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--- themis:history [2024/12/04 12:56] – created etienne
+++ themis:history [2024/12/16 16:23] (current) – etienne
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 The Origins and Development of the THEMIS (Télescope Héliographique pour l’Étude du Magnétisme et des Instabilités Solaires) solar telescope encompass a rich history of international collaboration, scientific ambition, and technological innovation.
-=== Scientific motivation and conceptualization===
+==== Scientific motivation, conceptualization (1970's) ====
 In the latter half of the 20th century, solar physicists recognized that the Sun's magnetic field plays a crucial role in various solar phenomena, including sunspots, solar flares, and coronal mass ejections. However, understanding the intricate details of the Sun's magnetic field required advanced observational tools capable of high-resolution measurements.
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 was presented for the first time to the Institut National d’Astronomie et de Géophysique (predecessor of INSU) in 1975.
+==== Site selection (1970's) ====
-=== International collaboration and formation of partnerships ===
+The site selection for THEMIS was part of a larger project to search for optimal location for international solar observations. The
+** Joint Organization for Solar Observations** (JOSO) was funded in Catania, Italy, in 1969 with the aim to at establish a modern optical solar observatory with advanced instrumentation for high-resolution observation of solar atmospheric structures. Between 1969 and 1985, the JOSO was concerned with locating and testing observatory sites in which solar seeing allows a spatial resolution of the order of 0.1 arcsec for long periods of time. After the evaluation of about 40 locations, two sites on the Canary Islands were selected: Izana in Tenerife, and Roque de Los Muchachos, in La Palma, both at an altitude of about 2400 m. Those now hosts the majors European telescopes, such as the the Vacuum Solar Telescope (Germany), the Swedish Solar Telescope (Scandinavia), Gregor (Germany) as well as the projected site for the future European Solar Telescope (EST).
-Securing adequate funding was a critical step in the development of THEMIS. The project received financial backing from national science agencies of the participating countries, as well as from European Union research funds aimed at fostering international scientific collaborations.
+The Teide Observatory on Tenerife, Canary Islands, was selected as the site for THEMIS due to its optimal geographical and climatic conditions for solar observations. The Canary Islands offer stable atmospheric conditions with minimal turbulence, essential for high-resolution imaging. The location provides relatively easy access for international teams, facilitating collaboration and maintenance.
-- **National Contributions:** Each partner country committed a portion of the budget, covering aspects such as construction, instrumentation, and operational costs.
-- **European Grants:** Additional funding was secured through European Union grants, which supported specific components like advanced spectropolarimetric instruments and adaptive optics systems.
-The THEMIS project was initiated as a collaborative effort primarily between three European countries: **France**, **Italy**, and **Spain**. This partnership leveraged the strengths of each nation's scientific institutions and expertise in astronomical instrumentation.
-- **France:** The Institut National des Sciences de l'Univers (INSU), part of CNRS, took the lead in coordinating the project.
-- **Italy:** The Instituto Nazionale di Astrofisica (INAF), part of CNR contributed significant expertise in solar physics and instrumentation.
-- **Spain:** The Spanish National Research Council (CSIC) and other Spanish institutions, in particular the Instituto de Astrofísica de Canarias (IAC) provides the site and logistical support.  provided support, particularly in site selection and infrastructure development.
-An agreement was signed between the French CNRS and the Italian CNR. The construction cost of 87.5 million francs was covered with 80% financed by the CNRS and 20% by the CNR. The same funding distribution applies to the operation of the instrument. Observation time is allocated as follows: 60% for the French, 15% for the Italians, 20% for the Spanish, and 5% for "international time." A Franco-Italian steering committee determines the general policies for the telescope's operation and development.
+==== Telescope design & Instrumentation Development (1980's) ====
+The design phase, directed by Jean Rayrole, focused on creating a telescope optimized for high-resolution spectropolarimetric observations. Key considerations included:
+  * Aperture Size: A 90 cm aperture was chosen to balance light-gathering power with the practicalities of ground-based operations.
+  * Polarimetry capabilities: A polarisation free telescope meant to have a polarimetric analyser at the first focus/image point (F1) of the telescope and being able to have an optical path that in which the polarisation state remains stable. Also advanced polarimetric instruments were integrated to measure the polarization of sunlight, which is essential for mapping the Sun's magnetic fields.
-=== Design and technological innovations ===
+Developing specialized instruments, as well as the telescope and instrument control system was a significant aspect of the project's technological innovation. Sophisticated control systems were developed to manage the telescope's operations, including moving the dome and telescope for tracking the Sun, and coordinating data acquisition.
-The design phase focused on creating a telescope optimized for high-resolution spectropolarimetric observations. Key considerations included:
+High-precision spectropolarimeters were designed to analyze the polarization states of light across different wavelengths, providing detailed information about magnetic fields. In THEMIS design, three first light instruments have been developed:
-- **Aperture Size:** A 90 cm aperture was chosen to balance light-gathering power with the practicalities of ground-based operations.
+  * **a spectrograph, MTR**: XXXX
-- **Polarimetry Capabilities:** Advanced polarimetric instruments were integrated to measure the polarization of sunlight, which is essential for mapping the Sun's magnetic fields.
+  * **a spectro-imager, IPM**: the Italian Panoramic Monochromator ([[https://aas.aanda.org/articles/aas/abs/1998/06/ds6554/ds6554.html| Cavallini, A&A, 1998]]) performed solar bidimensional spectroscopy. On a square field $33''\times 33''$, this instrument allowed to obtain monochromatic images of the solar surface with high spectral resolution (R > 256 000 at 5500 Å), preserving all the spatial resolution delivered by the telescope (~0.2''). IPM consisted of a Fabry-Perot interferometer, used in telecentric mounting, in series with a Universal Birefringent Filter, used as an order sorter.
+  * **an imaging spectrometer, MSDP**: XXXX
-=== Instrumentation Development ===
+==== Construction (1990's) ====
-Developing specialized instruments was a significant aspect of the project's technological innovation.
-- **Spectropolarimeters:** High-precision spectropolarimeters were designed to analyze the polarization states of light across different wavelengths, providing detailed information about magnetic fields.
-- **Control Systems:** Sophisticated control systems were developed to manage the telescope's operations, including tracking the Sun, adjusting for atmospheric turbulence, and coordinating data acquisition.
-=== Site selection and construction ===
+Securing adequate funding was a critical step in the development of THEMIS. The project received financial backing from national science agencies of the participating countries, as well as from European Union research funds aimed at fostering international scientific collaborations. Each partner country committed a portion of the budget, covering aspects such as construction, instrumentation, and operational costs.
-==Choosing the Teide Observatory==
+The THEMIS project was initiated as a collaborative effort primarily between three European countries: **France**, **Italy**, and **Spain**. This partnership leveraged the strengths of each nation's scientific institutions and expertise in astronomical instrumentation.
-The Teide Observatory on Tenerife, Canary Islands, was selected as the site for THEMIS due to its optimal geographical and climatic conditions for solar observations.
+  * France: The Institut National des Sciences de l'Univers (INSU), part of CNRS, took the lead in coordinating the project.
-- **Atmospheric Stability:** The Canary Islands offer stable atmospheric conditions with minimal turbulence, essential for high-resolution imaging.
+  * Italy: The Instituto Nazionale di Astrofisica (INAF), part of CNR contributed significant expertise in solar physics and instrumentation.
-- **Accessibility:** The location provides relatively easy access for international teams, facilitating collaboration and maintenance.
+  * Spain: Consejo Superior de Investigaciones Científicas(CSIC) and other Spanish institutions, in particular the Instituto de Astrofísica de Canarias (IAC) provides the site and logistical support.  provided support, particularly in site selection and infrastructure development.
-==Building the Telescope==
+An agreement was signed between the French CNRS and the Italian CNR. The construction cost of 87.5 million francs was covered with 80% financed by the CNRS and 20% by the CNR. The same funding distribution applies to the operation of the instrument. Observation time is allocated as follows: 60% for the French, 15% for the Italians, 20% for the Spanish, and 5% for "international time." A Franco-Italian steering committee then determined the general policies for the telescope's operation and development.
-Construction began in the early 1990s, involving meticulous planning and execution to assemble the telescope's complex components.
-- **Assembly:** The primary mirror and optical components were manufactured with high precision to meet the stringent requirements for spectropolarimetric measurements.
-- **Integration:** Integrating various subsystems, such as adaptive optics, control electronics, and data acquisition systems, was a challenging but essential task to ensure seamless operation.
-===Commissioning and early operations===
+Construction began in the early 1990s, involving meticulous planning and execution to assemble the telescope's complex components. The primary mirror and optical components were manufactured with high precision to meet the stringent requirements for spectropolarimetric measurements. Integrating various subsystems, such as adaptive optics, control electronics, and data acquisition systems, was a challenging but essential task to ensure seamless operation.
-Before full-scale operations commenced, extensive testing was conducted to verify the telescope's performance.
+==== Commissioning, first light and first phase of exploitation (1996-XXX) ====
-- **Optical Alignment:** Ensuring precise alignment of optical components was critical for achieving the desired resolution and polarimetric accuracy.
-- **Instrument Calibration:** Spectropolarimeters and other instruments underwent calibration processes to ensure accurate measurements.
-==First Light and early scientific results==
+Before full-scale operations commenced, extensive testing was conducted to verify the telescope's performance. Ensuring precise alignment of optical components was critical for achieving the desired resolution and polarimetric accuracy. Spectropolarimeters and other instruments underwent calibration processes to ensure accurate measurements.
-THEMIS achieved its "first light" in the march 1996, marking the beginning of its operational phase. The initial scientific goals focused on:
-- **Mapping Magnetic Fields:** High-resolution mapping of magnetic fields in sunspots and active regions.
-- **Studying Solar Instabilities:** Investigating the mechanisms behind solar eruptions and energy transfer processes in the solar atmosphere.
-- **Long-Term Monitoring:** Establishing a long-term observational program to track changes in solar magnetic activity over time.
-=== Evolution and Enhancements ====
+THEMIS received its first light on March 16, 1996, and was inaugurated that same year by the King and Queen of Spain, along with French and Italian authorities.
-#### **Upgrades and Technological Advancements**
+==== Evolution and redesign (2010's) ====
+xxx
 Over the years, THEMIS has undergone several upgrades to enhance its capabilities:
-- **THEMIS Adaptive Optics:** Upgrades to adaptive optics systems to further reduce atmospheric distortions, allowing for sharper images.
+  * **[[themis:technical:tao|THEMIS Adaptive Optics]]**: Upgrades to adaptive optics systems to further reduce atmospheric distortions, allowing for sharper images.
+  * Data Processing Improvements: Implementation of advanced data processing algorithms and high-performance computing resources to handle the increasing volume of observational data.
+  * Planetary observations: XXXX
-- **Data Processing Improvements:** Implementation of advanced data processing algorithms and high-performance computing resources to handle the increasing volume of observational data.
-### **Impact and Legacy**
+==== New life for the THEMIS telescope (2020's) ====
-#### **Scientific Contributions**
-Since its inception, THEMIS has made significant contributions to our understanding of solar magnetism and related phenomena:
-- **Detailed Magnetic Maps:** High-resolution magnetic field maps have been instrumental in refining models of solar magnetism and predicting solar activity.
-- **Energy Transfer Mechanisms:** Studies on energy transfer within the solar atmosphere have shed light on the processes driving solar flares and coronal mass ejections.
-- **Space Weather Prediction:** Data from THEMIS has enhanced models used for predicting space weather, which has implications for satellite operations and terrestrial technologies.
-#### **Educational and Training Role**
-THEMIS has also played a vital role in training the next generation of solar physicists and astronomers, providing hands-on experience with cutting-edge instrumentation and observational techniques.
-#### **Continued Relevance**
 Despite advancements in space-based solar observatories, THEMIS remains a valuable asset due to its unique capabilities and the ability to perform long-term, high-resolution observations from the ground.
-### **Challenges Faced During Development**
+==== To go further ====
-#### **Technological Hurdles**
-Developing the sophisticated spectropolarimetric instruments and ensuring their precise calibration posed significant technical challenges. Overcoming these required iterative testing, collaboration with instrument manufacturers, and incorporating feedback from initial observations.
-#### **Funding and Resource Constraints**
-Securing sustained funding over the long development period was a constant challenge. The project had to navigate changes in political landscapes, economic fluctuations, and shifting research priorities to maintain financial support.
-#### **Environmental and Logistical Issues**
-Constructing and operating a telescope at the Teide Observatory involved addressing environmental factors such as weather variability and ensuring the stability and reliability of infrastructure in a remote location.
-### **Conclusion**
+{{:themis:history:1986mmsai..57..pdf | The Joint Organization for Solar Observations (JOSO)}}, G. Godoli, Società Astronomica Italiana, Annual Meeting, 30th, Ravenna, Italy, May 1-3, 1986 Società Astronomica Italiana, Memorie (ISSN 0037-8720), vol. 57, no. 4, 1986, p. 631-654.
+{{:themis:history:histoire_des_observations_solaires_meudon.pdf|Histoire des observations solaires de Meudon}}, by Regis Le Cocguen (in French)
-The origins and development of the THEMIS solar telescope exemplify the power of international collaboration in advancing scientific knowledge. From its conception in the 1980s to its operational status in the late 1990s and beyond, THEMIS has continually evolved through technological innovation and strategic partnerships. Its sustained contributions to solar physics underscore its importance as a cornerstone in the quest to understand our Sun's magnetic mysteries and dynamic behavior.