Article

The DynaMICCS perspective. A mission for a complete and continuous view of the Sun dedicated to magnetism, space weather and space climate

Experimental Astronomy (Impact Factor: 2.97). 03/2009; 23(3):1017-1055. DOI: 10.1007/s10686-008-9111-z

ABSTRACT The DynaMICCS mission is designed to probe and understand the dynamics
of crucial regions of the Sun that determine solar variability,
including the previously unexplored inner core, the radiative/convective
zone interface layers, the photosphere/chromosphere layers and the low
corona. The mission delivers data and knowledge that no other known
mission provides for understanding space weather and space climate and
for advancing stellar physics (internal dynamics) and fundamental
physics (neutrino properties, atomic physics, gravitational moments...).
The science objectives are achieved using Doppler and magnetic
measurements of the solar surface, helioseismic and coronographic
measurements, solar irradiance at different wavelengths and in-situ
measurements of plasma/energetic particles/magnetic fields. The
DynaMICCS payload uses an original concept studied by Thalès
Alenia Space in the framework of the CNES call for formation flying
missions: an external occultation of the solar light is obtained by
putting an occulter spacecraft 150 m (or more) in front of a second
spacecraft. The occulter spacecraft, a LEO platform of the mini sat
class, e.g. PROTEUS, type carries the helioseismic and irradiance
instruments and the formation flying technologies. The latter spacecraft
of the same type carries a visible and infrared coronagraph for a unique
observation of the solar corona and instrumentation for the study of the
solar wind and imagers. This mission must guarantee long (one 11-year
solar cycle) and continuous observations (duty cycle > 94%) of
signals that can be very weak (the gravity mode detection supposes the
measurement of velocity smaller than 1 mm/s). This assumes no
interruption in observation and very stable thermal conditions. The
preferred orbit therefore is the L1 orbit, which fits these requirements
very well and is also an attractive environment for the spacecraft due
to its low radiation and low perturbation (solar pressure) environment.
This mission is secured by instrumental R and D activities during the
present and coming years. Some prototypes of different instruments are
already built (GOLFNG, SDM) and the performances will be checked before
launch on the ground or in space through planned missions of CNES and
PROBA ESA missions (PICARD, LYRA, maybe ASPIICS).

0 Bookmarks
 · 
69 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: From time immemorial men have strived to measure the size of celestial bodies. Among them, the diameter of the Sun was a source of curiosity and study. Tackled by Greek astronomers from a geometric point of view, an estimate, although incorrect, has been first determined, not truly called into question for several centuries. One must wait up to the XVIIth century to get the first precise determinations made by the French school of astronomy. Gradually, as the techniques were more and more sophisticated, many other solar diameter measurements were carried out, notably in England, Germany, Italy and US. However, even with instruments at the cutting edge of progress, no absolute value of the solar diameter has been provided yet, even if the community has adopted a canonical radius of 959.″63, given in all ephemeris since the end of the XIXth century. One of the major difficulties is to define a correct solar diameter. Another issue is the possible temporal variability of the size of the Sun, as first advocated at the end of the XIXth century by the Italian school. Today, this question is just on the way to being solved in spite of considerable efforts developed on ground-based facilities or on board space experiments. We will here give a review of some of the most remarkable techniques used in the past, emphasising how incorrect measurements have driven new ideas, leading to develop new statements for the underlying physics. On such new grounds, it can be speculated that the roundness of the Sun is not perfect, but developing a thin “cantaloupe skin” in periods of higher activity, with departures from sphericity being inevitably bounded by a few kilometers (around 80 km or 10 to 15 mas).
    European Physical Journal H, The 37(5). · 2.38 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Low-degree pulsation modes are the best way to scrutinize stellar cores. They also provide, due to their intrinsic nature, a way to follow varying activity in important subsurface layers. Following difficulties encountered with the Solar and Heliospheric Observatory (SoHO) in 1998, we study a new design that improves the detection at low and high frequencies in comparison with the Global Oscillations at Low Frequency (GOLF) instrument. It is based on a substantial increase in the counting rates to get better photon statistics, and a reduction of the solar turbulent noise in measuring simultaneously the Doppler velocity at 6-7 heights in the strong sodium spectral line. A prototype, GOLF-NG (GOLF New Generation), has been built with numerous laboratory checks of the performance and in situ solar measurements at Tenerife in 2008 and 2010. All the required specifications are now achieved, and so GOLD can be prepared for space observations with balloons or satellites. The substantial improvements allow an improved detection of weak signals at different frequencies and information on activity indicators, as the Na D lines are sensitive to the magnetic field between photosphere and chromosphere.
    09/2012;
  • [Show abstract] [Hide abstract]
    ABSTRACT: The stellar internal magnetism is presently poorly known, even we have now some evidence that it plays a crucial role in different stages of stellar evolution. I first recall the helioseismic results coming from the SOHO mission on the deep interior. Then I show how we hope to observe directly or indirectly the deep solar magnetism by the simultaneous detection of gravity modes, acoustic modes and other phenomena. The two following sections compare the different techniques of observation and show the interest of a multichannel resonant spectrometer both for studying the deep dynamics of the core and for putting some constraints on the stellar atmospheric models. The last section describes the DynaMICCS mission submitted to ESA in the framework of Cosmic Vision 2015-2025 and the observations of the coming decade with the GOLF-NG instrument dedicated to the magnetism of the core and to the region located between photosphere and chromosphere.
    EAS Publications Series 01/2009; 39:69-82.

Full-text (2 Sources)

Download
27 Downloads
Available from
May 21, 2014