SpaceX postpones launch of groundbreaking Swot satellite mission

For his 57the this year’s launch, SpaceXSpaceX will carry the Franco-American satellite SwotSwot (Surface Water Ocean Topography), built under the responsibility of Thales Alenia Space. The launch of the satellite, aboard a Falcon 9, will be carried out from the military base in Vandenberg, California. Main floor of launcherlauncher flew five times. This will therefore be its sixth reuse.

SpaceX delays Swot launch to Friday

Launch, originally scheduled for Thursday, December 15, 2022, was postponed by 24 hours to Friday, December 16 in a windowwindow 10-minute kickoff that begins at 12:46 Paris time. The satellite will be installed in an orbit inclined 77.6° at an altitude of 890 kilometers and has a repeatability of 20.86 days for at least three years. From this height, Swot will produce a complete map, unpublished today, of the topography of oceanic and continental water surfaces on the scale of the Earth, every 10 days!

Find the interviews of Sophie Coutin-Faye and Nicolas Picot below to know all about the “revolutionary” mission.

Follow the launch of the Swot satellite live. © Cnes, Youtube

Article by Remy DecourtRemy Decourt published on 11/12/2022

A few days before the launch of the Swot satellite, scheduled for December 15, we met Sophie Coutin-Faye, head ofheight measurementheight measurement, and Nicolas Picot, Swot downstream project manager. These two Cnes engineers inform us of the objectives of this mission, which they do not hesitate to describe as “technically spectacular” and “scientifically revolutionary”.

Then in August 1992 NasaNasa and CNES launches Topex-Poséeidon, which then marks the beginning of precision space altimetry, no one imagines that this discipline will revolutionize knowledge of the oceans. Even better, with an unprecedented ability to measure sea level to the nearest centimeter, the researchers quickly realized that they had a very good indicator of climate changeclimate change over a long period of time.

Thirty years later, the space altimeter is about to change dimension with the launch in a few days of the Swot satellite, Cnes and NASA. In the continuity of the previous altimetry satellites, this mission will open a new era in ” the observation of continental surface waters, lakes and rivers with revolutionary perspectives withinhydrologyhydrology continental and oceanography explains Sophie Coutin-Faye, head of the altimetry department at Cnes and Nicolas Picot, Swot downstream project manager at Cnes.

Why is the Swot satellite a revolution?

To do this, this satellite carries cutting-edge technology that will revolutionize knowledge of the water cycle on a planetary scale: “ Lakes, rivers, reservoirs and oceans… 90% of the earth’s surface water will be probed with a solutionsolution unmatched! If space altimetry began to take an interest in continental waters and ice many years ago, and especially since the Jason-2 and Envisat missions, we change dimension with Swot. With the current missions is the vision nadirnadir and centimeter performance in oceans, decimeter performance in continental waters; with Swot, the vision ” looks spectacular “.

Almost all the water on Earth’s surface observed by Swot

Thanks to two radar antennas placed at the ends of a 10 m mast, KaRIn becomes able to perform measurements togethera swath 120 km wide, while current altimeter radars are limited to a measurement vertically from the satellite (nadir vision) “. This wide track on the ground will provide access to ” spatial level field dwaters of rivers wider than 100 m, as well as lakes and areas ofsurface flooding greater than 250 mx 250 m, with decimeter precision for water bodies of 1 km2and to quantify the slopes with an accuracy of lorder of magnitude 1.7 cm/km “.

In other words, by being able to observe both “ spatial extent, height and slope of rivers, Swot will be able to see rivers in 3D »! These parameters are essential to calculate the information about debitsdebits rivers or volume variations on the lakes, ” poorly rated on a planetary scale “. On the world’s oceans The two-dimensional vision of this instrument and its precision will improve the ability to observe small oceanic phenomena by a factor of 10 that play a major role in the exchange of heat between the ocean and the atmosphere. “.

The SWOT mission must lead us to a better understanding of the water cycle on a global scale

The swot mission should lead us to a better understanding of the water cycleglobal scale “. In addition, the observation and understanding of the distribution of water resources and their variations ” essential to meet challenges that are not only scientific but also societal and economic “.

To understand the enthusiasm of the two engineers, you have to realize that if the Earth is approximately 71% covered in water, ” a very large part (97.5%) is salt water “. L’pure waterpure water is present in very limited amounts (2.5%), mainly “ contained in the glaciers, i polar capspolar caps and underground, aquifers “. Only 1% of this 2.5% (therefore 0.025%) is in soil, lakes and rivers and therefore ” directly accessible and usable for the vital needs of all forms of life “. But the cycle of this water is still poorly known and the flows poorly quantified, so we expect a revolution “.

The swot mission was summed up in less than three minutes. © NASA, CNES, CSA

And this is the whole point of the Swot mission, where one of the stakes is ” gain a better understanding of the water cycle on land, the rain cycle, which comes mainly from evaporation, which mainly occurs in the oceans, and to better quantify the amount of water coming from rivers to the oceans “to allow a better” forecast of climateclimate and fine-tuned control over the planet’s water resources (consumption and human activities such asagricultureurbanization, production ofwater powerwater powerriver navigation, etc.).

An unprecedented mission to study the topography of the oceans

In oceanography, Swot will not ” evidently not content with continuing to measure the level of the oceans and seas “. With its unprecedented altimetric performance, Swot will show us details hitherto invisible. With conventional nadir altimetry, the ocean is described at spatial scales close to 200 km. However, Swot and its KaRIn interferometric radar will provide access to ” smaller spatial scales and with almost global coverage » and therefore of describe mesoscale and sub-mesoscale ocean circulation down to spatial resolutions of 15 km »!

Our dossier: Ocean-atmosphere interactions: an important role for climate

Concretely and for the first time, Swot must deliver ” data on energy exchanges between the sea and atmosphereatmosphere which are mainly related to small-scale processes”. These ocean circulation processes contain a ” important part of oceanic kinetic energy and therefore plays a significant role in the transport of carbon and nutrientsnutrients so in an increasingly warming world, a better understanding of these phenomena is essential to understanding the future of climate change.

Finally, Swot is also a mission of ” technology demonstration with unprecedented use of a wide swath interferometric altimeter which, if convincing to the user community, could inspire the design of the Sentinel 3 NG Topo mission in the European Copernicus program “.

In the 90s, Topex PoseidonTopex Poseidonwas a revolution in the understanding ofocean “. In a few years, ” we would say the same about Swot ” Sophie Coutin-Faye and Nicolas Picot say at the end.


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