Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.mrao.cam.ac.uk/projects/aavp/presentations/Penny_SETI.pdf Дата изменения: Thu Dec 9 14:52:26 2010 Дата индексирования: Tue Oct 2 12:23:54 2012 Кодировка: Поисковые слова: images

SETI with SKA1 and SKA

2

Alan Penny1, Heino Falcke2, Mike Garrett

3

1 University of St Andrews and South African Astronomical Observatory PI: LOFAR Early Access Program LEA070 ­ 'A SETI Pilot Program' 2 Raboud University 3 ASTRON and Leiden University
AAVP2010 U Cambridge 8-10 December 2010


What a radio SETI search looks for

A narrow (perhaps1 Hz wide) spectral line


Sections
1. SETI 2. Experience of SETI with LOFAR and WSRT 3. SETI and SKA - needs


Sections
1. SETI 2. Experience of SETI with LOFAR and WSRT 3. SETI and SKA - needs


What a radio SETI search looks for

A narrow (perhaps1 Hz wide) spectral line


SETI Scientific Activity
Searches 101 significant searches 1960 - 2007 6 major (thousands of hours) Papers
Search for phrase "extraterrestrial intelligence" NASA ADS text Google Scholar 658 1,990

A number of these are minor articles and comments, but there are many hundreds of `real' papers


The National Science Foundation
Decadal Review - 2010
''The most promising signatures of life on planets around

other stars are features in the atmospheric spectra of planets around other stars, such as the "red edge" arising from photosynthesis. Less definitive is molecular oxygen, which is locked up in oxidized surface minerals unless continually replenished either by life (as on Earth) or catastrophic loss of surface water followed by photolysis Of H2O in the atmosphere (as on early Venus). The presence of both water and methane in a planetary atmosphere is a more reliable biosignature of water-based organic life than that of one or the other alone. A different approach is to look for signals produced by technologically advanced entities elsewhere in our galaxy.''



SKA Design Reference Mission - 0.4
The Cradle of Life The existence of life elsewhere in the Universe has been a topic of speculation for millennia. In the latter half of the 20th Century, these speculations began to be informed by observational data, including organic molecules in interstellar space, and proto-planetary disks and planets themselves orbiting nearby stars. With its sensitivity and resolution, the SKA will be able to observe the centimeterwavelength thermal radiation from dust in the inner regions of nearby proto-planetary disks and monitor changes as planets form, thereby probing a key regime in the planetary formation process. On larger scales in molecular clouds, the SKA will search for complex prebiotic molecules. Finally, detection of transmissions from another civilization would provide immediate and direct evidence of life elsewhere in the Universe, and the SKA will provide sufficient sensitivity to enable, for the first time, searches for unintentional emissions or "leakage."


The Four Facts of SETI
FACT 1) We are here 2) Other Earths exist 3) 'We' happened at the end
- The Anthropic Principle

IMPLICATION ETI is possible ETIs are possible ETI is rare? No ETI?

4) 'They' are not here
- The Fermi Paradox


Methods of Searching
Distant
EM radiation
radio optical/IR X-ray gamma-ray gravity lensing

Nearby
Particles (beams)
neutron molecule bacteria neutrino charged particle dark matter supersymmetry particle Earth Earth orbit Moon Earth-Moon system asteroid belt planets and moons Solar System

Artefact
- object - pattern

Gravity waves Alfven waves

Exotica - tachyon - worm hole - telepathy

Buried message Invitation Waiting


What a radio SETI search looks for

A narrow (perhaps1 Hz wide) spectral line


Radio Sky Background

Ghz
1m 10 cm 1 cm 10 mm



Moore's law in SETI spectral channels


Project Dorothy ­ Nov 2010 ­ 15 sites


ATA observations Eps Eri

10 mins

277 channels out of 64M

277 Hz 1418.356267 MHz

(SETI Insitute, Harp and Ackermann)


ATA observations Eta Are

10 mins

277 channels out of 64M

277 Hz 1417.890272 MHz

(SETI Insitute, Harp and Ackermann)


Sections
1. SETI 2. Experience of SETI with LOFAR and WSRT 3. SETI and SKA - needs


Using LOFAR and WSRT/Apertif

Time allocated

EoI accepted


LOFAR - Different Beams

LOFAR Array
Station-Beam

(i ATred) Br am e aytm en a er e hn-B coo i Inat St

Station
AnteamaBe nn

Antennae


ATA ­ many SETI beams in one pointing


SETI surveys with LOFAR
In Progress 1) LEA 070: A SETI Pilot Program in LOFAR Commissioning Time Planned 1) Tied-Beam survey of nearby stars 2) All-sky search derived from Transients KSP 3) Piggyback
One Second All Sky Survey Incoherent beam transients Transients Key Project Cosmic Rays Key Project


Detection limits
BMEWS radar 1 month obs EIRP 8kHz bandwith



1 Hz spectral resolution with LOFAR
(0.004% of data)

Flux 21.3940

21.3935 Frequency (MHz)

(Zarka, Griessmeier, Girad)

21.3930


1 Hz spectral resolution with LOFAR
60

5

Time (secs)

dB

0

0 21.3940

21.3935 Frequency (MHz)

21.3930


Sections
1. SETI 2. Experience of SETI with LOFAR and WSRT 3. SETI and SKA - needs


SKA Design Reference Mission - 0.4
The Cradle of Life Finally, detection of transmissions another civilization would provide immediate and evidence of life elsewhere in the Universe, and the SK provide sufficient sensitivity to enable, for the first searches for unintentional emissions or "leakage." from direct A will ti m e,

But no discussion of SETI needs in the DRM


SETI possibilities and needs for SKA
- Many millions of narrow 1 Hz wide channels - Very large data handling and storage rates - For AA
- Tied-beams (many) - All-sky mode - Signal triggering

1

- For dish array
- Tied-beams (many) - FPAs

- Spigots for both


Radio Sky Background

Ghz
1m 10 cm 1 cm 10 mm



SETI further possibilities s for SKA
- Transient pulses - Time scales - Signal spectral widths - Fish-eye modes - ATA-type piggy-back spigots


Immediate tasks for SETI-SKA study
1) Do SETI needs lie outside present DRM?

2) A detailed investigation of h/w and s/w needs for many millions of channels of 1 Hz width
- extra h/w and s/w - data flow and storage - analysis software - pointed and all-sky modes

3) Possible less ultimate modes in the near future


The End
What a radio SETI search looks for

A narrow (perhaps1 Hz wide) spectral line


The End