What are Capture Bags, the new technology to detect and capture asteroids?

Joel Sercel, an aeronautical engineer, former Caltech instructor, and founder of TransAstra, explains that asteroid mining requires solving four major challenges: detecting, capturing, moving, and processing an asteroid. A successful mining system must identify viable targets, secure them, transport them safely, and extract their raw materials.

Under Sercel’s leadership, TransAstra has made significant technological progress in this field, holding around 21 patents and adding roughly one new patent per month. In October, the company conducted a major test of its Capture Bag aboard the International Space Station (ISS), marking a key milestone toward building a full-scale version. The research is supported through private investment and NASA funding. TransAstra has also identified hundreds of candidate asteroids—particularly those with Earth-like orbits—and plans to begin its first mining operation in 2028, a mission the company hopes will spark an industrial revolution in space.

TransAstra’s approach

TransAstra has raised approximately $12 million in venture capital and $15 million through contracts, including collaborations with NASA and the U.S. Space Force. Sample collection from asteroids remains extremely complex and costly; only three government missions, by the U.S. and Japan, have successfully returned samples, and two high-profile private ventures—Planetary Resources and Deep Space Industries—collapsed before achieving major breakthroughs.

To locate potential mining targets, TransAstra deploys a network of “Sutter” telescopes in Arizona, California, Australia, and soon Spain, evoking comparisons to the California Gold Rush.

The company has successfully tested a one-meter-diameter Capture Bag on the ISS, demonstrating its rapid development cycle and functionality in microgravity. The largest design could envelop an asteroid weighing up to 10,000 tons, and TransAstra is currently building a 10-meter version with $5 million in funding—half from NASA. Before attempting to capture valuable asteroids, the technology will first be tested on space debris to minimise risk. Ultimately, Sercel envisions processing mined materials in space, enabling the in-orbit manufacturing of spacecraft and infrastructure rather than transporting raw materials back to Earth.

Refining the Capture Bag for space missions

Interest and investment in both asteroid capture and space-junk removal have surged. U.S.-based startup Astroforge, for example, launched its probe Odin to survey an asteroid, though contact was lost shortly after its launch on the IM-2 lunar mission.

While a variety of concepts have been proposed—ranging from advanced robotics to simpler nets—the Capture Bag stands out as a practical, cost-effective alternative. As Sercel notes, a single bag design can handle objects of many shapes and sizes, potentially reducing costs as the technology scales.

Eleonora Botta, an associate professor at the University at Buffalo, emphasises the bag’s ability to manage objects with differing spin rates, making it valuable for both asteroid capture and debris removal. Still, substantial engineering hurdles remain—particularly in deploying large, flexible structures in the harsh, microgravity environment of space.

TransAstra recently secured additional NASA funding to continue refining this technology. John Crassidis, also of the University at Buffalo, praised the company’s innovative approach, particularly its use of Sutter telescopes to track small asteroids. Although he remains uncertain whether enough suitable asteroids can be found to justify the costs, he considers the company’s 2028 target ambitious yet promising.