Google’s Project Suncatcher prototype is scheduled to fly on SpaceX’s Transporter-18 mission on Oct. 1, 2026, with the launch window opening at 11:18 a.m. Pacific Time. The planned orbital test is designed to gather data on how Google Tensor Processing Units (TPUs) handle launch stress, radiation and thermal conditions. Planet Labs developed the refrigerator-sized prototype in partnership with Google.
Project Suncatcher is Google’s long-term research into whether solar-powered satellite constellations carrying TPUs could eventually support machine-learning workloads in orbit. The planned flight is a hardware test within that effort.
What Google wants to learn from the prototype
Google’s ground tests address the forces and radiation hardware faces before the planned flight. The company says it shook the satellite along all three axes to mimic launch vibration. Google describes launch acceleration loads of up to 10 g for the spacecraft and loads of 50–100 g for individual components.
Google also reports testing Trillium TPUs with a proton beam at UC Davis’s Crocker Nuclear Laboratory. The chips withstood a total ionizing dose greater than the shielded dose Google expects over a five-year mission. That is a ground-test result for Trillium hardware.
Cooling remains a central engineering challenge
On Earth, data centers move air over hot components to carry heat away. In space, Google is researching heat pipes and pumped-fluid loops that move heat to radiators, which release it through radiation. The company has also tested thermal systems in a thermal-vacuum chamber on Earth.
The heat-removal problem is a matter of scale: Google researchers say radiators dissipate on the order of a few hundred watts per square meter, while TPUs generate thousands of watts. Google is still refining the approach as part of its research into thermal management.
A prototype test within a much larger research effort
Google’s proposed system would connect satellites with free-space optical links—laser communications between spacecraft. A bench-scale demonstrator using one transceiver pair reached 800 Gbps in each direction, or 1.6 Tbps total. The proposed network would use those links between satellites.
Google Research’s illustrative design models a formation of 81 satellites at a mean altitude of 650 km. The company’s next planned milestone with Planet Labs is a two-prototype learning mission by early 2027 to test its models, TPU hardware and optical inter-satellite links.
