The Planck, a European Space Agency mission with significant participation from NASA, has captured its first rough images of the sky, demonstrating that the observatory is working and ready to measure light from the dawn of time. Planck will survey the entire sky to learn more about the history and evolution of our universe. The space telescope started surveying the sky regularly on Aug. 13 from its vantage point far from Earth. Planck is in orbit around the second Lagrange point of our Earth-sun system, a relatively stable spot located 1.5 million kilometers (930,000 miles) from Earth. “We are beginning to observe ancient light that has traveled more than 13 billion years to reach us,” said Charles Lawrence, the project scientist for the mission at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena. “It’s tremendously exciting to see these very first data from Planck. They show that all systems are working well and give a preview of the all-sky images to come.” One of Planck’s first images is shown as a strip superimposed over a two-dimensional projection of the whole sky as seen in visible light. The strip covers 360° of sky and, at its widest, is about 15° across. The prominent horizontal band is light from the Milky Way galaxy. The image shows how the sky looks at millimeter-long wavelengths. Red areas are brighter; blue areas are darker. The large red strips show the Milky Way. The small bright and dark spots far from the galactic plane are from the cosmic microwave background – relic radiation from the birth of our universe. Planck is measuring the sky at nine wavelengths of light, one map of which is shown here. (Image: ESA, LFI & HFI Consortia, background optical image: Axel Mellinger.) Following launch on May 14, the satellite’s subsystems were checked out, along with the cool-down of its instrument detectors. The detectors are for sensing temperature variations in the cosmic microwave background, which is radiation left over from the early universe. The temperature fluctuations are a million times smaller than one degree. To measure differences this minute, Planck’s detectors are cooled to extremely low temperatures, some very close to the lowest temperature theoretically attainable. Instrument commissioning, optimization and initial calibration were completed by the second week of August. During the “first light” survey, which took place Aug. 13 to 27, Planck surveyed the sky continuously. This initial stage was for verifying the stability of the instruments and the accuracy of their calibration over long periods of time. The survey yielded nine maps of a strip of the sky – one for each of Planck’s nine frequencies. Preliminary analysis indicates that the quality of the data is excellent. Routine operations will now continue without a break for at least 15 months. During this time, Planck will gather data for two independent all-sky maps. To fully exploit the high sensitivity of Planck, data compilation will require delicate calibrations and careful analysis. The mission promises to produce a treasure trove of data that will keep cosmologists and astrophysicists busy for decades. JPL contributed mission-enabling technology for both of Planck’s scientific instruments. European, Canadian and US scientists will collaborate on data analysis. JPL is managed by the California Institute of Technology in Pasadena. For more information, visit: www.nasa.gov/planck