The PhotonStar SETI project is an enterprise to detect extraterrestrial laser signals that involves many individual small telescopes acting together as a geographically diverse large array which together comprise a large collection area, thereby, offering a better chance of detection if signals exist. Widely separated small telescopes, each with a sensitive photon detection capability, can be aimed simultaneously at the same star system with precise timing that enables looking at the same time for short pulse detection. Each individual telescope can be located via GPS so that the differential distance from the star compared to every other telescope can be determined beforehand. Coordination via the Internet would enable each telescope to operate as one element of the array. This project allows direct public participation by amateur astronomers into the search for extraterrestrial intelligence as there are thousands of telescopes of eight inches or greater in use, so that the total collection area can be very substantial with public participation. In this way, each telescope is part of a larger array with data being sent via the Internet to a central station. This approach is only feasible now with the advent of GPS, the Internet, and relatively low- cost single photon detector technology.
A detailed design approach is given for a low-cost, large aperture laser reciever capable of detecting and recognizing short laser pulses of unknown frequency. The design results from development of three basic rules for detection of extraterrestrial signals. The paper looks at both frequency and time domain issues, and configures a specific design to accomplish detection and recognition. This design enables a large aperture system that costs orders of magnitude less than that of a diffraction-limited astronomical telescope of equivalent capability for detection of SETI laser pulses. Implementation of this design will enable the detection of laser signals, if present, that have previously been undetectable.
In every society throughout history key decisions have been based on economics. Constrained by the technology of their day, each society always have more demands on its wealth than it can readily dispense. There are always competing recipients of the same limited funds (i.e., new post office building or another C-17 transport). This paper shows why the laser is a far more economic choice than RF or microwaves for transmission over many light years. This is based on antenna gain considerations, 'habitable regions' near a star, and knowledge of the star types that can sustain intelligent life.
A breadboard sync satellite terminal has been developed incorporating a unique concept of a gimballess multi-access transceiver, which is capable of simultaneously communicating with six independent, asynchronous LEO satellites. The developmental hardware illustrates that low power, weight, and volume is achievable compared to multiple independent gimballed transceivers, while also putting a lesser burden of power, size, and weight on the LEO satellite transceivers that communicate with the multiple-access transceiver. Evaluation tests demonstrate the feasibility of the concept.
Very low duty cycle short pulse high peak power laser modulation enables sending of signals great distances with low average power and high efficiency. Significant information can be sent by each pulse in digital pulse position modulation when M is very large. Direct detection can be utilized, enabling use of photon buckets, because the signal energy in a short pulse can overcome the generated noise by the star's spectrum. Exact optical frequency knowledge is not required because of the high background discrimination of the short pulse approach, although Fraunhaufer lines offer possible choices. Pictorial data is feasible and readily reconstructed using this modulation approach. The ability to use photon buckets enables the construction of large area collectors at low cost.
A breadboard sync satellite terminal has been developed incorporating a unique concept of a gimballess multi-access transceiver, which is capable of simultaneously communicating with six independent, asynchronous LEO satellites. The developmental hardware illustrates that low power, weight, and volume is achievable compared to multiple independent gimballed transceivers, while also putting a lesser burden of power, size, and weight on the LEO satellite tranceivers that communicate with the multiple-access transceiver.
A 'many points in one point' multiaccess laser system has been examined, and results are reported which indicating the feasibility of optical communications multiaccess communications is feasible and that the resultant terminal size and with savings are very substantial compared to the dedicated optical terminals or RF multiaccess approaches. A preliminary design has been accomplished of a package that can weigh less than 150 pounds and which uses a 10-in. effective diameter fixed telescope and requires less than 100 W of regulated power and less than 8 cu ft of space.