Fermi Gamma-ray Space Telescope is an orbiting observatory used to study gamma rays from outer space. Gamma rays rank as the most energetic kind of electromagnetic radiation. The United States National Aeronautics and Space Administration (NASA) launched Fermi on June 11, 2008. At the time, the craft was known as the Gamma-ray Large Area Space Telescope (GLAST). NASA later renamed GLAST to honor the Italian-born American physicist Enrico Fermi, who was a pioneer in the study of high-energy physics. The Fermi telescope is a joint project of NASA and the U.S. Department of Energy, with contributions from scientific institutions in France, Germany, Italy, Japan, and Sweden.
Loading the player...Fermi Gamma-ray Space Telescope
Gamma rays originate in extremely high-energy environments. For example, they might come from a rapidly spinning, highly magnetic, dense core of an exploded star called a pulsar or from a supermassive black hole, an object whose gravitational pull is so strong that nothing can escape from it (see Black hole). Furthermore, they may come from an undiscovered physics process, such as dark matter particle interactions. Some gamma rays come in flashes known as gamma-ray bursts. One of Fermi’s major objectives is to investigate the cause of such bursts. By observing gamma rays with Fermi, scientists hope to learn more about how such exotic objects work and to uncover new science.
Fermi weighs 9,500 pounds (4.3 metric tons). The craft orbits Earth at an altitude of 350 miles (565 kilometers).
Fermi is designed to be more sensitive and to have a wider field of view than previous gamma-ray telescopes. Its main instrument, the Large Area Telescope (LAT), can observe about 20 percent of the sky at a time. The LAT can thus observe the entire sky in the course of only two orbits, or about three hours. A sophisticated onboard electronics system, including three computers, processes the huge amount of data gathered by the LAT. A second instrument, the Gamma-ray Burst Monitor (GBM), consists of a series of sensors placed around the spacecraft. These sensors detect lower-energy gamma rays.
Loading the player...Antimatter created in thunderstorms
On Aug. 26, 2008, NASA announced that Fermi was operational and gathering data. On October 16, scientists announced that they had discovered a new class of pulsar that pulses only gamma rays. Most known pulsars give off many different kinds of pulsed electromagnetic radiation, particularly radio waves. Since then, Fermi has discovered many new gamma-ray pulsars, as well as other gamma-ray sources.
In 2011, scientists announced that Fermi had detected gamma rays originating from Earth. The rays were detected coming from lightning strikes. The finding confirms the idea that lightning produces particles of antimatter. Antimatter resembles ordinary matter but with certain properties of its particles, such as electric charge, reversed. When an antimatter particle encounters an ordinary matter particle, the two particles are destroyed. The destruction produces the gamma rays detected by Fermi.
In 2012, the telescope was modified to better study terrestrial gamma-ray flashes (TGF’s). These mysterious flashes originate above thunderstorms on Earth and produce not only gamma rays but powerful radio waves.
