Satellite: ESA SENTINEL-1


With the ambitious aim of creating a better understanding of the Earth, the European Space Agency (ESA) started the Copernicus program – “Europe’s eye on the earth”. This was much more than just collecting high-quality data, this was about providing an operational service – that can support emergency response and civil security to logistics and climate monitoring

Sentinel-1 was the first mission to provide that level of service. 

ESA’s Sentinel-1, is a Synthetic Aperture Radar (SAR)  satellite, can see at night and through clouds millimeter accuracy when measuring elevation.  As it can operate independent of weather, unlike optical satellites, it is always providing useful data.

The Sentinel-1 missions are composed of two separate satellites S-1A and S-1B. Both satellites serve the same purpose and have the same equipment. Having two means more frequent updates with higher revisit times.

The results gleaned from Sentinel-1, and the wider Copernicus program will almost certainly influence the future of the human race – from changing how we see climate change to improving transport and logistics.

SENTINEL-1 (S-1), launched in 2014, was the first in ESA’s Copernicus Program. and is their only SAR (Synthetic Aperture Radar) satellite.


ESA - Sentinel-1

Sentinel-1 The first of ESA’s Copernicus missions

The First Copernicus Mission

S-1 was the first of the original five missions ESA launched under the Copernicus program, launching in 2014 and is one the larger satellites coming in at nearly twice the weight of SENTINEL-2 and SENTINEL3.  SENTINEL-1 is actually a mission of two satellites, SENTINEL-1A and SENTINEL-1B – they both serve the same purpose and have the same equipment, but having two provides more frequent updates  – “higher revisit times”

SENTINEL-1 – Radar Satellite

As S-1 is a radar satellite, rather than optical (e.g. SENTINEL-2) or an environment sensor (e.g SENTINEL-5) it doesn’t generate images of earth that can be seen by the human eye. S-2 generates fascinating images –  such as pictures of algae blooms or lakes – which is what most people think of when they hear about satellite images.

S-1, generates data from radar that requires detailed analysis and interpretation – the results providing an entirely new perspective of our world. 



Technical Details

SENTINEL-1A and SENTINEL-1B share the same orbital plane and both use Synthetic Aperature Radar.

The S-1 satellite houses the C-SAR instrument, which allows it to offer reliable wide-range monitoring, which also has shorter revisit times.

The C-band imaging system, also included in the S-1 satellite, operates in four exclusive imaging modes, with different resolutions, down to 5m, and up to 400km.


SENTINEL-1 is designed to work on imaging global landmasses, coastal zones, and shipping routes at high resolution. 






First launch




Orbit type

SSO (Sun-synchronous Orbit) 12 day repeat cycle LTAN = 18:00 hours

SSO 10 day repeat cycle LTDN = 10:30 hours

SSO 27 day repeat cycle LTDN = 10:00 hours

Orbital altitude

693 km

786 km

800 km

Sensor complement

C-SAR (C-band Synthetic Aperture Radar)

MSI (Multi-Spectral Instrument)

SRAL (Sentinel-3 Radar Altimeter) MWR (Microwave Radiometer) OLCI (Ocean and Land Color Instrument) SLSTR (Sea and Land Surface Temperature Radiometer)

Spacecraft mass Spacecraft size Spacecraft power

2300 kg 3.4 m x 1.3 m x 1.3 m 4.8 kW (EOL)

1100 kg 3.0 m x 1.7 m x 2.2 m 1.7 kW (EOL)

1250 kg 3.9 m x 2.2 m x 2.2 m 2.05 kW (EOL)

Downlink X-band data rate

520 Mbit/s

520 Mbit/s

520 Mbit/s

TT&C S-band

64 kbit/s uplink 128 kbit/s or 2 Mbit/s downlink

64 kbit/s uplink 128 kbit/s or 2 Mbit/s downlink

64 kbit/s uplink 128 kbit/s or 2 Mbit/s downlink

Science data storage

1.4 Tbit (EOL)

2 Tbit (EOL)

300 Gbit (EOL)

Required data quality

BER (Bit Error Rate): < 10-9

FER (Frame Error Rate): < 10-8

FER (Frame Error Rate): < 10-7

Operational autonomy

8 days

14 days

27 days

Prime contractor

TAS-I (Thales Alenia Space-Italy)

EADS Astrium GmbH, Germany

TAS-F (Thales Alenia Space-France)

Baseline launcher

Soyuz (Kourou)

Vega (Kourou)

Vega (Kourou)