Global AquaInsights: The Next-Gen SWOT Satellite Revolutionizing Water Surveillance

So how does the Surface Water and Ocean Topography mission plan to assess what’s flowing within the planet’s lakes, rivers, and oceans? A notably engaged project manager elucidates.

What volume of water exists in the Earth’s lakes, rivers, and oceans? How does that quantity fluctuate over time? The forthcoming Surface Water and Ocean Topography (SWOT) mission aims to uncover these answers. Targeting a launch period in late-2022, this SUV-sized satellite will gauge the elevation of Earth’s water. SWOT will assist researchers in comprehending and monitoring the volume and distribution of water – a limited resource – worldwide, constituting NASA’s inaugural truly global survey of the planet’s surface water.

The information gathered will aid in observing variations in floodplains and wetlands, quantify how much fresh water enters and exits the Earth’s lakes and rivers before returning to the ocean, and monitor regional changes in sea level at unprecedented scales. It will furnish details about small-scale oceanic currents, thereby supporting real-time marine operations influenced by tides, currents, storm surges, sediment movement, and water quality challenges. Furthermore, the data harvested by SWOT will deliver, for the first time, global observational proof of how circular flows, known as eddies, influence changes in the ocean, such as its energy and heat retention, along with the movement of carbon through the marine ecosystem.

However, before the mission can achieve all these objectives, engineers and specialists must finalize constructing the spacecraft. The payload carrying the scientific instruments for this substantial satellite is taking form in a clean room at NASA’s Jet Propulsion Laboratory in Southern California, where thorough testing is currently being conducted. In late June, it will then head to France, where engineers and technicians from the French space agency Centre National d’Etudes Spatial (CNES), their main contractor Thales Alenia Space, and JPL will finalize the build and prepare the satellite for transport to its launch site in California at Vandenberg Air Force Base.

JPL Project Manager Parag Vaze (pronounced vah-zay) plays a crucial role in ensuring a seamless handover to his CNES counterpart Thierry Lafon. With a background in engineering, Vaze has dedicated 25 years to Earth-satellite missions at JPL. He has served as the project manager for several missions assessing sea levels, including Jason-2, Jason-3, and the Sentinel-6 Michael Freilich satellite, which was launched into low-Earth orbit last November while SWOT was in assembly at JPL.

SWOT is a large satellite with considerable aspirations and a stringent timeline. Vaze took a moment to respond to inquiries regarding the significant work that lies ahead.

What captivates you the most about SWOT?

The fresh water component of the mission is what captivates me the most. Ocean science is absolutely essential for understanding what is occurring with Earth in the medium- to long-term context of climate change and sea level rise. However, since I hail from India, I have personally encountered the struggles of securing clean fresh water for populations. I genuinely believe that this will be one of the significant challenges of the forthcoming century – surpassing even the quest for oil and energy alternatives.

In what way will SWOT contribute to tackling that challenge?

Initially, grasping a problem necessitates information. There are millions of lakes and rivers on Earth that serve as excellent sources of fresh water, yet we lack consistent data on them. The majority of the available information comes from ground-based instruments in populated regions.

The capability to consistently measure those lakes and rivers not only in populated regions but also in remote areas that are currently unmonitored will enhance scientific understanding. Additionally, it could assist in identifying further sources of fresh water. SWOT will gather information on water bodies globally, and this data will be freely accessible to everyone who requires it.

SWOT is set to deliver extraordinarily high-resolution data concerning the planet’s surface water. What instruments will it employ to accomplish that?

We possess the primary instrument, the Ka-band Radar Interferometer [KaRIn], which is novel. It sends radar pulses toward the water’s surface and captures the returning signals using two distinct antennas simultaneously. This enables us to triangulate the elevation of the water’s surface. This is an advanced radar system capable of “seeing” rivers and various small water bodies on Earth’s surface. The antennas, protruding approximately 16 feet [5 meters] on either side of the satellite, will enable coverage of around 30 miles [50 kilometers] on each side of the spacecraft.

Additionally, there is an altimeter that will look straight down to measure the height of the ocean’s surface. This instrument is akin to the altimeters utilized on satellites like Jason-3 and Sentinel-6 Michael Freilich. We have incorporated this more conventional instrument to facilitate cross-validation with KaRIn data.

We have also integrated a radiometer. Atmospheric water vapor influences the transmission of radar pulses from the altimeter or KaRIn, which can distort surface height measurements. A radiometer enables us to correct for this by measuring the amount of water vapor present between the spacecraft and Earth’s surface.

Lastly, we have several precision orbital positioning instruments – including a global positioning system – that indicate where the satellite is situated in space. Those comprise the scientific instruments.

It appears that you’ll be producing a vast amount of information. How much data are we discussing, and how will SWOT manage it?

We aim to gather data around the clock, every day of the week. Thus, overall, we anticipate downlinking approximately one terabyte of data daily. We have implemented a few enhancements to the payload to manage this information load. We are engaging in onboard processing – not merely compression but genuine processing of the oceanic data – to effectively handle the considerable amounts of data returned to us by the satellite. Furthermore, we have a specialized X-band downlink system capable of transmitting over 620 megabits per second.

What kind of labor goes into constructing a spacecraft of this nature?

SWOT began taking shape around 2010 and has since escalated to involve hundreds of engineers and scientists collaborating from the U.S. and Europe, many of whom have devoted a considerable segment of their careers to this initiative. The teams have tackled numerous ambitious developmental challenges, not only concerning the satellite but also regarding the ground systems and algorithms.

A number of the missions you’ve participated in have been executed alongside international collaborators. This mission includes CNES as well as the Canadian Space Agency and the United Kingdom Space Agency. Why has this level of collaboration been such an integral component of your work?

Planning, executing, and financing these types of missions is a substantial undertaking, necessitating commitment and mutual trust. We have succeeded in this collaboration because we can distribute the burden and risk. Furthermore, we have achieved this because the global demand for the kind of information these satellites provide is well acknowledged. The issues they address are not confined to regions such as North America or Europe or Africa; they are global challenges.

What aspect of the mission causes you sleepless nights?

Everything and yet nothing. Each day presents various and distinctive challenges, many of which I cannot predict, even with years of experience. Nevertheless, I manage to sleep well knowing that we have exceptionally skilled and devoted individuals uniting to tackle whatever hurdles we encounter.

SWOT is being collaboratively developed by NASA and CNES, with contributions from the Canadian Space Agency (CSA) and the United Kingdom Space Agency (UKSA). JPL, which is overseen for NASA by Caltech in Pasadena, California, spearheads the U.S. segment of the project. For the flight system, NASA is supplying the Ka-band Radar Interferometer (KaRIn) instrument, a GPS scientific receiver, a laser retroreflector, and a two-beam microwave radiometer. CNES is contributing the Doppler Orbitography and Radioposition Integrated by Satellite (DORIS) system, nadir altimeter, and the KaRIn RF subsystem (supported by UKSA). CSA is providing the high-power transmitter assembly for KaRIn. NASA is offering the associated launch services.

To discover more about the mission, visit:

Jane J. Lee / Ian J. O’Neill
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0307 / 818-354-2649
jane.j.lee@jpl.nasa.gov / ian.j.oneill@jpl.nasa.gov

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