ACADEMY TRANSACTIONS NOTE TETHERED SYSTEM TO GET MAGNIFIED RADIO PICTURES OF THE GALACTIC CENTER FROM A DISTANCE OF 550 AU

摘要

The mass of the Sun is by far the largest mass in the solar system. The light-bending effect predicted by general relativity is thus by far larger around the Sun than around any other body in the solar system. The Schwarzschild solution to the Einstein equations yields its value: 4GM/(r c~2), r denoting the "impact parameter", i.e. the minimal distance between the center of the Sun and the bent light path. Now suppose that the light rays come from very far away, specifically from the Galactic Center 32,000 light years (ly) away. This light source may practically be regarded as infinitely distant and it is easy to see that light rays and radio waves from the Galactic Center graze the surface of the Sun and are then focussed by its mass into a point on the other side whose distance is about 550 Astronomical Units (AU), or 3.l7 light days, over l4 times beyond Pluto. This point is the "nearest focus" of the gravitational lens of the Sun, but it is important to realize that every point beyond 550 AU is a focus also because hit by radii having higher impact parameter and so less deflected. A space mission sent along the focal axis (the straight line from the Galactic Center thru the center of the Sun) to 550 AU and beyond would take advantage of the huge radio magnifications of any object lying on the other side of the Sun with respect to the spacecraft position. Such a mission, dubbed "FOCAL" by this author, is described in a formal Proposal submitted to ESA in l993 and in a book published by the author in l997. These studies, however, were restricted by one limitation: the area (of the Galactic Center) hugely magnified by the FOCAL spacecraft is very small: namely, it is a circle equal to the Sun disk or a little more. This restriction is removed in the present paper by the adoption of two antennas, rather than one, tied together by a Tether. We prove that this Tether may have only the modest length of about 2 km if FOCAL is going to magnify the Black Ho1e supposedly located at the Galactic Center (with assumed mass of about a million Sun masses).