Why Outer Space May Not Save Us from Data Centers

By Greg Ritchie

Messenger Reporter

MESSENGER OFFICE — I have been thinking about data centers in space since our discussion of the proposed facility near Mustang Prairie.

At first, the idea sounds simple: Put the computers in orbit, use the sun for power and let the cold of space take care of the heat.

The trouble is that space is not a giaant walk-in freezer.

Consider a cup of hot coffee left on a table. The coffee may warm the small amount of air directly around it, but the overall movement is in the other direction. The cooler air, the cup and the table draw heat away from the coffee. As that heat spreads into the much larger room, the coffee cools.

The heat does not disappear. It simply spreads out.

Now consider a thermos. A thermos helps keep coffee hot partly by creating a vacuum around it. With very little air available to carry heat away, the coffee stays hot longer.

That is closer to the reality of space than the image of a cold room full of air.

There is no air in space. A fan cannot blow hot air away because there is no air to blow. There is no cool breeze moving in to replace it. A computer placed in a vacuum does not automatically become cold simply because the surrounding darkness is cold.

A computer still produces heat.

Anyone who has used a laptop for too long has felt this. The computer warms up, the fan starts running and the machine tries to move that heat away. A powerful gaming computer does the same thing on a larger scale. A data center is essentially an enormous collection of computers, all producing heat at the same time.

The proposed facility near Mustang Prairie is described as roughly 100,000 square feet and capable of using as much as 96 megawatts of electricity. And we don’t need to memorize those numbers to understand the basic problem.

Nearly all of that electrical energy eventually becomes heat.

On Earth, we have familiar ways to deal with it. Fans move warm air. Water carries heat away. Cooling systems transfer heat outside. Cooling towers release heat into the atmosphere.

In space, those methods do not work in the same way.

Instead, the heat would have to be carried through the equipment to large radiator panels. Those panels would release the heat as invisible infrared energy. It is somewhat like a radiator on a car, except there is no air flowing across it. The panel has to send the heat away directly as energy.

A rough calculation suggests radiating away the heat from a 96-megawatt facility could require between 800,000 and 1.35 million square feet of radiator surface, depending on the design and operating temperature.

That is roughly 14 to 23 football fields devoted just to getting rid of the heat.

The solar panels needed to power the facility would add millions of square feet more. They would have to generate electricity for the computers, communications systems, batteries and all the equipment required to keep the platform operating. Batteries would also be needed whenever the platform passed through the shadow of Earth.

When I sketched out a rough illustration of what that might look like, I placed the 100,000-square-foot computer facility in the middle. Around it, I added the solar arrays and radiator panels.

The complete structure stretched roughly 4,000 feet from end to end—about three-quarters of a mile.

I admit I am no engineer. It was simply a way to make the scale understandable. The point was that the computers themselves would be only one part of the system.

Then there is the problem of getting all of that equipment into orbit.

A rocket may look enormous from the ground, but most of its mass is fuel and rocket hardware. The payload—the part actually being carried into orbit—may represent only about 2% of the rocket’s total launch mass, depending on the vehicle and the orbit.

Using that rough figure, putting one pound of equipment into orbit could require roughly 50 pounds of total launch mass.

That means the rockets would not be carrying only servers. They would also have to carry the solar panels, radiator panels, batteries, wiring, shielding, support structure and communications equipment. Even a relatively small orbital data center would require a great deal of material to be lifted out of Earth’s gravity.

The facility proposed for Houston County may be small compared with the largest data centers on Earth. It would not be small if every part of it had to be launched into space.

Space also makes ordinary maintenance much harder.

On Earth, if a fan fails at a data center, a technician can drive to the building with a replacement. If a piece of equipment breaks, workers can walk inside and repair it.

In orbit, a failed computer, damaged solar panel or malfunctioning radiator may require a robotic repair or another launch. Space debris and tiny particles moving at orbital speeds can damage equipment. Solar panels deteriorate. Computers eventually fail.

A technician cannot simply pull a truck up to the front door.

None of this means that computers in space are impossible. Smaller systems may eventually make sense for specific purposes. A satellite could process photographs or other information before sending only the most important material back to Earth.

That is different from moving a large, Earth-based data center into orbit.

Elon Musk has helped bring the idea of space-based artificial-intelligence computing into public discussion. Ambitious ideas deserve serious attention. But an idea, a proposal or an announcement is not the same thing as an operating facility.

The phrase “data center in space” makes the concept sound easier than it is.

Space may provide sunlight, but sunlight is not free electricity. Space may be cold, but it does not provide cold air. Space may provide plenty of room, but every panel, computer, cable and support structure has to be launched, assembled, protected and eventually repaired.

When I picture the proposed facility near Mustang Prairie, I see a building on the ground with computers, power equipment and cooling systems.

When I picture the same challenge in orbit, I see millions of square feet of solar panels, as much as 23 football fields of radiator panels and a long list of equipment that would have to be carried there by rockets whose payload is only a small fraction of their total mass.

The location changes. The basic problem does not: If a machine produces heat, that heat still has to go somewhere.

Greg Ritchie can be reached at [email protected]