NASA's Arcstone mission uses the Moon as a stable reference point to improve the accuracy of satellite sensors, a project that could standardise space-based Earth observations worldwide.
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NASA's project introduces a novel approach to sensor calibration by measuring lunar reflectance directly from orbit. Researchers hope this space-based method will provide a reliable, universal standard that avoids the inconsistencies caused by Earth's atmosphere and helps align data across a wide range of Earth-observing missions.
Why Calibration Matters
Satellite sensors must be precisely calibrated to provide accurate data about our planet’s climate, oceans, and land. Previously, this has involved using ground-based references or observing the Sun and Moon from Earth. But, atmospheric conditions, clouds, dust, and gases can affect these calibration methods, scattering or absorbing light, and skewing data.
The Moon, however, is remarkably stable. Its surface reflectance properties don’t change much over time and are well understood, making it an ideal candidate for calibration. Until now, the challenge has been measuring it reliably without the atmosphere getting in the way.
The Arcstone Mission
That’s where Arcstone comes in. Still ongoing, NASA’s mission will launch a small CubeSat equipped with a spectrometer to orbit the Earth and observe the Moon directly from space. By measuring the light reflected off the Moon without atmospheric interference, the team aims to create an extremely accurate, SI-traceable reference that can be used to calibrate other satellites.
The spectrometer will collect spectral radiance data (how much light is reflected at different wavelengths) during various lunar phases and angles. By fully analyzing the Moon this way, the data collected will account for changes in how the Moon is lit and viewed from space, ensuring its robustness and wide applicability.
Designed for precision and practicality, the CubeSat features advanced optics, stable detectors, and onboard calibration tools. Its six-month mission will focus on capturing high-fidelity measurements and minimizing errors from instrument drift or misalignment.
Why This Matters
Although full results aren’t yet available, the Arcstone mission is expected to produce the most detailed and reliable lunar reflectance dataset to date. In doing so, it could substantially improve how sensors on Earth-observing satellites are calibrated, helping ensure consistent, high-quality data across different missions.
Standardising calibration using the Moon could reduce discrepancies between different satellites, enhance climate models, and improve environmental monitoring. It also has the potential to recalibrate historical satellite data, giving scientists a clearer picture of long-term climate trends.
The Arcstone mission presents a more stable, autonomous calibration system. Results from the study may shape the next generation of remote sensing instruments, creating sensors that are less dependent on ground-based corrections and more capable of independently maintaining accuracy.
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Looking Ahead
If successful, Arcstone could pave the way for the Moon to become a go-to standard for satellite calibration, accessible to both public and private missions. As a more reliable source of calibration, it would simplify and improve the accuracy of data retrieved from satellite sensors, marking a major step forward in how we observe and understand Earth from space.
Journal Reference
Press Release. NASA. NASA Tech to Use Moonlight to Enhance Measurements from Space. Accessed on 20th June 2025. https://www.nasa.gov/science-research/science-enabling-technology/nasa-tech-to-use-moonlight-to-enhance-measurements-from-space/