Transcript of the GLAST Video

Humanity's place among the stars finds us somewhere between the very large and the very small. Exploring the infinite and the infinitesimal, scientists now believe that all forces - those that bind the atom, and those that hold the Universe together - may be different parts of the same phenomenon.

The time has come to launch a mission into space that will seek to connect the cosmic with the atomic - bridging the gap between a cosmos shaped by gravity - and a subatomic world controlled by quantum forces.

The Gamma Ray Large Area Space Telescope, known as GLAST, is the next mission designed to seek out the most powerful energy sources known in the cosmos, places where nature combines gravity and quantum forces at tremendous energies - locations that strip away space, warp time, and generate intense beams of gamma rays.

Planned for Launch in 2006 on a Delta-class rocket, GLAST will orbit the Earth and survey the high-energy universe in unprecedented detail - exploring the gamma-ray sky.

Gamma rays are the most energetic form of light. They move like bullets at light speed as tiny particles of light called photons - with millions to billions of times more energy than visible light. Imagine standing on a mountain top and gazing at the night sky with gamma ray eyes. The familiar look of the nighttime stars would give way to the exotic and the mysterious - collapsed spinning stars in supernova remnants, massive black holes, and gamma-ray bursters, the most powerful sources of energy seen across the known Universe.

Many galaxies in the cosmos are much more active than our own. And scientists now agree that a colossal engine lies deep in the center of each active galaxy - a black hole generating enough power to accelerate high-energy particles to nearly the speed of light. This particle acceleration is a process that begins at the sub-atomic level and reveals itself in a spectacular jet thousands of light-years long. It's an extreme process that occurs in many different cosmic sources - and GLAST is designed to detect thousands of them.

One way to produce gamma rays is when photons of lower-energy light smash into fast-moving electrons. This direct collision steals energy from the electron and boosts the light's energy, producing gamma rays. But detecting these photons can be tricky. Gamma rays shoot right through optical lenses and mirrors, so conventional telescopes can't focus them for detection. To solve this challenge, GLAST borrows techniques from high-energy physics - adopting technologies used in earthbound laboratories.

Peering into the quantum world, physicists use particle detectors and accelerators to probe matter on a nuclear scale. GLAST will use these high-energy detector technologies to view the cosmos - recording gamma rays from immense particle accelerators that operate on scales far beyond anything achieved on Planet Earth. But most cosmic gamma rays are blocked by the Earth's atmosphere - unable to reach detectors on the ground. So, the GLAST mission must be carried out from space. When these gamma ray photons interact with matter, they create pairs of oppositely charged particles. Light turns into matter and antimatter, such as an electron and positron.

The creation of particle pairs from purely energetic gamma rays is described by Einstein's famous equation, E=mc^2. This pair conversion process is the scientific basis for the first of GLAST's two instruments, the Large Area Telescope. Known as the LAT, this device is one of sixteen towers that can precisely track these charged particle pairs - pointing back to the source of the incoming gamma ray. With sensitivity at least 30 times better than previous experiments, the LAT will seek out thousands of gamma-ray sources - from exploding stars to distant galaxies with massive black holes at their cores - places in the Universe where charged particles are accelerated to make gamma-rays.

The second detector array on board is the GLAST Burst Monitor, or GBM. Gamma-ray Bursts represent the most powerful cosmic explosions visible across the Universe. And this instrument will detect visible light flashes produced when gamma rays interact in the device's scintillating crystals. With a wider field of view than the LAT, the GLAST Burst Monitor will detect up to 200 Gamma Ray Bursts per year.

Together, these two instruments will permit scientists to probe the deepest reaches of space, exploring the many cosmic particle accelerators, hunting for the mysterious substance known as dark matter, and searching for clues to the nature of gravity.

As a mission of tremendous scope, GLAST combines the best in astrophysics and particle physics - a global collaboration between NASA and the United States Department of Energy - as well as significant contributions from France, Germany, Italy, Japan, and Sweden. It's a powerful alliance with one important goal: the successful exploration and mapping of the high-energy gamma-ray sky.

GLAST is a key mission in our quest to unite the cosmic and quantum worlds - a journey of great promise to join the physics of the very large to the very small.

Credits:

Visible Sky Panorama by Axel Mellinger
Gamma-ray Sky simulation by Seth Digel
GLAST Animations by Tim Carnahan and Cherie Congedo

Content Consultation:
Jerry Bonnell, Lynn Cominsky, Neil Gehrels, Christopher Wanjek, and Scott Lambros

GLAST LAT P. I.: Peter Michelson, Stanford

GLAST GBM P. I.: Charles Meegan, NASA's Marshall Space Flight Center

GLAST PROJECT:

Project Scientist: Jonathan Ormes
Project Manager: Elizabeth Citrin
NASA's Goddard Space Flight Center

Artwork by Joe Bergeron, courtesy "Sky & Telescope Magazine"

Written, Produced, and Directed by Mike Zeko