The Defense Advanced Research Projects Agency (DARPA) has issued a program solicitation for a novel mission: Lunar Assay via Small Satellite Orbiter (LASSO). This ambitious project aims to develop a small lunar orbiter capable of operating in very low lunar orbits, as low as 10 kilometers, while simultaneously prospecting for water ice.
DARPA's interest in LASSO is twofold. First, the mission will serve as a crucial testbed for navigation and propulsion technologies required for operations in these challenging low orbits. The irregular lunar gravitational field, caused by mass concentrations, necessitates frequent maneuvers to maintain a safe orbit. The technologies developed for LASSO will have broader applications in cislunar space, aligning with the Space Force's interest in cislunar space situational awareness (SSA). "Sustained and advanced maneuverability for spacecraft is key to enabling further improvements of SSA in cislunar space," the solicitation emphasizes.
Secondly, LASSO will map the lunar surface to pinpoint concentrations of water ice. The objective is to identify regions with subsurface water ice concentrations of at least 5%, large enough to justify the cost and energy of retrieval. The goal is to map the entire lunar surface within four years. "LASSO will benefit DARPA, and eventually [the U.S. Space Force], by establishing new technologies that can offer increased maneuverability and SSA while also supporting commercial space capabilities and NASA missions by identifying the existence of proven reserves of water," DARPA stated.
The procurement process involves a phased approach. DARPA is initially seeking six-page abstracts, followed by oral presentations. Selected proposals will then undergo a six-month conceptual design study (Phase 1A), followed by an 18-month Phase 1B. A single provider will be chosen for Phase 2, a one-year effort to construct the LASSO spacecraft. While DARPA's involvement ends with the completed spacecraft, collaboration with NASA is planned for launch.
The spacecraft must fit within a standard ESPA payload adapter. This project contrasts with NASA's own challenges in lunar water ice prospecting, with recent setbacks experienced by missions such as Lunar Trailblazer and VIPER. DARPA requires a "rough order of magnitude" cost estimate in initial proposals, with a more detailed price needed in the oral presentation, emphasizing the need for a "reasonable, realistic, and affordable" approach.
LASSO is the latest in a series of DARPA's lunar initiatives, building upon the 10-Year Lunar Architecture (LunA-10) project and the Lunar Operating Guidelines for Infrastructure Consortium (LOGIC). Michael Nayak, a DARPA program manager, highlighted the need for large-scale power and thermal systems to support lunar mining, directly relevant to LASSO's objectives. He also mentioned DARPA's interest in "very-low-altitude prospecting around the moon."