Sentinel-2A gets “night vision”: ESA tested the Copernicus satellite in the dark and opened the door to a new generation of imaging
After more than ten years in orbit, the Copernicus Sentinel-2A satellite is once again in the spotlight – this time because of an experiment that until recently was considered outside the scope of its mission. During special tests, the European Space Agency (ESA) activated its optical instrument during night passes as well, even though the current generation of Sentinel-2 satellites is not designed to systematically image in darkness. According to ESA’s announcement of 15 January 2026, under such conditions the satellite managed to register a range of night-time targets, from flares at oil fields to traces of major fires and the lights of fishing vessels.
The experiment comes at a time when, operationally, the Sentinel-2 mission is led by the younger “family members”, Sentinel-2B and Sentinel-2C. Precisely for that reason, ESA could direct part of the older satellite’s remaining resources to tests that should help develop the Copernicus Sentinel-2 Next Generation mission, which is under development and aims to introduce targeted night-time imaging of certain areas.
Copernicus and Sentinel-2: why “camera-like images” are crucial for Europe
Copernicus is the Earth-observation component of the European Union’s space programme. The system combines satellite observations and in-situ data from Earth, with the goal of providing accurate and timely information for environmental management, understanding and mitigating the impacts of climate change, and supporting civil security and public policies.
Within Copernicus, the Sentinel-2 mission plays the role of “colour” – an optical, multispectral view of land and coasts, with an emphasis on agriculture, forests, water resources, coastal areas and surface change. ESA stresses that Sentinel-2 is particularly important for the Copernicus Land Monitoring Service, because it provides continuity of high-spatial-resolution imaging with a revisit rate that enables tracking changes over time. The imagery is used to derive indicators of vegetation condition, changes in land cover and land use, traces of soil degradation, the impacts of droughts and floods, as well as mapping major events such as fires.
Sentinel-2 satellites carry a multispectral instrument with 13 spectral bands. Standard mission specifications include spatial resolution down to 10 metres, a swath width of 290 kilometres and a typical revisit time of about five days for the same area when the system operates with two satellites. Such a combination of breadth and detail is one of the reasons Sentinel-2 products have become a “workhorse” for many services, researchers and companies.
How Sentinel-2A became the mission “veteran”
Sentinel-2A was launched on 23 June 2015 with a planned lifetime of seven years, but ESA notes that the satellite has significantly exceeded its expected lifetime. Sentinel-2B was launched on 7 March 2017 so that, in a two-satellite configuration of nearly identical spacecraft, optimal coverage and faster data availability could be ensured. Sentinel-2C was launched on 5 September 2024 as the next step in maintaining mission continuity, with the intention of taking over Sentinel-2A’s role in the nominal operational constellation.
In operational updates, the Copernicus Data Space Ecosystem stated that in-orbit commissioning for Sentinel-2C was completed at the end of December 2024 and that radiometric cross-calibration between Sentinel-2C and Sentinel-2A was performed, with the aim of maximising consistency of the products users receive. The transfer of primary operational duties from Sentinel-2A to Sentinel-2C was planned for 21 January 2025, with a “seamless” approach intended to reduce the risk of interruptions or sudden changes in data quality.
Such a transfer is not merely a formality. Copernicus services and users rely on a stable series of measurements, and time comparisons can be sensitive to even the smallest calibration differences. That is why cross-calibration and phased handover of duties are treated as a fundamental prerequisite for continuity – especially in analyses tracking vegetation trends, soil degradation or coastal changes over years.
Why night was a “no-go zone” for Sentinel-2
Sentinel-2 is an optical mission. In practice this means the instrument, “like a camera”, primarily uses sunlight reflected from Earth’s surface and atmosphere. When the satellite passes over areas that are in night-time, the available amount of light drops drastically, so in standard operations the instrument is switched off to avoid consuming power and loading the system without a clear gain.
But Earth at night is not completely dark. Some phenomena and activities produce a signal strong enough that an optical sensor, with appropriate settings and processing, can register it. These are sources that emit light themselves or scatter it strongly, such as industrial flares, major fires, clusters of vessels with spotlights or intense city lighting.
Such targets have been monitored for years by satellites and sensors intended for night observations. NOAA, for example, notes through the VIIRS instrument that night-time multiband observations are used to identify city lights, ships, maritime traffic, fires and combustion sources such as flares. Until now, Sentinel-2A has not been counted among “night” tools precisely because it was designed for daytime multispectral imaging.
How the experiment was carried out and what exactly was imaged
On 15 January 2026, ESA announced that Sentinel-2A was switched on during night-time as well during recent trials to assess how the instrument performs under dark conditions. As particularly successful examples, it cited scenes of flares at facilities in the Middle East, a fire in India, and groups of fishing vessels off the coast of South Korea. The announcement emphasises that the current generation of Sentinel-2 satellites is not designed for night imaging, but that the next, Next Generation mission plans to introduce that capability over certain regions.
Operational details of the campaign are also supported by separate announcements related to data access. Sentinel Online and the Copernicus Data Space Ecosystem announced that Sentinel-2A began a dedicated night-time imaging campaign that started on 3 December 2025. The campaign was limited to selected locations and was intended to cover one full Sentinel-2A cycle, collecting night-time Level-1B data during the ascending part of the orbit.
The campaign announcement states that the data are collected in specific instrument operating modes, including VIC (vicarious) and RAW. This note is important for the expert community, because it means the night scenes are not a “standard product” as in daytime mode, but require additional processing, more careful interpretation and comparison with other sources. In practice, the level and method of data acquisition determine how easily reliable detection algorithms can be built and how comparable the results are with other missions.
What ESA wants to gain: a bridge to Sentinel-2 Next Generation
ESA’s scientist for the Sentinel-2 Next Generation mission, Simon Proud, said in published statements that the results are encouraging because they show Sentinel-2A can register not only very strong sources such as flares, but also subtler targets such as fires and ships, and that during the night. In the same context, he stressed that the current Sentinel-2 mission continues to deliver a large volume of data for Copernicus operational services, the commercial sector and science, but that these tests further push the boundaries of what an optical mission can do.
Proud also stated that the tests help determine what the next generation should be able to see at night and how technically feasible such imaging is. Among the night targets ESA explicitly mentions are city lights, flares and monitoring fishing activities. Such scenes, according to ESA’s interpretation, can also have security value, while city lights are highlighted as one indicator of urban growth and infrastructure expansion.
ESA’s Sentinel-2 mission manager, Ferran Gascon, further emphasised that night imaging is energy-intensive and naturally loads the satellite, but that the experiment was carefully prepared and proved valuable. In his assessment, despite more than ten years of operation and this demanding mode, Sentinel-2A is still in good condition and continues to deliver data to a large number of users across a wide range of everyday applications.
Potential applications: from environmental policy to maritime surveillance
Night-time imaging from orbit is often associated with eye-catching visuals, but the operational value can be very concrete – provided limitations and methodology are clearly defined. In the context of Sentinel-2A tests and the planned Next Generation mission, several areas are highlighted where night data could complement existing sources.
- Energy sector and flares – intense light sources associated with the flaring of excess gas can be striking detection targets. Linking such observations with other data can help understand the geography and dynamics of on-the-ground activity. Scientific papers already combine daytime Sentinel-2 multispectral imagery with night observations from other sensors for flare detection and analysis, pointing to the possibility of creating more robust methods when different sources are fused.
- Fishing activities and “lights at sea” – in some fishing practices, vessels use powerful lights that can be registered from space. Such signals can complement existing vessel tracking systems, with the caveat that operational use must be based on clear rules, avoiding misidentifications and protecting legitimate activities.
- Fires and emergencies – night scenes can be useful in situations where fires develop rapidly or when additional confirmation of an event’s location and intensity is needed. Optical night imaging does not replace thermal sensors, but it can offer an additional layer of information under certain conditions and in combination with other data.
- City lighting and urbanisation – changes in night lights are often used as a proxy indicator of the growth of settlements and infrastructure. ESA notes that such scenes can also have a security dimension, for example in situations where it is important to monitor sudden changes in lighting or activity on the ground.
The key difference is between “seeing something at night” and “imaging night like day”. Sentinel-2A demonstrates the ability to register selected night targets, especially those that emit a strong signal themselves. This does not mean the same system could be used for detailed mapping of dimly lit landscapes or for routine night imaging of the entire Earth. That is precisely why ESA stresses that Next Generation wants to image certain regions and certain types of targets at night, not everything.
Data continuity as a public interest
For Copernicus users, the most important thing is that the system operates stably and predictably. The Copernicus Land Monitoring Service, for example, states that it provides geographic information on land cover and land use and their changes, vegetation status, water and other variables, for Europe and globally. Such products become a basis for planning, scientific analyses and policy evaluation. In that sense, the transfer of operations to Sentinel-2C and the parallel “experimental” use of Sentinel-2A show a dual approach: maintain a stable operational service and at the same time use the older spacecraft’s remaining time as a learning platform.
If night imaging proves technically and operationally feasible in a future mission, Copernicus could gain an additional layer of information: not only about changes on land and coasts under daytime sun, but also about the segment of activity best seen at night – industrial combustion sources, fishing fleets, major fires and the spread of urban lights. ESA’s message from January 2026 is clear: even a satellite at the end of its life cycle can play an important role in designing what comes next, if its resources are used thoughtfully and with a clear goal.
Sources:- European Space Agency (ESA) – „Sentinel-2 explores night vision” (announcement 15 January 2026; description of tests, goals and statements by ESA experts) (link)- European Space Agency (ESA) – Sentinel-2 mission page (basic specifications: 10 m resolution, 13 spectral bands, 290 km swath width, 5-day revisit; launch dates) (link)- Copernicus Data Space Ecosystem – „Sentinel-2 Nighttime Imaging Campaign” (campaign start 3 December 2025, thematic targets, Level-1B data and imaging modes) (link)- Copernicus Data Space Ecosystem – „Transfer of Duty from Sentinel-2A to Sentinel-2C” (completion of commissioning phase and planned transfer 21 January 2025; cross-calibration) (link)- DLR – „A new era for Copernicus: the Sentinel-2C satellite launches” (Sentinel-2C launch 5 September 2024 and replacement context) (link)- European Commission – Copernicus: Earth Observation (description of Copernicus as a component of the EU space programme and core services) (link)- Copernicus Land Monitoring Service (CLMS) – basic description of the service and product areas (link)- NOAA NESDIS – „Revealing the Night Sky…” (context of night observation from space and typical targets such as city lights, ships, fires and flares) (link)
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