NASA is set to launch a groundbreaking instrument named Arcstone, designed to enhance the precision of data collected by Earth-viewing sensors in orbit. This mission marks a significant technological advancement as it will be the first to focus exclusively on measuring lunar reflectance from space, a method known as lunar calibration. The goal is to establish a high-accuracy, universal standard that can be utilized by the international scientific community and commercial space industry.
The initiative aims to ensure the accuracy of satellite and airborne sensors by calibrating them against a known standard measurement. Arcstone is poised to be a game-changer, providing this crucial calibration by measuring sunlight reflected from the Moon. This approach is expected to improve the quality of data obtained from Earth-observing instruments in orbit.
Revolutionizing Calibration with Lunar Reflectance
The mission involves a visualization of how Arcstone will operate in orbit, measuring lunar reflectance to establish a new calibration standard for future Earth-observing remote sensors. The satellite platform for Arcstone was developed by Blue Canyon Technologies, a leader in satellite manufacturing.
‘One of the most challenging tasks in remote sensing from space is achieving required instrument calibration accuracy on-orbit,’ said Constantine Lukashin, principal investigator for the Arcstone mission and physical scientist at NASA’s Langley Research Center in Hampton, Virginia. ‘The Moon is an excellent and available calibration source beyond Earth’s atmosphere. The light reflected off the Moon is extremely stable and measurable at a very high level of detail.’
Arcstone’s mission is to improve the accuracy of lunar calibration, thereby enhancing the quality of spaceborne remote sensing data products for future generations. Over its planned six-month mission, Arcstone will utilize a spectrometer to measure lunar spectral reflectance, providing a detailed analysis of light by separating it into its constituent wavelengths.
Innovative Design and Global Impact
Expected to launch in late June as a rideshare on a small CubeSat, Arcstone will begin collecting data approximately three weeks after reaching orbit, a milestone known as first light. The mission showcases a new, cost-efficient instrument design, hardware performance, operations, and data processing to achieve high-accuracy reference measurements of lunar spectral reflectance.
‘The mission demonstrates a new, more cost-efficient instrument design, hardware performance, operations, and data processing to achieve high-accuracy reference measurements of lunar spectral reflectance,’ said Lukashin.
By measuring lunar reflectance at necessary ranges of lunar phase angles and librations, Arcstone aims to build a highly accurate lunar reference. This capability will allow other instruments to use the Moon to calibrate sensors, overcoming the atmospheric interference that affects Earth-based measurements.
Establishing a Universal Calibration Standard
Currently, there is no internationally accepted standard (SI-traceable) calibration for lunar reflectance from space. Researchers already use the Sun and Moon for calibration, but not with the precision that could be achieved with a universal standard.
‘Dedicated radiometric characterization measurements of the Moon have never been acquired from a space-based platform,’ said Thomas Stone, co-investigator for Arcstone and scientist at the U.S. Geological Survey (USGS). ‘A high-accuracy, SI-traceable lunar calibration system enables several important capabilities for space-based Earth observing missions.’
If successful, Arcstone could pave the way for a longer mission, allowing scientists to make the Moon the preferred reference standard for many satellites. This new calibration standard could also be applied retroactively to previous Earth data records, improving their accuracy and filling in data gaps.
Future Implications and Collaborations
The Arcstone project is funded by NASA’s Earth Science Technology Office’s In-space Validation of Earth Science Technologies and is led by NASA’s Langley Research Center. It involves collaboration with Colorado University Boulder’s Laboratory for Atmospheric and Space Physics, USGS, NASA Goddard Space Flight Center, Resonon Inc., Blue Canyon Technologies, and Quartus Engineering.
‘Earth observations from space play a critical role in monitoring the environmental health of our planet,’ said Stone. ‘Lunar calibration is a robust and cost-effective way to achieve high accuracy and inter-consistency of Earth observation datasets, enabling more accurate assessments of Earth’s current state and more reliable predictions of future trends.’
As the world increasingly relies on satellite data for environmental monitoring and other applications, the success of Arcstone could have far-reaching implications. By establishing a universal calibration standard, NASA is not only enhancing the accuracy of current data but also ensuring the reliability of future space missions.
