Google's Suncatcher satellite: four TPUs, 1 kW, one chip at a time

Google Suncatcher's prototype space data center is online and communicating with the ground, according to TechCrunch. It launched earlier this month on a SpaceX Falcon 9, alongside more than 100 other spacecraft. The satellite carries four Google Tensor Processing Units and generates up to 1 kW of electricity. Google's plan is for it to pave the way for future networks of close-flying satellites that run large inference workloads in orbit. A spokesperson told TechCrunch the satellite was operating nominally. Before it started work, engineers spent about three weeks on a commissioning process that tested the spacecraft's subsystems.

The power demands of the TPU mean the satellite can only turn one on for roughly 20 minutes at a time. That complicates space-to-ground communications, which the source describes as already tricky. The correction appended to the report is precise: the prototype has four TPUs onboard but can operate only one at a time. So the headline number is four chips, while the working number is one.

When engineers sent their first prompt this week, they asked the model pre-loaded on the satellite, Google DeepMind's Gemma 4, to write a haiku about being in space. The result: "Blue marble below / Data streams in silent grace / Starlight feeds my core." Google said it also tested the model with space-themed limericks. More practically, the company asked the spacecraft to report on the orbital conditions around the satellite.

The ongoing campaign will look at how the chips perform under thermal stress and in the space radiation environment. Google has tested its TPUs extensively in particle accelerators on Earth. Now it needs to see how radiation's real effects on the hardware in space affect the processor. Radiation can cause bit flips, changing a stored value in computer memory. That can corrupt data without setting off typical monitoring tools. Ground testing suggested radiation would have minimal impact on inference workloads and be more of a problem for training a model. The team will now assess those dynamics in reality rather than simulation.

If the TPUs on this spacecraft prove capable, the next step is launching two more satellites with the advanced chips in 2027. Those spacecraft are meant to support higher power generation and demonstrate inter-satellite optical links. Google's Suncatcher project plans high-speed links between satellites to support coherent distributed workloads. SpaceX's data centers are also expected to use laser links, but to orbit too far apart to share processing effectively, per the report. Starcloud and Cowboy Space expect to run inference loads on individual satellites. Alphabet, Google's parent, holds a significant investment stake in SpaceX.