A Satellite That Sees Heat Just Went Live. It Can Tell Which Buildings Are Running, Which Ships Are Moving, and Which Bases Just Lit Up — In Complete Darkness.

A satellite switched on today that doesn't care about your city's lights.

It sees your city's heat.

Every building that's running. Every ship moving through a dark harbor. Every factory that ramped up at 3 a.m. — or quietly went cold. HotSat-2 just started commercial operations. It's a thermal imaging satellite owned by a British startup called SatVu. And what it reads from 500 kilometers up is more revealing than any photograph ever could be.

Light Lies. Heat Doesn't.

A standard satellite image shows you what's visible. Thermal infrared imaging shows you what's active.

A building can look dark from above. But if its servers are running, if its workers are inside, if its engines are on — the heat bleeds through. Infrared sensors catch it all. A facility that appears completely dormant on optical imagery might be pulsing with warmth on thermal. There's no turning that off.

Sub-degree temperature resolution. From space. That's finer than the difference between a warm body and a cold room. It means if a hangar is occupied, the satellite knows. If a ship's engine is idling, the satellite knows. If a power plant went offline two hours ago, the satellite knows — even in total darkness, even through cloud cover.

The First One Didn't Make It

SatVu is not a government agency. It's a London-based startup. Founded by people who believe that thermal satellite data — until now mostly locked inside classified military programs — deserves a commercial market.

Their first satellite, HotSat-1, launched in June 2023. It failed. The exact cause was never publicly disclosed. For a startup staking its entire business model on a single spacecraft, that's not a setback — it's an existential moment.

Most companies don't survive losing their first satellite.

SatVu did.

HotSat-2 launched earlier this year. Today it announced the start of commercial services. That means paying customers. Real contracts. A business model that finally has a product to deliver.

What Does a Thermal Satellite Actually See?

Here's where it gets interesting. And a little unsettling.

Thermal imaging from orbit isn't just useful for watching volcanoes or measuring sea surface temperatures — though it does both. The commercial applications are genuinely strange:

• Industrial monitoring: You can tell if a steel plant is at full capacity or sitting idle just from its heat signature. Commodity traders pay significant money for this information.
• Ship tracking in darkness: A vessel's engine exhaust has a distinct thermal signature. Even with its AIS transponder switched off, even at night, a thermal satellite can track it. This is not hypothetical — it's already being used.
• Military intelligence: An airbase that appears empty on optical imagery might show active heat signatures from underground fuel lines, heated hangars, and personnel areas. Thermal doesn't lie about presence.
• Wildfire early warning: Thermal catches a hotspot forming under dense smoke cover hours before visible-light sensors detect anything. Minutes matter in a firestorm.
• Energy compliance: Buildings have legally required energy efficiency ratings. A satellite that measures actual heat loss from rooftops and walls can verify — or expose — violations without a single inspector on the ground.

The Market Nobody Talks About

SatVu isn't alone in thermal imaging from orbit — but they're among the very few operating commercially. Most of what exists is classified. The agencies that run black-budget reconnaissance programs have had this capability for decades. They used it to monitor Soviet industrial production during the Cold War. They use it today to track nuclear facilities, military mobilizations, and energy infrastructure.

What SatVu is doing is making a version of that capability available to anyone with a contract.

To be fair: SatVu operates under UK export control regulations and has publicly stated it screens customers and use cases. The company positions itself as a climate and energy intelligence tool, not a surveillance service. That distinction matters — and it's one they'll have to defend as the constellation grows and the data gets sharper.

For a deeper look at what the full Earth-observation satellite picture looks like right now — every eye in orbit, by country, by purpose — the SkyLens live tracker maps all 15,894 tracked objects in real time. Earth-observation satellites are a small but critical fraction of that number.

Why Decades of Classified Tech Is Going Commercial Now

The pattern is familiar. GPS started military. Satellite imagery started classified — then Google Earth put it in everyone's browser. Signals intelligence started in government bunkers — now commercial companies sell RF emissions data to hedge funds.

Thermal imaging is following the same arc. The sensors got cheaper. The rockets got cheaper. The launch cadence went from once a year to multiple times a week. What cost a billion dollars in 1990 now costs tens of millions. That's the real story behind HotSat-2.

SatVu's long-term plan is a constellation — multiple satellites, shorter revisit times, near-continuous thermal coverage of any location on Earth. With one satellite, a target might be imaged once per day. With twelve, you're approaching real-time. That's the end goal. Today's commercial launch is the first revenue that makes it financially possible.

The Bigger Picture

There's something worth sitting with here. For most of human history, the night hid things. Darkness was cover — for military movements, for industrial operations, for anything people didn't want observed.

Thermal satellites remove that cover. Not completely, not yet. But progressively. A satellite that sees heat doesn't care that it's 3 a.m. It doesn't care about cloud cover. It reads the infrared spectrum — the universe's way of broadcasting what's warm, what's active, what's alive.

HotSat-2 isn't the end of that story. It's the beginning of it going mainstream.

If you want to understand how different satellites see the world — radar, optical, multispectral, thermal — the SkyLens learn section breaks down each sensor type and what it actually reveals. More stories on the commercial space race, Earth observation, and what's happening in orbit right now are on the SkyLens blog.