FOCAL (spacecraft)

Fast Outgoing Cyclopean Astronomical Lens (FOCAL) is a proposed space telescope that would use the Sun as a gravity lens. The gravitational lens effect was first derived by Einstein,[1] and the concept of a mission to the solar gravitational lens was first suggested by professor Von Eshleman,[2] and analyzed further by Italian astronomer Claudio Maccone[3] and others.[4]

In order to use the Sun as a gravity lens, it would be necessary to send the telescope to a minimum distance of 550 astronomical units away from the Sun,[3]:4–7 enabling very high signal amplifications: for example, at the 203 GHz wavelength, amplification of 1.3·1015.[5] Maccone suggests that this should be enough to obtain detailed images of the surfaces of extrasolar planets.[6]

Other uses of the mission

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,[3]:18 enabling various further scientific discoveries.[3]:18–22 It could also study the interstellar medium,[3]:22 the heliosphere,[3]:27 observe gravitational waves,[3]:25 check for the possible variation of the gravitational constant,[3]:25 observe the cosmic infrared background,[3]:26 characterise interplanetary dust within the Solar system,[3]:27–28 more precisely measure the mass of the Solar system[3]: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.[5] 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.[3]:33[5]

External links

References

  1. ↑ Einstein, Albert (1936). "Lens-Like Action of a Star by the Deviation of Light in the Gravitational Field". Science. 84 (2188): 506–507. Bibcode:1936Sci....84..506E. doi:10.1126/science.84.2188.506. PMID 17769014.
  2. ↑ Eshleman, Von R., "Gravitational lens of the sun: its potential for observations and communications over interstellar distances," Science, Vol. 205, No. 4411 (1979) pp. 1133-1135.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 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.
  4. ↑ Turyshev, S. G. and Andersson, B-G., “The 550-AU Mission: a critical discussion”, Mon. Not. R. Astron. Soc. 341, pp. 577–582 (2003).
  5. 1 2 3 Chorost, Michael (2013-06-26). "The Seventy-Billion-Mile Telescope".
  6. ↑ Villard, Ray (2011-01-10). "Using The Sun as a Magnifying Glass".
This article is issued from Wikipedia - version of the 10/13/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.