Astropulse
Encyclopedia
Astropulse is a distributed computing
project that uses volunteers across the globe to lend their unused computing power to search for primordial black holes, pulsars, and ETI. Volunteer resources are harnessed through Berkeley Open Infrastructure for Network Computing
(BOINC) platform. In 1999, the Space Sciences Laboratory
launched SETI@home
, which would rely on massively parallel computation on desktop computers scattered around the world. SETI@home utilizes recorded data from the Arecibo
radio telescope
and searches for narrow-bandwidth radio signals from space, signifying the presence of extraterrestrial technology. It was soon recognized that this same data might be scoured for other signals of value to the astronomy and physics community.
, so that the massive network of SETI participants could also contribute to the search for other astronomical signals of value. Astropulse also makes contributions to the search for ET: first, project proponents believe it may identify a different type of ET signal not identified by the original Seti@Home algorithm; second, proponents believe it may create additional support for SETI by providing a second possible concrete result from the overall search project.
Final development of Astropulse has been a two-part endeavor. The first step was to complete the Astropulse C++
core that can successfully identify a target pulse. Upon completion of that program, the team created a trial dataset that contained a hidden pulse, which the completed program successfully found, thus confirming the ability of the Astropulse core to successfully identify target pulses. Since July 2008, research has focused on a series of refinements to the Beta version which are then rolled out to full universe of Seti participants. At the programming level, developers first seek to assure that new versions are compatible with a variety of platforms, after which the refined version is optimized for greater speed. As of April, 2009, Astropulse is testing Beta version 5.05.
The future of the project depends on extended funding to SETI@home
.
The BOINC idea is to divide (split) large blocks of data into smaller units, each of which can be distributed to individual participating work stations. To this end, the project then began to embed the Astropulse core into the SETI beta client and began to distribute real data, split into Astropulse work units, to a team of beta testers. The challenge has been to assure that the Astropulse core will work seamlessly on a broad array of operating systems. Current research focuses on implementing algorithm refinements that eliminate or reduce false positives.
s and exploding primordial black hole
s, both of which would emit brief wideband pulses. The primary purpose of the core Astropulse algorithm is coherent de-dispersion of the microsecond radio pulses for which Astropulse is searching. Dispersion of a signal occurs as the pulse passes through the interstellar medium
(ISM) plasma, because the high frequency radiation goes slightly faster than the lower frequency radiation. Thus, the signal arrives at the radio-telescope dispersed depending upon the amount of ISM plasma between the Earth and the source of the pulse. Dedispersion is computationally intensive, thus lending itself to the distributed computing model.
Astropulse utilizes the distributed computing power of SETI@home, delegating computational sub-tasks to hundreds of thousands of volunteers' computers, to gain advantages in sensitivity and time resolution over previous surveys. Wideband pulses would be "chirp
ed" by passage through the interstellar medium; that is, high frequencies would arrive earlier and lower frequencies would arrive later. Thus, for pulses with wideband frequency content, dispersion hints at a signal's extraterrestrial origin. Astropulse searches for pulses with dispersion measures ranging from to (chirp rates of to per microsecond), allowing detection of sources almost anywhere within the Milky Way
.
Project proponents believe that Astropulse will either detect exploding black holes, or establish a maximum rate of , a factor of 104 better than any previous survey.
), during the first few moments after the Big Bang, pressure and temperature were extremely great. Under these conditions, simple fluctuations in the density of matter may have resulted in local regions dense enough to create black holes. Although most regions of high density would be quickly dispersed by the expansion of the universe, a primordial black hole would be stable, persisting to the present.
One goal of Astropulse is to detect postulated mini black holes that might be evaporating due to "Hawking radiation
". Such mini black holes are postulated to have been created during the Big Bang, unlike currently known black holes. Martin Rees has theorized that a black hole, exploding via Hawking radiation, might produce a signal that's detectable in the radio. The Astropulse project hopes that this evaporation would produce radio waves that Astropulse can detect. The evaporation wouldn't create radio waves directly. Instead, it would create an expanding fireball of high-energy gamma rays and particles. This fireball would interact with the surrounding magnetic field, pushing it out and generating radio waves.
s (RRATs) are a type of neutron stars discovered in 2006 by a team led by Maura McLaughlin from the Jodrell Bank Observatory at the University of Manchester
in the UK. RRATs are believed to produce radio emissions which are very difficult to locate, because of their transient nature. Early efforts have been able to detect radio emissions (sometimes called RRAT flashes) for less than one second a day, and, like with other single-burst signals, one must take great care to distinguish them from terrestrial radio interference. Distributing computing and the Astropulse algorithm may thus lend itself to further detection of RRATs.
dispersed burst, less than 5 milliseconds in duration, located 3° from the Small Magellanic Cloud
. They reported that the burst properties argue against a physical association with our Galaxy or the Small Magellanic Cloud. In a recent paper, they argue that current models for the free electron content in the universe imply that the burst is less than 1 gigaparsec
distant. The fact that no further bursts were seen in 90 hours of additional observations implies that it was a singular event such as a supernova or coalescence (fusion) of relativistic objects. It is suggested that hundreds of similar events could occur every day and, if detected, could serve as cosmological probes. Radio pulsar surveys such as Astropulse-SETI@home offer one of the few opportunities to monitor the radio sky for impulsive burst-like events with millisecond durations. Because of the isolated nature of the observed phenomenon, the nature of the source remains speculative. Possibilities include a black hole-neutron star
collision, a neutron star-neutron star collision, a black hole-black hole collision, or some phenomenon not yet considered.
However, in 2010 there was a new report of 16 similar pulses from the Parkes Telescope which were clearly of terrestrial origin.
radiation from outer space was first discovered by Karl G. Jansky (1905–1950), who worked as a radio engineer at the Bell Telephone Laboratories to studying radio frequency interference from thunderstorms for Bell Laboratories. He found "...a steady hiss type static of unknown origin", which eventually he concluded had an extraterrestrial origin. Pulsars (rotating neutron stars) and quasar
s (dense central cores of extremely distant galaxies) were both discovered by radio astronomers. In 2003 astronomers using the Parkes
radio telescope
discovered two pulsars orbiting each other, the first such system known. Explaining their recent discovery of a powerful bursting radio source, NRL astronomer Dr. Joseph Lazio stated: "Amazingly, even though the sky is known to be full of transient objects emitting at X- and gamma-ray wavelengths, very little has been done to look for radio bursts, which are often easier for astronomical objects to produce." The use of coherent dedispersion algorithms and the computing power provided by the SETI network may lead to discovery of previously undiscovered phenomena.
Distributed computing
Distributed computing is a field of computer science that studies distributed systems. A distributed system consists of multiple autonomous computers that communicate through a computer network. The computers interact with each other in order to achieve a common goal...
project that uses volunteers across the globe to lend their unused computing power to search for primordial black holes, pulsars, and ETI. Volunteer resources are harnessed through Berkeley Open Infrastructure for Network Computing
Berkeley Open Infrastructure for Network Computing
The Berkeley Open Infrastructure for Network Computing is an open source middleware system for volunteer and grid computing. It was originally developed to support the SETI@home project before it became useful as a platform for other distributed applications in areas as diverse as mathematics,...
(BOINC) platform. In 1999, the Space Sciences Laboratory
Space Sciences Laboratory
The Space Sciences Laboratory is an Organized Research Unit of the University of California, Berkeley. It is located in the Berkeley Hills above the university campus...
launched SETI@home
SETI@home
SETI@home is an Internet-based public volunteer computing project employing the BOINC software platform, hosted by the Space Sciences Laboratory, at the University of California, Berkeley, in the United States. SETI is an acronym for the Search for Extra-Terrestrial Intelligence...
, which would rely on massively parallel computation on desktop computers scattered around the world. SETI@home utilizes recorded data from the Arecibo
Arecibo Observatory
The Arecibo Observatory is a radio telescope near the city of Arecibo in Puerto Rico. It is operated by SRI International under cooperative agreement with the National Science Foundation...
radio telescope
Radio telescope
A radio telescope is a form of directional radio antenna used in radio astronomy. The same types of antennas are also used in tracking and collecting data from satellites and space probes...
and searches for narrow-bandwidth radio signals from space, signifying the presence of extraterrestrial technology. It was soon recognized that this same data might be scoured for other signals of value to the astronomy and physics community.
Development
For about 6 years, Astropulse existed in an experimental beta testing phase not available to the general community. In July 2008, Astropulse was integrated into SETI@homeSETI@home
SETI@home is an Internet-based public volunteer computing project employing the BOINC software platform, hosted by the Space Sciences Laboratory, at the University of California, Berkeley, in the United States. SETI is an acronym for the Search for Extra-Terrestrial Intelligence...
, so that the massive network of SETI participants could also contribute to the search for other astronomical signals of value. Astropulse also makes contributions to the search for ET: first, project proponents believe it may identify a different type of ET signal not identified by the original Seti@Home algorithm; second, proponents believe it may create additional support for SETI by providing a second possible concrete result from the overall search project.
Final development of Astropulse has been a two-part endeavor. The first step was to complete the Astropulse C++
C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
core that can successfully identify a target pulse. Upon completion of that program, the team created a trial dataset that contained a hidden pulse, which the completed program successfully found, thus confirming the ability of the Astropulse core to successfully identify target pulses. Since July 2008, research has focused on a series of refinements to the Beta version which are then rolled out to full universe of Seti participants. At the programming level, developers first seek to assure that new versions are compatible with a variety of platforms, after which the refined version is optimized for greater speed. As of April, 2009, Astropulse is testing Beta version 5.05.
The future of the project depends on extended funding to SETI@home
SETI@home
SETI@home is an Internet-based public volunteer computing project employing the BOINC software platform, hosted by the Space Sciences Laboratory, at the University of California, Berkeley, in the United States. SETI is an acronym for the Search for Extra-Terrestrial Intelligence...
.
The BOINC idea is to divide (split) large blocks of data into smaller units, each of which can be distributed to individual participating work stations. To this end, the project then began to embed the Astropulse core into the SETI beta client and began to distribute real data, split into Astropulse work units, to a team of beta testers. The challenge has been to assure that the Astropulse core will work seamlessly on a broad array of operating systems. Current research focuses on implementing algorithm refinements that eliminate or reduce false positives.
Scientific research
Astropulse searches for both single pulses and regularly repeating pulses. This experiment represents a new strategy for SETI, postulating microsecond timescale pulses as opposed to longer pulses or narrowband signals. They may also discover pulsarPulsar
A pulsar is a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation. The radiation can only be observed when the beam of emission is pointing towards the Earth. This is called the lighthouse effect and gives rise to the pulsed nature that gives pulsars their name...
s and exploding primordial black hole
Primordial black hole
A primordial black hole is a hypothetical type of black hole that is formed not by the gravitational collapse of a large star but by the extreme density of matter present during the universe's early expansion....
s, both of which would emit brief wideband pulses. The primary purpose of the core Astropulse algorithm is coherent de-dispersion of the microsecond radio pulses for which Astropulse is searching. Dispersion of a signal occurs as the pulse passes through the interstellar medium
Interstellar medium
In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space...
(ISM) plasma, because the high frequency radiation goes slightly faster than the lower frequency radiation. Thus, the signal arrives at the radio-telescope dispersed depending upon the amount of ISM plasma between the Earth and the source of the pulse. Dedispersion is computationally intensive, thus lending itself to the distributed computing model.
Astropulse utilizes the distributed computing power of SETI@home, delegating computational sub-tasks to hundreds of thousands of volunteers' computers, to gain advantages in sensitivity and time resolution over previous surveys. Wideband pulses would be "chirp
Chirp
A chirp is a signal in which the frequency increases or decreases with time. In some sources, the term chirp is used interchangeably with sweep signal. It is commonly used in sonar and radar, but has other applications, such as in spread spectrum communications...
ed" by passage through the interstellar medium; that is, high frequencies would arrive earlier and lower frequencies would arrive later. Thus, for pulses with wideband frequency content, dispersion hints at a signal's extraterrestrial origin. Astropulse searches for pulses with dispersion measures ranging from to (chirp rates of to per microsecond), allowing detection of sources almost anywhere within the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
.
Project proponents believe that Astropulse will either detect exploding black holes, or establish a maximum rate of , a factor of 104 better than any previous survey.
Challenges
Any radio astronomy project confronts issues arising from interference, and the challenges are especially great when the target signals are weak or of transient duration. Military radar noise which is regularly occurring and of known duration can be "blanked" at the radio telescope source. A variety of techniques have been explored in the literature to develop algorithms that detect and account for radar sources that cannot be blanked in this way.Results
Astropulse started computing in mid-July 2008. , the results have been used in a variety of ways. Development staff, aided by volunteers, have worked to assure that the client works effectively on a broad array of operating systems. Code has been refined and optimized to reduce calculation time on the local work station. Results have been analyzed so that the algorithms can be adjusted to reduce false positives that may result from interference or from random background noise. To date, a target signal has not yet been found.Potential pulse finds
Primordial black holes
According to the Big Bang Model (also called the Standard ModelStandard Model
The Standard Model of particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles. Developed throughout the mid to late 20th century, the current formulation was finalized in the mid 1970s upon...
), during the first few moments after the Big Bang, pressure and temperature were extremely great. Under these conditions, simple fluctuations in the density of matter may have resulted in local regions dense enough to create black holes. Although most regions of high density would be quickly dispersed by the expansion of the universe, a primordial black hole would be stable, persisting to the present.
One goal of Astropulse is to detect postulated mini black holes that might be evaporating due to "Hawking radiation
Hawking radiation
Hawking radiation is a thermal radiation with a black body spectrum predicted to be emitted by black holes due to quantum effects. It is named after the physicist Stephen Hawking, who provided a theoretical argument for its existence in 1974, and sometimes also after the physicist Jacob Bekenstein...
". Such mini black holes are postulated to have been created during the Big Bang, unlike currently known black holes. Martin Rees has theorized that a black hole, exploding via Hawking radiation, might produce a signal that's detectable in the radio. The Astropulse project hopes that this evaporation would produce radio waves that Astropulse can detect. The evaporation wouldn't create radio waves directly. Instead, it would create an expanding fireball of high-energy gamma rays and particles. This fireball would interact with the surrounding magnetic field, pushing it out and generating radio waves.
RRATs
Rotating radio transientRotating radio transient
Rotating radio transients are sources of short, moderately bright, radio pulses, which were first discovered in 2006. RRATs are thought to be pulsars, i.e. rotating magnetised neutron stars which emit more sporadically and/or with higher pulse-to-pulse variability than the bulk of the known pulsars...
s (RRATs) are a type of neutron stars discovered in 2006 by a team led by Maura McLaughlin from the Jodrell Bank Observatory at the University of Manchester
University of Manchester
The University of Manchester is a public research university located in Manchester, United Kingdom. It is a "red brick" university and a member of the Russell Group of research-intensive British universities and the N8 Group...
in the UK. RRATs are believed to produce radio emissions which are very difficult to locate, because of their transient nature. Early efforts have been able to detect radio emissions (sometimes called RRAT flashes) for less than one second a day, and, like with other single-burst signals, one must take great care to distinguish them from terrestrial radio interference. Distributing computing and the Astropulse algorithm may thus lend itself to further detection of RRATs.
Extragalactic pulses
D. R. Lorimer and others analyzed archival survey data and found a 30-janskyJansky
The flux unit or jansky is a non-SI unit of spectral flux density equivalent to 10−26 watts per square metre per hertz...
dispersed burst, less than 5 milliseconds in duration, located 3° from the Small Magellanic Cloud
Small Magellanic Cloud
The Small Magellanic Cloud is a dwarf galaxy. It has a diameter of about 7,000 light-years and contains several hundred million stars. It has a total mass of approximately 7 billion times the mass of our Sun....
. They reported that the burst properties argue against a physical association with our Galaxy or the Small Magellanic Cloud. In a recent paper, they argue that current models for the free electron content in the universe imply that the burst is less than 1 gigaparsec
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
distant. The fact that no further bursts were seen in 90 hours of additional observations implies that it was a singular event such as a supernova or coalescence (fusion) of relativistic objects. It is suggested that hundreds of similar events could occur every day and, if detected, could serve as cosmological probes. Radio pulsar surveys such as Astropulse-SETI@home offer one of the few opportunities to monitor the radio sky for impulsive burst-like events with millisecond durations. Because of the isolated nature of the observed phenomenon, the nature of the source remains speculative. Possibilities include a black hole-neutron star
Neutron star
A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...
collision, a neutron star-neutron star collision, a black hole-black hole collision, or some phenomenon not yet considered.
However, in 2010 there was a new report of 16 similar pulses from the Parkes Telescope which were clearly of terrestrial origin.
ET
Previous searches by SETI@home have looked for extraterrestrial communications in the form of narrow-band signals, analogous to our own radio stations. The Astropulse project argues that since we know nothing about how ET might communicate, this might be a bit closed-minded. Thus, the Astropulse survey can be viewed as supplementing the narrow-band SETI@home survey as a by-product of the search for physical phenomena.Undiscovered phenomena
RFRadio frequency
Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...
radiation from outer space was first discovered by Karl G. Jansky (1905–1950), who worked as a radio engineer at the Bell Telephone Laboratories to studying radio frequency interference from thunderstorms for Bell Laboratories. He found "...a steady hiss type static of unknown origin", which eventually he concluded had an extraterrestrial origin. Pulsars (rotating neutron stars) and quasar
Quasar
A quasi-stellar radio source is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than...
s (dense central cores of extremely distant galaxies) were both discovered by radio astronomers. In 2003 astronomers using the Parkes
Parkes Observatory
The Parkes Observatory is a radio telescope observatory, 20 kilometres north of the town of Parkes, New South Wales, Australia. It was one of several radio antennas used to receive live, televised images of the Apollo 11 moon landing on 20 July 1969....
radio telescope
Radio telescope
A radio telescope is a form of directional radio antenna used in radio astronomy. The same types of antennas are also used in tracking and collecting data from satellites and space probes...
discovered two pulsars orbiting each other, the first such system known. Explaining their recent discovery of a powerful bursting radio source, NRL astronomer Dr. Joseph Lazio stated: "Amazingly, even though the sky is known to be full of transient objects emitting at X- and gamma-ray wavelengths, very little has been done to look for radio bursts, which are often easier for astronomical objects to produce." The use of coherent dedispersion algorithms and the computing power provided by the SETI network may lead to discovery of previously undiscovered phenomena.
Astronomy in the schools
Astropulse and its older partner, SETI@home, offers a concrete way for secondary school science teachers to involve their students with astronomy and computing. A number of schools maintain distributed computing class projects.Related websites
- Astropulse Science
- Von Korff, Astropulse: A Search for Microsecond Transient Radio Signals Using Distributed Computing
- Astropulse FAQ
- Website
- SETI@home forum thread about Astropulse
- SETI@home Beta forum thread about Astropulse
- Astropulse Wiki
- Electromagnetic Radiation
- A multibeam sky survey