From: LARRY KLAES (ljk4_at_msn.com)
Date: Wed Oct 24 2007 - 12:45:42 PDT
>From: Centauri Dreams <gilster_at_mindspring.com>
>Reply-To: Centauri Dreams <gilster_at_mindspring.com>
>Subject: Centauri Dreams
>Date: Wed, 24 Oct 2007 14:04:40 -0500 (CDT)
>
>Centauri Dreams
>
>///////////////////////////////////////////
>PLATO: A New ESA Planet Hunter Concept
>
>Posted: 24 Oct 2007 12:34 PM CDT
>http://www.centauri-dreams.org/?p=1534
>
>
>Looking through the list of candidate missions selected by the European
>Space Agency recently, my attention was immediately drawn to PLATO, a
>planet-finder spacecraft designed to study transiting exoplanets and to
>measure the seismic oscillations of the stars they orbit. Although at first
>reminiscent of COROT, PLATO (Planetary Transits and Oscillations of Stars)
>is really more like an enhanced version of NASAs upcoming Kepler mission,
>as Im reminded by Centauri Dreams regular Vincenzo Liguori, who passed
>along helpful background information.
>
>One immediate difference turns out to be field-of-view, which in PLATO is
>wide indeed due to the observation strategy involved. Unlike COROT or
>Kepler, PLATO would put photometric techniques to work in the study of
>relatively bright stars 100,000 of these, with another 400,000 studied
>down to 14th magnitude. The earlier mission concepts are aimed at surveying
>fainter and more distant stars in a smaller field.
>
>Note the significance of this: If COROT or Kepler identifies interesting
>planets around much fainter stars, follow-up studies in particular direct
>imaging and spectroscopic investigation become much more difficult than
>they would be with PLATOs brighter targets. This mission description from
>LESIA (Laboratoire dEtudes Spatiales et dInstrumentation en Astrophysique)
>further explains the difference:
>
>Moreover, for this sample of 100,000 stars, similar in size as that of
>Kepler, PLATO will reach a noise level at least three times lower than the
>average level of noise of Kepler, and will therefore allow us to detect
>smaller planets in front of cool dwarf stars, or terrestrial planets in
>front of hotter and larger stars, thus significantly extending our
>knowledge of the statistics of exoplanetary systems.
>
>In addition, PLATO is designed to detect terrestrial planets in the
>habitable zone down to about mV = 14, a performance very similar to that of
> Kepler. Due to the larger size of the surveyed field, PLATO will monitor
>about 400,000 stars down to this magnitude, extending by approximately a
>factor of four the sample of detected planetary systems over Kepler.
>
>
>
>And two concepts for the satellite are in play. The first involves 100
>small, wide-field telescopes mounted on a single platform, all of these
>looking at the same field with its own set of 24 CCDs. This so-called
>staring concept involves a first phase in which the same field is studied
>continuously for several years. The second, the spinning concept, uses
>three identical instruments pointing 120 degrees from one another, in the
>words of LESIA sweeping out a great circle on the sky perpendicular to the
>spin axis. Both designs assume insertion into an L2 orbit by a Soyuz-Fregat
>launcher.
>
>Images: Above: One configuration for PLATO, the so-called staring concept.
>Below: The spinning concept. Credit: LESIA.
>
>It will be interesting to see how this mission evolves, especially since
>PLATO should be able to observe smaller exoplanets than could be detected
>by the two earlier missions. Moreover, since the stars it studies will be
>three magnitudes brighter, spectroscopy and astroseismology follow-up
>studies as well should be correspondingly more precise. Tying in PLATOs
>findings with subsequent James Webb Space Telescope data could help pin
>down exoplanet atmosphere information.
>
>
>
>Youll find the complete PLATO proposal here. ESAs other proposed missions
>give us much else to think about, including two proposals for a dark energy
>mission, the Marco Polo asteroid return mission, and new mission concepts
>for Jupiter and Saturn. The candidates undergo an assessment period that
>should end with two missions emerging as the winners, their proposed
>launches in 2017 and 2018 respectively. Need I point out how much depends
>upon budgetary considerations in making these choices and deciding if and
>when they fly?
>
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