Back to the Moon with Nuclear Rockets

• The study of the explosive nuclear fusionprocesses in supernovae of Type I.INTEGRAL will be able to identify them byusing the spectral line of cobalt-56 up to distancesof some 50 million light-years.• A survey of nearly all the remnants ofsupernovae that have exploded in the MilkyWay in the past 300 years. They are detectablein the radiation of the titanium-44spectral line.• Determination of locations in ourgalaxy at which nuclear synthesis has occurredon a large scale within the last millionyears. Here the aluminum-26 spectralline is exploited.• Investigation of active galactic nuclei ina broad spectral region.• Spectral analysis of the galactic nucleus.• A scan of the galactic plane for variablegamma sources such as novae.Another milestone in gamma astronomy isthe NASA project GLAST (Gamma-Ray LargeArea Space Telescope), now in the initialstages of study. The 3-ton telescope is to besent into Earth-orbit at an altitude of 600 kmwith a Delta II rocket, and will scan the gamma sky with unprecedentedsensitivity. The spectral region accessible toGLAST runs from 10 MeV to 300 GeV, beginning where INTE­GRAL leaves off. GLAST therefore closes the gap between thesofter (longer wave) segments of the gamma spectrum—thoseobserved by CGRO and other satellites—and the extremegamma radiation in the region of tera-electron volts, detectableuntil now only indirectly with Earth-bound Cerenkov counters(the Gamma-Ray Project of the Whipple Observatory). GLASTwill discover some 200 to 300 gamma-ray bursts per year, andwill be able to localize about half of them to within 10 arc-minutes.GLAST will obtain a high-resolution gamma spectrum forsome two dozen gamma-ray bursts per year, from which thephysical mechanism can be more closely studied.Successors to the 10-meter Whipple instrument, newlybuilt or now under construction, are most promising. Theywill register shock waves in Earth's atmosphere caused by extremely-short-wavelengthgamma radiation. The entire atmospherefunctions here almost like a giant scintillator. A proposalfor one such instrument, the MAGIC Telescope, wasmade by the Max Planck Institute for Physics in Munich in1 998: this instrument is to have a diameter of 1 7 meters andbe at least 15 times more sensitive than the Whipple instrument.Although these Earth-bound stations also study numerousother phenomena of the gamma sky, they have a crucialrole to play in solving the puzzle of gamma-ray bursts. If theCerenkov counters should register an impact in the atmospherein the TeV region, while space-based satellites simultaneouslyregister a gamma ray burst in the same region ofthe sky, this it would be a severe blow against the cosmologicalinterpretation of the phenomenon. Outer space ought tobe impenetrable to gamma radiation in the TeV region, atleast over distances of billions of light-years and more, becauseof the absorption of the intergalactic medium. ThatThe 10-Meter Optical Reflectoi is the instrument of the Gamma-Ray Project ofthe Whipple Observatory near Tucson, Arizona. It detects Cerenkov radiationproduced by gamma rays in tht TeV range striking the upper atmosphere.21stCENTUR >NASAwould leave he theoreticians standing there with emptyhands, and tr e solution would require new principles ofphysics or astr anomy.CodaIn May 199!, newspapers all over the world published sensational,front- 3age headlines about a highly dramatic gammaray burst. Thes > results, announced by astronomers at Kitt PeakObservatory ir Arizona and the Keck Telescope in Hawaii onMay 6, 1998, were welcomed with headlines such as "TheBiggest Explo; ion Since the Big Bang." This burst in the BigDipper constel ation had been detected by BeppoSAX on Dec.14, 1997. The Arizona observatory had registered an opticalafterglow onl' 12 hours after the burst. One hour later, astronomerShri n'vas Kulkarni and his team at the Keck Telescopealso observed a faintly glowing nebula in the immediatevicinity of the Durst. The spectrum of this nebula correspondsto that of a gal axy with a high rate of star formation. It manifests,however, a very high redshift (z = 3.42), far surpassingthe redshift of he presumed galaxy of origin of the gamma rayburst of May f, 1997 (z = 0.835). The distance of the galaxywas estimated at 1 2 billion light-years, so that the burst musthave discharg ;d 3 x 10 46 joules of energy. From the standpointof all of he models, this just goes too far. At the May 6,1998, press conference at NASA Headquarters in Washington,D.C., Kul ;arni recited all of the usual attempts at an explanation,frc m "black holes" to "hypernovas." Then headded, that he e we have such an extreme phenomenon, thatwe might well be dealing with "something completely unexpectedand pei haps far more exotic."Lothar /Com/ > is an editor of the German-language magazineFusion, and an economics writer for the Executive IntelligenceReview. This i rticle first appeared in Fusion, Vol. 19, No. 2,1998, and was translated into English by George Gregory.