Solar storms speed up satellite decay in Low Earth Orbit
When the Sun erupts with solar storms, the Earth-facing side of space becomes a dynamic, sometimes hazardous environment for satellites. Recent observations and comments from space agencies highlight a notable effect: low Earth orbit (LEO) objects—ranging from communication satellites to scientific platforms—experience increased drag during solar storms, leading to faster orbital decay. This phenomenon challenges mission planners and underscores the importance of space weather monitoring for ongoing operations in LEO.
What causes the accelerated decay?
Solar storms eject charged particles and emit heightened levels of ultraviolet radiation and X-rays. As these solar energetic particles (SEPs) and coronal mass ejections (CMEs) interact with Earth’s upper atmosphere, they heat and expand the exosphere. The result is a thicker, more buoyant air layer at altitudes where satellites orbit. Even a modest expansion can raise atmospheric density by orders of magnitude, increasing atmospheric drag on fast-moving spacecraft. For satellites in roughly 160 to 2,000 kilometers above the Earth, this extra drag reduces velocity, lowers altitudes, and shortens orbital lifetimes if unmitigated.
Monitoring and mitigation: ISRO’s Master Control Facility
Intent on safeguarding assets, ISRO relies on its Master Control Facility (MCF) to closely monitor the orbits of operational satellites during periods of heightened solar activity. The facility, which coordinates all primary orbital control operations for Indian satellites, tracks perigee and apogee shifts induced by atmospheric drag. When an event like a solar storm is detected, satellite operators may adjust altitudes or orientations to minimize energy loss and maintain mission objectives. In some cases, thruster firings or mission-specific attitude changes can compensate for the drag-induced perturbations, preserving pointing accuracy and communication links.
Active regions and sunspot activity influence space weather
A cluster of sunspots named Active Region 4274 has drawn attention for its potential to drive space weather. Sunspots, dark blemishes on the Sun’s surface, indicate regions of intense magnetic activity. When these regions unleash eruptions, they can generate streams of charged particles that reach Earth within hours to days. These events contribute to geomagnetic storms and enhanced atmospheric heating, directly impacting satellite drag in LEO. Space agencies and private operators alike track sunspot groups and solar flux to forecast disturbances and issue warnings for mission-critical operations.
Operational implications for satellites in LEO
Increased atmospheric drag during solar storms can perturb satellite orbits, complicating collision avoidance, ground tracking, and orbit maintenance. Operators may see short-term altitude drops, which can require more frequent propulsion maneuvers or adjustments to maintain required ground coverage or constellation geometry. For multinational fleets, coordinated orbital corrections are essential to prevent closer approaches and to keep communication and observation schedules on track. The current understanding is that the most pronounced effects occur during elevated phases of solar activity, particularly when the Sun emits high-energy particles toward Earth.
Forecasting space weather and safeguarding assets
Accurate space weather forecasting relies on a network of solar observatories and terrestrial sensors. By analyzing solar wind parameters, X-ray flux, and the structure of magnetic fields on the Sun, scientists predict geomagnetic disturbances and the potential increase in drag. Operators translate these forecasts into operational steps: scheduling safe modes, delaying non-critical maneuvers, and prioritizing essential communications tasks. Ongoing research aims to refine drag models for LEO and improve degradation predictions for satellite subsystems, ensuring resilience amid the Sun’s variability.
Conclusion
Solar storms are a natural part of the space environment, but their impact on orbiting satellites is tangible. The accelerated decay of satellites in Low Earth Orbit during solar activity underscores the need for proactive space weather monitoring, precise orbit control, and robust mission design. With facilities like ISRO’s Master Control Facility and global space weather networks, operators can anticipate disturbances and implement mitigations to keep satellites orbiting safely and serving their missions.
