Plans to build data centers in space are drawing growing concern from scientists, former space officials, and environmental groups. They warn that large networks of satellites proposed by several technology and space companies could create new pollution in Earth's atmosphere and lead to long-term environmental damage. The concerns come as companies seek approval to launch millions of satellites that would support orbital data centers. These projects are designed to provide computing power from space instead of using traditional facilities on Earth. Environmental groups have now filed a petition asking federal regulators to pause approvals for these projects until a full environmental review is completed. The petition was submitted to the Federal Communications Commission, which oversees satellite licensing in the United States. The groups argue that current applications do not fully explain the environmental effects of placing such a large number of satellites into orbit. According to the petition, the proposed systems could release large amounts of pollution into the upper atmosphere. Rockets and satellites produce black carbon, aluminum oxides, rare metals, and other particles during launches and when spacecraft burn up as they return to Earth. Experts say scientists still know very little about how these materials behave once they reach the stratosphere. Some researchers believe the pollutants could affect the ozone layer, change atmospheric chemistry, or increase climate-related risks over time. Scientists also warn that the pollution may eventually return to Earth's surface. In addition, millions of satellites could make light pollution much worse, reducing the natural darkness of the night sky. Former government space officials have also questioned whether giant orbital data centers are practical. Even if the technology becomes possible, they believe the environmental impact deserves careful study before large-scale deployment begins. Steve Volz, the former leader of the satellite office at the National Oceanic and Atmospheric Administration, said spacecraft contain many complex materials that should not be allowed to build up in the atmosphere. He explained that pollution from satellites should be treated with the same level of concern as pollution released from industrial smokestacks because both can affect the environment. The idea of placing data centers in orbit gained attention after technology companies faced growing opposition to building new facilities on land. Local communities have raised concerns about electricity use, water consumption, and the environmental effects of large data centers. The number of satellites already orbiting Earth has increased rapidly over the past decade. There were about 1,400 active satellites in 2015. Today, that number has reached roughly 15,000. Industry forecasts suggest that as many as 100,000 satellites could be operating before the end of the decade. Proposed orbital data center projects would add many more spacecraft beyond those already planned. Scientists are continuing to study how satellite pollution affects the atmosphere. In late 2023, researchers found metals inside sulfuric acid particles high above Earth during a scientific measurement flight. These particles help regulate Earth's temperature by reflecting part of the sun's energy back into space. Researchers say it is still unclear how metals released from satellites may interact with this natural system. Scientists have called for more research before satellite launches increase further. They say the current level of knowledge is not enough to predict the long-term effects. Environmental groups are also concerned about light pollution. They say brighter skies can affect wildlife that depends on natural darkness, including insects, birds, and other animals. The petition also highlights concerns about the growing demand for rare metals needed to build large satellite networks. Producing millions of satellites would require significant natural resources, creating additional environmental pressure on Earth. The groups argue that federal law requires regulators to determine whether satellite projects serve the public interest before granting licenses. They also believe environmental laws require a detailed review of potential impacts before approvals are issued. The petition says current applications do not provide enough information about how companies plan to reduce pollution, limit satellite debris, or manage the environmental effects of large satellite networks. Supporters of the petition are calling for a temporary pause on new approvals until independent environmental studies can examine the possible risks. They say a careful review would help regulators better understand the long-term effects of orbital data centers before millions of additional satellites are placed into space.