GUANO project sends up balloons for near-space atmosphere experiments
Doug Forbes and Darlene English prepare the GUANO cosmic ray detector for launch.
By Pamela Gill
The Grenfell Upper-Atmosphere and Near-space Observatory (GUANO) is a project which sends high altitude balloons about 30-35 kilometres into the stratosphere as a platform for conducting experiments in a near-space environment.
“The primary aim of the project is to involve students in the planning, construction, and flying of experiments to study the nature of high-energy cosmic rays,” said Doug Forbes, a Grenfell physics prof who is heading up the project. Dr. Forbes is joined by Darlene English of Grenfell’s Division of Science in conducting the experiments. “The outcomes of the project will be that students gain direct experience with how modern collaborative research is done, and will be exposed to concepts of astrophysics and particle physics, as they attempt to answer some of the most fundamental questions about the world we live in.”
He explained that Earth is constantly pelted by cosmic rays. Described as ‘a thin rain of charged particles,’ cosmic rays range from low-energy particles originating in the sun to extremely high energy particles that originate outside our own Milky Way galaxy in stellar explosions known as supernovae.
“Some of these particles can have far higher energies than we can ever hope to duplicate in accelerators on Earth, and their study may shed light on the fundamental structure of matter, and on the structure and origin of the universe,” said Dr. Forbes.
When a cosmic ray enters Earth’s atmosphere, it eventually collides with atoms in the stratosphere. This collision begins a chain reaction in which the broken bits of the atom move on to break apart other atoms, and so on. The result is a shower of secondary particles. Most of these particles have low energy and they decay or are absorbed in the air before they reach the surface. The only particles that arrive at the ground are either very energetic or relatively stable. One such particle is the muon, which is a high-energy, heavier version of the electron.
“At sea level, about 600 particles from cosmic ray air showers bombard your body every minute,” said Dr. Forbes.
The extraterrestrial nature of cosmic rays was first discovered by Victor Hess, who, starting in 1911, made a series of balloon flights and noticed that the intensity of ionizing radiation at a height of five kilometres was significantly greater than at sea level. This meant the radiation was entering the atmosphere from outer space. The intensity of particles increases with height because the lower atmosphere filters out the lower energy secondary particles. At an altitude of about 25 kilometres the flux begins to decrease as fewer of the unfiltered secondaries and more of the primary particles begin to be detected.
The GUANO project will send technology known as a Geiger counter into ‘near-space’ to detect individual cosmic rays. Each click of the Geiger counter is the detection of a single atomic nucleus originating from a star – perhaps the sun, or more likely, a distant supernova. The highest energy cosmic rays probably originate in other galaxies.
“The GUANO project is designed to fly inexpensive cosmic ray detectors to high altitudes, where the primary particles may be studied,” said Dr. Forbes. “One example of the kind of phenomenon that will be studied is the variation in the average flux of cosmic rays, which can provide information on solar activity and its effects on Earth’s magnetic field. We are currently in the middle of a minimum in solar activity; by flying GUANO payloads several times per year through to solar maximum in mid-2012, valuable information will be obtained.”
A GUANO flight typically takes about three to four hours to reach its greatest height. After the balloon bursts, the package falls to Earth beneath a parachute.
“There is no provision for recovering the payload after landing, but there is a reward for its safe return, should anyone find it!” he said.
Two successful GUANO flights were launched on June 22 and July 9. The balloon reached heights of 35 kilometres.
“At that height, the temperature was a frosty -35° C,” said Dr. Forbes. “An observer riding on the balloon would have easily seen the curvature of the Earth beneath a black sky.”
As for the future of the project, Dr. Forbes said he hopes to continue flying cosmic ray payloads several times a year over the next few years, at least until the expected solar maximum in 2012.
“We are also hoping to make a GUANO flight the centerpiece of a particle physics/astrophysics camp for Grade 11 students in western Newfoundland, now in the planning stages,” he said, adding that the proposed three-day camp would be titled SNAP: School for Nuclei, Astrophysics, and Particles. “In the very near future, GUANO may offer students a chance to fly a mission to the very edge of space.”
For more information on this project visit www2.swgc.mun.ca/physics/GUANO/index.html.