CAPSTONE: Revolutionizing Lunar Exploration with Cislunar Autonomous Positioning System Technology.

In the pursuit of advancing human exploration beyond the confines of Earth, NASA, in collaboration with international space agencies, is dedicated to the development of the Lunar Gateway space station. This ambitious project entails ensuring the orbital stability of the Gateway and testing cutting-edge navigation systems. CAPSTONE (Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment) emerges as a groundbreaking mission meticulously designed to address these crucial objectives. This article delves into the profound significance of CAPSTONE, outlining its mission objectives, spacecraft particulars, launch details, and its pivotal role within NASA's Artemis program.

Background

The Lunar Gateway, a concept nurtured since 2018 through a collaborative effort between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA), embodies a pivotal hub for scientific research, communication, and transient habitation on the Moon. Serving as a rendezvous point for rovers and robots, the Gateway facilitates lunar surface activities. A key architectural element of the Gateway is the innovative near-rectilinear halo orbit (NRHO), a lunar orbit that combines exceptional long-term stability with minimal propellant requirements for orbital station-keeping.

Read more about the gateway at :  https://www.nasa.gov/gateway/overview

CAPSTONE Mission Objectives

The CAPSTONE mission launched on June 28, 2022. Rocket Lab’s Photon satellite bus delivered CAPSTONE into a trajectory toward the Moon.

Credits: Illustration by NASA/Daniel Rutter

The primary aim of the CAPSTONE mission lies in validating the theoretical orbital stability simulations for the Lunar Gateway by deploying an operational spacecraft. CAPSTONE boasts the distinction of being the first spacecraft to operate within the NRHO, thereby generating invaluable data to affirm the precision and feasibility of the planned orbital trajectory.

Furthermore, CAPSTONE seeks to test the pioneering Cislunar Autonomous Positioning System (CAPS), an advanced navigation system. CAPS empowers the spacecraft to autonomously determine its position relative to NASA's Lunar Reconnaissance Orbiter (LRO) without relying on ground-based tracking stations. The successful demonstration of CAPS will pave the way for enhanced autonomous navigation capabilities in future lunar missions.

Spacecraft Overview

CAPSTONE takes the form of a 12-unit CubeSat, a compact satellite platform comprised of modular cube-shaped units. The prestigious $13.7 million contract for the mission was awarded to Advanced Space, a private company headquartered in Boulder, Colorado, through a Small Business Innovation Research (SBIR) contract. Advanced Space assumed project management responsibilities and played a pivotal role in developing crucial technologies, including the CAPS positioning navigation system.

The spacecraft bus, responsible for housing the CubeSat components and providing necessary subsystems, was developed and constructed by Tyvak Nano-Satellite Systems in Irvine, California. Stellar Exploration, Inc, specialized in the development of the propulsion systems for CAPSTONE, employing Hydrazine as the propellant.

Launch Details

CAPSTONE was successfully launched on June 28, 2022, aboard a Rocket Lab Electron booster. Originally planned for liftoff from the Mid-Atlantic Regional Spaceport (MARS) in Virginia, the launch site was subsequently changed to Mahia, LC-1 in New Zealand. The launch contract with Rocket Lab was valued at approximately $9.95 million.

Upon separation from the second stage, the Rocket Lab's Photon kick stage orchestrated CAPSTONE's transfer into a lunar trajectory over the course of six days. This trajectory involved a series of precisely calculated engine burns to gradually increase the orbital apogee. Following the trans-lunar injection (TLI) burn, CAPSTONE was successfully deployed, embarking on its monumental voyage towards the Moon.

You can watch the launch here: 

CAPSTONE Mission Progress

Shortly after separating from the Photon stage, NASA encountered a temporary communication loss with CAPSTONE. However, on July 6, mission operators managed to re-establish contact with the spacecraft, underscoring the resilience and determination of the mission team. By September 30, CAPSTONE achieved "power positive" status, affirming a stable trajectory towards the Moon.

The mission encountered a challenge with a partially open valve on one of the thrusters, resulting in unintended thrust when the propulsion system was pressurized. The mission team worked diligently to rectify the issue, and on October 7, they successfully regained full 3-axis attitude control, ensuring CAPSTONE remained on course to reach its intended orbit.

Ballistic Lunar Transfer

Diverging from conventional direct Hohmann transfers, CAPSTONE employs a ballistic transfer trajectory to reach the Moon. Although this approach lengthens the travel time to approximately four months, it significantly reduces the propulsion requirements, enabling a higher payload capacity. Departing from Earth orbit, CAPSTONE traversed a distance of about 1.5 million kilometers, where the gravitational influence of the Sun became prominent. Subsequently, the spacecraft descended back towards the Earth, intersecting the Moon's orbit and ultimately entering the intended NRHO on November 14, 2022.

Mission Operations

Upon attaining lunar orbit, CAPSTONE initiated its primary mission phase, projected to span approximately six months. Throughout this duration, the spacecraft diligently gathers essential data, conducting close flybys within 1,000 miles (1,600 km) of the Moon's North Pole and reaching a farthest distance of approximately 43,500 miles (70,000 km) from the South Pole. These data will yield critical insights into the lunar environment, NRHO behavior, and contribute to the refinement of future lunar exploration strategies.

Conclusion

The CAPSTONE mission represents a significant leap towards advancing lunar exploration and bolstering NASA's Artemis program. By validating orbital stability simulations and testing the revolutionary Cislunar Autonomous Positioning System (CAPS), CAPSTONE assumes a pivotal role in ensuring the success of the Lunar Gateway space station. Through its extraordinary journey to the Moon and the collection of invaluable data, CAPSTONE epitomizes the ingenuity, determination, and unwavering commitment of the mission team in pushing the boundaries of human exploration and expanding our understanding of the cosmos. This pioneering mission establishes the foundation for future lunar endeavors, cementing our presence on the Moon and propelling us further into the realms of space exploration.