We're weighing clouds in ways we couldn't before G-band
From a laboratory at NASA's Jet Propulsion Laboratory, a small but consequential instrument has emerged that may quietly reshape how humanity reads the sky. CloudCube, a compact multifrequency radar, fires three simultaneous signals into clouds — including a frequency never before sent to space — to reveal the hidden architecture of precipitation and ice that drives weather and climate alike. It is a reminder that the most transformative tools are often not the largest, but the most precisely conceived.
- Weather and climate models have long carried a blind spot: thin clouds laden with ice and liquid water that existing space-based radar simply cannot see.
- CloudCube breaks that barrier by simultaneously transmitting Ka-, W-, and G-band radar signals — the G-band being an entirely new frontier for space instrumentation — allowing researchers to weigh clouds in ways previously impossible.
- The engineering challenge was immense: adding a third frequency without inflating mass or power consumption required stripping components to their essentials and deploying high-efficiency frequency-multiplication devices generating hundreds of milliwatts at 240 gigahertz.
- The instrument has already survived eleven months of continuous ground operation in Alaska and flown aboard a NASA aircraft through winter snowfall campaigns, proving it is ready for the rigors of real-world deployment.
- The team is now processing airborne data for public release, with the compact, low-cost design positioning CloudCube as a potential standard aboard future Earth-observing satellites.
A team at NASA's Jet Propulsion Laboratory has built CloudCube, a radar instrument compact enough to fly on an aircraft yet capable of seeing inside clouds in ways no space-based system has achieved before. It transmits three radar signals simultaneously — Ka-band, W-band, and G-band — spanning frequencies from 36 to 240 gigahertz, each tuned to detect different sizes of water droplets and ice particles. Ka-band maps rainfall, W-band tracks the cloud particles that become rain, and G-band, never before launched into space, measures ice and liquid water hidden inside thin clouds that other instruments miss entirely.
The engineering feat was not simply adding a third frequency but doing so without expanding the instrument's mass or power draw. The team achieved this through high-efficiency frequency-multiplication devices and by eliminating all non-essential components — producing an instrument designed to be genuinely affordable to launch and operate. Systems engineer Raquel Rodriguez Monje describes CloudCube as a deliberate step toward lighter, cheaper Earth-observation missions.
CloudCube has already demonstrated its worth in the field. Its G-band channel ran continuously for eleven months during a Department of Energy cloud study in Alaska, and all three bands recently flew together aboard a NASA Gulfstream III aircraft during a winter storm forecasting campaign. Co-investigator Matt Lebsock frames the achievement plainly: the combination of frequencies allows researchers to weigh clouds in ways that were simply impossible before. The question is no longer whether the technology works, but how soon it reaches orbit.
A team at NASA's Jet Propulsion Laboratory has built a radar instrument small enough to fit on an aircraft, yet capable of seeing inside clouds in ways no space-based system has managed before. Called CloudCube, it fires three different radar signals simultaneously—at frequencies spanning from 36 to 240 gigahertz—each tuned to detect different sizes of water droplets and ice particles suspended in the atmosphere.
The innovation lies partly in what CloudCube can do and partly in how it does it. The instrument transmits Ka-band, W-band, and G-band signals all at once. Ka-band excels at mapping where rain falls; W-band detects the cloud particles that eventually become rain; and G-band, which has never before been launched into space, can measure the amount of ice and liquid water hiding inside thin clouds that other instruments miss entirely. By combining data from all three frequencies, researchers gain a more complete picture of how clouds form, evolve, and produce precipitation—information that feeds directly into weather forecasts and climate models.
Raquel Rodriguez Monje, the systems engineer leading the project, describes CloudCube as a deliberate step toward cheaper, lighter Earth-observation missions. Building a multifrequency radar, especially one that includes G-band capability, represents genuinely novel engineering. The challenge was not just adding a third frequency but doing so without ballooning the instrument's mass or power draw. The team solved this by using high-efficiency frequency-multiplication devices that generate hundreds of milliwatts at 240 gigahertz—the G-band frequency—from a compact, low-power source. They also stripped away unnecessary radio frequency components, keeping only what was essential. The result is an instrument designed to be affordable to launch and operate.
CloudCube has already proven itself in the field. A ground-based prototype of its G-band channel ran continuously for eleven months during a Department of Energy cloud study in Alaska. More recently, all three frequency bands operated together aboard a NASA Gulfstream III aircraft, collecting airborne observations of snowfall during a winter weather campaign designed to improve forecasts of severe storms. The team is now calibrating and processing that data for public release.
Matt Lebsock, a co-investigator on the project, frames the capability in simple terms: the combination of frequencies allows researchers to weigh clouds in ways that were impossible before G-band data became available. This is not incremental improvement. It is a new dimension of observation. As climate models grow more sophisticated and weather forecasting demands greater precision, instruments like CloudCube—compact, efficient, and capable of simultaneous multifrequency measurement—may become standard equipment on future Earth-observing satellites. The question now is not whether the technology works, but how quickly it can be deployed.
Notable Quotes
We're making a low-power, low-mass instrument to facilitate new cost-efficient missions for atmospheric observations. Building a multifrequency radar, especially at G-band, is very novel.— Raquel Rodriguez Monje, systems engineer and principal investigator for CloudCube
We're weighing clouds using these combinations of frequencies in a way that we couldn't do before we had the G-band.— Matt Lebsock, JPL researcher and co-investigator
The Hearth Conversation Another angle on the story
Why does it matter that G-band has never been used from space before?
Because G-band wavelengths are short enough to detect very small ice crystals and water droplets in thin clouds. From the ground, you can build a big antenna. From space, you need something compact. No one had figured out how to do that until now.
So this is about resolution—seeing smaller things?
Partly. But it's also about sensitivity. A thin cloud might contain ice that other radars can't measure. G-band can. And when you combine G-band data with Ka and W-band data, you get a complete picture of what's inside the cloud.
The article mentions "weighing clouds." What does that actually mean?
It means measuring the total mass of water—liquid and ice—in a given volume of air. Different frequencies interact with different particle sizes. Together, they let you calculate how much water is really there, not just whether it's there.
Why would climate models care about that?
Clouds are one of the biggest uncertainties in climate science. They reflect sunlight, trap heat, produce rain. If you don't know their properties accurately, your climate predictions are less reliable. Better cloud data means better predictions.
And the compact design—why is that important for the future?
Launching things into space is expensive. If you can build an instrument that does more work while using less power and weighing less, you can fit it on cheaper missions. That means more frequent observations, more satellites, better coverage of Earth.