00:00On December 31st, 2021, NASA launched the NISA satellite into low Earth orbit.
00:07NISA is an acronym for NASA's Ice, Cloud and Land Elevation Satellite.
00:14A joint venture between NASA and the Indian Space Research Organization,
00:19after about three months of orbiting the planet, the satellite is now fully operational.
00:25And when it comes to NISA's R's instruments, there are two main instruments, which are the L.
00:32And see, Band Synthetic Aperture Radar, or SAR, and the 7-Band,
00:37fully accessible Synthetic Aperture Radar, or FPAR.
00:43The goal of these instruments is to measure changes in ice sheets, glaciers, and the cryosphere,
00:50down to a resolution of 10 centimeters or 4 inches.
00:53The reason why this mission was started is because we need to know how water moves around the planet.
01:00Water plays a vital role in regulating our planet's climate.
01:05And we can see this when we look at where clouds form, where deserts are found,
01:10where rainforests are found, when even where snow and ice exist.
01:15To better understand what's happening on Earth,
01:18we need to use satellites that can view the planet in different ways.
01:22Like with infrared cameras to see the heat coming off of the surface,
01:26or radar, which is a type of radio wave that can penetrate clouds, smoke, and even light cover.
01:34There are already a number of satellites that use various forms of radar to map our planet from space.
01:41But this new satellite will be mapping our planet using two different types of radar waves,
01:46the L-band and the C-band.
01:48The goal is for these two satellites to work together to track changes over time.
01:54There are a few other satellites out there that are also using similar radar frequencies.
02:00But the difference here is that those satellites either focus on the ocean or just one of the frequencies.
02:07NISA is the first satellite to use both frequencies and track changes over time.
02:12These types of measurements have been helpful for a number of reasons.
02:17For example, they help us understand when ice shelves break apart,
02:21which could cause ice to flow faster into the ocean.
02:25This would then cause sea levels to rise.
02:29These satellites can also help us understand how the frozen ground,
02:33known as permafrost, degrades and releases methane into the atmosphere.
02:39We don't want to do that.
02:41So this is good information to know.
02:44They can also be used to determine the volume of water held in snowpacks,
02:49which directly impacts our water supply during drier months.
02:53And they can also monitor forest types,
02:56which can help scientists understand what regions might become more or less forested in the future,
03:02due to things such as drought or rising temperatures.
03:05Basically, these two radars can help us understand what's happening on Earth.
03:10Especially to things like water and ice,
03:14which are important factors when it comes to our climate.
03:18But the question is, how do we collect data from space and turn it into images that we can actually use?
03:25Well, this is where synthetic aperture radar, or SAR, comes in.
03:30As the name implies, this type of radar creates an image by generating a synthetic aperture.
03:36If you were to take a picture of a building using a regular camera,
03:40the building would appear the same, no matter where the sun is shining.
03:44But radar doesn't work like this.
03:47With radar, you need an illuminated area to detect any reflected waves.
03:52In order to get an image of the building,
03:55you need the radar to be able to rotate.
03:58And face each side of the building,
04:00so that you can get an image of the front side and back of the building.
04:04Because radar works this way,
04:06you need to be able to generate a synthetic aperture,
04:10or in layman's terms, create an illusion.
04:13Radar does this by moving the antenna across the building in small increments,
04:18and recording the returning signal after each rotation,
04:22once all the data has been collected.
04:25The computer can then combine all of the images together
04:29to create one complete image.
04:32So, the synthetic aperture radar on the NYSA satellite
04:35will emit a series of radar pulses towards the Earth-S surface
04:40and record the returning signals.
04:42The radar will repeat this process every 45 days,
04:47and the frequency will change from the L-band to the C-band.
04:51This will allow scientists to compare the radar images over time
04:55and see any changes that have occurred.
04:58The thing is, radar isn't perfect.
05:01Sometimes the radar pulse will reflect off of multiple targets,
05:06which causes what's called speckle noise.
05:09Speckle noise looks like this,
05:12and it makes it difficult to discern details in the image.
05:15To overcome this, NYSA uses something called polarimetry.
05:20Polarimetry involves sending multiple radar pulses
05:23with slightly different polarization states.
05:27Polarization, in simple terms,
05:30is the orientation of the electric field within the radar wave.
05:34It can be vertical, horizontal, or at any angle in between.
05:39By sending multiple pulses with slightly different polarizations,
05:43the satellite can collect more information about the target below.
05:48This allows the satellite to distinguish between targets
05:51that may have been grouped together due to speckle noise.
05:55The goal is that by using polarimetry,
05:58NYSA will be able to distinguish between different types of ice and vegetation,
06:02which will allow scientists to gain a better understanding of what's going on.
06:07NYSA-AS-FAPAR instrument will emit four separate radar pulses,
06:13one horizontally polarized, one vertically polarized,
06:17one with a diagonal polarization, and one with a circular polarization.
06:22The combination of these four radar pulses,
06:26along with the sea, band radar from the other instrument,
06:30should give scientists an unprecedented amount of information.
06:33When it comes to measuring the properties of materials on Earth-S surface,
06:39using this information,
06:41NYSA will be able to produce highly detailed maps of ice sheets, glaciers, and the cryos.
06:47And these maps will help us better understand what's happening to the ice
06:51and how it's changing over time.
06:54The data from the NYSA satellite will be freely available to the public once it's processed.
07:00And hopefully, with this data, we can come up with some sort of solution.
07:05When it comes to these problems that we're refacing today,
07:09the mission is expected to last six years.
07:12But the instruments on board are expected to continue working well beyond that.
07:16When it comes to space,
07:18there are some very exciting things happening right now.
07:22There's people going to space,
07:24rovers exploring Mars,
07:26and rovers exploring Saturn's moon Titan.
07:29You might think that there's nothing else going on,
07:32but there's actually something else big that's happening.
07:35Scientists all around the world are launching new telescopes,
07:40including the James Webb Space Telescope.
07:43With these telescopes,
07:45we'll be able to learn so much more about the universe.
07:49I hope you enjoyed this video.
07:51If you did,
07:52make sure to subscribe so you can be notified when I upload a new video.
07:57If you want to learn more about NISA,
08:00check out the link in the description below.
08:03Thanks for watching,
08:04and I'll see you in the next one.
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