top of the station, virtually the highest point on Mawson’s rock.
What is a cosmic ray?
Simply put, cosmic rays are pieces of atoms (mainly protons and atomic nuclei), flying through space at nearly the speed of light. Because these particles have mass as well as high speed, they can carry enormous levels of energy. Trying to harness that energy has, so far, been impossible.
Where do they come from?
When first discovered in the early twentieth century it was thought that all cosmic rays probably originated from our sun but that was disproved early on. The rate of cosmic rays detected at a certain point on earth is basically the same at night as it is during the day.
It is difficult to determine exactly where they come from. These high speed cosmic particles are charged, so they interact with the earth’s magnetic field — or any other magnetic field in space (e.g. from other stars and planets). This changes their direction so once they eventually reach our telescopes, or rather neutron monitors to be exact, it’s often difficult to tell exactly where they originated.
So, the true source of cosmic rays is unknown but they are believed to originate from any one of the following: supernova (or exploding stars), active galactic nuclei, quasars and gamma-ray bursts, with supernova currently edging the others out as the most likely source.
In Antarctica, the amount of cosmic rays detected here is reasonably constant all year round with only some slight variations from year to year.
Can we see them?
The short answer is no. Cosmic rays are observed indirectly by a device known as a neutron monitor. When cosmic ray particles enter the Earth’s atmosphere they interact with the nuclei of the air molecules to produce secondary radiation. This consists of pions (which decay to muons) and a shower of protons and neutrons. The neutrons predominate in this secondary radiation because the protons being charged are more easily attenuated in subsequent travel. The cosmic ray detector actually detects these secondary neutrons and as a consequence is referred to as a neutron monitor.
The CosRay building at Mawson houses an array of cosmic ray muon telescopes and neutron monitors, large multiple horizontal tubes with detectors within. Both count the numbers of cosmic rays from space but the muon telescopes are also able to provide a better indication of where these particles come from.
What do they do?
The main impact of cosmic rays to us is that they have sufficient energy to alter the states of circuit components in electronic integrated circuits, thus causing transient errors to occur such as corrupted data in electronic memory devices, or incorrect performance of CPUs, often referred to as “soft errors” (not to be confused with software errors caused by programming mistakes/bugs and station leaders). This has been a problem in extremely high-altitude electronics, such as in satellites, but with transistors becoming smaller and smaller, this is becoming an increasing concern in ground-level electronics as well. Studies by IBM in the 1990s suggest that computers typically experience about one cosmic-ray-induced error per 256 megabytes of RAM per month. To alleviate this problem, the Intel Corporation has proposed a cosmic ray detector that could be integrated into future high-density microprocessors, allowing the processor to repeat the last command following a cosmic-ray event.
And one for all you air travellers: cosmic rays are suspected as a possible cause of an in-flight incident in 2008 where a Qantas Airbus A330 airliner twice plunged hundreds of feet after an unexplained malfunction in its flight control system. Many passengers and crew members were injured, some seriously. After this incident, the accident investigators determined that the airliner’s flight control system had received a data spike that could not be explained, and that all systems were in perfect working order. This has prompted a software upgrade to all A330 and A340 airliners worldwide, so that any data spikes in this system are filtered out electronically.
Over two million cosmic rays fly through your body every day. It’s hard to avoid them.
We cannot possibly create a cosmic ray on earth!
Cosmic ray science still has many unanswered questions and challenges ahead.
If this article has tickled your galactic senses and you can’t find the time or money to visit Buzz and his pals at Disneyland, check out the following links. The information contained on the Wikipedia page is very detailed and very interesting.
Steve Robertson, Station Leader