NASA discovers mysterious radio noise in space

Signal in the radio wave range six times stronger than expected background noise

Stratospheric balloon with a highly sensitive radio instrument on board. The whitish horizon symbolizes the strange radio noise. © NASA / ARCADE / Roen Kelly
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In space, things are louder than expected. A radio wave measuring balloon from NASA has discovered extremely loud background noise in the radio area, which also astonished the astronomers. Because so far they have no idea where this smoking could come from, known sources exclude it.

In July 2006, NASA launched a stratospheric balloon with a highly sensitive radio instrument on board. The "Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission", ARCADE for short, climbed to a height of nearly 37 kilometers, hovering in an area where the atmosphere of the Earth merged into the vacuum of space. His task: to record the weak background radiation emanating from the first, oldest generation of stars.

Six times stronger than background noise

But what the instrument recorded then astonished the astronomers: "The universe really surprised us, " explains Alan Kogut of NASA's Goddard Space Flight Center in Greenbelt. "Instead of the faint signal we hoped to find, there was this booming noise, six times louder than anyone would have expected."

Source of the drone still unknown

In detailed analysis, the scientists were able to exclude old stars or well-known radio sources in space, and the gas in the outer shell of our Milky Way, the Halo, was out of the question. So what could this loud radio noise bring about? So far, the astronomers are here before a puzzle. Because there are not really enough radio galaxies in the universe to produce such signal strength as ARCADE had recorded. "You'd have to put them in a rifle like sardines in the universe, " says team member Dale Fixsen from the University of Maryland in College Park. "Then there would be little room left between one galaxy and the next."

The signal that the probe should actually record remains completely hidden behind this loud background noise. Because the radiation of 13 billion years ago shortly after the Big Bang first stars is definitely much weaker. On the other hand, the noise could provide valuable clues to the development of younger galaxies. display

"That's what makes science so exciting, " explains Michael Seiffert of NASA's Jet Propulsion Laboratory in Pasadena. "You start on a way to measure something - in this case, the radiation of the very first stars - and then you find something completely different, something previously unexplained."

Earlier receivers are not sensitive enough

The noise has never been detected before because ARCADE is the first probe whose instruments are sensitive enough to register the strong radio signal. To achieve this sensitivity, their receivers are embedded in just under two cubic meters of ultracold helium and cooled to just 2.7 degrees above absolute zero. Their temperature corresponds to that of the cosmic background radiation, the relic of the Big Bang, which was discovered in 1965 as cosmic noise.

Precisely because ARCADE has cooled so much, the researchers also rule out a falsification of the newly discovered signal by the instrument itself: If ARCADE has the same temperature as the microwave background, then the W "The instrument does not contaminate the cosmic signal, " says Kogut. Where the strange noise comes from, should now further investigations kl ren.

(NASA, 09.01.2009 - NPO)