NASA, Rocket Lab and Advanced Space are standing down from the launch of the CAPSTONE (Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment) mission planned for June 27. The teams are evaluating weather and other factors to determine a date for the next launch opportunity.
The next launch opportunity for the mission within the current period is on June 28. But CAPSTONE’s trajectory design means that the spacecraft will arrive at its lunar orbit on November 13, no matter when its launch date falls during the current launch period, which will offer launch opportunities every day till July 27.
As part of CAPSTONE, a microwave oven-sized CubeSat weighing around 25 kilograms will serve as the first spacecraft to test a unique, elliptical lunar orbit. CAPSTONE will help reduce risk for future spacecrafts by validating innovative navigation technologies and verifying the dynamics of this halo-shaped orbit as a pathfinder for Gateway, a Moon-orbiting outpost that is part of NASA’s crucial Artemis program.
The orbit, called a near rectilinear halo orbit (NRHO) is very elongated and its location is at a precise balance point in the gravities of the Earth and the moon. This offers stability for long-term missions like Gateway and will require minimal energy to maintain. The orbit will also establish a location that is an ideal staging area for missions to the Moon and beyond.
On its near pass, the orbit will bring CAPSTONE within 1,600 kilometres of one lunar pole and within 60,000 kilometres at its peak every seven days. This will mean that less propulsion capability will be required for spacecrafts flying to and from the Moon’s surface than other circular orbits.
After a four-month-long journey to the target destination, CAPSTONE will orbit this area around the Moon for at least six months to understand the characteristics of the orbit. Importantly, it will validate the power and propulsion requirements for maintaining its orbit as predicted by NASA’s models, reducing logistical uncertainties. The mission will also demonstrate the reliability of innovative spacecraft-to-spacecraft navigation solutions as well as communication capabilities with Earth. The NRHO provides an unobstructed view of Earth, along with coverage of the lunar South Pole.
CAPSTONE will carry a dedicated payload flight computer and radio that will perform calculations to determine where the CubeSat is in its orbital path. NASA’s Lunar Reconnaissance Orbiter (LRO), which has been circling the moon since 2009, will serve as a reference point for CAPSTONE. The idea is that CAPSTONE will communicate directly with LRO and utilise the data obtained from this crosslink to measure how far it is from LRO and how fast the distance between the two changes, which will help determine CAPSTONE’s position in space.
This information will then be used to evaluate CAPSTONE’s autonomous navigation software, called Cislnar Autonomous Positioning System (CAPS). If successful, the software will allow future spacecrafts to determine their location without having to rely exclusively on Earth-based tracking.
If this capability becomes viable, future space missions could potentially perform without support from the ground, allowing Earth-based antennae to prioritise valuable science data over routine operational tracking. CAPSTONE will launch aboard a Rocket Lab Electron rocket from the company’s Launch Complex 1 in New Zealand when it is ready.