NASA, the French space agency Centre National d’Études Spatiales (CNES), and SpaceX will launch the Surface Water and Ocean Topography (SWOT), satellite.

SWOT is the first satellite mission that will survey all water on Earth. Viewing Earth’s water in higher definition than ever before will inform water equity and water management decisions, provide new insights into Earth’s water and energy cycle, and help prepare communities for rising seas and changing coastlines in a warming climate.

Years in development, the instrument has been designed to capture very precise measurements of the height of water in Earth’s freshwater bodies and the ocean. KaRIn will measure the height of water in the ocean, “seeing” features like currents and eddies that are less than 13 miles (20 kilometers) across – up to 10 times smaller than those detectable with other sea level satellites. It will also collect data on lakes and reservoirs larger than 15 acres (62,500 square meters) and rivers wider than 330 feet (100 meters) across.

“For freshwater, this will be a quantum leap in terms of our knowledge,” said Daniel Esteban-Fernandez, KaRIn instrument manager at NASA’s Jet Propulsion Laboratory in Southern California. For example, researchers currently have good data on only a few thousand lakes around the world; SWOT will increase that number to at least a million.

The cutting-edge KaRIn instrument lies at the heart of this international mission, the latest in a longstanding collaboration between NASA and the French space agency Centre National d’Études Spatiales (CNES), with contributions from the Canadian Space Agency (CSA) and the UK Space Agency.

Until now, researchers looking to study a body of water relied on instruments that measure at specific locations – like gauges in rivers or the ocean – or that are space-based, gathering data along narrow “tracks” of Earth they can see from orbit. Researchers then have to extrapolate if they want a broader idea of what’s happening in a water body.

KaRIn is different. The radar instrument uses the Ka-band frequency at the microwave end of the electromagnetic spectrum to penetrate cloud cover and the dark of night. As a result, it can take measurements regardless of weather or time of day. The instrument configuration consists of one antenna at each end of a boom that’s 33 feet (10 meters) long. By bouncing radar pulses off the water’s surface and receiving the return signal with both antennas, KaRIn will collect data along a swath 30 miles (50 kilometers) wide on either side of the satellite.

“With KaRIn data, we’ll be able to actually see what’s happening, rather than relying on these extrapolations,” said Tamlin Pavelsky, the NASA freshwater science lead for SWOT, based at the University of North Carolina, Chapel Hill.

The two KaRIn antennas will see the same spot on Earth from 553 miles (890 kilometers) above. Since the antennas look at a given point on Earth from two directions, the return signals reflected back to the satellite arrive at each antenna slightly out of step, or phase, with one another. Using this phase difference, the distance between the two antennas, and the radar wavelength, researchers can calculate the height of the water that KaRIn is looking at.

Such a remarkable instrument demanded a lot from the team that developed it. For starters, there was the need for stability. “You have two antennas looking at the same spot on the ground, but if their footprints don’t overlap, you won’t see anything,” said Esteban-Fernandez. That was one of the many technical challenges the mission faced in creating KaRIn.

Engineers also need to know exactly how SWOT is positioned in space to ensure the accuracy of KaRIn’s data. If researchers don’t know the spacecraft is tilted, for instance, they can’t account for that in their calculations. “Imagine that the boom rolls because the spacecraft moves, so one antenna is slightly higher than the other,” Esteban-Fernandez said.

“That will skew the results – it’ll look like all your water is on a slope.” So engineers included a high-performance gyroscope on the satellite to account for shifts in SWOT’s position.

Engineers designing KaRIn also had to contend with the amount of radar power transmitted. “To measure things down to centimeter accuracy, you need to transmit radar pulses of 1.5 kilowatts, which is a huge amount of power for a satellite like this,” said Esteban-Fernandez. “In order to generate that, you have to have tens of thousands of volts operating on the satellite.”

The engineers needed to use designs and materials specific to high-voltage systems when manufacturing the electronics to help the satellite accommodate such high-power and high-voltage needs.

The team spent years overcoming those and a multitude of other challenges to deliver the KaRIn instrument. Very soon the interferometer will fly for the first time on the SWOT satellite and start sending back terabytes of data. “KaRIn will be putting something on the table that just didn’t exist before,” said Esteban-Fernandez.

Credit: Jane J. Lee / Andrew Wang / Jet Propulsion Laboratory, Pasadena, Calif.

Falcon 9 is a reusable, two-stage rocket designed and manufactured by SpaceX for the reliable and safe transport of people and payloads into Earth orbit and beyond.

Falcon 9 is the world’s first orbital-class reusable rocket.

Stats
Total launches: 324

Total landings: 282

Total reflights: 255

The Falcon 9 has launched 49 humans into orbit since May 2020

Specs

Height: 70 m / 229.6 ft

Diameter: 3.7 m / 12 ft

Mass: 549,054 kg / 1,207,920 lb

Payload to LEO: 22,800 kg / 50,265 lb

Payload to GTO: 8,300 kg / 18,300 lb

Payload to Mars: 4,020 kg / 8,860 lb

On January 24, 2021, Falcon 9 launched the first ride-share mission to Sun Synchronous Orbit. It was delivering a record-setting 143 satellites to space. And while this was an important mission for SpaceX in itself, it was also the moment Falcon 9 overtook United Launch Alliance’s Atlas V for the total number of consecutive successful launches.

SpaceX’s Falcon 9 had become America’s workhorse rocket, launching 31 times in 2021. It has already beaten that record this year, launching almost an average of once a week. While most of the launches deliver Starlink satellites to orbit, the company is still launching the most commercial payloads to orbit, too.

Falcon 9 is a medium-lift launch vehicle, with the capability to launch over 22.8 metric tonnes to low earth orbit. Unlike any other rocket, its first stage lands back on Earth after separating from its second stage. In part, this allows SpaceX to offer the cheapest option for most customers with payloads that need to reach orbit.

Under its ride-share program, a kilogram can be placed in a sun-synchronous orbit for a mere 1.1 million dollars, far cheaper than all other currently operating small satellite launch vehicles.

The reusability and fast booster turnaround times have made Falcon 9 the preferred choice for private companies and government agencies. This has allowed SpaceX to capture a huge portion of the launch market.

Image: SpaceX / Ben Cooper

Space Launch Complex 4 at Vandenberg Space Force Base is SpaceX’s west coast launch and landing facility. The launch pad is named SLC-4E (as it is the eastern-most of the two areas).

Originally built in the early 1960s for Atlas-Agena rockets, SLC-4E served that rocket line until 1967, when it was taken offline and then rebuilt for the Titan IIID rockets.

It launched the Titan IIID from 1971 to 1988, after which it was reconfigured and used for the Titan IV between 1991 and 2005.

SpaceX leased SLC-4E in 2011 and spent two years rebuilding the pad for the Falcon 9 rocket.

The pad exclusively launched Falcon 9 polar missions from 2013 to 2019.  However, in 2020, SpaceX began splitting those launches between Vandenberg and Cape Canaveral after the Air Force agreed to allow polar launches from Florida after a 51 year ban (because of the then-dangers of overflying Cuba during launch).

Despite new launch opportunities from Florida, SpaceX is not abandoning Vandenberg; many more launches are planned from this location.

Photo: Pauline Acalin

Landing Zone 4 (LZ-4) is SpaceX’s only west coast landing pad for the Falcon 9 first stage.

Activated in 2018, the landing pad is built on the former SLC-4W launch pad.

SLC-4W was built just 427 meters (1,400 feet) from SLC-4E for the Atlas-Agena rockets between 1963 and 1965.  After that, it was rebuilt for the Titan IIIB rocket and used for that program from 1966 to 1987.

With the Titan IIIB’s retirement, the pad was reconfigured for the Titan 23G rocket between 1988 and 2003.

SpaceX leased SLC-4W in 2015 and renamed it Landing Zone 4 and created a landing pad for the Falcon 9 rocket’s first stage.

The first Return To Launch Site landing of a Falcon 9 to Landing Zone 4 took place on October 7th, 2018.

Image: Pauline Acalin for Supercluster