A new radar satellite, built by NASA and India’s space agency, will precisely map nearly all of Earth’s land and ice regions, detecting shifts as small as a centimeter, or less than half an inch. The data will be turned into three-dimensional maps that will help scientists and policymakers respond to natural disasters like volcanic eruptions and earthquakes, help farmers by monitoring soil moisture and crop growth, and track long-term changes to Antarctica’s ice sheets and other parts of the planet.
The satellite is known as the NASA-ISRO Aperture Radar mission, or NISAR. ISRO is the acronym for India’s space agency, the Indian Space Research Organization.
When is the launch, and how can I watch it?
Launch from the Satish Dhawan Space Center on India’s southeastern coat is scheduled for Wednesday at 8:10 a.m. Eastern time, or 5:40 p.m. in India. The launch window is 10 minutes long, allowing a little leeway for weather and technical issues.
NASA will provide coverage of the launch beginning at 7 a.m.
What will NISAR do?
NASA describes NISAR as the most advanced radar system it has ever launched.
Because radar signals pass through clouds, they are ideal for continual monitoring of the surface.
Deformations in Earth’s surface could provide early warning of impending natural disasters like volcanic eruptions and landslides. Measurements of ice sheets will reveal which areas are melting and which are growing through accumulated snowfall.
The data could also reveal flooded areas that would otherwise be hidden by bad weather, providing help to rescue teams.
“NISAR is a model for the next generation of Earth-observation capabilities,” Karen St. Germain, director of NASA’s Earth science division, said Monday during a news conference.
What happens after launch?
NISAR will be lifted to orbit on an ISRO rocket known as a Geosynchronous Satellite Launch Vehicle. The orbit will pass close to the North and South Poles at about 464 miles above Earth’s surface.
The first 90 days will be devoted to deploying the spacecraft, including extending a 39-foot-wide gold-mesh antenna reflector, which looks a bit like a giant beach umbrella.
The primary mission is scheduled to last three years. If the spacecraft is still operational at that point, it will be carrying enough propellant to continue for another couple of years.
How does NISAR work?
The main part of the spacecraft is 18 feet long and weighs more than 5,000 pounds. Two 18-foot-long solar arrays will generate power.
The satellite includes two radar systems. One, built by NASA, will transmit microwaves with a wavelength of 25 feet. The other, built by ISRO, transmits 10-foot-long microwaves. The two wavelengths will provide details at different size scales. For the study of vegetation, the shorter wavelengths will provide more detail about bushes and shrubs, while the longer wavelengths will provide a clearer picture of taller plants like trees.
Transmitters on the spacecraft will generate microwave pulses that will bounce off the gold-mesh reflector and travel down to Earth, bounce off the surface and return to the spacecraft.
Multiple radar signals along the orbit will be combined to simulate a larger reflector. Bouncing radar signals from multiple angles allows the creation of three-dimensional views.
Why is NASA collaborating with India on this mission?
Every decade, earth scientists put together a study sponsored by the National Academies of Sciences, Engineering and Medicine that lays out the field’s top priorities for observing Earth from space. The 2007 decadal survey recommended a radar mission.
“We’ve been studying it, trying to come up with something that’s cost-effective and capable that meets the requirements that were outlined in the decadal survey,” Paul Rosen, the project scientist for the mission, said during a news conference two weeks ago.
NASA was not able to find an international partner to share the work and cost until Dr. Rosen visited ISRO. “And India said, This is exactly the kind of thing we would like to do next,” Dr. Rosen said.
In 2014, NASA and ISRO announced their partnership to build and operate NISAR.
Is NISAR affected by President Trump’s proposed cuts to NASA?
In its budget request to Congress, the Trump administration proposed deep cuts to NASA’s science program, including canceling several current and future Earth missions.
NISAR was not among the proposed cuts, and budget subcommittees in the Senate and the House of Representatives have proposed much higher funding levels for NASA in the next fiscal year, which begins Nov. 1.
“Our passion is to do the most advanced science we can do with the budget we’re allocated,” Dr. St. Germain said.
Once there is clarity about the NASA budget, she added, “we will move forward with planning for the future missions, and we are, of course, hoping for a nice, long life for NISAR.”
Kenneth Chang, a science reporter at The Times, covers NASA and the solar system, and research closer to Earth.
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