Critical point in the CAPSTONE spacecraft’s deep space path to the Moon

Today, November 13, CAPSTONE will reach the Moon, becoming the first spacecraft to enter a unique, elongated orbit that will support

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Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment (CAPSTONE) is a microwave oven-sized satellite, weighing just 55 pounds, that will be the first CubeSat to fly to and operate at the Moon. It serves as a pathfinder for Gateway, a Moon-orbiting space station that is part of NASA’s Artemis program. CAPSTONE’s mission will help reduce risk for future spacecraft, including Orion, by validating innovative navigation technologies and verifying the dynamics of a type of halo-shaped orbit that has never been flown before.

The pull of gravity from Earth and the Moon interact in this unique orbit – formally known as a near rectilinear halo orbit (NRHO) –  to allow for a semi-stable orbit. There, physics does most of the work of keeping spacecraft in orbit at the Moon. This reduces the need for spacecraft to use fuel to maintain the NRHO compared to other similar orbits. NASA already has big plans for this special type of orbit. Engineers expect it will allow them to park bigger spacecraft – including Gateway – in orbit at the Moon for at least 15 years. Fuel efficiency is key for such long-duration missions.

In this animation, the projected trajectory of CAPSTONE’s near-rectilinear halo orbit (NRHO) is shown in red. The NRHO insertion maneuver and two subsequent correction maneuvers ensure that the spacecraft is correctly inserted into the NRHO. Without a properly executed insertion maneuver, CAPSTONE will fly past the Moon without entering orbit, shown in blue. Credit: Advanced Space/Matt Bolliger

Over the past four months, CAPSTONE has navigated an unusual yet effective deep space path to the Moon. This route—called a ballistic lunar transfer—follows the gravitational contours of space and allows spacecraft to reach their destination without expending any energy. Advanced Space, a small Colorado company that owns and operates CAPSTONE on behalf of NASA designed this unique orbit.

CAPSTONE has performed five maneuvers over the past few months to adjust its trajectory for orbit insertion, where the team has adapted to unexpected challenges to keep CAPSTONE on track. A final maneuver on October 27 accelerated the spacecraft’s arrival at the moon.

“What this CAPSTONE team has overcome so far has been incredible, demonstrating resilience while gaining valuable knowledge. We are grateful to the exceptional individuals who have gone above and beyond NASA, Terran Orbital, Stellar Exploration, NASA’s Deep Space Network and Advanced Space for their tireless work on recovery efforts,” said Bradley Cheetham, principal investigator for CAPSTONE and executive officer at Advanced Space. “Overcoming challenges is the goal of a Pathway mission—CAPSTONE leverages that goal.”

CAPSTONE Revealed in Moonrise: CAPSTONE will fly in cislunar space – the orbital space near and around the Moon. The mission will demonstrate an innovative spacecraft-to-spacecraft navigation solution on the Moon from a near rectilinear halo orbit planned for Artemis’ Gateway. Credit: Illustration by NASA/Daniel Rutter

When CAPSTONE reaches the end of its gravity-driven track and arrives at the Moon, its approach will be perfectly timed for NRHO deployment—the critical point on its route. Although the schedule for CAPSTONE’s previous maneuvers was flexible based on spacecraft performance and other factors, this orbital insertion must occur at precisely the right time for CAPSTONE to enter the correct orbit. While traveling 3,800 miles per hour, it will perform its delicate, precisely timed propulsion maneuver to enter orbit, like a flying trapeze artist leaping from one arch to another with a decisive, acrobatic movement.

The first orbit insertion maneuver is scheduled for Sunday, November 13 at 7:18 PM EST (4:18 PM PST). The CAPSTONE team expects it will take at least five days to analyze the data, perform two cleanup maneuvers, and confirm successful insertion into the near-rectilinear halo orbit.

Beyond that, there are still other goals ahead for this pathfinder CubeSat. Once in lunar orbit, CAPSTONE is scheduled to fire its thrusters once every six and a half days, if necessary, to stay in its orbit for at least six months, allowing NASA and its partners to understand how to operate in this unique orbit . Specifically, CAPSTONE will validate the propulsion requirements to maintain its orbit as predicted by models, reducing logistical uncertainties for future spacecraft.

In addition, a key software technology – the Cislunar Autonomous Positioning System (CAPS) – will be tested in the coming months. CAPS will demonstrate innovative spacecraft-to-spacecraft navigation solutions that will enable future spacecraft to determine their location without relying solely on tracking from Earth. CAPSTONE will do this by communicating directly with NASA’s Lunar Reconnaissance Orbiter – which has been orbiting the moon since 2009 – to determine its own position in space. This capability could enable future spacecraft to perform on their own with less support from the ground and allow ground-based antennas to prioritize valuable science data over more routine operational tracking.

CAPSTONE’s mission will demonstrate several technologies that will lay the foundation for commercial support for future lunar operations. NASA partners are testing ground-breaking tools for mission planning and operations, paving the way and expanding capabilities for small and more affordable space and exploration missions to the Moon,

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CAPSTONE is commercially owned and operated by Advanced Space in Westminster, Colorado. It represents an innovative collaboration between NASA and industry to provide rapid results and feedback to inform future exploration and science missions.  The spacecraft was designed and built by Terran Orbital. Operations are performed jointly by teams at Advanced Space and Terran Orbital.

NASA’s Small Spacecraft Technology program within the agency’s Space Technology Mission Directorate (STMD) funds the demonstration mission. The program is based at NASA’s Ames Research Center in California’s Silicon Valley. The development of CAPSTONE’s navigation technology is supported by NASA’s Small Business Innovation Research and Small Business Technology Transfer (SBIR/STTR) program, also within STMD. The Artemis Campaign Development Division within NASA’s Exploration Systems Development Mission Directorate funded the launch and supports mission operations.