seti on the ska - arecibo observatorynaic.edu/~ska/ska_talks/11tarter.pdf · 2000. 4. 7. ·...

SETI on the SKA

US SKA Consortium Meeting

Feb 28, 2000

Jill TarterBernard M. Oliver ChairSETI Institute

For SETI, We Don’t Know...

• Where To Look

• At WhatFrequency

• When To Look

• For What Signal

• From How Far


• Where To Look


• When To Look

• For What Signal

• From How Far

• Stars!


• Where To Look


• When To Look

• For What Signal

• From How Far

As Much Of TheSpectrum AsPossible

(Terrestrial µWave

Window, Optical, IR)


• Where To Look


• When To Look

• For What Signal

• From How Far

Multiple Looks

(Scintillation, and

Time Varying Signals)


• Where To Look


• When To Look

• For What Signal

• From How FarTechnology Nature

(Compressed In

Frequency Or Time)


• Where To Look


• When To Look

• For What Signal

• From How Far All The Sensitivity WeCan Get!!!

SETI On Telescopes Today

• Sky SurveysSERENDIP IV

( SETI@home )

[BETA]META IISo. SERENDIPProject Argus

• Targeted SearchesProject Phoenix10 micron IRHarvard OpticalBerkeley OpticalColumbus OSETI

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 threshold @ 15 σ• 2.5 MHz time series data

to SETI@home

Dan WerthimerDavid Anderson

Project Phoenix At Arecibo

• Microwave search from 1.2 to 3 GHz

Real Time Signal DetectionFrequency

Tim

e

Fully samplefrequency-time plane

Drifting CWdetectionalgorithmMN2 →

MN logN

N

M

Real Time Signal DetectionFrequency

Tim

e

ThresholdedSparseData Set

TripletPulse DetectionAlgorithm

Unique to Project Phoenix

2 Antennaslinked as apseudo-interferometer

6700 km

Unique to Project Phoenix• Original selection of

candidate signal is basedon power detection withspectral resolution of 1Hz

• Coherent integration onfollow up with spectralresolution that may be asfine as 0.01 Hz

• Differential Dopplersignature is key to RFIexcision

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 1012 W EIRP @ 155 lt yr 8x10-27 W/m2 ≈ 1 Jy

Coverage of the Cosmic Haystack

Phoenix is

most comprehensive

but looks

at only 1000 stars

How, Most Comprehensive??

• Hard to compare targeted searches with sky surveys• If you assume starsstars 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(Figure = # of Stars x BW x log(FFhihi//FFlolo) x (1+ log q) ) x (1+ log q) of Merit of Merit where q = number of looks

Merit vs EIRP (watts )

-1

1

3

5

7

9

6 8 10 12 14 16 18

log(EIRP)

log

(Me

rit)

P hoenix

1kT

S IV

1hT S S

SERENDIP IVsearches forintrinsicallystrong sourcesin sky visiblefrom Arecibo

Phoenixseaches for faint sources nearby and intrisically strong sourcesin the background

Coverage of the Cosmic Haystack

Results: NothingTo Date

We Needa Better

Telescope!The First Step

The One Hectare Telescope (1hT)

Notes Added After Meeting:

The next slide is VERY IMPORTANT!

It shows that no matter where on the sky YOU ARE LOOKINGthere 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 traditionalradio 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 bean infrequent conflict.)

1hT Speeds Up SETIMultiplexing

For a target list of1 million stars(from GAIA mission)there will be morethan 1 star in the fieldof view of a 5m (orsmaller) dish up to 10GHz and

Increased BW

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12

Frequency in GHz

Ta

rge

t S

tars

pe

r B

ea

m (

5m d

ish

)

100000 stars

1000000 stars

TS SETI Observations with 1hT• 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

# of targets = 100,000 stars

TS SETI Observations with 1hT• 100 m equivalent





• Processing bandwidth = .5 GHz



• Total time for search = 8 years

# of targets = 100,000 stars

SS SETI Observations with 1hT• 100 m equivalent





• Processing bandwidth = 1GHz




+30 to +60 Declination

Improved Search Space

Merit vs EIRP (watts )

6 8 10 12 14 16 18

log(EIRP)

log

(Me

rit)

P hoenix

1kT

S IV

1hT S S

Me rit vs EIRP(watts )

-1

1

3

5

7

9

6 8 10 12 14 16 18

log(EIRP)

log

(Me

rit)

BETAmax S IV

1hT S S 1hT TS

Log (EIRP)

Log

(M

erit

)

Phoenix S IV 1hT TS 1hT SS

In 20 year arraylifetime, the1hT can do both:

TS with 12 beams

SS with 100 beams


• Where To Look


• When To Look

• For What Signal

• From How Far All The Sensitivity WeCan Get!!!

• Stars! A MillionOr More

This Is a Job For

SKA

SETI Observations with SKA

• Factor of 100 in sensitivity over the 1hTobservations

• Factor of 100 decrease in transmitter EIRPfor current target star list

• Factor of 10 in distance or 1000 times asmany stars for current limit of 1012 W EIRP

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 - 1020 ops)

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 0.5-10 GHz

SETI Observations with SKA• Bin width = 0.01 Hz


• Threshold = 11 sigma = 1.2 E-23 W

• Processing bandwidth = 9 GHz





• Total number of targets = 1,000,000

Bets on Moore’s Law

Merit vs EIRP(watts )

0

2

4

6

8

10

6 8 10 12 14 16

log(EIRP)

log

(Me

rit)

P hoenix

1 kT

1hT TS

Conclusions:A sensitivesearch of amillion nearbystars will takeabout 10 yearswith the SKA

It can be donein parallel withtraditional RA,assuming - 10 beams 9 GHz BW

SKA

seti on the ska - arecibo observatorynaic.edu/~ska/ska_talks/11tarter.pdf · 2000. 4. 7. ·...

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