Washington, Dec 7 (PTI) NASA scientists in Antarctica areset to launch a balloon-borne instrument to collectinformation on cosmic rays, high-energy particles from beyondthe solar system that enter Earth's atmosphere every day.
The instrument, called the Super Trans-Iron GalacticElement Recorder (SuperTIGER), is designed to study rare heavynuclei, which hold clues about where and how cosmic raysattain speeds up to nearly the speed of light.
It will be launched on December 10. In 2013, theSuperTIGER had broken flight duration records while flyingover Antarctica.
"The previous flight of SuperTIGER lasted 55 days,setting a record for the longest flight of any heavy-liftscientific balloon," said Robert Binns, the principalinvestigator at Washington University in the US, which leadsthe mission.
"The time aloft translated into a long exposure, which isimportant because the particles we're after make up only atiny fraction of cosmic rays," said Binns.
The most common cosmic ray particles are protons orhydrogen nuclei, making up roughly 90 per cent, followed byhelium nuclei (eight per cent) and electrons (one per cent).
The remainder contains the nuclei of other elements, withdwindling numbers of heavy nuclei as their mass rises.
With SuperTIGER, researchers are looking for the rarestof the rare - so-called ultra-heavy cosmic ray nuclei beyondiron, from cobalt to barium.
"Heavy elements, like the gold in your jewelry, areproduced through special processes in stars, and SuperTIGERaims to help us understand how and where this happens," saidJohn Mitchell at NASA's Goddard Space Flight Center in the US.
"We're all stardust, but figuring out where and how thisstardust is made helps us better understand our galaxy and ourplace in it," said Mitchell.
When a cosmic ray strikes the nucleus of a molecule ofatmospheric gas, both explode in a shower of subatomicshrapnel that triggers a cascade of particle collisions.
Some of these secondary particles reach detectors on theground, providing information scientists can use to infer theproperties of the original cosmic ray.
However, they also produce an interfering background thatis greatly reduced by flying instruments on scientificballoons, which reach altitudes of nearly 40,000 metres andfloat above 99.5 per cent of the atmosphere.
The most massive stars forge elements up to iron in theircores and then explode as supernovas, dispersing the materialinto space.
The explosions also create conditions that result in abrief, intense flood of subatomic particles called neutrons.
Many of these neutrons can "stick" to iron nuclei.
Some of them subsequently decay into protons, producingnew elements heavier than iron.
Supernova blast waves provide the boost that turns theseparticles into high-energy cosmic rays. As a shock waveexpands into space, it entraps and accelerates particles untilthey reach energies so extreme they can no longer becontained.
Over the past two decades, evidence accumulated fromdetectors on NASA's Advanced Composition Explorer satelliteand SuperTIGER's predecessor, the balloon-borne TIGERinstrument, has allowed scientists to work out a generalpicture of cosmic ray sources.
Roughly 20 per cent of cosmic rays were thought to arisefrom massive stars and supernova debris, while 80 per centcame from interstellar dust and gas with chemical quantitiessimilar to what is found in the solar system. PTI MHN SARMHN.
This is unedited, unformatted feed from the Press Trust of India wire.