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Newly launched telescope scans gamma-ray sky

June 11, 2008
Courtesy NASA
and World Science staff

A tel­e­scope just launched in­to or­bit will al­low us to see ob­jects in space in a new way, sci­en­tists say.

NASA’s Gam­ma-Ray Large Ar­ea Space Tel­e­scope, or GLAST, was launched aboard a rock­et early Wed­nes­day af­ter­noon from Cape Ca­nav­er­al Air Force Sta­t­ion in cen­tral Flor­i­da.

This artist's con­cept shows GLAST in or­bit around Earth. Click here for ani­ma­tion (mpeg4). (Cour­tesy NA­SA/ God­dard Space Flight Cen­ter Con­cep­tual Im­age Lab)
“The uni­ver­se looks re­markably dif­fer­ent out­side the nar­row range of col­ors in the spec­trum that we can see with our eyes,” said Da­vid Thomp­son, dep­u­ty proj­ect sci­ent­ist for the tel­e­scope at the agen­cy’s God­dard Space Flight Cen­ter, Green­belt, Md.

The in­stru­ment “will give us a spec­tac­u­lar high-en­er­gy ‘gam­ma-ray vi­sion,’” said Thomp­son. Gam­ma rays are the high­est-en­er­gy form of light and can­not be seen by the na­ked eye.

“If you’re in space with gam­ma-ray vi­sion, there are gam­ma-rays com­ing from all di­rec­tions. The Milky Way would be a bril­liant swath of light, and you’d see a sky con­stantly chang­ing with ob­jects dim­ming and bright­en­ing on dif­fer­ent time scales. If you see a blind­ing flash, that would be a gam­ma-ray burst,” Thomp­son said, re­fer­ring to blasts of­ten as­so­ci­at­ed with stel­lar ex­plo­sions.

GLAST’s gam­ma-ray “vi­sion” is ex­pected to help sci­en­tists an­swer ques­tions such as: How do black holes ac­cel­er­ate jets of ma­te­ri­al to nearly light speed? What is the mys­te­ri­ous “dark mat­ter” be­lieved to per­me­ate the cos­mos, but so far de­tected only through its gra­vi­ta­t­ional ef­fects? Ex­actly what pro­duces gam­ma-ray bursts? How do so­lar flares gen­er­ate high-en­er­gy par­t­i­cles? How do ex­ot­ic, highly com­pact stars known as pul­sars work? What is the or­i­gin of cos­mic rays? and shat else out there is shin­ing gam­ma rays?

“One thing that’s ex­cit­ing is the cutting-edge in­stru­menta­t­ion,” said Pe­ter Mi­chel­son of Stan­ford Uni­ver­s­ity in Cal­i­for­nia, prin­ci­pal in­ves­ti­ga­tor for the Large Ar­ea Space Tel­e­scope, or LAT, aboard the sat­el­lite. With­in the tel­e­scope, “gam­ma-rays con­vert to mat­ter and an­ti-mat­ter,” par­t­i­cles that are twins of or­di­nary mat­ter par­t­i­cles but op­po­site in cer­tain prop­er­ties, he ex­plained. “By the di­rec­tion of the par­t­i­cles, we can de­tect which di­rec­tion the gam­ma-ray came from and find its or­i­gin in space.”

The de­vice is al­so “the first im­ag­ing gam­ma-ray ob­serv­a­to­ry to sur­vey the en­tire sky eve­ry three hours,” over a great range of gam­ma-ray en­er­gies, said Steve Ritz, proj­ect sci­ent­ist at God­dard. This is im­por­tant be­cause the gam­ma-ray sky is con­stantly chang­ing in stun­ning ways. The ob­serv­a­to­ry, a gam­ma-ray burst mon­i­tor, “s­pans a fac­tor of 10 mil­lion in en­er­gy from the high­est to the low­est en­er­gy gam­ma rays it will de­tect.”

Eight­een in­sti­tu­tions in six coun­tries—France, Ger­ma­ny, It­a­ly, Ja­pan, Swe­den, and the U.S.—were in­volved in the crea­t­ion of GLAST.

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Homepage image of GLAST liftoff courtesy NASA

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A telescope just launched into orbit will allow us to see objects in space in a new way, scientists say. NASA’s Gamma-Ray Large Area Space Telescope, or GLAST, was launched aboard a rocket early this afternoon from Cape Canaveral Air Force Station in central Florida. “The Universe looks remarkably different outside the narrow range of colors in the spectrum that we can see with our eyes,” said David Thompson, deputy project scientist for the telescope at the agency’s Goddard Space Flight Center, Greenbelt, Md. The instrument “will give us a spectacular high-energy ‘gamma-ray vision,’“ said Thompson. Gamma rays are the highest-energy form of light and cannot be seen by the naked eye. “If you’re in space with gamma-ray vision, there are gamma-rays coming from all directions. The Milky Way would be a brilliant swath of light, and you’d see a sky constantly changing with objects dimming and brightening on different time scales. If you see a blinding flash, that would be a gamma-ray burst,” Thompson said, referring to blasts often associated with stellar explosions. GLAST’s gamma-ray “vision” is expected to help scientists answer questions such as: How do black holes accelerate jets of material to nearly light speed? What is the mysterious “dark matter” believed to permeate the cosmos, but so far detected only through its graviational effects? What precisely leads to gamma-ray bursts? How do solar flares generate high-energy particles? How do exotic, highly compact stars known as pulsars work? What is the origin of cosmic rays? and shat else out there is shining gamma rays? “One thing that’s exciting is the cutting-edge instrumentation,” said Peter Michelson of Stanford University in California, principal investigator for the Large Area Space Telescope, or LAT. Within the telescope, “gamma-rays convert to matter and anti-matter,” particles that are twins of ordinary matter particles but opposite in certain properties, he explained. “By the direction of the particles, we can detect which direction the gamma-ray came from and find its origin in space.” The device is also “the first imaging gamma-ray observatory to survey the entire sky every three hours,” over a “huge” range of gamma-ray energies said Steve Ritz, project scientist at Goddard. This is important because the gamma-ray sky is constantly changing in stunning ways. The observatory, a gamma-ray burst monitor, “spans a factor of 10 million in energy from the highest to the lowest energy gamma rays it will detect.” Eighteen institutions in six countries—France, Germany, Italy, Japan, Sweden, and the U.S.—were involved in the creation of GLAST.