Autumn: Calipso moves from A-Train to C-Train orbit
9 November: annual CNES/NASA JSG meeting. Mid-year review of the mission and space segment, and first results since the change of orbit: the outcome is positive and the Calipso and CloudSat missions are once again operating together to acquire tandem measurements after being apart for 9 months. Science results are excellent.
13 September to 17 October: operations to move from A-Train to C-Train orbit. Operations go according to plan, with the exception of the final inclination manoeuvres, which have to be aborted due to a thruster nozzle anomaly. Calipso and CloudSat are nevertheless perfectly positioned in the C-Train orbit.
6 September: CNES/NASA Calipso JSG meeting to confirm the decision to change Calipso’s orbit and join CloudSat in the new C-Train orbit and give go-ahead for start of operations.
25 July 2018: Calipso/CloudSat Orbit Change Reconfiguration Review
NASA review to examine moving the Calipso and CloudSat missions to the new C-Train orbit less than 17 km from the A-Train orbit. Assessment of operational impacts and risks, as well as science mission impacts: the review clearly approved this orbit change, concluding that Calipso will better advance the mission’s science goals in tandem with CloudSat in the C-Train than by remaining in the A-Train without CloudSat.
From an operational perspective, the orbit change can be accomplished from September 2018, with no risk or extra cost, and no change to the nominal mission lifetime bar a short interruption of about 1 week. The science value of doing this is undeniable:
- Pursuing tandem observations by Calipso and CloudSat is vital to characterize the main parameters affecting cloud-climate variability, as cloud observations need to be performed simultaneously due to the timescales involved.
- This change will ensure continuity and consistency of combined CloudSat-Calipso time-series data products through to 2021.
- Calipso was designed to accomplish its science goals in the A-Train, for which the Imaging Infrared Radiometer (IIR) and Wide-Field Camera (WFC) were included in the payload.
- All Calipso science will be maintained. Synergies between Calipso-MODIS aerosol data will be retained, as aerosols are more uniform spatially and temporally, have a longer lifetime and can tolerate time differences on the order of 1 hour, compatible with the new orbit geometry. Ten percent of MODIS-Calipso cloud synergies will be retained and the remainder will be substantially offset by WFC and IIR.
- Calibration/validation with future missions remains a possibility as this is independent of the orbit.
- Calipso-CloudSat will orbit underneath MODIS’s swath, thus affording a wide range of viewing angles, which will prove useful for studying the impact of higher viewing angles.
- There will be no notable impact on data/products (no reprocessing or version change will be required)
- Lastly, should CloudSat be lost, scientific exploitation of the satellite mission is the same for both orbits (A-Train and C-Train).
16/05-17/05/2018: 11th CALIPSO REVEX in Dulles (U.S) with NASA LARC, CNES and AERIS/ICARE teams
The review was successful as regards the full capacity of the space segment (bus, ground segment and payload) as well as the extent of science accomplished, which has gone from strength to strength over the 12 years of the mission. Three key points are worthy of note:
- Laser performance: contrary to what was expected a year earlier, the primary laser’s performance is still good outside the SAA zone (less than 1% of laser firings are affected) and the mission will continue to operate with this instrument as long as its performance remains satisfactory. Switching to the back-up laser is therefore no longer a consideration for the time being.
- A presentation was given explaining the strategy and science value of changing Calipso’s orbit to continue tandem measurements with CloudSat. This option was given the green light. The French scientific community clearly expressed its preference for this option (see document attached), for NASA a Mission Reconfiguration Review is still required before a final decision by JSG CNES-NASA.
- A presentation was given of the platform technology experiments that will be conducted after the end of the Calipso mission to characterize and analyse nozzles, measure battery performance and perform end-of-life RAM analysis.
From January 2018: Laser replacement and associated performance assessment
December: CloudSat leaves A-Train
Calipso’s companion satellite leaves the A-Train after the failure of a reaction wheel impairs its emergency manoeuvring capability.
This marks the start of a long scientific evaluation period, with teams seeking orbital strategies and conducting engineering analyses to decide whether Calipso should join CloudSat in a new orbit to pursue their tandem mission.
November 2017: Technological experiments selection for the end of the Calipso mission
July 2017: The latest version of level 1 IIR Standard data (V2-00) is now available for US and French data centres (ASDC and AERIS/ICARE)
Version 2.00 of the IIR Level-1 product is the first major revision since the initial release in 2006. The calibration procedure has been adjusted to reduce known small seasonal calibration biases in the Northern Hemisphere, which were caused by thermal drifts synchronized with the elapsed time since the night-to-day transition.
05/2017 : CNES REDEM and NASA Senior Review for CALIPSO.
After 11 successful years of science operations, CNES and NASA agreed to extend the Calipso mission for another 3 years (2018-2020).
In addition to maintaining the French scientific community’s dynamic and structure in the field of space lidar, 4 essential objectives have been identified to justify a 3-year extension:
- Extending Calipso’s timeframe: a major requirement for climate change studies. An observation period of over 10 years is necessary in order to detect potential trend on relevant variables. Contributing to World Climate Research Programme (WCRP) projects such as CMIP6 is also a possibility. These exercises provide content for the Intergovernmental Panel on Climate Change (IPCC) reports. An extended observation period also allows for richer statistical sampling and increases the chances to observe punctual events such as volcanic eruptions.
- Observational continuity with future missions: extending the Calipso mission to 2020 will ensure continuity with the CATS (NASA, lidar aboard the ISS, already in orbit), ADM-Aeolus (ESA, planned for launch in early 2018), and possibly Earth-Care (ESA, launch due in August 2019) missions. ESA missions Aeolus and EarthCare will operate lidars on different wavelengths (355 nm instead of 532 and 1064 nm), so data will have to be recalibrated in order to provide continuous series from active sensors. A longer simultaneous observation period will provide a better comparison and analysis of specific data from each of these missions. Calipso also improve these missions’ Cal/Val exercises (as suggested in a co-written letter from the Aeolus and Earthcare mission scientists).
- Contributing to several upcoming scientific campaigns: EUREC4A (S. Bony, the Field Study, 2020), EXAEDRE (Eric Defer, 2018), MOSAIC (Arctic, 2020)
- Developing new applications: Two new research activities are growing rapidly: data mining using air quality prediction models (the Copernicus C3S and CAMS services, as well as the French national meteorological service Météo-France, have expressed great interest for this field), and assessing the oceanic surface layer’s optical properties.
When it comes to the space segment of the Calipso mission, the satellite has been in orbit for over 11 years; every redundancy is still in place and the payload is still operating at full capacity with comfortable leeway for both temperature and power. Calipso will be able to stay its course on the A-Train at least until 2019, and then slowly drift eastward from Aqua, but without any effect on the satellite or its mission. The WFC and IIR instruments remain fully operational and the lidar’s performance is generally excellent. However, low-energy impulses can be observed in the SAA above the planet’s poles, and the laser’s pressure levels lead to Corona impulses such as the one observed on the primary laser in 2009. Therefore the current laser should soon be switched off to be replaced by the primary laser, which should be out of the critical pressure zone.
05/17-05/18/2017: 10th CALIPSO REVEX
The 10th Calipso REVEX was held in Toulouse with NASA’s LARC teams and French scientists from contributing laboratories (AERIS/ICARE, LMD, IPSL).
The review was a success for the space segment (spacecraft bus, ground segment, payload) as well as for the scientific part of the mission which has been prolific for the past 11 years in orbit.
The REVEX also showed the good level of readiness displayed by the instruments, operations, and science teams for the upcoming laser change planned for autumn.
04/2017: 3rdA-Train Symposium held in Pasadena, California
For over a decade, the 705-km high Afternoon (A-Train) Satellite Constellation has brought together a rich array of instruments to better understand Earth’s changing climate and environment. The 3rd International A-Train Symposium was an opportunity to learn and exchange information about A-Train scientific breakthroughs and to highlight how Earth science has benefitted from the long, continuous, multi-sensor data set.
Additional information regarding the meeting is available on the symposium web site.
11/22/2016: 10th Joint Steering Group meeting
Components review (platform, payload and science) and preparation of the next mission extension (2018-2019) which will be evaluated in spring 2017 (CNES REDEM / NASA Senior Review).
11/08/2016: New version (V4.10) of standard Lidar data product Level 1 and Level 2 are available both at the US and French data centers (ASDC and AERIS/ICARE).
V4.10 Level 1 CALIOP: algorithms unchanged since V4.00, but improvement of the digital models and meteorological forecasts.
V4.10 Level 2 CALIOP: major revision since 2010 with the correction of numerous artifacts and significant enhancement of both content and quality of the scientific data. Moreover, the V4.10 introduces merged layer product which compiles spatial and optical properties of cloud and aerosol layers in a single file (https://www-calipso.larc.nasa.gov/).
06/08-06/10/2016: "CALIPSO-CloudSat Ten-Year Progress Assessment and Path Forward Workshop" took place in Paris at the "Maison des océans" to celebrate the 10 years of scientific measurements.
More information on this web site: https://calipsocloudsat.sciencesconf.org/. Objectives:
- To pesent the scientific breakthrough after 10 years of observation with the two complementary missions CALIPSO and CloudSat.
- To demonstrate the synergy with other missions displayed by the A-Train and to highlight the benefits of such an international cooperation.
- To prepare the future.
The French celebration of the CALIPSO measurements' 10-year anniversary was chaired by Jean-Yves La Gall in front of numerous French (CNRS-IPSL, THALES ALENIA SPACE, SODERN, AERIS/ICARE) and American (NASA) partners, see the CNES Press Release
04/28/2016: Calipso 10 years: Calipso celebrated its 10 years in orbit on April 28 (Press Release UPMC/J. Pelon).
This event was celebrated on April 21 at LARC (NASA center, Hampton USA): cf NASA Press Release
04/20-04/21/2016: 9th CALIPSO Operations Review, at NASA Langley Research Center (LaRC) in Hampton , USA
Again a very positive outcome for this year for both the ground segment and the scientific aspects: 1650 publications and counting, and the combined LIDAR+CloudSat (DARDAR) measurements are in the top 10 products used at AERIS/Icare center. Since October 2015, measurements are performed for "ocean color" applications, at the rate of 1 orbit every 15 days over the Pacific Ocean, the satellite being tilted at 30°: the first results are very positives, the scientists want to pursue this over different seasons, over the Atlantic as well as at high latitudes and over polar areas.
05/19-05/20 and 05/26/2015 : 8th CALIPSO Operations Review, 3rdMission Extension Review (REDEM) at CNES Toulouse
After 9 years of operation, the satellite and payload performances are still excellent and the Calipso mission is considered as a real success.
Thanks to their high precision vertical resolution, Calipso observations are a unique contribution to the study of clouds and aerosols, and to the validation of climate models, as highlighted by the latest GIEC report.
A new 2-year extension of the Calipso mission in the A-TRAIN is confirmed for 2016-2017, with the following objectives:
- Long term observation needed to understand the role of clouds and aerosols on the Earth's climate
- Calipso/OCO-2 dual observations to study the influence of the aerosols on the CO2 restitution
- An overlap or continuity with the CATS, ADM-Aeolus, EarthCare and SAGE III missions
- To estimate the contribution of the Lidar measurements to the ocean color thematic, by a measurement campaign using the 30 degrees depointing capability in order to observe the phytoplankton while minimizing the specular reflections .
02/24/2015: Sand travelling from the Sahara to the Amazon as seen by Calipso
Read the full story on NASA's website.
11/27/2014: CALIPSO just passed the 5 billion laser shots mark
1.62 billion shots for the primary laser and 3.38 for the secondary laser (nominally used since 2009), for a total of 100 seconds of light emission for 8 years and 7 months of data in orbit!
11/25/2014: 9th Joint Steering Group meeting
Nominal mission continuation, we are moving towards a future mission extension (2016-2017) with Calipso still a part of the A-Train.
11/13/2014: New version (4.0) of the LIDAR level 1 scientific products
This updated version substantially improves both the 532 nm and 1064 nm calibration accuracies. Part of the mission data is already available in this version, more information on LARC web site
11/04-11/06/2014: Cloudsat/Calipso Science Team meeting, Alexandria, USA<
Presentations of work done in the context of the science team Calipso-CloudSat 2014 towards an improved use of observations (precipitations/snow, and clouds/clouds-aerosols). The programme is available on the conference web site.
06/11-06/12/2014: 7thCALIPSO Exploitation Review at CNES, Toulouse
After 8 years of service, the platform and the payload are in excellent shape and all redundancies are available. From a scientific point of view, Calipso products are now classified as "Climate data Record".
11/19/2013: 8th Joint Steering Group meeting / confirmation of a new 2-year extension of the CALIPSO mission
After the Senior Review processes for NASA and the REDEM for CNES, the 2 agencies declared that they were again favorable to an additional 2 years extension of the mission (2014-2015), thus CNES and NASA pursue their productive cooperation in the exploitation of CALIPSO mission.
From now on, due to the shutdown in October 2013 in USA, the formal review cycle between CNES and NASA is reversed: JSG (Joint Steering Group) in autumn and REVEX (REVues d'EXploitation) in May/June.
06/28/2013: Mission Extension Review Steering Committee (REDEM)
The REDEM Steering Committee approves a new 2-year extension of the CALIPSO mission (2014-2015) and predicts the possibility of 2 more years.
10/18-10/19/2012: Sixth CALIPSO Exploitation Review in Greenbelt, USA
After 6 years, platform and payload alike perform at nominal levels. On the science side, the number of scientific users as well as publications continue to its progress in a notable way.
07/03/2012: The active observations from space, a new key to understand the complexe relationships between clouds, aerosols and radiation.
A joint CALIPSO/CloudSat/EarthCARE satellite missions workshop was held from 18-22 June 2012 at the Institut Océanographique de Paris. This workshop brought together over 200 of the world's leading scientists working to improve our understanding of Earth's atmosphere and climate using advanced remote sensing technologies operating from space. The workshop showcased many remarkable achievements with the CloudSat and CALIPSO data - data which is revolutionary in its ability to observe the vertical distribution of clouds and aerosols.
Already CloudSat and CALIPSO data have led to breakthroughs in the scientific understanding of clouds, aerosols and their impact on Earth's climate. Many new discoveries have been revealed about clouds, precipitation and the way aerosols interfere with clouds and rain. The new observations suggest that past depictions of cloud-related processes, of Earth's energy balance and estimates of the radiative forcing of climate by aerosols, and even the description of aerosol effects on clouds require significant revision.
The CloudSat and CALIPSO missions, launched by NASA in April 2006, generated new innovative observations of clouds and aerosols using spaceborne lidar and cloud radar technologies. The EarthCARE mission, a partnership of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) in partnership with the Japan National Institute of Information Communication and Technology (NICT), is planned for launch in 2015 and will carry even more-advanced cloud radar and lidar instruments, as well as other important radiometry instruments. The workshop results highlight the importance of the planned EarthCARE mission that will provide continuity and significant scientific breakthroughs following its launch. Additionally, the workshop demonstrated the importance of sustaining these new and vitally important measurements, even beyond the EarthCARE mission, to continue to improve understanding of the key atmospheric processes that shape climate change.
The CALIPSO mission, a joint endeavor of NASA and CNES, has completed six years of operations, with some 3.5 billion shots taken by the primary and backup lasers. More than 80 terabytes of data have been processed.
The CloudSat mission, a joint endeavor of NASA and the Canadian Space Agency (CSA), has completed six years of operations with the first space borne 94 GHz cloud radar built by the Jet Propulsion Laboratory, California Institute of Technology, with hardware components contributed by CSA.
Nearly 1000 publications have referenced CloudSat and/or CALIPSO. This workshop has emphasised the great value of fostering scientific international cooperation capitalizing on A train understanding the complex puzzle of clouds aerosols and radiation interactions.
06/18-06/22/2012: A joint workshop, "The Role of Clouds and Aerosols in Weather and Climate", of the NASA/CNES CALIPSO, NASA/CSA CloudSat and the ESA/JAXA EarthCARE satellite missions will be held in Paris, France.
04/28/2012: CALIPSO has just celebrated its 6th anniversary in orbit and pursues its nominal mission observing the atmosphere.
11/21/2011: Positive response of the LOS bureau for CALIPSO mission extension.
10/19-10/21/2011: A-TRAIN operational coordination meeting (MOWG) in Biarritz, France.
This year, CNES hosted the A-Train constellation MOWG meeting. During this MOWG, the possible return of Cloudsat satellite into the A-Train constellation was largely discussed, notably the eventual impacts on CALIPSO mission exploitation. A process describing the main steps to make the analysis of this return have been setup as well as formal decision reviews.
10/17-10/18/2011: 5th CALIPSO Exploitation Review in Biarritz, France.
This 5th REVEX highlighted the excellent operational results of the satellite and the Ground Segment and confirmed the operations extension until the end of 2013.
09/26/2011: NASA confirms CALIPSO mission 2 years extension
CNES and NASA wished to continue their cooperation relative to the CALIPSO mission exploitation and confirmed the mission extension by 2 additional years (2012-2013).
09/08/2011: Signature of the new Implementing Arrangement (IA) between CNES and NASA.
This new IA signed between CNES and NASA allows the continuation of the cooperation between the 2 agencies to continue CALIPSO mission. It replaces the MOU signed on June 18, 2003 which was coming to its end.
05/26/2011: Mission Extension Review Steering Committee (REDEM).
The REDEM Steering Committee gave a favourable answer to the CALIPSO mission 2 years extension (2012-2013). At the same time, a senior review process is on going on NASA side and an answer will be given by the end of August, 2011 about the CALIPSO mission extension. On CNES side, a new position of the LOS bureau is expected to ratify this extension.
04/04/2011: Mission Extension Review (REDEM).
End 2010, the scientific community asked for a 2 years extension of CALIPSO mission. CNES instructed this request and presented the results during the REDEM on April 4, 2011. Since the application of the "Loi d'Opérations Spatiales" (LOS: Space Operations Law) in December 2010, a mission exploitation extension must respect as much as possible the criteria defined by the new law and the advices emitted by the LOS bureau.
10/25-10/28/2010: International Symposium on the A-Train Satellite Constellation 2010, New Orleans, USA
The International Symposium on the A-Train Satellite Constellation 2010 follows and expands on the first A-Train Symposium held in Lille, France in 2007. It aims to provide a forum to exchange information on the latest scientific advancements using multisensor measurements from the A-Train. An additional objective of the Symposium is to better inform new and present users on recent enhancements to A-Train data sets and subtleties related to their use. Because the instruments employ different measurement techniques, fusing the observations and/or data products is often challenging. Consequently, another important objective is to highlight key issues and strategies for combining the diverse measurements.
10/07-10/08/2010: 4th CALIPSO products Exploitation Review in Orlando, Florida, USA
10/04-10/06/2010: MOWG in Orlando, Florida, USA
05/2010: New version (3.01) of CALIPSO Scientific Products
The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite mission is pleased to announce the immediate public release of its version 3.01 cloud and aerosol data products. The new release includes all Level 1 and Level 2 products derived from the Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements. At present, no new data products are being released for the Imaging Infrared Radiometer (IIR) and the Wide Field Camera (WFC).
The quality and quantity of the information provided in the CALIOP version 3 data products are substantially improved over previous releases. These improvements are attributed to a number of factors, including significant enhancements to the daytime calibration procedures; incorporation of advanced probability distribution functions for more reliable separation of clouds and aerosols; implementation of a new algorithm for determining cloud thermodynamic phase; refinements to layer base detection for boundary layer aerosols; and several important corrections to the CALIOP extinction retrieval code. Data usability is greatly enhanced by the addition of numerous diagnostic and quality assurance parameters. In addition, several new optical parameters (e.g., ice-water content/path and particulate depolarization ratios) have been added to the Level 2 products, and range-resolved uncertainty estimates are now provided for all optical profile data. The organization of the CALIOP version 3 profile products has changed also significantly. In particular, the aerosol profile products have been completely restructured, and now are reported on the same spatial grid as the cloud profile products. The horizontal resolution of the cloud and aerosol profile products is now identical to the horizontal resolution of the 5-km cloud and aerosol layer products, thus enabling unambiguous identification of the profile data associated with each layer reported in the 5-km layer products.
The CALIOP version 3.01 data products are presently available for 2006 and 2007 at the Atmospheric Science Data Center (ASDC) (https://eosweb.larc.nasa.gov). These products will also be soon available at the ICARE data center in France (http://www.icare.univ-lille1.fr).
Additional data for 2008-2010 will be posted at both facilities as they are processed over the next few weeks.
04/2010: Fourth year in orbit for CALIPSO on April 28, 2010.
Since the laser switch in March 2009, the mission continues nominaly and the laser performances are excellent.
The CALIPSO mission, initialy scheduled to last 3 years, has been extended for 2 years (2010-2011). For all the teams that contributed or still contribute to the success of this mission, it is a great joy and a huge success.
05/2009: Third anniversary in orbit for CALIPSO on April 28th. It begun its fourth year notably thanks to its second laser!
03/2009: Complete success for the CALIPSO laser switch campaign
The laser switch campaign initially scheduled from 24/02/2009 to 18/03/2009 has been postponed from 6/3/2009 to 19/3/2009 after the anomaly of the 16/02/2009 on laser 2. The laser 1 switch operations have been done in close cooperation with LARC and enabled a nominal restart of the mission on 17/03/2009. Laser 2 has been definitively stopped on 06/03/2009.
11/2008: CALIPSO in the press interview of the CoPI of the mission (in french).
10/2008: 2nd CALIPSO Exploitation Review on October 6 and 7, followed by the A-TRAIN operational coordination meeting (MOWG) on October 8, 9 and 10 in Norfolk, Virginia (USA).
04/28th/2008: Second anniversary in orbit for CALIPSO!
01/2008: CALIPSO level 2 Lidar products are available at ASDC (Atmospheric Science Data Center)
It includes the extinction and backscattering optical properties of clouds and aerosols, cloud phases (ice, liquid) as well as aerosol types. These products have begun to be distributed on 28/01/08 and the data reprocessings since June 13th, 2006 are already available.
11/2007: Since November 28, 2007 19:24:20 UTC, Calipso has definitively changed its tilt (pitch from 0,3° to 3°) following tests performed from November 6 to 15, 2006 and from August 21 to September 7 2007.
To insure the best possible footprint overlap, Cloudsat has modified its position with respect to Calipso by moving 5 secondes away ahead of Calipso.
New A-Train phasing
10/2007: An "A-Train Lille Symposium 2007" was held in Lille - Grand-Palais - from October 22 to 25, 2007
The goal of this international meeting was: "Bringing together A-train observations and modelling to understand aerosols and clouds"
06/2007: First CALIPSO Operations Review at CNES Toulouse
04/28/2007: CALIPSO's first successful year! Preliminary results
03/2007: CALIPSO data with browse facility are available at ICARE
01/2007: Examples of level 1 qualified products from the Infrared Imager.
The level 1 processing combines rough measurements of the IIR with, on the one hand, calibration data, and on the other hand, measurements of attitude and navigation of the CALIPSO platform. The outputs of this processing consist in files of radiances, directly usable by the scientific community. The quality of level 1 products has been optimized during the assessment phase: cancellation of the image of the moon in the deep space views, accurate location of the IIR images, correction of the normalization of the spectral responses of the IIR channels. Level 1 images have been centered on the lidar track on the Earth. Here are some examples.
12/2006: Public release of CALIPSO Data Products
The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite mission has started the distribution of its data products. This data release consists of data beginning in mid June 2006 and includes Level 1 radiances from each of the instruments. This release also includes the lidar Level 2 vertical feature mask and cloud and aerosol layer products. The CALIPSO data are available through the Atmospheric Science Data Center (ASDC) at NASA Langley Research Center and can be accessed at the following URL:
12/2006: A-train operational coordination meeting at NASA
10/2006: CALIPSO's science team meeting is scheduled for October 3-5, 2006 in Annapolis (MD)
09/2006: The Operation Handover Review will take place on Sept 7 in Newport
It will conclude the commissioning phase and transfer responsability to the Science Operations organization of LaRC.
07/2006: One day (June 15, 2006) of lidar profiles was released to the science team on July 27, 2006.
07/2006: A press relase from July 26, 2006 presents first data.
07/2006: The CALIPSO In-Flight assessment Review was held on July 11-12, 2006 in Toulouse.
06/2006: CALIPSO has joined the A-train.
CALIPSO operations are nominal with all spacecraft systems in good health. The three science instruments have been powered up and the initial assessment of data is positive. Here is one of the first images from the Imaging Infrared Radiometer provided by CNES.
(Credits : Nasa for the images Terra/Modis and CNES for the images Calipso/IIR).
For more information... (in French)