Organic macromolecular matter is the dominant carrier of volatile elements such as carbon, nitrogen and noble gases in chondrites—the rocky building blocks from which Earth formed. How this macromolecular substance formed in space is unclear. Here we show that its formation could be associated with the presence of dust traps, which are prominent mechanisms for forming planetesimals in planet-forming disks. We demonstrate the existence of heavily irradiated zones in dust traps, where small frozen molecules that coat large quantities of microscopic dust grains could be rapidly converted into macromolecular matter by receiving radiation doses of up to several tens of electronvolts per molecule per year. This allows for the transformation of simple molecules into complex macromolecular matter within several decades. Up to roughly 4% of the total disk ice reservoir can be processed this way and subsequently incorporated into the protoplanetary disk midplane where planetesimals form. This finding shows that planetesimal formation and the production of organic macromolecular matter, which provides the essential elemental building blocks for life, might be linked.

有机大分子物质是球粒陨石中碳、氮和稀有气体等挥发性元素的主要载体，球粒陨石是形成地球的岩石构件。这种大分子物质是如何在太空中形成的尚不清楚。在这里，我们表明它的形成可能与尘埃陷阱的存在有关，尘埃陷阱是在行星形成盘中形成星子的重要机制。我们证明了灰尘捕集器中存在严重辐射区域，其中覆盖大量微观尘埃颗粒的小冷冻分子可以通过每年每个分子接受高达数十电子伏特的辐射剂量而迅速转化为大分子物质。这允许在几十年内将简单分子转化为复杂的大分子物质。高达大约 4% 的盘冰库可以通过这种方式处理，并随后合并到形成星子的原行星盘中面。这一发现表明，星子的形成和有机大分子物质的产生可能存在联系，而有机大分子物质为生命提供了必要的基本元素。