NASA Wants to Float Microscopic 'Tracers' on Sunlight to Map the Edge of Space

NASA has developed a new technology called photophoretic sensors that can float in the "ignorosphere," a region between 30-100 kilometers where traditional methods like balloons and satellites are insufficient. The sensors, made of transparent materials with a dark bottom, use sunlight to create a temperature differential, generating a small thrust that allows them to float at atmospheric levels. This technology, developed by Benjamin Schafer of Rarefied Technologies, can stay in the ignorosphere for months, providing long-term data on atmospheric conditions that influence weather globally. The sensors are designed to degrade in UV light, ensuring they return to Earth without becoming space debris.

• "The sensors are deployed using high-altitude balloons or sounding rockets to reach 30 km, then autonomously rise to 90-100 km."
• "The sensors are too light to require batteries or active data transmission."
• "Satellites will track them using LIDAR light reflections to study wind flow patterns."
• "The technology is still in the early stages, with a Phase I grant of a few hundred thousand dollars."
• "The mission aims to provide real-time data on ionospheric weather conditions with unprecedented sensitivity."

The photophoretic effect works best in the upper atmosphere, where there is enough gas to create the necessary kinetic energy transfer. However, it is not effective at sea level or in a vacuum. The sensors are designed to intentionally degrade in UV light, ensuring they return to Earth once their surfaces are sufficiently damaged. While the technology shows promise, it still faces challenges, including altitude loss during the night and the complexity of tracking thousands of sensors. The mission represents a bold step in space exploration, highlighting the potential of innovative, low-cost sensors to improve our understanding of the upper atmosphere.

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