Cold Space... But GPUs Still Won't Cool Down? [Tech Talk]

Radiative cooling bottlenecks for space data centers
Conventional cooling systems do not work in space
Specialized heat shields and heat pipe technologies are essential

Musk Elon, Tesla Chief Executive Officer (CEO), has completed the merger of his space company SpaceX with his artificial intelligence (AI) company xAI. This has brought CEO Musk one step closer to realizing his ambition for a "space data center." While he predicts that space will become "the cheapest place" to build data centers, the technological barriers remain extremely high. In particular, the challenge of cooling the heat generated by graphics processing units (GPUs) will continue to plague SpaceX.

Will space become the cheapest place to build data centers?

Musk Elon, Tesla Chief Executive Officer (CEO). Reuters Yonhap News Agency

Earlier, on January 30 (local time), SpaceX submitted an application to the U.S. Federal Communications Commission (FCC) for a satellite launch license to build a space data center. The idea is to launch up to 1 million satellites equipped with GPUs and configure them to function as one gigantic data center. In the application, SpaceX explained that "a constellation of 1 million satellites is the first step toward harnessing all of the Sun's energy."

CEO Musk has previously expressed optimism about "space data centers." In November last year, he asserted that "within the next five years, space will be the cheapest place to realize AI and quantum computing."

On the surface, this sounds reasonable. The solar panels on satellites can generate energy around the clock, and the near minus 270 degrees Celsius environment of outer space, close to "absolute zero," seems like an ideal cooling environment. If the issue of satellite launch costs can be solved, space might appear more suitable than Earth for operating data centers.

The paradox of vacuum: computers cool down more slowly in space

In reality, however, operating a data center in space is far more difficult. Ironically, space is actually the worst place to address the problem of heat generation in computer chips.

SpaceX's satellite payload. SpaceX

Ground-based data centers solve heat issues by building cooling systems. They either suppress heat with air-conditioning units inside the data center, or they use cooling water to absorb the heat and then re-cool the heated water in a circulation system.

In space, it is different. Space is a vacuum where no atmosphere exists. In other words, there is no "convection" (the circulation process in which hot liquids or gases move downward and cold liquids or gases move upward, transferring heat). Because of this, heat that accumulates inside a satellite has difficulty escaping to the outside. Instead, heat in space is released through "radiation": it is converted into infrared and slowly emitted outward. Put simply, heat does dissipate in space, but unlike on Earth, where it can be cooled rapidly, in space it can only be released slowly.

For this reason, space agencies and aerospace technology research institutes around the world, including the National Aeronautics and Space Administration (NASA), have long focused on the problem of thermal management for spacecraft. Currently, thermal control for satellites and spacecraft is mainly handled by heat pipes and heat shields. Heat pipes transfer generated heat to heat shields, and the heat shields release the accumulated heat as quickly as possible so that the internal temperature of the vehicle remains at a constant level.

Satellite companies focus on heat shields

SpaceX-developed spacecraft heat shield. Screenshot from X

The research agenda of tech companies developing space data centers has also focused on managing heat inside satellites. According to IT outlet The Verge, the space data center startup Starcloud is experimenting with a method that uses satellites equipped with large infrared panels to promote radiative cooling. Starcloud successfully conducted a test late last year in which it ran a Google AI model on a GPU computer installed inside a satellite.

SpaceX, too, has spent many years building up its heat shield technology. It originally developed ceramic tiles to withstand the extreme heat generated when spacecraft re-enter Earth's atmosphere. These tiles are black, hexagonal panels filled with fibrous filler material. The heat shield is known to withstand temperatures of up to 1,400 degrees Celsius.