Proba-3 lost contact with the Coronagraph spacecraft: ESA investigates the failure and seeks a way to recover the mission
The European Space Agency announced on 6 March 2026 that an attempt is under way to re-establish contact with the Coronagraph spacecraft, one of the two satellites that make up the Proba-3 mission. According to the official statement, the problem began during the weekend of 14 and 15 February 2026, when an anomaly on the spacecraft triggered a chain of events that led to a gradual loss of attitude in space. This also prevented entry into safe mode, which is a key protective mechanism for missions of this kind in extraordinary circumstances.
ESA has not yet stated a final cause of the failure, but the description of events suggests that the problem quickly worsened because the solar panels lost their proper orientation. When the panel was no longer facing the Sun, the battery began to drain rapidly. This eventually drove the spacecraft into so-called survival mode, a state in which only minimal electronics remain active, while data transmission to Earth is interrupted. In practice, this means that operators no longer have access to the usual telemetry stream and that every recovery attempt must start from very limited information about the actual state of the system.
Why the problem is serious, but also why the mission is not yet lost
The loss of contact with one of the two satellites is particularly sensitive for Proba-3 because this is a mission that functions as a precisely coordinated pair. Coronagraph and Occulter were not conceived as two separate devices performing tasks independently, but as a single space instrument made up of two spacecraft flying in a strictly coordinated formation in orbit. In the most precise operating mode, they are separated by approximately 150 metres and must maintain their relative position with millimetre-level accuracy. It is precisely this level of precision that allows Occulter, with its disc, to block the Sun’s glare, while Coronagraph observes the otherwise difficult-to-see inner corona from within the shadow.
Despite the loss of communication with Coronagraph, ESA stresses that the other spacecraft, Occulter, remains healthy and operational. At this moment, that is the most important piece of good news for the entire mission. Occulter is not merely the “other half” of the experiment, but also a potential tool for saving the situation. One of the priorities of the operations team is now to assess whether that spacecraft could safely approach Coronagraph and observe its orientation in space from close range. Such a manoeuvre would not serve a sensational “rescue docking”, but rather the collection of visual and navigation data that could help specialists on Earth better understand the attitude of the damaged spacecraft and whether there is a realistic chance of restoring communication.
A mission that had been delivering world firsts before the problem
The seriousness of the current standstill becomes even more apparent when one looks at what Proba-3 achieved before the anomaly. ESA describes this mission as its first “eclipse-making” mission, that is, the first project dedicated to creating an artificial solar eclipse in orbit. The two satellites were launched on 5 December 2024 from India’s Satish Dhawan Space Centre aboard a PSLV-XL rocket, and the initial phase of the mission was controlled from the European ESEC centre in Redu, Belgium. From the outset, Proba-3 carried technological risk, but also great scientific potential, because it was meant to demonstrate that two spacecraft can fly as one virtual instrument.
And it succeeded. During 2025, Proba-3 achieved the first autonomous precise formation flying of its kind in orbit, and in June 2025 ESA also released the first images of an artificially induced solar eclipse. This confirmed that the two satellites can align with the Sun so that Occulter’s disc, 1.4 metres in diameter, casts a narrowly defined shadow onto the ASPIICS optical instrument on Coronagraph. That shadow passes across an instrument aperture only a few centimetres wide, which says enough about how technically demanding the entire undertaking is. The success was important also because it opened the way to multi-hour observations of the solar corona, rather than only short “captured” moments such as those made possible by natural total eclipses seen from Earth.
What Proba-3 sees that other instruments struggle to capture
The scientific value of the mission lies in the fact that it fills one of the most stubborn observational gaps in solar physics. Ground-based and space-based instruments can see the solar disc and the outer parts of the corona well, but the inner region of the corona long remained less accessible, except during rare and brief natural eclipses. It is precisely there, according to ESA’s explanations, that the solar wind accelerates before spreading through the Solar System, and from the same region many coronal mass ejections also develop, phenomena that can have a measurable effect on space weather, communication systems, navigation, and power infrastructure on Earth.
ASPIICS, the main coronagraph on the Coronagraph spacecraft, was developed for ESA under the leadership of Belgium’s Centre Spatial de Liège. The instrument’s task is not only to produce an attractive image of the Sun’s halo, but to enable stable and detailed observations very close to the solar limb, with minimal influence from scattered light. That is exactly why Proba-3 must have two separate satellites: when the occulting disc and the telescope are physically separated by about 150 metres, it is possible to achieve optical quality that is much harder to obtain with conventional solutions. As early as late 2025, ESA announced that the mission had already produced more than 50 artificial eclipses and around 250 hours of observations spread across 50 orbits, providing scientists with an amount of data that, in the assessment of the project team, can be compared with thousands of ground-based campaigns tracking total eclipses.
The anomaly struck the spacecraft that leads the formation
The current situation is made even more serious by the fact that Coronagraph had a leading role in the mission’s operational architecture. ESA’s technical materials state that this spacecraft leads the formation, manages its acquisition and separation, and carries the main scientific instrument pointed at the Sun. If it is precisely the leading spacecraft that has lost stable attitude, the consequences are not only communicational but also dynamic: the mission loses a key reference element for precise alignment, and any possible approach by Occulter must be planned carefully so as not to increase the risk of collision or further loss of control.
From the beginning, Proba-3 was designed with the awareness that safety is more complex than with typical small satellites. In its description of operations, ESA states that the mission has one of the most critical safe modes among projects in the Proba family precisely because two bodies fly relatively close together and must avoid both mutual collision and external threats such as space debris. That is why, in the current case, it is particularly indicative that the anomaly, according to the official statement, did not allow entry into safe mode. In other words, a sequence of failures or incorrect states occurred that bypassed or disabled the protective scenario designed specifically for crisis moments.
From 14 February to 6 March: what can currently be concluded from the official data
The time gap between the event itself and the public announcement is also telling. ESA states that the anomaly occurred during the weekend of 14 and 15 February 2026, while the news of the loss of contact was published on 6 March 2026. This suggests that the operations teams were not merely reacting to an immediate communication outage, but spent more than two weeks trying to understand the state of the spacecraft, assess the available options, and define what could safely be communicated to the public at that stage. Such caution in space operations is not unusual: a premature announcement of incomplete conclusions could create a misleading picture of the nature of the problem and, even more importantly, could divert attention from the operational work of recovering the mission.
According to the information currently available, several elements are nonetheless clear. First, the problem did not affect the entire mission, but specifically the Coronagraph spacecraft. Second, Occulter remained functional. Third, communication with the affected spacecraft was lost gradually, after the loss of attitude and battery depletion, rather than in a single sudden event such as a known breakup, explosion, or confirmed collision. Fourth, the teams still see enough reason to consider active recovery, including the possible use of the other spacecraft to observe the situation in orbit. This does not guarantee success, but it shows that the situation has not been declared hopeless in advance.
Why attitude is crucial for a satellite’s survival
In public discussion, the loss of spacecraft attitude is often perceived as a technical detail, but in reality it is one of the most critical problems a satellite can experience. Attitude determines where the solar panels, antennas, sensors, and instruments are pointing. If the spacecraft can no longer reliably orient itself toward the Sun, the energy balance becomes negative: the battery is depleted and the available power drops below the level needed to operate key systems. If, at the same time, the antenna can no longer maintain a favourable position toward Earth, communication weakens further or disappears entirely. In the case of Proba-3, this is particularly sensitive because the spacecraft is not carrying out a simple stabilised observation mission, but is part of a two-satellite system that must maintain extremely precise geometry.
ESA’s earlier explanations also show why safe mode was supposed to be the last line of defence. That operating mode is intended to simplify spacecraft behaviour as much as possible in emergency circumstances: reduce the activity of non-essential systems, stabilise attitude as far as possible, and maintain the basic energy and communication function until operators on Earth take over the next steps. In this case, according to the official description, that protection was not achieved. This left the spacecraft more exposed to rapid energy collapse, which explains why it ended up in survival mode with minimal electronics and no data transmission.
Broader consequences for science and for future missions
Although saving the spacecraft itself is the immediate priority, this event also has broader significance. Proba-3 is not only a scientific mission focused on the solar corona, but also a demonstrator of precise formation-flying technologies that could in the future be important for servicing satellites in orbit, complex rendezvous operations, and even advanced research projects in deep space. Any serious failure on such a mission is therefore both an operational problem and a valuable source of lessons for the future design of autonomy, navigation, attitude-control systems, and crisis procedures.
That is especially important because Proba-3 has so far served as proof that extremely precise coordination between two spacecraft is not merely a theoretical possibility, but an operational reality. ESA has repeatedly stressed that the mission had already fulfilled its core technological goals. In other words, even before this anomaly, Proba-3 had already entered history through its demonstration of formation flying with previously unseen precision. But that is precisely why the current crisis is also, in a way, a test of the “other side” of technological ambition: not only how accurate a system can be when everything works, but also how resilient it can be when something goes wrong.
What comes next in the coming days
At this moment, there is no official confirmation that contact with Coronagraph has been restored. ESA’s latest publicly available statement, as of 7 March 2026, states only that the investigation and recovery attempts are ongoing. This means that any speculation about the final outcome would be premature. Possible scenarios range from a partial recovery of communication and limited stabilisation, through a prolonged attempt at diagnosis with a minimal signal, all the way to the possibility that Coronagraph may never be returned to full operational function. At this moment, none of those outcomes has been confirmed.
For the scientific community and for the European space sector, the two most important things will be these. The first is whether it will be possible to extract at least basic data on the cause of the anomaly from the affected spacecraft. The second is whether the remaining healthy part of the mission, Occulter, can contribute to recovery or at least provide key information about the condition of its partner in orbit. The fact that ESA speaks openly about that possibility shows that the operations team has not abandoned an active approach. And while waiting for a new official bulletin, Proba-3 remains a reminder that even the greatest technological successes in space are inseparable from risk, but also that the true value of such missions is often measured precisely by the way they cope with unforeseen failures.
Sources:- European Space Agency (ESA) – official statement on the loss of contact with the Coronagraph spacecraft and recovery attempts (link)- European Space Agency (ESA) – official Proba-3 mission page with the latest updates and basic mission data (link)- European Space Agency (ESA) – announcement on the first artificial solar eclipse in orbit and the operation of the ASPIICS instrument (link)- European Space Agency (ESA) – overview of the mission’s scientific results and data on more than 50 artificial eclipses and around 250 hours of observations (link)- European Space Agency (ESA) – description of mission operations, safe mode, and the operational risks of precise formation flying (link)- European Space Agency (ESA) – press release on the launch of Proba-3, its orbit, and mission goals (link)- European Space Agency (ESA) – frequently asked questions about Proba-3, the planned mission duration, and the industrial framework (link)
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