Engineers Race to Overcome Challenges of Ultra-Low Orbit Satellites

As low Earth orbit becomes crowded, scientists are turning to an even closer frontier: very low Earth orbit satellites. With over 15,000 satellites currently orbiting Earth at altitudes above 1,200 miles (2,000 km), the planned expansion of constellations like SpaceX's Starlink threatens to further congest traditional low Earth orbit (LEO).

Researchers are now exploring the 60-250 mile (100-400 km) range of very low Earth orbit (VLEO), where satellites could offer enhanced imaging resolution for agriculture and climate science, reduced communication latency, and improved weather forecasting capabilities.

However, VLEO presents significant engineering challenges. Atmospheric drag at these altitudes causes satellites to deorbit within weeks or days without active propulsion systems.

Atomic oxygen corrosion and extreme thermal fluctuations—reaching up to 1,500°C—also threaten satellite longevity. A Penn State-led team is developing an air-breathing microwave plasma thruster to counteract drag, leveraging atmospheric gases as propellant.

This technology, funded by the U.S. Department of Defense, aligns with Red Wire's Otter project, which explores atmosphere-breathing thrusters for sustained VLEO operations.

"Atmosphere itself can be used as a fuel," noted Sven G. Bilén, highlighting the potential of air-breathing propulsion." The Earth's atmosphere is still thick enough to slow down satellites."

While these advancements address immediate technical barriers, the projected $220 billion investment in VLEO-related missions over three years remains speculative, representing proposed initiatives rather than realized infrastructure.

Researchers emphasize that confirmed advantages—such as imaging resolution and latency reduction—must be distinguished from hypothetical applications like global internet access or real-time climate monitoring.