Monday, September 28, 2009

Planck is Up and Mapping Ancient Light

The Planck mission has produced its first rough images of the ancient sky, demonstrating that the new observatory is working and ready to measure cosmic microwave background radiation—ancient light from the dawn of time.

Cosmic microwave background radiation, or CMBR for short, is thought to play a key role in the field of cosmology—the study of the origin and nature of the universe. CMBR is a form of electromagnetic radiation which fills the universe. While the space between the stars and galaxies appears pitch black in an optical telescope, a radio telescope reveals a faint background glow, almost exactly the same in all directions, that is not associated with any star, galaxy, or other object. This glow is strongest in the microwave region of the radio spectrum, leading to the name cosmic microwave background radiation. CMBR was discovered in 1964 by radio astronomers Arno Penzias and Robert Wilson and was the culmination of work initiated in the 1940s. Their discovery earned them the 1978 Nobel Prize.

According to the Big Bang model of cosmology, before the formation of stars and planets, the universe was much smaller, much hotter, and filled with a uniform glow from its white-hot fog of hydrogen plasma. As the universe expanded, both the plasma and the radiation filling it grew cooler. When the universe cooled enough, stable atoms formed. These atoms were no longer able to absorb the thermal radiation, and the universe became transparent instead of being an opaque fog. The photons that existed at that time have been traveling ever since, though growing fainter and less energetic, since the exact same photons fill a larger and larger universe.

The objective of the Planck mission is to detect and map these ancient photons. Planck is a European Space Agency (ESA) mission that has significant participation from the National Aeronautics and Space Administration (NASA). NASA played key roles in the development of the Planck mission and is providing important contributions to the science analyses of mission data.

The mission is named after German physicist Max Planck (1858 – 1947), considered to be the founder of quantum theory. The Planck mission was launched (along with the Herschel mission) on May 14, 2009 aboard an Ariane 5 rocket from Europe’s Spaceport in French Guiana. Since July 2, Planck has been orbiting the Earth-Sun Lagrange Point 2 (L2), about 1.5 million kilometers (930,000 miles) from Earth in the direction opposite the Sun. This dark location, combined with an onboard cooling system, allows Planck to be very cold indeed, with an operational temperature of -273.05°C (-459.5°F). This temperature allows Planck’s detectors to study the CMBR.

And extensive checkout and initial calibration of Planck's instruments was completed by the second week of August. Planck's "first light" survey, which ran continuously from August 13 to 27, verified the stability of its instruments and their ability to be calibrated over long periods to the extreme accuracy that is needed. The survey produced maps of a 360° strip of the sky, one map for each of Planck's nine observed frequencies. Preliminary analysis indicates that the quality of the data is excellent.

Astronomers expect that Planck will provide the best views to date of the early moments of our universe, over 13 billion years ago. Planck will survey the entire sky continuously for at least 15 months, yielding at least two full and independent all-sky images. The mission promises to contain a treasure trove of data that will keep cosmologists and astrophysicists busy for decades to come.

The Planck mission follows in the footsteps of previous missions which studied the CMBR, including NASA's Cosmic Background Explorer (COBE) , NASA's Wilkinson Microwave Anisotropy Probe (WMAP) , NASA's and the Netherlands (NIVR) Infrared Astronomical Satellite (IRAS) , and other orbital and ground-based missions. For more on the Planck mission and earlier CMBR missions, check out these sites:

Planck Mission, ESA Home Page

Planck Mission, NASA Home Page

NASA’s Legacy Archive for Microwave Background Data Analysis

NASA's Cosmic Background Explorer (COBE) Archive Page

NASA's Wilkinson Microwave Anisotropy Probe (WMAP) Archive Page

NASA's and the Netherlands (NIVR) Infrared Astronomical Satellite (IRAS) Archive Page

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