Two small spacecraft will practice meeting each other around the Moon

NASA plans to send a matched pair of small spacecraft into lunar orbit to rehearse one of the hardest parts of future Moon missions: finding, approaching and flying near another vehicle without constant control from Earth. CAPSTONE 02 is targeted for launch in 2027 and remains in development.

The mission will not carry astronauts or land on the Moon. It is a technology demonstration intended to expose navigation software, sensors and operating procedures to the three-body dynamics created by the combined gravity of Earth and the Moon.

Two identical spacecraft will trade roles

The NASA mission announcement describes two identical spacecraft of about 400 kilograms, or 882 pounds, built by Terran Orbital Systems. During a series of exercises, one vehicle will act as the chaser and the other as the target. Each can switch roles, allowing operators to test more scenarios without relying on two differently equipped craft.

The pair will conduct rendezvous and proximity operations, loiter near one another and practice formation flight. Those tasks require accurate relative position, controlled closing speeds and reliable rules for breaking away when measurements disagree. Small errors that are manageable at long distance can become dangerous as two spacecraft approach.

Rendezvous is a sequence rather than a single maneuver. Controllers first establish both vehicles’ orbits, reduce the distance in planned stages and hold at checkpoints while the navigation solution is assessed. A chaser also needs a safe retreat path if a sensor stops reporting or an unexpected drift develops. Repeating those phases with the roles reversed will show whether the hardware and software behave consistently instead of succeeding only under one favorable arrangement.

Lunar navigation cannot depend entirely on Earth

Most spacecraft navigation still relies heavily on ground tracking and commands. That arrangement becomes less efficient as activity around the Moon grows and vehicles must respond quickly to one another. CAPSTONE 02 will combine ground measurements with optical sensors, celestial references and inter-spacecraft information so one vehicle can locate and approach the other.

The demonstration will test three NASA-developed navigation software suites. Each will collect data during a low-energy transfer that carries the vehicles beyond the Moon before they settle into lunar orbit. The spacecraft will also carry an optical imaging payload from Lawrence Livermore National Laboratory to support navigation and photograph the Moon.

Three-body orbits make the rehearsal difficult

In low Earth orbit, mission planners can model motion primarily around one dominant body. Near the Moon, both lunar and terrestrial gravity materially shape a spacecraft’s path. These three-body trajectories can be efficient, but their geometry and changing forces make close operations more complex.

NASA says the planned techniques resemble those needed when the Orion crew capsule approaches a lunar lander in deep space. A future crew transfer depends on knowing that navigation systems can guide vehicles together safely without conditions that can be fully recreated in a ground laboratory. Flight testing supplies the environmental and operational evidence that simulations cannot.

CAPSTONE 02 builds on a smaller pathfinder

The original CAPSTONE mission used a 12-unit CubeSat to enter a near-rectilinear halo orbit around the Moon. It validated communication, networking and autonomous navigation techniques, including peer-to-peer ranging with the Lunar Reconnaissance Orbiter. That mission focused on proving an orbit and basic cislunar operations with one small vehicle.

The current CAPSTONE 02 page lists the follow-on as “In Development.” The new mission shifts from orbit validation to coordinated operations between two substantially larger spacecraft. It will also continue measuring radiation around the Moon and test cislunar communications, giving the flight more than one technology objective.

Autonomy is part of a larger lunar infrastructure

NASA frames the mission as groundwork for Artemis, a planned Moon Base and commercial services in cislunar space. More spacecraft will create demand for repeatable navigation, docking, communications and traffic coordination. Automating routine position calculations could reduce the load on ground teams and allow vehicles to cooperate when direct contact with Earth is delayed or interrupted.

The mission also represents a procurement model. NASA awarded Advanced Space a contract to lead the demonstration and used a Small Business Innovation Research Phase III arrangement. Cost-effective, rapidly deployable spacecraft could let agencies test capabilities in flight without putting every experiment on a large flagship mission.

The 2027 target is a plan, not a completed milestone

Launch dates and spacecraft designs can change during development. NASA’s July 2026 materials establish the mission, its contractor, intended spacecraft and targeted year, but they do not show that integration, environmental testing or launch readiness has been completed. The strongest current claim is that the two-vehicle rehearsal is funded and in development.

If it flies as planned, success will not be measured by a dramatic destination. The value will come from repeatable close approaches, reliable role changes and navigation data that future crewed and robotic missions can use. Practicing with small uncrewed vehicles places the risk where a technology demonstration can absorb it.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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