SETI - An alternate strategy
To date most SETI research has focused on the assumption that an advanced extra- terrestrial society will want to "communicate" with similar beings throughout the universe. But it is my belief that given the vast distances and time that communication via a "communications channel" even if it is one way, such as optical or radio frequency transmissions will be impractical.
Current SETI searches assume that an advanced civilization will use extremely powerful omni-directional transmitters or highly directional and focused signals targeted at our solar system. The challenge with either approach is the fact that successful one-way communication between intelligent species is the dependency on the “L” term in the Drake equation. L represents the length of time for which such civilizations release detectable signals into space. If L is relatively short then possibility of two separate intelligent civilizations being coincident in time to send and receive a signal is very small. So even though there may have been many intelligent civilizations we will probably never be aware of their existence.
Given these constraints I suggest instead that we look for extra-terrestrial intelligence in a similar way we searched for signs of intelligence on earth prior to the modern age. We cannot hope to communicate to prehistoric man, but we know that intelligent beings existed on earth thousands of years ago through archaeological evidence such as cave paintings, pyramids, monuments, etc.
More recently societies have been burying time capsules for future generations to discover and hopefully marvel at our accomplishments and perspectives of the future. Indeed several spacecraft have included time capsules to be hopefully discovered by humans or extra-terrestrial intelligent beings in the far future. Part of the Apollo 11 Lunar Module, still on the moon, includes a plaque showing the arrangement of the Earth's continents in 1969. The LAGEOS satellite (which will re-enter the atmosphere in 8.4 million years) contains a plaque showing the arrangement of the Earth's continents in the past, present, and future. Pioneer 10 and Pioneer 11 both contain plaques that give pictorial information about their time and place of origin. The two Voyager spacecraft each contain a golden record that contains pictures and sounds of Earth, along with symbolic directions for playing the record and data detailing the location of Earth.
The understandable challenge of physical time capsules is the probability of locating and/or discovering these time capsules by future generations or aliens. Given the vast distances of space it is highly improbable that these time capsules will ever be discovered by any kind of intelligent being.
So rather than deploying physical time capsules can we think of a way of deploying electromagnetic time capsules made from self amplifying or self re-generating optical and RF signals that propagate forever and are easily discoverable and locatable? SETI researchers, in the past, have often speculated on self replicating robots that could travel to distant planets and recreate themselves by using local materials, but the complexity of such a device boggles the mind. Self amplifying and regenerating electromagnetic signals on the other hand would conceivably be much easier to deploy and possibly be achievable with current technology.
Self amplification and regenerating signals could use natural physical process such as gravitational lensing, stellar corona pump amplification, orbital angular momentum and other techniques to propagate electromagnetic signals indefinitely. But rather than being a straight line propagation in the direction of the original signal, self amplification and regenerated signals may propagate in all sorts of random directions depending on the physical properties of the amplification and regeneration process itself. As such the signals may be bouncing around the galaxy from one star to another in no particular predetermined direction.
Given that they depend on natural physical processes for amplification and regeneration the originating transmission does not to be that powerful or directional. It is conceivable that low power transmissions are that all is required to launch a self amplifying and regenerating electro-magnetic signal. The signals may also be in a part of the spectrum that is not usually commonly assumed for inter-stellar transmission but rather exist in parts of the spectrum associated with the physical amplification and regeneration process.
There are a host of problems with current inter-stellar electromagnetic signaling such as attenuation, dispersion, group delay, etc etc. Given these limitations how could we hope to deploy a self replicating optical signal that will maintain its integrity over the vast distances and time of space?
One intriguing possible solution is using gravitational lenses to refocus and amplify a inter-stellar electromagnetic signal. In an interesting post (http://www.centauri-dreams.org/?p=10123) by Paul Gilster of Centauri Dreams he calculates that a ‘Sun-Alpha Centauri direct radio bridge exploiting both the two gravitational lenses, this minimum transmitted power is incredibly… small! Actually it just equals less than 10-4 watts, i.e. one tenth of a milliwatt is enough to have perfect communication between the Sun and Alpha Cen through two 12-meter FOCAL spacecraft antennas.`
One should also note that a gravitational lens acts like a lens with a gradient refractive index which also collimate and reduce electromagnetic dispersion.
Other possible mechanisms for self replicating signals include RF Orbital Angular Momentum (OAM), quantum entanglement and using stellar corona as pump amplifiers. As an example see the recent post about solar corona masering. I am sure there are other possible candidates. I challenge the reader of this missive to think of other ways of creating self replicating electromagnetic time capsules.
If we can come up with a plausible mechanism for deploying self replicating optical/rf time capsules the next obvious step would be to see if we can detect any such phenomena in our local inter stellar region.
Instead of searching for communications signal from an extra terrestrial intelligent civilization we should perhaps instead look for "archaeological" evidence of their existence with the most likely candidate being a easily discoverable self replicating electromagnetic time capsule.
If you have any suggestions or comments, or think I am completely nuts please feel free to contact me at
Tuesday, November 18, 2008
Want to leave a message for whatever comes next?
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For the Cypriot company see KEO Ltd
KEO is a space time capsule which will be launched in 2010 or 2011 carrying messages from the citizens of present Earth to humanity 50,000 years from now, when it will reenter Earth's atmosphere.
The KEO project is supported by UNESCO (who voted it "Project of the 21st century"), Hutchison Whampoa and the European Space Agency, among other institutions. Its name is supposed to represent the three most frequently used sounds common to the most widely spoken languages today, [k], [e] and [o], though this is in fact mistaken, as the most common sound is [a].
* 1 Personal messages
* 2 Other contents
* 3 Technical aspects
* 4 Project history
* 5 Similar Projects
* 6 See also
* 7 Notes
* 8 References
* 9 External links
 Personal messages
Every person is invited to write a message addressed to the future inhabitants—the deadline is December 31, 2009. Messages can be posted via the the project's website, or sent by postal mail. The organizers encourage everybody to gather messages from children, senior citizens and the illiterate so that every culture and demographic on Earth is represented. The satellite has enough capacity to carry a four-page message from each of the more than six billion inhabitants on the planet. Once the satellite is launched, the messages (with personal names removed) will be made freely available on the web.
 Other contents
KEO will also carry a diamond that encases a drop of human blood chosen at random and samples of air, sea water and earth. The DNA of the human genome will be engraved on one of the faces. The satellite will also carry an astronomical clock that shows the current rotation rates of several pulsars; photographs of people of all cultures; and "the contemporary Library of Alexandria", an encyclopaedic compendium of current human knowledge.
 Technical aspects
The messages and library will be encoded in glass-made radiation-resistant DVDs. Symbolic instructions in several formats will show the future finders how to build a DVD reader.
The satellite itself is a hollow sphere 80 cm in diameter. The sphere is engraved with a map of Earth and surrounded by an aluminium layer, a thermal layer and several layers of titanium and other heavy materials intertwined with vacuum. The sphere is resistant to cosmic radiation, atmosphere re-entry, space junk impacts and so on. For its first few years in orbit, KEO will sport an artful pair of wings 10 meters across that will aid in its spotting from Earth. As the satellite enters the atmosphere, the thermal layer will produce an artificial aurora to give a signal of the satellite's re-entry. The passive satellite will not carry any communications or propulsion systems. It will be launched by an Ariane 5 rocket into an orbit 1,800 km high, an altitude that will bring it back to Earth in 500 centuries, the same amount of time that has elapsed since early humans started to draw in cavern walls.
The satellite has not been built and no contract has been tendered for its construction.
 Project history
The KEO project was conceived in 1994 by French artist-scientist Jean-Marc Philippe, a pioneer of space art. Messages began to be collected, and an initial launch date was set for 2001. Technical feasibility demonstration and other various delays have moved the launch date to 2010 or 2011.
 Similar Projects
Several previous spacecraft have included time capsules for humans (or aliens) in the far future. The Apollo 11 Lunar Module (now on the moon) includes a plaque showing the arrangement of the Earth's continents in 1969. The LAGEOS satellite (which will re-enter the atmosphere in 8.4 million years) contains a plaque showing the arrangement of the Earth's continents in the past, present, and future. Pioneer 10 and Pioneer 11 both contain plaques that give pictorial information about their time and place of origin. Most famously, the two Voyager spacecraft each contain a golden record that contains pictures and sounds of Earth, along with symbolic directions for playing the record and data detailing the location of Earth. The Pioneers and Voyagers have left the solar system for interstellar space.
 See also
* Bracewell probe
* Crypt of Civilization
* Westinghouse Time Capsules
1. ^ Current launch date estimation
2. ^ Official FAQ page
3. ^ Ian Maddieson and Sandra Ferrari Disner, 1984, Patterns of Sounds. Cambridge University Press
4. ^ Edge Life Magazine, May 2003
* Bridges, Andrew (Jul. 31, 2000). KEO: The 50,000-Year Mission to Earth Space.com
* Stenger, Richard (Aug. 29, 2000). KEO time capsule could remain in orbit until 52001 AD CNN.com
* HowStuffWorks.com (Sept. 5, 2000). Time Capsule to Orbit Earth for 50,000 Years HowStuffWorks.com
* The Hindu Business Line (Aug. 29, 2002). Hutch brings space-time capsule project to India The Hindu Business Line
* ChennaiOnline.com (Sept. 4, 2002). KEO, a time capsule in space! ChennaiOnline.com
* The Digital Skyline (August 2003). A Message to the Future The Digital Skyline
* Ashraf, Syed Firdaus (Oct. 15, 2003). Once upon a time, 50,000 years ago... Rediff.com
* EUROPA (May. 28, 2004). New satellite carries hopes and dreams of humanity EUROPA
 External links