5, 4, 3, 2, 1... 18h02m16s. As planned, to within a second – the window allowed for this launch – the Ariane 6 launcher, 60 metres high and weighing 500 tonnes, lifted off northwards on Tuesday, 4 November, from Kourou (French Guiana), carrying the Sentinel 1D satellite, weighing 2.2 tonnes, for the European Copernicus programme for Earth observation.
From the Toucan site, 5 km from the launcher, there is silence – only the countdown to the launch can be heard. Then, in the distance, the engines ignite and the Ariane 6 rocket rises into the sky, followed by a white cloud from the ground. After about twenty seconds, the sound and ground vibrations reach us.
But the rocket was already high in the sky and after two minutes, the boosters detached and fell back into the ocean. A minute later, the fairing separated from the launcher as Ariane 6 left the atmosphere. This was followed by a waiting period. After 34 minutes of flight, the satellite detached from Ariane 6 and was officially in orbit – a heliosynchronous orbit at 693 km. “The accuracy (of the satellite’s positioning) is around 200 metres, which is incredible”, said David Cavaillolès, CEO of Arianespace.
Shortly afterwards, teams from the European Space Agency (ESA) received the satellite’s transmission signal. Cheers and congratulations followed throughout the control room for this successful launch.
The achievement was hailed on Wednesday 5 November by the European Commissioner for Defence and Space, Andrius Kubilius, who said that the launch was “an important reminder of what we are capable of when we work together”, with a European satellite carried by a European launcher.
The Sentinel 1D satellite is the fourth in the Sentinel 1 series, and the last of this generation. It is equipped with a C-band Synthetic Aperture Radar (SAR), enabling it to see day and night, through clouds, even in areas such as the Arctic and Antarctic. “With the two satellites 1C (launched in December 2024) and 1D, we’ll be passing over the same point on the globe every six days at most. On the European latitude, it’s almost every other day”, explained Grégory Ladurée, Sentinel mission system engineer at ESA, to Agence Europe. The satellite is travelling at a speed of 7 km per second.
“Sentinel 1 allows us to see the changes taking place on the ground. In the event of flooding, by comparing before and after images, you can find out where the flooding occurred. The same applies to earthquakes”, explained Mauro Facchini, head of the Earth Observation Unit at the European Commission, on 30 October. Other phenomena observed by Sentinel 1 include the monitoring of glaciers, deforestation and marine pollution.
Enhanced surveillance of vessels. Like 1C, Sentinel 1D is also equipped with an Automatic Identification System (AIS), which enables more sophisticated maritime surveillance in terms of vessel tracking and shipping. “It’s an antenna that receives the mandatory information generated by the boats, indicating their position, speed, etc. At the same time, the radar can see the boats and, therefore, by comparing the information we receive, we can identify the boats that are not sending these messages”, explained Mauro Facchini. This could improve monitoring of piracy or illegitimate transport, but also of the vessels of the Russian ‘shadow fleet’.
After a calibration period of four to six months – ESA hopes to declare the satellite fully operational around April 2026 – Sentinel 1D will replace Sentinel 1A, which was launched in 2014 and will then be de-orbited. A few months ago, Sentinel 1C replaced Sentinel 1B, which had broken down (see EUROPE 13541/27).
The Copernicus programme relies on 12 Sentinels (including 1D) in operation. While Sentinel 1 is equipped with radar, the others have other instruments on board, such as optical altimetry observations, radiometers and spectrometers.
All these Sentinels are the property of the European Commission: once they are developed, launched and fully operational, ESA transfers ownership of these satellites to the Commission. “Copernicus is not just about satellites, it’s about services. It’s not just to feed a space component, but above all to create services that can generate products available to users” all over the world, Mauro Facchini pointed out.
There are six different services: an atmospheric observation service, a seas and oceans service, a territorial management service, a climate change observation management service, a civil protection support service in the event of a crisis, and security elements, especially for maritime security and border observation.
Copernicus generates data that is free and available to all, including scientists, institutions and private bodies. “We’re talking about more than 25 terabytes (TB) of data available every day”, according to the European Commission. The data is free, but the market for Earth observation data and value-added services is expected to reach nearly 6 billion dollars by 2033. Its societal, environmental and economic benefits outweigh the cost of the programme by 3.7 times, according to the European Commission.
However, access to AIS data will be restricted and the data will be passed on to agencies such as Frontex and the European Maritime Safety Agency.
Further development of Copernicus. Several satellites in the Copernicus programme have yet to be launched. In 2025, before 1D, two Sentinels (4A and 5A) had already been launched and Sentinel 6B is due to be launched on 17 November, in cooperation with NASA, from California. A Sentinel 3C could be launched in September 2026 on Vega C. “The projection between now and 2028 is five launches, and 18 launches between 2028 and 2034”, added Pier Bargellini, responsible for the Copernicus space segment programme at the ESA.
The aim is also to develop new-generation Sentinels. “The idea is to try to sign the contract by early 2026 at the latest. We’re in the process of finalising the procurement process and negotiations with the industry. The idea is to launch (the 1st satellite) in 2032. This is a new generation that is not simply a continuation of Sentinel 1”, announced Simonetta Cheli, Director of Earth Observation Programmes at ESA, last week.
Sentinel 1D is designed to have a service life of around 7.5 years, but it will have fuel for another 5 years. According to Mr Ladurée, the aim is to replace Sentinel 1C and D within 8 or 9 years.
Securing its financial future. While the Sentinel’s technical future seems assured, its financial future has yet to be decided.
At the ESA, Ministerial Council in Bremen at the end of November, the Agency will be asking its Member States to provide €850 million in funding for the two new-generation Sentinel 2 and 3 missions.
This will be supplemented by funding from the European Commission for 2028-2034, in connection with the next Multiannual Financial Framework which has yet to be negotiated and agreed. “We have a principle of co-financing for the development of Sentinel missions. On the other hand, the European Commission is financing all the operations, access to contributing data and the launch”, explained Pierre Potin, head of the Sentinel 1 mission at ESA. (Original version in French by Camille-Cerise Gessant)