SMILE and the New Era of Space Weather Observation: How It Compares to Cluster, MMS, and Solar Orbiter

Image Credit: ESA/ATG medialab

Understanding space weather requires more than a single vantage point. Over the past decades, heliophysics missions have progressively uncovered how energy and particles travel from the Sun to Earth, shaping the environment around our planet. Yet, each mission has traditionally focused on a specific layer of this complex system.

The upcoming SMILE mission (Solar wind–Magnetosphere–Ionosphere Link Explorer) represents a significant shift in this approach. Rather than zooming in on isolated processes, SMILE is designed to observe the system as a whole—bridging a longstanding gap between global context and local measurements.

Looking Upstream: The Solar Perspective

While Cluster and MMS focus on Earth’s immediate environment, Solar Orbiter shifts attention to the source of space weather—the Sun.

Solar Orbiter studies the solar wind, magnetic fields, and energetic events such as solar flares and coronal mass ejections. By linking solar activity to the heliosphere, it provides critical insight into how disturbances originate and propagate through space.

Yet, despite its importance, Solar Orbiter does not directly observe how these disturbances interact with Earth’s magnetosphere.

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SMILE: A System-Level Approach

This is where SMILE mission introduces a transformative capability.

SMILE is the first mission specifically designed to image Earth’s magnetosphere on a global scale. By combining soft X-ray imaging, ultraviolet observations of auroras, and in-situ measurements, it will capture the full chain of interactions from the solar wind to the ionosphere.

Its most innovative feature—global X-ray imaging—will allow scientists to visualize the boundary between the solar wind and Earth’s magnetic field, known as the magnetopause. This boundary is highly dynamic, constantly reshaped by solar activity, yet it has never been observed continuously at a global level.

In effect, SMILE will provide something analogous to a weather satellite for near-Earth space, offering continuous, large-scale observations of processes that have previously been studied only in fragments.

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Complementarity, Not Competition

Rather than replacing earlier missions, SMILE enhances their scientific value by providing the missing context.

• Data from MMS can reveal the fine-scale physics of magnetic reconnection—but SMILE will show where and when these events occur globally.
• Cluster’s multi-point measurements can map local plasma structures—while SMILE tracks how those structures evolve across the entire magnetosphere.
• Solar Orbiter identifies disturbances at their origin—SMILE observes their impact on Earth’s space environment.

Together, these missions form a multi-scale observational system:

• Solar Orbiter → origin of space weather at the Sun
• SMILE → global response of Earth’s magnetosphere
• Cluster & MMS → underlying physical processes

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A Step Toward Predictive Space Weather

One of the major challenges in space weather science is moving from observation to prediction. This requires not only understanding the physics at small scales, but also capturing how those processes unfold across the entire system.

By linking global imaging with in-situ measurements, SMILE is expected to play a crucial role in this transition. It will enable scientists to connect localized events—such as reconnection—to large-scale consequences, including geomagnetic storms and auroral activity.

The evolution of heliophysics missions reflects a broader trend in space science: from isolated measurements toward integrated, system-level understanding.

Cluster and MMS have revealed the fine details of plasma behavior. Solar Orbiter has illuminated the origins of solar activity. SMILE now brings these perspectives together, offering the first comprehensive view of how energy flows through the Sun–Earth system.

In doing so, it marks the beginning of a new era—one in which space weather can be observed not just as a collection of events, but as a fully connected, dynamic system.