Cebreros

The Cebreros station, DSA 2 (Deep Space Antenna 2), is located 77 kms west of Madrid, Spain. It hosts a 35-metre antenna with transmission and reception in X-band and reception in Ka-band. It provides daily support to Venus Express and GAIA for routine operations and back-up support to Mars Express and Rosetta.

Location
The coordinates of the 35m antenna are +40° 27' 09.68", -04° 22' 03.18", and the antenna is sited at 794.1 metres with respect to the GRS 80 geocentric coordinates, epoch 2005, day 65 (6 March 2005). The GRS 80, or Geodetic Reference System 1980, coordinate system is a geodetic reference system consisting of a global reference ellipsoid and a gravity field model.

The ground station is situated about 12 kms south of Cebreros; Cebreros is situated in the province of Avila.

History
Cebreros station (DSA 2) was inaugurated in 2005 and is the second in the Agency’s trio of 35-metre deep space stations; the other two are in New Norcia, Australia (DSA 1), and Malargüe, Argentina (DSA 3). The three are some of the world’s most sophisticated and technically advanced tracking stations used for satellite control, and are capable of communicating with missions orbiting as far away as Jupiter, i.e. up to about 3 to 4 AU.

They are part of ESA’s Estrack network, a worldwide system of ground stations providing links between satellites in orbit and our ESOC operations centre in Darmstadt. The core Estrack network comprises 10 stations in seven countries.

Facilities & technology
Cebreros' technical facilities comprise X-band transmission and X- and Ka-Band reception, plus facilities for tracking, telemetry, telecommand and radiometric measurements (ranging, Doppler, meteo).

The station has a frequency and timing system, a monitoring and control system and communications are enabled via the ESA Operations Network (OPSNET). The site is equipped with a no-break power plant.

The antenna's radio frequency (RF) system comprises a Cassegrain Beam Wave Guide system operating with frequency-sensitive (dichroic) mirrors and X- and Ka-band feeds, helium cooled X- and Ka-band low-noise amplifiers, a 400-Watt solid-state power amplifier, and 2- and 20-kilowatt X-band transmitters.

Operations
Cebreros provides routine operations support to Venus Express and backup support to Mars Express (and Rosetta as needed), as well as other agencies' missions under resource-sharing agreements.

Construction on the Cebreros station started in early 2004 and the station was formally inaugurated in September 2005. The first X-band signal was received from Venus Express on 10 November 2005, marking the start of operations.

The antenna dish is 35 metres in diameter and the entire structure is 40 metres high and weighs about 630 tonnes. Engineers can point the antenna with a speed of 1 degree per second in both axes. Cebreros' servo control system assures the highest possible pointing accuracy under the site's environmental, wind and temperature conditions.

For routine operations, Cebreros is controlled from ESOC. On-site management and maintenance is provided by ISDEFE - Ingeniería de Sistemas para la Defensa de España.

The Cebreros antenna incorporates state-of-the-art technology and the site was chosen for ESA's second deep-space antenna for several reasons. Since this antenna must be positioned 120 degrees East or West of our first deep-space antenna, DSA 1, in Australia, an ideal location would have been ESA's European Centre for Space Astronomy, located in Villafranca, near Madrid. However, active urban development in the ESAC surroundings could have caused interference.

The Cebreros location, which formerly hosted a NASA tracking station, is equally good and is away from densely populated areas.

There are plans to upgrade the station in the future to enable data transmission in the Ka-band (32 GHz), which will become the future international standard for deep-space missions.

Cebreros will also support future ESA deep-space missions, including potentially Lisa-Pathfinder and BepiColombo.

Delta DOR, GPS-TDAF, Radio Science
The station is also equipped with Delta DOR (Delta Differential One-Way Ranging), a new technology enabling highly precise spacecraft location and tracking.

A GPS-TDAF (GPS Tracking and Data Analysis Facility) dual-frequency receiver system with geodetic accuracy is installed on the site, which delivers continuous measurements to the ESOC Navigation Facility.

The station also hosts facilities enabling scientists to analyse received signals to perform radio science experiments.

Evolution
26GHz

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Supported Missions
Venus Express (VEX): supported as dedicated station since 2005. Mission terminated (Satellite end of life) in January 2015.

Rosetta (ROS)

Mars Express (MEX)

Gaia (GAIA)