Cosmic Rays, the Space Station, and You

Welcome new blogger Spaceports! He has a schedule of projected 2007 launches and other interesting information on spaceflight.

Our parents would insist upon us finishing one big task before starting another. Some have argued for abandoning ISS and moving on to the Moon or Mars. For the US to pull out would gravely disappoint international partners like the ESA and Russia. These scientific collaborations have gone on for decades, transcending differences over trade and war.

One of those international projects is the EUSO, the Extreme Universe Space Observatory. Previously we have heard about the ANITA balloon experiment using the Antarctic ice as a cosmic ray detector. It would be even better to go into Space where you have the entire Earth below you. As planned, EUSO would be attached to the side of ISS, allowing the station to accomplish some real science.

Looking quantitatively, there seems to be no upper limit to the energy of cosmic rays. The so-called GZK cutoff may be non-existent, as there are well-documented particles with greater energies. Diagram below is from Halloran, Sokolsky and Yoshida, "The Highest Energy Cosmic Rays" in PHYSICS TODAY January 1995. There is no cutoff at all for low-redshift particles, indicating that energetic events could come from relatively nearby. There is also the possibility of high-energy neutrinos being detected. Detection of ultra-high energy cosmic rays opens the door for exotic theories of physics.

How does this affect us? The answer may be involve one of nature's most awe-inspiring displays, the lightning bolt. We are taught in school that lightning results from the buildup of charged particles in storm clouds. Once the battery is charged, what sets it off? Cosmic rays fall on Earth fairly constantly, rain or shine. A few researchers have quietly suggested that they may trigger lightning.

Assuming that EUSO is orbited, this supposition may be tested with a fairly simple experiment. Many time-lapse cameras have recorded lightning flashes. All we need do is set up a camera (or two, for stereo ranging) in a lightning-prone area beneath the ISS track. With patience, eventually we would record a thunderstorm during a time when EUSO is overhead.

If cosmic rays are found to correlate with lightning, it would show once again that our lives are intimately connected with the heavens.