SETI on the SKA. US SKA Consortium Meeting Feb 28, Jill Tarter Bernard M. Oliver Chair SETI Institute

Transcription

1 SETI on the SKA US SKA Consortium Meeting Feb 28, 2000 Jill Tarter Bernard M. Oliver Chair SETI Institute

2 For SETI, We Don t Know... Where To Look At What Frequency When To Look For What Signal From How Far

3 For SETI, We Don t Know... Where To Look Stars! At What Frequency When To Look For What Signal From How Far

4 For SETI, We Don t Know... Where To Look At What Frequency When To Look For What Signal From How Far As Much Of The Spectrum As Possible (Terrestrial µwave Window, Optical, IR)

5 For SETI, We Don t Know... Where To Look At What Frequency When To Look For What Signal From How Far Multiple Looks (Scintillation, and Time Varying Signals)

6 For SETI, We Don t Know... Where To Look At What Frequency When To Look For What Signal From How Far Technology Nature (Compressed In Frequency Or Time)

7 For SETI, We Don t Know... Where To Look At What Frequency When To Look For What Signal From How Far All The Sensitivity We Can Get!!!

8 SETI On Telescopes Today Sky Surveys SERENDIP IV ( SETI@home ) [BETA] META II So. SERENDIP Project Argus Targeted Searches Project Phoenix 10 micron IR Harvard Optical Berkeley Optical Columbus OSETI

9 SERENDIP IV At Arecibo UC Berkeley SSL Piggyback (commensal) Almost 4 years of data 1420 MHz +/- 50 MHz 0.6 Hz resolution 12 seconds per beam Simple 15 σ 2.5 MHz time series data to SETI@home David Anderson Dan Werthimer

10 Project Phoenix At Arecibo Microwave search from 1.2 to 3 GHz

11 Real Time Signal Detection Frequency M Fully sample frequencytime plane N Drifting CW detection algorithm MN 2 MN logn Time

12 Real Time Signal Detection Frequency Thresholded Sparse Data Set Triplet Pulse Detection Algorithm Time

13 Unique to Project Phoenix 2 Antennas linked as a pseudointerferometer 6700 km

14 Unique to Project Phoenix Original selection of candidate signal is based on power detection with spectral resolution of 1Hz Coherent integration on follow up with spectral resolution that may be as fine as 0.01 Hz Differential Doppler signature is key to RFI excision

15 Current Status of Project Phoenix Arecibo and Jodrell Bank 12 am +/- 6 hr, 40 d/yr 500 stars down, 500 to go BW = 20 MHz 100 MHz (RCP and LCP) Sensitivity limits W 155 lt yr 8x10-27 W/m 2 1 Jy

16 Coverage of the Cosmic Haystack Phoenix is most comprehensive but looks at only 1000 stars

17 How, Most Comprehensive?? Hard to compare targeted searches with sky surveys If you assume stars are what matters (not interstellar spacecraft between the stars) Can use sensitivity of the various searches to calculate the number of stars that are accessible within any given beam on the sky for both TS & SS Comparison can then be made for any ETI power Figure = # of Stars x BW x log(f hi /F lo ) x (1+ log q) of Merit where q = number of looks

18 9 7 Phoenix 1kT S IV 1hT SS Merit vs EIRP (watts) SERENDIP IV searches for intrinsically strong sources in sky visible from Arecibo log(merit) Phoenix seaches for faint sources nearby and intrisically strong sources in the background log(eirp)

19 Coverage of the Cosmic Haystack Results: We Need a Nothing Better Telescope! To Date The First Step

20 The One Hectare Telescope (1hT)

21 Notes Added After Meeting: The next slide is VERY IMPORTANT! It shows that no matter where on the sky YOU ARE LOOKING there will be multiple SETI target stars in the large field of view of a small dish. Therefore for the cost of the beam-forming and backend SETI processing systems, SETI can observe all the time without interfering with scheduled observations of traditional radio astronomy sources. (There would have to be some small accommodation so that the field of view is not changed while an interesting candidate signal is being pursued, but that will be an infrequent conflict.)

22 1hT Speeds Up SETI Target Stars per Beam (5m dish) stars stars Multiplexing For a target list of 1 million stars (from GAIA mission) there will be more than 1 star in the field of view of a 5m (or smaller) dish up to 10 GHz and Frequency in GHz Increased BW

23 TS SETI Observations with 1hT # of targets = 100,000 stars 100 m equivalent Number of beams = 3 Bin width = 0.01 Hz Integration time = 400 sec Threshold = 9 sigma = 1.7 E-23 W Processing bandwidth =.5 GHz Frequency range = 1 to 3 GHz Number of relooks = 3 Total time for search = 6.3 years

24 TS SETI Observations with 1hT # of targets = 100,000 stars 100 m equivalent Number of beams = 12 Bin width = 0.01 Hz Integration time = 400 sec Threshold = 9 sigma = 1.7 E-23 W Processing bandwidth =.5 GHz Frequency range = 1 to 10 GHz Number of relooks = 3 Total time for search = 8 years

25 SS SETI Observations with 1hT +30 to +60 Declination 100 m equivalent Number of beams = 100 Bin width = 0.01 Hz Integration time = 150 sec Threshold = 25 sigma = 9.3 E-23 W Processing bandwidth = 1GHz Frequency range = 1 to 3 GHz Number of relooks = 1 Total time for search = 11 years

26 Improved Search Space

27 In 20 year array lifetime, the 1hT can do both: TS with 12 beams SS with 100 beams log(merit) Log log(merit) (Merit) Phoenix 1kT BETAmax S IV 1hT SS 1hT SS Phoenix S IV 1hT TS 1hT SS S IV 1hT TS Me rit vs EIRP(watts ) Merit vs EIRP (watts) log(eirp) log(eirp) Log (EIRP)

28 For SETI, We Don t Know... Where To Look This Is a At What Job For Frequency SKA When To Look For What Signal From How Far Stars! A Million Or More All The Sensitivity We Can Get!!!

29 SETI Observations with SKA Factor of 100 in sensitivity over the 1hT observations Factor of 100 decrease in transmitter EIRP for current target star list Factor of 10 in distance or 1000 times as many stars for current limit of W EIRP

30 SETI Issues Targeted searches prefer large FOV multiplexing advantage Sky surveys prefer all sky imaging tiles or Luneberg lenses probably can t afford high resolution processing transients are attractive possibility (OSS for strong transients ops)

31 SETI Issues Targeted searches prefer large FOV Sky surveys prefer all sky imaging 1-10 thousand km maximum baselines? OK pencil beams all too small for background stars Maximum instantaneous BW Frequency range GHz

32 Bets on Moore s Law SETI Observations with SKA Bin width = 0.01 Hz Integration time = 1000 sec Threshold = 11 sigma = 1.2 E-23 W Processing bandwidth = 9 GHz Number of beams = 10 Frequency range = 1 to 10 GHz Number of relooks = 3 Total time for search = 10 years Total number of targets = 1,000,000

33 log(merit) Phoenix SKA 1 kt Me rit vs EIRP(watts ) 1hT TS log(eirp) Conclusions: A sensitive search of a million nearby stars will take about 10 years with the SKA It can be done in parallel with traditional RA, assuming - 10 beams 9 GHz BW