An upcoming satellite mission will provide a first-of-its-kind, hyper-detailed view of Earth — and a glimpse of how shifting geopolitics on the ground may play out in space.

Why it matters: Earth-observing is now a key space capability for countries. The technology helps answer crucial questions about the impacts of climate change and guide officials in managing resources and disaster response.

• The NASA-Indian Space Research Organisation (ISRO) Synthetic Aperture Radar (NISAR) mission is the largest and first truly joint collaboration in space between the U.S. and India.
• It comes as the two countries deepen their scientific ties more broadly.

What's happening: NISAR, which is a decade in the making, will amass a trove of data that could help to tackle global challenges.

• The satellite's two radar instruments give it the ability to observe tiny changes in Earth's surface from earthquakes and volcanoes, as well as shifts in forests, wetlands, crops, glaciers and sea ice.
• Both radar systems — one built by NASA, the other by ISRO — operate at long wavelengths that can cut through clouds and collect measurements at night.
• The radar from one of the instruments can penetrate tree canopies and give researchers better estimates of the density of trees, which can be used to track the capture and release of carbon from forests — key information for climate models.
• NISAR can also detect deformations in Earth's surface with a precision on the order of millimeters for some measurements, says Paul Rosen, a project scientist for the mission at NASA's Jet Propulsion Laboratory.

Details: The instruments will collect measurements of 240-kilometer-wide swaths of the planet's surface as the satellite orbits Earth.

• Data from the longer wavelength radar system will be used to create a map of much of Earth's land and ice every 12 days.
• That data can be combined with measurements from the shorter wavelength system, which is more sensitive to smaller structures, and will focus on collecting data about India and surrounding countries, Antarctica and elsewhere.
• The satellite, which is slated to launch from southern India later this spring but not before mid-April, will orbit about 750 kilometers above Earth.
• "It's first-of-its-kind because it has a high resolution as well as a wide swath coverage," says Deepak Putrevu, who co-leads the mission's science team for ISRO.

The big picture: Historically, India "found itself trying to balance between the U.S. and the Soviet Union," says the Secure World Foundation's Victoria Samson.

• But as India developed its human spaceflight program, it looked toward Russia. More recently, as Russia deepens its ties with China, India has grown closer to the U.S. when it comes to space.
• "NISAR predates a lot of that — but India and the U.S. are finding more opportunities to cooperate," Samson says. The mission agreement was signed in 2014.
• NASA is planning to train an Indian astronaut, and India last year signed on to the U.S.-led Artemis Accords that lays out governance for exploring the Moon.
• The U.S. and India have also begun to work more closely on security in the Indo-Pacific, innovation and other issues but the relationship has its challenges, including most recently an alleged plot directed by an Indian government employee to assassinate a U.S. citizen in New York.

Between the lines: The NISAR mission will generate massive amounts of data — about 100 petabytes each year.

• NASA has long required its data be free and open-source. ISRO has adopted a new policy that allows "free data download for any resolutions coarser than 5 [meters], for any mission ... in tune with global user requirements," Putrevu says.
• India's remote sensing program has historically focused on the country and surrounding regions, and the societal and economic benefit to India.
• But national security, space exploration and commercialization of space are now driving India's space ambitions. The country's space policy released last year emphasizes pursuing international relations around space activities.

"India is bringing a lot to this partnership," Samson says.

• It has a "strong launch capability and satellites," and they were the fourth country to soft land on the Moon and to test anti-satellite weapons, she says.
• "They belong to an elite group."

What to watch: There are dozens of SAR satellites above Earth — from the European Union, Japan, Argentina, China, and Canada as well as the U.S., India and others. Commercial systems are also in orbit, including satellites operated by Iceye and Capella Space.

• Rosen is part of an international working group looking at common science objectives among countries with these Earth-observing abilities and trying to determine how programs can complement one another to do "better than each individual agency could do in a vacuum," he says.
• "It's a very challenging problem since programs are not well-aligned."