# Presentation: 434254

## The SETI@home, SERENDIP, SEVENDIP, Astropulse, and SPOCK SETI Programs

- ‘Dan Werthimer, Dave Anderson, Jeff Cobb,
- Paul Demorest, Eric Korpela, Cecile Kim, Geoff Marcy
- University of California, Berkeley

- _[http://](http://setiathome.ssl.berkeley.edu/)__[seti](http://setiathome.ssl.berkeley.edu/)__[.berkeley.edu/](http://setiathome.ssl.berkeley.edu/)_

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## NOT  FUNDED

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## FUNDED!

- Porno in space:

## Drake Equation

- N=R fs fp ne fl fi fc L
- N = number of communicating civilizations in our galaxy

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## Planet  Detection

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## First Radio SETI

- Nikola Tesla (1899)
- Announces “coherent signals from Mars”
- Guglielmo Marconi (1920)
- Strange signals from ET
- Frank Drake (1960)
- Project Ozma
- one channel, 1420-1420.4 MHz

## Signal Types

- 1.  **Artifact    ** (radio, radar, ~TV, ????)
- 2.  **Deliberate** (easy to decode, pictures, language lessons)

- First civilization we contact is likely to be a billion years ahead of us.

- Targeted Search Strategy:
-           Project Phoenix         -   Seti Institute
- Sky Survey Strategy:
- 	  Serendip, SETI@home    -    UC Berkeley
-            Beta                        -   Harvard
-            Southern Serendip    -   Australia
-            Meta II                    -   Argentina
-            Seti Italia                 -  Medicina Obser.

## Quick History of Berkeley SETI

- Radio SETI
- SERENDIP	Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations
- SERENDIP I-III (1979-1997)
- SERENDIP IV (1997-)
- SERENDIP V (2004-)

## The Berkeley Radio SETI Family Tree

- SERENDIP

- SERENDIP II

- SERENDIP III

- SERENDIP IV

- SERENDIP V

- SETI@home
- Data Recorder

- SETI@home II
- Data Recorder

- SETI@home
- Clients

- SETI@home II
- Clients

- SETHI@Berkeley
- HI Survey

- AstroPulse
- Pulse Survey

- SETI Italia

- Southern
- SERENDIP

- OSU

## SETI Programs at the University of California

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## SERENDIP IV

- 168M channels
- 100 MHz Band centered on 1420 MHz

- Carriage House 1 line feed
- Operating since 1997

- Photos Courtesy NAIC Arecibo Observatory, a facility of the NSF

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## Why SETI@home?

- Coherent Doppler drift correction
- Narrower Channel Width->Higher Sensitivity
- Variable bandwidth/time resolution
- Search for multiple signal types
- Gaussian beam fitting
- Search for repeating pulses

- Problem: Requires TFLOP/s processing power.

- Solution: Distributed Computing

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## The SETI@home Client

##           SETI@home Statistics

-           SETI@home Statistics
-        TOTAL                 RATE

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## Structure of SETI@home

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## The Input and Output

- 1 Work-Unit=9.8 kHz x 220 samples (107 sec.)
- 256 Workunits across 2.5 MHz band centered on 1420.0 MHz.
- Workunits overlap in time by ~25 sec.
- Each workunit sent to multiple computers for result verification
- Typically 4 TFLOP/workunit.
- Output=Typically ~5 potential signals.

## Spikes

- Power distribution in the Fourier transformed data is exponential if no RFI.
- SPIKE: Any bin in the spectrum above 22X the mean power (7.8x10-25 W/m2)

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## Gaussians

- Weighted 2 fit to beam profile (vs time).
- Gaussian must exceed a power and 2 threshold
- Score inversely proportional to probability of arising due to noise
- Sensitivity 8.4x10-25 W/m2

## Triplets	

- Three evenly spaced spikes above 7.75X the mean power. (5.3X10-25 W/m2)

## Pulses	

- Modified Fast folding algorithm w/ dynamic threshold
- Logarithmically spaced periods from 3ms to 35s
- Sensitivity as low as 10-26 J/m2

## Candidate Identification

- Candidate: A signal or group of signals
- Within a positional window (~1 beamwidth typ.)
- Within a frequency window (variable)
- Above a score or power threshold (variable)
- With time separation » typical transient RFI timescale
- Score:
- Relative ranking of a candidate’s probability of arising due to random noise.
- Should be independent of signal type
- Can also include probability of coincidence /w celestial objects

## Gaussian Candidates

## AstroPulse

- Sky survey
- Covers decs 0 to 30
- ~3 years of data recorded so far.
- Good time resolution
- Sensitive to 0.4 μs radio pulses at 21 cm
- DM range
- -100 to +100 pc/cm3
- Sensitivity
- 10-18 W/m2 peak (Coherent de-dispersion)

## Pulsed vs. CW

- Concentrating power into short bursts can be more efficient than a “constantly on” transmitter.
- Pulsed signals can be easier to see above background noise.

## Dispersion

- ... eventually becoming very weak.
- However, we can correct for dispersion ...

## AstroPulse

- Only ~1.5 searches for single pulses on μs timescale before (O’Sullivan, Phinney)
- Pulsar searches: ms time scales, folded
- SETI@home:  0.8 ms single pulses.
- With interesting astrophysics as well as SETI applications.
- Evaporating primordial black holes?
- Pulsars, Other astrophysical exotica?

## Computation

-  ... but it takes a lot of CPU time!
- To search DMs up to 100 pc/cm3 in real time, we need about 500 GigaFLOPs.
- (This would take ~1000 years of your PC working full time)

- Conclusion: We need more computers!

## BOINC

- Berkeley Open Infrastructure for Network Computing
- General-purpose distributed computing framework.
- Open source.
- Will make distributed computing accessible to those who need it. (Starting from scratch is hard!)

## AstroPulse/BOINC

- AstroPulse will be the first to use BOINC.
- It is a good “beta-test” application:
- Simple data analysis/reduction.
- “Only” needs a few thousand computers.
- Other projects which plan to use BOINC:
- SETI@home II
- Global climate modeling/prediction (Oxford)

## AstroPulse Testing

- Sample batch of data run through shows expected noise characteristics, and little else ...
- ... so (hopefully) little RFI contamination for this type of signal.

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## HI Column Density

## OPTICAL SETI

- OPTICAL PULSE SEARCH
- Pulsed laser power output continues to grow.
- Petawatt pulses achieved at Livermore Labs. (Mjoule in 1nS)
- can detect at earth technology at 1Kpc
- little background noise,  even from bright stars in whole visible band

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## OSETI Detector

- 3-Photomultiplier fast coincidence detector
- Sensitive to 1ns pulses
- Low background
- False alarm rate: 1 per 300 hours (10-6 Hz)
- Double false alarm rate: 1 per 600 years!
- Good sensitivity
- 10-8 W/m2 peak
- 10-19 W/m2 average

## Optical SETI

- Uses Leuschner Observatory (UCB)
- Automated 0.8m telescope
- Targeted Search
- Nearby F,G,K,M stars
- ~2,000 stars observed so far
- Soon to include galaxies

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## Amy Reines and Geoff Marcy

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## 10-meter Keck Telescope

**Survey:  650  F8 – M5   V, IV**

- Hipparcos
-    V < 8.5
- B-V > 0.55 (F8V)
- Sep > 2 arcsec
- Age > 2 Gyr

## Doppler Instruments

- Echelle Spectrometer
- Resolution: 60,000
- Iodine Abs. Cell.
- Superimpose I2 lines
- Wavelength Calib.

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## Piggyback ALFA Sky Survey

- SETI Instruments
- Dedicated spectrometer (SERENDIP V)
- 300 MHz bandwidth, 2 pols, 7 beams
- 5 * 109 channels, 0.8 Hz resolution
- SETI@home II data recorder
- 10 MHz, 1 pol, 7 beams
- Steps across 300 MHz band

## Piggyback ALFA Sky Survey

- Improved sensitivity
- Tsys, integration time
- Uniform sky sampling
- galactic plane concentration
- Multibeam RFI rejection
- Larger Bandwidth

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## Our Generous Sponsors

- The Planetary Society
- The University of California
- Sun Microsystems
- Friends of SETI@home
- Network Appliance
- Fujifilm
- IBM
- Quantum
- HP
- Xilinx

- The SETI Institute
- Informix
- EDT
- Netscreen
- Intel
- O’Reilly & Associates
- SpaceSounds
- Dillon Engineering
- NAIC, Arecibo Observatory
- ~4 million volunteers

- Maybe, someday, the U.S. Government

## SETI HAIKU

##   Seti.berkeley.edu

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