Keeping the Link at Interstellar Distances by Exploiting the Sun as a Gravitational Lens.
- Paper number
IAC-06-D3.P.02
- Author
Mr. Nicolo Antonietti, Politecnico di Torino, Italy
- Coauthor
Mr. Salvatore Pluchino, Visiting Research Fellow, IRA-INAF Radiotelescopes, Italy
- Coauthor
Dr. Claudio Maccone, Member of the International Academy of Astronautics, Italy
- Year
2006
- Abstract
Einstein’s general theory of relativity predicts that electromagnetic waves emitted by a distant source and passing in the proximity of the Sun are deflected by the Sun’s gravitational field. This deflection is proportional to the Sun’s mass and inversely proportional to the distance from the Sun’s centre. The electromagnetic waves are thus made to focus at a point opposite to the source along the source-Sun-focus straight line. This “focus” is actually an infinity of focal points starting from the minimal distance of 550 AU (3.17 light days i.e. 14 times the Sun-to-Pluto distance), that any spacecraft must reach to exploit the Sun as a gravitational lens. But what is the “gain” of such a FOCAL space mission? The gain is literally the antenna gain, that is the huge focussing effect caused by the large mass of the Sun upon the electromagnetic waves of the source. For instance, at the hydrogen line frequency of 1.420 GHz the Sun’s gain is about 57 dB, to which one must add the spacecraft antenna's own gain, with a total gain that may exceed 100 dB. One of the authors (C. Maccone) published a research book about these topics, entitled “The Sun as Gravitational Lens: Proposed Space Missions”, that was awarded the 1999 Book Award by the International Academy of Astronautics (IAA). But now about the future. In view of launching a space probe towards any nearby star, one clearly has to face the problem of keeping the link with such a probe. The largest antennas today available on Earth (such as NASA’s Deep Space Network antennas, or similar dishes) could hardly keep the link because they are “too small” to detect the very weak signals sent by spacecrafts several light years away. Thus, we must look for the one “antenna” having the largest possible gain in the whole solar system. This “best antenna” is the Sun itself because so much more massive than any other solar system body! A new FOCAL space mission is thus required in the opposite direction to any future space mission launched from the solar system. This paper is devoted to the actual computation of the antenna gains that must be achieved by every future FOCAL mission in order to assure the link between the Earth and any future interstellar probe venturing to distances some light-years away from the Sun.
- Abstract document
- Manuscript document
IAC-06-D3.P.02.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.