When did the plan for SWOT start and how it’s gonna impact our daily lives?

When can humanity 100% explored ocean depth?

I mean we have a rocket in space right now.

Approximately what percent of water cannot be seen with this system?

What differentiates the SWOT satellite from the others ones orbiting earth (sensors, orbit height, etc)?

Why couldn't this be done by the current satellites?

Will the technology used in SWOT be applicable to locating sunken ships?

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Is this entirely macro, or will there be any specific places you look, such as the Nile which might be facing problems soon?

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Thanks for joining us! It seems like one of the underlying goals is to understand freshwater fluxes. I'm curious how you'll convert river level heights to volumes / cross-sectional areas to asses changes through time, i.e., how will you get at the channel cross sectional geometry / wetted perimeter to pair with the surface heights to be able to calculate volumes? I'm also wondering if you're planning on validating these data with discharge measurements from relevant gages?

Presumably SWOT will not be in a geosynchronous orbit in order to catelogue all the different bodies of water, so is the orbit intended to repeat at substantially the same spot to account for seasonal fluctuations or will it require many years to actually assess declines/gains by those different bodies of water?

What is SWOT hoping to gain that ground surveys of surface water bodies cannot?

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Can the SWOT scan for the sea beds ? And how deep Can it scan ?

Will SWOT be placed in a polar orbit in order to track most/all bodies of water? Also, how will this information be made available to the public?

Is all water accounted for and is there stable amount? For example rain runoff, water that feeds plants, frozen water, and our excretions of water? Is it always the same total amount just in different forms and places? Or are we losing water to something?

Will you be able to account for groundwater or just surface water?

Are you concerned that this information may be used negatively given that water is the next resource Nations will go to war over and the tangible data could make certain nations take stock of their own supply versus nations around them?

What findings are you most looking forward to discovering?

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Can you give some concrete examples of what bodies of water, or changes over time, you can see with this system that you can’t with current satellites?

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Calling this thing SWOT sounds straight out of a Captain Underpants book!

NASA seem fairly consistent at these fun acronyms, (eg. Naming a satellite intended to hit an asteroid DART) so I'm really curious to know how they end up happening?

Do you have any plans for a mobile app/GPS? Or a link to Google Earth? I love being able to gather info about where I am.

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Does the amount of water in plastic bottles and containers affect the overall water cycle? There must be a substantial amount of water “taken out of” the water cycle at any given time and that amount must be going up day by day.

You say this is NASA's first mission to survey global freshwater reserves. Are other satellites from other agencies already doing something similar? How much will you collaborate with other agencies and international partners?

And most importantly, how will this mission benefit turtles?

Thank you for doing this AMA! I am curious about the potential of the SWOT mission in understanding the migratory patterns of aquatic animals and if it will include relevant data about circatidal or circalunar rhythms of aquatic animals. Are there any specific projects in this mission that will focus on these topics?

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Does rain over the Ocean occur more than in the past?

I'm looking forward to watching the launch Dec 5 at Vandenberg.
Will the orbit be sun synchronous? Thinking maybe not if this uses radar only. How frequently will the surface be sampled? spatial and height resolution?

Are you looking at potential new locations for reservoirs? With large amounts of rain falling in locations that cannot store it every few years across the world - is there a possibility to select new locations for future reservoirs?

That way we could keep extra fresh water from uselessly flowing into the oceans.

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How is KaRIn able to differentiate between water level and soil level beneath it? What's the maximum design depth it's supposed to be able to measure (i.e. what's the design margin you took)?

How do you process the data to account for measurement errors and false positives? I'm thinking a patch of water covered in algae could be detected as soil.

What does the SWOT bring in for the Maritime Sector? Any new developments which can be made using SWOT?

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Have any of you observed things moving in and out of the water unabated?

What does SWOT say about Mumbai? Is it under threat from Climate Change?

"nearly all water". Do you have examples of what it will miss?

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Why do people tell me (an American) to conserve water? It’s not like I can change the amount of water there is. Is it just like a waste to go through all the trouble to treat and sanitize it?

What’s your favourite thing about water?

Does SWOT have any groundwater or ice cap measuring abilities?

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Does all the water look the same? If no, then why?

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Will you be releasing extensive data on all the freshwater deposits in Antarctica?

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What are the strengths and weaknesses of the mission?

What are some opportunities and threats it might face?

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What will be the spatial and temporal resolution of SWOT images?

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Will the data be available in a 3D form, or strictly 2D topographical maps / data? Also, what type of sensors are being used to retrieve the data?

Is it possible to hoard enough water in one place to throw off the balance of the earths rotation?

Will this SWOT mission do anything to help with the increasing trend of droughts around the world?

is the Ka-band Radar Interferometer (KaRIn) something that is new? what kind of radar is it

How screwed is the human race, given none of our leaders are making any serious efforts to address climate change?

Can we follow the progress of the project on social media, like the JPL on Instagram for example?

SWOT is the first satellite mission that will observe nearly all water on the planet’s surface. It will measure the height of water in Earth’s ocean, rivers, lakes and reservoirs between 78 degrees south (where Antarctica is located) and 78 degrees north (where Greenland is located).

For water that is on the land, SWOT will be able to see rivers wider than 330 feet (100 meters) and lakes that are larger than about 15 acres. Over the ocean, SWOT will be able to see smaller scale features called eddies that are less than 60 miles (96 km) across. No single satellite has been able to observe all of these features.

SWOT will also repeat the measurements over the Earth’s surface every 21 days, so we’ll be able to track changes over time associated with climate change or population change. - BH

From space, water does indeed look different. It can be different in color or clarity, but the “roughness” of the water is more relevant for SWOT.

The water can be smooth, like on a calm lake, or very rough, like in a stormy ocean. SWOT will be able to make measurements in both of these situations. -BH

SWOT will measure over 90% of the water on Earth. SWOT will measure the Earth's surface between 78 degrees south (where Antarctica is located) and 78 degrees north (where Greenland is located). So, it won't see any water located at very high latitudes near the poles. -BH

We're not losing water to anything. The total amount of water that is on Earth has been the same since the beginning of time. We have great knowledge on how much water is stored in bodies of water, and how much flows into and out of the various components of the water cycle. For example, our colleagues at the US Geological Survey built this amazing chart: https://www.usgs.gov/special-topics/water-science-school/science/water-cycle-diagrams

However, our knowledge is based on long-term averages. Our planet is living and keeps changing as a function of external forces (like energy coming from the sun) and internal forces (like what humans do with the water). So it's always changing. Also, we're now nearly 8 billion people on Earth, whereas we were just 1 billion in the early 1800s.

So: same overall amount of water as ever, many more people than before, and continuing changes in how the water is stored and moves around between, clouds, snow, rain, rivers, lakes, groundwater, and oceans (CD).

It sounds like although other satellites exist that can measure these individual features, the benefit of SWOT is having a single satellite able to continuously gather measurements on all of them?

That would be really cool, but unfortunately no! (BH)

Great question!

SWOT will not be able to ‘scan’ the seabed, per se. SWOT will only measure the surface height of the ocean.

However, the surface height is not independent of the shape of the sea bed (or, the “bathymetry” of the ocean). Some geophysicists who study ocean bathymetry can use SWOT and other satellites that view what we call the surface topography of the ocean to infer the shape of the sea bed. (MS)

Will the satellite data be made public? Are collaborations with Google Earth on the way? Google Earth has a big problem of not showing the earth's water on a majority-ocean planet!

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Yes! You can find the latest at swot.jpl.nasa.gov or follow us on social media @NASAEarth and @NASAJPL (on Twitter, Instagram and other social platforms).

SWOT is scheduled to launch in December from Vandenberg Space Force Base in California.

The SWOT satellite includes a novel instrument called KaRIn (Ka-band Radar Interferometer) that enables measurements of water height with an order of magnitude better resolution than current satellites.

This precise measurement requires advanced radar processing techniques that in the case of KaRIn are done on board the satellite, as compared to previous satellites that downlinked the collected data to be analyzed on the ground. This processing reduces the amount of data that has to be transferred from the satellite to the ground.

Even so, SWOT produces an unprecedented amount of data to achieve a global measurement of Earth's water. -EP

SWOT is designed so that the signal that it sends bounces off the surface of liquid water, like the top of a lake, a reservoir, a river, a wetland, or an ocean, and eventually returns to the satellite. That same signal does not reflect off of land or ice.

What this means is that the information that comes back to the satellite is about liquid water that we can see on Earth's surface. For liquid water that is underground (groundwater), we have another mission called the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission. GRACE-FO measures gravity changes on Earth, and because water is so heavy, we can observe any changes in groundwater using those gravity measurements.

For solid water that is on top of the surface (ice caps), we have another mission called Ice, Cloud and land Elevation Satellite (ICESat-2). -CD

Have you considered integrating this technology onto a CubeSat platform? It seems like latency and accessibility could be vastly improved by implementing this technology on a CubeSat constellation.

First of all, congratulations on all the work you have put in and the upcoming launch! The advances in remote sensing are so exciting and I can’t wait to see how much we will learn from this and other similar endeavors.

Few questions about the radar side of things. In the link it states that SWOT will be using a nadir altimeter and two side-looking antenna to form a 2d scene from a one dimensional orbit. How much of a concern will the height variation that comes from waves be for your backscatter calculations to accurately form that footprint? It also states that the goal here is to get much higher resolution data than previously available. What kind of resolution performance are you expecting? And finally, what kind of processing will be necessary to remove any Doppler effects coming from satellite motion?

SWOT will measure 90% of the surface water on Earth. It won't measure the water that is at a higher latitude than 78 degrees North or 78 degrees South.

It also won't be able to measure very small lakes (smaller than 15 acres) or small rivers (narrower than 330 feet, or 100 meters). (BH)

The KaRIn radar instrument operates at the Ka-band frequency: so the signal that bounces back from the ocean, rivers, and lakes is much stronger than the signal that's reflected from land.

Using image processing techniques, the SWOT team is developing algorithms that will be able to differentiate between different surface types. (EP)

The radar signal will not penetrate through the water, so we won't be measuring how deep the water is, just how high the surface of the water is.

Knowing the shape of the land underneath the water (the bathymetry) still remains a mystery except for some pristine water bodies which are very clear and for which the bottom can be detected with other satellites like the Ice, Cloud and land Elevation Satellite (ICESat-2). (CD)

Yes! The scientific engine of the SWOT satellite, the Ka-band Radar Interferometer (KaRIn) instrument, will measure the height of water in Earth’s lakes, rivers, reservoirs, and the ocean.

To do that, KaRIn will transmit radar pulses to Earth’s surface and use two antennas to triangulate the return signals that bounce back. Mounted at the ends of a boom 33 feet (10 meters) long, the antennas will collect data over two swaths of Earth’s surface, each of them 30 miles (50 kilometers) wide and located on either side of the satellite.

KaRIn will operate in two modes. A lower-resolution mode over the ocean will involve significant onboard processing of the data to reduce the volume of information sent during downlinks; the higher-resolution mode will be used mainly over land to look at freshwater. (BH)

Could I use this data in cooperation with my university to monitor the Gulfstream? I am on a mission planned for Jan 2024 that will allow the placement of an experiment, that might piggyback off your work.

SWOT will just measure surface water. The data from SWOT will be publicly available and will have many positive benefits by allowing people to track changes in water over time and manage water resources more effectively.

Personally, I'm most excited about what SWOT will tell us about the changes in the ocean close to the coast. Our other satellites that measure sea level are not able to get as close to the coast as SWOT will be able to, and there is a great deal we can learn about the response of sea level to climate change. (BH)

There is no conclusive evidence that it is raining more over the ocean than it has in the past. Understanding how the global water cycle and precipitation patterns are changing under a warming climate is really important for both scientific and societal reasons.

While SWOT won't give us all the answers, the measurements it provides and its ability to measure almost all of the surface water on Earth (land and ocean) will support brand new insights and scientific discoveries.

The data from SWOT will be publicly available and scientists will be able to explore the SWOT "data sandbox", yielding new and unexpected discoveries. (BH)

SWOT is going to provide some cool things over the ocean. First, it will measure closer to the coast than our other satellites. This will provide an improved understanding of how sea levels are rising and allow us to improve models for things like storm surge.

Second, SWOT is going to measure smaller scale features in the ocean. 90% of the excess heat trapped in our atmosphere gets absorbed by the ocean. We think that much of that heat is absorbed by the smaller scale, short-lived ocean features like fronts and eddies. SWOT will collect data on these ocean features and help us understand how the climate is responding to ongoing warming.

Understanding these features and ocean currents better will have benefits for shipping and navigation. (BH)

Data from NASA satellites is used in many aspects of land and water management by operational agencies in the U.S. and internationally. We are a data and information resource for these agencies, but we are not, for example, in the business of doing water management. This information will be able to support planning for dam operations.

You can learn more about one specific example of how SWOT data may be used in Egypt in this way at https://swot.jpl.nasa.gov/applications/early-adopters/#AlexandriaU. (MS)

Are there any other viable or potentially viable solutions to stopping climate change outside of cutting greenhouse gases?

The SWOT orbit has an average revisit time on the order of approximately 11 days at low latitudes. This temporal sampling is similar to that obtained by previous ocean altimeter missions. It also allows appropriate sampling of river dynamics in the tropics. At high latitudes, the sampling will produce shorter revisit periods, compatible with arctic river dynamics. This temporal sampling choice is a trade-off for maintaining global coverage including the high-latitude regions and for minimizing the tidal aliasing.

SWOT will allow global measurements even in remote areas that are not easily accessible, which is not feasible with ground surveys. Measurements of the the global storage change in terrestrial water bodies at sub-monthly, seasonal, and annual time scales will provide insight into important questions such as the temporal and spatial scales of the hydrologic processes controlling fresh water storage and transport across the world's continents, as well as the impacts of humans on fresh water resources.
(EP)

The SWOT mission was initially recommended in 2007 in a report by the National Research Council (NRC) called “Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond” for implementation by NASA.

SWOT, like many other NASA and international satellite missions, is a science-focused mission but will have many ancillary benefits to society that extend beyond the research objectives of the mission!

Some of the areas of societal benefit for SWOT include improved flood forecasting and better water resource management through monitoring of changes in water levels of reservoirs and in better knowledge of river discharge. Forty percent of the global population lives within 100 km of the coast, and SWOT will provide better quality data closer to the coasts that can feed into models for improved forecasts of the state of the ocean and some extreme events that may impact people living at the coasts. It will also provide critical information for fisheries management practices and safety at sea.

You can read more about these at https://swot.jpl.nasa.gov/applications/applications-areas/. (MS)

The SWOT mission is actually a collaboration between NASA and the French Space Agency (called CNES), with contributions from the UK and Canadian Space Agencies. This is therefore very much a collaboration with international partners.

NASA, and other space agencies, already have multiple satellites that look at various components of Earth's freshwater. For example: soil moisture (SMAP), rain (GPM), snow cover (Terra/Aqua), elevation of the largest lakes and reservoirs (Sentinel-6 Michael Freilich), and extent of lakes and reservoirs (Landsat, Sentinel 1, Sentinel 2).

What makes SWOT so special for Earth's freshwater reserves is that it will measure the elevation of water and the extent of water bodies at the same time. And it will do so for many more rivers, lakes, reservoirs and wetlands than we've ever seen before. That means we'll know where the water is and where it's going like we've never known before. SWOT will also see the Earth's saltwater (like the oceans) in a much more detailed way than we've ever done before, and that will help us to understand ocean currents.

If we could speak with turtles, we'd tell them how to use this knowledge for a quick ride back to Hawaii, but I think they've already figured this one out! (CD)

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I think the strengths/opportunities and weaknesses/threats I see are connected to the same thing: the measurement SWOT is making is new!

This means there are new engineering and science challenges that must be tackled and solved to make the mission a success (which our capable team has been doing and will continue to do!).

But, this is also a strength and opportunity. SWOT is going to measure things over the land and the ocean we’ve never been able to see from space before. The potential for scientific discovery is huge, as is the potential usefulness of this data for communities across the globe. (BH)

Yes! The data will be publicly available for everyone to use.

Jan 2024 will be in the heart of the SWOT science mission, so it will be a great time to be looking at the data. (BH)

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SWOT data will be used to support model predictions of drought, which will help in monitoring these highly impactful events.

Models can be greatly enhanced through the integration of space-based observations (like SWOT and other satellites like GRACE-FO), as well as on-the-ground measurements, to improve observations and predictive capabilities. (MS)

What are some of the biggest challenges you've faced or continue to face, technical or otherwise. I'm a chemistry major and I was wondering if there are any material science limitations your team is facing? Basically, what improvements in material science do you see needing to be made in the future? TIA and keep up the great work!

We discussed SWOT's orbit a bit in this answer upthread.

SWOT provides continuous global measurements of the Earth's water bodies. The ocean circulation will be determined from the ocean height measurements at spatial resolutions of 15 km for 68% of the ocean.

Lakes, reservoirs and wetlands whose surface area exceeds (250m)^2 will be measured with a height accuracy better than 25 cm, and rivers whose width exceeds 100m will be measured with a height accuracy of 10 cm for 10 km sections of the river at a time. (EP)

The current plan from the SWOT Science Team is to use river width together with the elevation of the water surface that will be directly measured by SWOT. We'll calculate the slope of the top of the river from measurements of elevation, and we'll infer changes in the cross-sectional area from joint changes in elevation and in width. However, this does leave a big unknown: the minimal (unseen) cross-sectional area.

We will make a best guess for that based on many months of data through fitting with a simple equation for hydraulics (Manning Equation). Everything we produce, including our estimates of river discharge, will come with an estimate of uncertainty.

And, of course, we'll be using ground measurements at selected locations around the Earth for validation. (CD)

We'd love to do SWOT-style cubesats!

The biggest challenge here is that SWOT uses a very powerful radar with a big antenna. Miniaturizing this is no small feat, but we've been thinking about ways to leverage geostationary radars. There is also some existing work on miniaturizing the previous radar altimetry technology (from missions such as Jason, Sentinel 3, and others).

Look for the mission concept being developed by colleagues from the French Space Agency called SMall Altimetry Satellites for Hydrology (SMASH) which is designed to be a constellation of small satellites. (CD)

SWOT will “see” much of the surface water between 78 degrees north and south latitudes on Earth.

We have a specific study area on the Nile river which you can read more about at https://swot.jpl.nasa.gov/applications/early-adopters/#AlexandriaU. (MS)

SWOT will “see” areas of the Earth between about 78 degrees north and south latitude, so that is most of the surface water on land and in the ocean.

You can use the SWOT Swath Visualizer to see if your area of interest will be covered by SWOT. (MS)

The SWOT measurement accuracy will be impacted by waves. The SWOT requirements will be met for significant wave heights of 2 meters. The Doppler effects from satellite motion will be compensated for using radar processing techniques on board the satellite.

We shared some information on the resolution side of things in our previous answer here. (EP)

Great explanation. Thanks

Thank you, BH! I’m desperately concerned about the Gulf Stream and the changing speed of the current, and apparent temperatures changes as well.

What the best way to become an astronaut?

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If you see a sea monster what are your orders

Is the satellite able to detect water that's underground, too, or does it just register the water that's visible from bird eye view?

We already know water comes from the sink

I am 60 to 70% water. Will you be observing ME?

Do you think this data be very valuable as fresh water becomes even more of a finite resource due to runaway effects of climate change?

How will water providers / municipalities / enterprise / everyday people access the raw data for use in their own analysis?

What will constitute fresh water? Water that is not salt water? Water we can drink safely after boiling? Etc..

What kinds of data do you predict will not be easy to get accurately, or at all, that you believe will still be important to try and get a hold of?

Since H2O is a finite resource, what will we do with all of the excess Hydrogen and Oxygen as it depletes?

Is it possible to detect and quantify groundwaters by SWOT?

I am an ESA engineer. And my question is: Is this a rip-off of our SWARM mission?

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How do you plan on observing every single one of the water resources on earth's surfaces? And what makes the water on earth finite if we have the water cycle? Doesn't that like replace the water overtime?

can we measure the plastic soup in the giant ocean and how the ocean cleanup efforts affect it?

Do I have time to flush my toilet before the snap?

Are you thirsty?

What will this mean for marine archeology?

Why haven’t you guys thought about more infrastructure like sky hooks? If the government is responsible for most infrastructure you guys aren’t exactly best at building plausible designs that make it easier to get anything into space.

What kind of SWOT analysis did you do on the name of the mission?

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I’m really psyched about NASA and what y’all represent in humanity and like rockets are really cool. I don’t have anything to add something gave me a chuckle. I thought, theres an avenue for me to tell a NASA employee, a representative of the worlds top scientist that their water science team sounds like snot. So yeah anyways, continue on with your all’s day. Thanks for your all’s work :)

I used to do agricultural research for the USDA, specifically water use. Is NASA taking evaporation into account, in addition to measuring the height of the surface of the water. Can I assume that the lasers on the satellite are similar to the lasers that measure snow pack on those other satellites?

Will you have any pathways or summer internships available?

What are you wearing? ;)

Do you consider yourselves hydrohomies?

Will swot be able to capture spatial temporal progress of ephemeral streams?

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What is the total cost of the satellite?

If one wanted to go into a space communication type field such improving as voice or data transfer between space and earth, what degree would you recommend?

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How do you measure depth of different part of the ocean? And what new do you expect to find?

So what are its strengths, weaknesses, opportunities, and threats?

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Will SWOT be used to monitor fresh water stored in glaciers and in the polar ice caps as they are particularly at risk of being affected by climate change? Or are there already similarly sophisticated technologies that are capable of monitoring these sources of fresh water already?

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Is water wet?

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Did you do SWOT (Strengths, Weaknesses, Oppurtunities, Treaths) analysis during planning?

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