Abstract
AbstractPulsars have at least two impressive applications. First, they can be used as highly accurate clocks, comparable in stability to atomic clocks; secondly, a small subset of pulsars, millisecond X-ray pulsars, provide all the necessary ingredients for a passive galactic positioning system. This is known in astronautics as X-ray pulsar-based navigation (XNAV). XNAV is comparable to GPS, except that it operates on a galactic scale. I propose a SETI-XNAV research program to test the hypothesis that this pulsar positioning system might be an instance of galactic-scale engineering by extraterrestrial beings. The paper starts by exposing the basics of pulsar navigation, continues with a critique of the rejection of the extraterrestrial hypothesis when pulsars were first discovered. The core section of the paper proposes lines of inquiry for SETI-XNAV, related to the pulsar distribution and power in the galaxy; their population; their evolution; possible pulse synchronizations; pulsar usability when navigating near the speed of light; decoding galactic coordinates; directed panspermia; and information content in pulses. Even if pulsars are natural, they are likely to be used as standards by ETIs in the galaxy. I discuss possible objections and potential benefits for humanity, whether the research program succeeds or not.
Highlights
Navigation is a universal problem whenever one needs to go from point A to point B
The need of autonomous space navigation is timely, as our epoch is experiencing a renewal of space exploration, with numerous scientific missions inside the solar system, and bolder missions funded by billionaires, such as to colonize Mars (Elon Musk), or to reach Alpha Centauri (Yuri Milner)
Even if SETI-X-ray pulsar-based navigation (XNAV) fails, the program still promises various benefits because it will contribute to XNAV research and may help to augment or design more efficient and cheaper global navigation satellite systems here on Earth
Summary
Navigation is a universal problem whenever one needs to go from point A to point B. These discoveries changed pulsar navigation, as MSPs have stabilities comparable with atomic clocks used in GNSS satellites. Multiplied by the speed of light, this translates into errors of 90 cm and 30 m, respectively This means that navigation with X-ray MSPs has the potential to be accurate down to 30 m on a galactic scale. MSPs represent about 10% of the total known pulsar population They are distributed isotropically in the galaxy, by contrast with normal pulsars that are more concentrated in the galactic disk. This may be an important property for navigation purposes if the observation is not entirely due to selection effects (Lorimer & Kramer 2005, 26). More distinguishing features can be found in the literature (e.g. Kramer et al 1998)
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