French Scientists: 'Background' light of universe measured

The brightness of the background of light photons that has filled the universe since its formation has been measured for the first time, French researchers say.

Scientists at the country's National Center for Scientific Research say their findings could provide new insight into the size of the universe, the formation of stars and the evolution of galaxies.

Download the CNRS Press Release here

The light emitted by all the objects in the universe, such as stars and galaxies, ever since its birth fills intergalactic space with an "ocean" of photons known as the "diffuse extragalactic background light," the researchers said.

The shine of our own galaxy makes it impossible to directly measure this fossil record of the light emitted in the universe, so astrophysicists made use of gamma rays, with energy more than 500 billion times greater than that of visible light, as an alternative, indirect method of measuring this light, a release from the center said.

These measurements made it possible to estimate for the first time the intensity of the starlight contained within all the universe at wavelengths ranging from the near infrared to the ultraviolet, including visible wavelengths, it said.

A better understanding of this diffuse light should yield information about the first stars, shedding light on their formation and on the evolution of galaxies, astronomers said.

NASA Mars Rover Curiosity: ChemCam Laser-Zapped it's First Rock Sample

This composite image, with magnified insets, depicts the first laser test by the French designed Chemistry and Camera, or ChemCam, instrument aboard NASA's Curiosity Mars rover. 

The composite incorporates a Navigation Camera image taken prior to the test, with insets taken by the camera in ChemCam.

The circular insert highlights the rock before the laser test. The square inset is further magnified and processed to show the difference between images taken before and after the laser interrogation of the rock.

The test took place on Aug. 19, 2012.

In the composite, the fist-sized rock, called "Coronation," is highlighted.

Coronation is the first rock on any extraterrestrial planet to be investigated with such a laser test.

The widest context view in this composite comes from Curiosity's Navigation Camera. The magnified views in the insets come from ChemCam's camera, the Remote Micro-Imager.

The area shown in the circular inset is 6 centimeters (2.4 inches) in diameter. It was taken before the rock was hit with the laser.

The area covered in the further-magnified square inset is 8 millimeters (about one-third of an inch) across.

It combines information from images taken before and after the test, subtracting the "before" image from the "after" image to make the changes in the rock visible.

ChemCam hit Coronation with 30 pulses of its laser during a 10-second period. Each pulse delivered more than a million watts of power for about five one-billionths of a second.

The energy from the laser excited atoms in the rock into an ionized, glowing plasma. ChemCam also caught the light from that spark with a telescope and analyzed it with three spectrometers for information about what elements are in the target.

This initial use of the laser on Mars served as target practice for characterizing the instrument but may provide additional value.

Researchers will check whether the composition changed as the pulses progressed. If it did change, that could indicate dust or other surface material being penetrated to reveal different composition beneath the surface.

ChemCam was developed, built and tested by the U.S. Department of Energy's Los Alamos National Laboratory in partnership with scientists and engineers funded by France's national space agency, Centre National d'Etudes Spatiales (CNES) and research agency, Centre National de la Recherche Scientifique (CNRS).