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Jill Tarter Robert Ackermann William Barott Peter Backus Michael Davis John Dreher Gerald Harp Jane Jordan Tom Kilsdonk Seth Shostak Ken Smolek 《Acta Astronautica》2011,68(3-4):340-346
The Search for ExtraTerrestrial Intelligence (SETI) finally has its own full-time telescope. The Allen telescope array (ATA) in Northern California was dedicated on October 11, 2007. This array, which will eventually be composed of 350 small radio antennas, each 6.1 m in diameter, is being built as a partnership between the SETI Institute and the University of California Radio Astronomy Laboratory. Last October, Paul G. Allen (who provided the funds for the technology development and the first phase of array construction) pushed a silver button and all 42 antennas of the current ATA-42 slewed to point in the direction of the distant galaxy M81. Specialized electronic backend detectors attached to the ATA began making a radio map of that galaxy and simultaneously began SETI observations of HIP48573, a G5V star near M81 on the sky and a distance of 264 light years from Earth. The Allen telescope array will greatly improve the speed of conducting SETI searches over the next few decades, and it will allow a suite of different search strategies to be undertaken. This paper summarizes some of the earliest SETI observations from the array, and describes the search strategies currently being planned. 相似文献
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Jill Tarter Peter Backus Gary Heiligman John Dreher Sam LaRoque Project Phoenix Team 《Acta Astronautica》2000,46(10-12)
During 16 weeks of continuous SETI observing at the Parkes Observatory in New South Wales, Australia, a set of time-averaged data with 643 Hz resolution were recorded and returned to the SETI Institute for post-processing. These data are the 14 second (10 frame) average powers in each of 15,552 “subband” channels covering 10 MHz of the spectrum in both right and left circular polarizations that were used by the signal detection hardware to baseline and threshold the 1 Hz high resolution SETI spectra. The observations covered frequencies from 1.2 to 3 GHz, tracking 209 stellar targets across the sky. The data at each frequency were averaged over all directions and then interrogated to attempt to determine the prevalence of radio frequency interference (RFI). Estimates were made for the probability of encountering RFI at a particular frequency. Particular attention has been paid to those portions of the spectrum that are allocated as primary use status, or footnote protection for radioastronomy. This sixteen-week snapshot of the RFI situation at Parkes is by now out of date. Unfortunately, a year later, the situation has undoubtedly worsened. 相似文献
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MIRO: Microwave Instrument for Rosetta Orbiter 总被引:1,自引:0,他引:1
S. Gulkis M. Frerking J. Crovisier G. Beaudin P. Hartogh P. Encrenaz T. Koch C. Kahn Y. Salinas R. Nowicki R. Irigoyen M. Janssen P. Stek M. Hofstadter M. Allen C. Backus L. Kamp C. Jarchow E. Steinmetz A. Deschamps J. Krieg M. Gheudin D. Bockelée-Morvan N. Biver T. Encrenaz D. Despois W. Ip E. Lellouch I. Mann D. Muhleman H. Rauer P. Schloerb T. Spilker 《Space Science Reviews》2007,128(1-4):561-597
The European Space Agency Rosetta Spacecraft, launched on March 2, 2004 toward Comet 67P/Churyumov-Gerasimenko, carries a
relatively small and lightweight millimeter-submillimeter spectrometer instrument, the first of its kind launched into deep
space. The instrument will be used to study the evolution of outgassing water and other molecules from the target comet as
a function of heliocentric distance. During flybys of the asteroids (2867) Steins and (21) Lutetia in 2008 and 2010 respectively,
the instrument will measure thermal emission and search for water vapor in the vicinity of these asteroids.
The instrument, named MIRO (Microwave Instrument for the Rosetta Orbiter), consists of a 30-cm diameter, offset parabolic
reflector telescope followed by two heterodyne receivers. Center-band operating frequencies of the receivers are near 190
GHz (1.6 mm) and 562 GHz (0.5 mm). Broadband continuum channels are implemented in both frequency bands for the measurement
of near surface temperatures and temperature gradients in Comet 67P/Churyumov-Gerasimenko and the asteroids (2867) Steins
and (21) Lutetia. A 4096 channel CTS (Chirp Transform Spectrometer) spectrometer having 180 MHz total bandwidth and 44 kHz
resolution is, in addition to the continuum channel, connected to the submillimeter receiver. The submillimeter radiometer/spectrometer
is fixed tuned to measure four volatile species – CO, CH3OH, NH3 and three, oxygen-related isotopologues of water, H2
16O, H2
17O and H2
18O. The basic quantities measured with the MIRO instrument are surface temperature, gas production rates and relative abundances,
and velocity and excitation temperature of each species, along with their spatial and temporal variability. This paper provides
a short discussion of the scientific objectives of the investigation, and a detailed discussion of the MIRO instrument system. 相似文献
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Tarter JC Backus PR Mancinelli RL Aurnou JM Backman DE Basri GS Boss AP Clarke A Deming D Doyle LR Feigelson ED Freund F Grinspoon DH Haberle RM Hauck SA Heath MJ Henry TJ Hollingsworth JL Joshi MM Kilston S Liu MC Meikle E Reid IN Rothschild LJ Scalo J Segura A Tang CM Tiedje JM Turnbull MC Walkowicz LM Weber AL Young RE 《Astrobiology》2007,7(1):30-65
Stable, hydrogen-burning, M dwarf stars make up about 75% of all stars in the Galaxy. They are extremely long-lived, and because they are much smaller in mass than the Sun (between 0.5 and 0.08 M(Sun)), their temperature and stellar luminosity are low and peaked in the red. We have re-examined what is known at present about the potential for a terrestrial planet forming within, or migrating into, the classic liquid-surface-water habitable zone close to an M dwarf star. Observations of protoplanetary disks suggest that planet-building materials are common around M dwarfs, but N-body simulations differ in their estimations of the likelihood of potentially habitable, wet planets that reside within their habitable zones, which are only about one-fifth to 1/50th of the width of that for a G star. Particularly in light of the claimed detection of the planets with masses as small as 5.5 and 7.5 M(Earth) orbiting M stars, there seems no reason to exclude the possibility of terrestrial planets. Tidally locked synchronous rotation within the narrow habitable zone does not necessarily lead to atmospheric collapse, and active stellar flaring may not be as much of an evolutionarily disadvantageous factor as has previously been supposed. We conclude that M dwarf stars may indeed be viable hosts for planets on which the origin and evolution of life can occur. A number of planetary processes such as cessation of geothermal activity or thermal and nonthermal atmospheric loss processes may limit the duration of planetary habitability to periods far shorter than the extreme lifetime of the M dwarf star. Nevertheless, it makes sense to include M dwarf stars in programs that seek to find habitable worlds and evidence of life. This paper presents the summary conclusions of an interdisciplinary workshop (http://mstars.seti.org) sponsored by the NASA Astrobiology Institute and convened at the SETI Institute. 相似文献
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