FOCAL (spacecraft)

FOCAL is a proposed space telescope that would use the Sun as its gravity lens, through the Solar lens effect. The mission was first suggested by professor Von Eshleman,[1]:3 and developed in detail by Italian astronomer Claudio Maccone.

In order to use the Sun as a gravity lens, it would be necessary to send the telescope 550 astronomical units away from the Sun,[1]:4–7 enabling very high signal amplifications: for example, at the 203 GHz wavelength, amplification of 1.3·1015.[2] This should be enough to obtain detailed images of the surfaces of extrasolar planets.[3]

Even without using the Sun as the lens, FOCAL could perform various, otherwise impossible measurements: a telescope could be used to measure stellar distances by parallax, which would, using the baseline of 550AU, measure the precise position of every star in the Milky Way,[1]:18 enabling various further scientific discoveries.[1]:18–22 It could also study the interstellar medium,[1]:22 the heliosphere,[1]:27 observe gravity waves,[1]:25 check for the possible variation of the gravitational constant,[1]:25 observe the cosmic infrared background,[1]:26 characterise interplanetary dust within the Solar system,[1]:27–28 more precisely measure the mass of the Solar system[1]:26 and similar.

Limitations

FOCAL does not require any non-existing technology, however it has various limitations. A space mission of this duration and distance has never been attempted. A gravity lens will bend objects behind it, so that images from the telescope would be difficult to interpret.[2] FOCAL would be able to observe only objects that are right behind the Sun from its point of view, which means that for every observed object a new telescope would have to be made.[1]:33[2]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 Maccone, Claudio (2009-06-09). Deep Space Flight and Communications: Exploiting the Sun as a Gravitational Lens. Berlin: Springer Science & Business Media. ISBN 9783540729426. Retrieved 2015-01-18.
  2. ↑ 2.0 2.1 2.2 Chorost, Michael (2013-06-26). "The Seventy-Billion-Mile Telescope".
  3. ↑ Villard, Ray (2011-01-10). "Using The Sun as a Magnifying Glass".

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