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High gain Antenna Deployment and Pointing Mechanism of the Euclid probe

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Sener Space / Communications in Space / Space

High gain Antenna Deployment and Pointing Mechanism of the Euclid probe

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Client: TAS-E / TAS-I / ESA

Country: Space

Sener is developing the high gain antenna deployment and pointing mechanism (HGA ADPM) for the Euclid scientific space probe. It is a precision assembly comprised of three axes, one for antenna deployment and the other two for pointing. The assembly transmits two radio-frequency signals from the satellite to the antennae. The signals are on the K band (between 25.5 and 27 GHz) for the high gain antenna, and on the X band (between 7.1 and 8.5 GHz) for the low gain antenna.

Main mechanism components:

Actuators: The number of actuators and rotation axes are the same.

Main mechanism components:

Actuators: The number of actuators and rotation axes are the same. In this case there are three: for deployment, azimuth, and elevation. Each one of them comprises among others:

Stepper motor
Integrated bearing system
Gear (harmonic)
Positioning sensors (fine and coarse potentiometers for each Az. & El.))
Machined parts
Internal ball bearing
K band rotary joint: a rigid joint used to transmit the radiofrequency single despite the assembly”s rotation. There is one on each actuator.
X band cable: used to transmit the X band signal.
Flexible cable: used to send the electric signals and power to the actuator, sensors, thermistors and thermal resistances.
L-structure: the structural element that joins the actuators.
Support: the structural element that joins the deployment actuator to the interface with the satellite.
The K band rotary joint and the actuator are specific Sener developments.

Characteristics:

Mass: 10.5 kg.
Power: 6.5 W per moving axis (steer).
Pointing precision: ±0.005º in open loop.
Speeds: 0.3º/s per axis.
Radio frecuency (RF):
· Insertion Loss (K band/X band): < 1.2 dB / 1.5 dB
· Return Loss (K band/X band): > 18 dB / > 16.5 dB
· Radio-frequency power handling (K band/X band): min. 100 W/ min. 20 W

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Solar Orbiter High Gain Antenna Subsystem (HGA S/S)

Sener/InternationalPage 13

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Sener Space / Communications in Space / Space

Solar Orbiter High Gain Antenna Subsystem (HGA S/S)

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Client: Airbus DS UK / ESA

Country: Space

The main objective of the project was to design, manufacture, integrate, test and deliver the satellite’s complete antenna subsystem. This subsystem comprises four independent devices:

High Gain Antenna Major Assembly (HGAMA)

In turn, the HGAMA consists of:

An “axially displaced ellipse” reflector antenna made of titanium whose main reflector has a diameter of 1100 mm.
A boom that permits antenna operation separately from the satellite.
A two-axis antenna pointing mechanism (APM).
Thermal shields and blankets to protect the entire assembly.

The main objective of the project was to design, manufacture, integrate, test and deliver the satellite’s complete antenna subsystem. This subsystem comprises four independent devices:

High Gain Antenna Major Assembly (HGAMA)

In turn, the HGAMA consists of:

An “axially displaced ellipse” reflector antenna made of titanium whose main reflector has a diameter of 1100 mm.
A boom that permits antenna operation separately from the satellite.
A two-axis antenna pointing mechanism (APM).
Thermal shields and blankets to protect the entire assembly.
Four Hold-down and Release Mechanisms
Antenna Pointing Mechanism Electronics (APME) located inside the satellite to control antenna pointing.

Medium Gain Antenna Major Assembly (MGAMA)

In turn, the MGAMA consists of:

A horn antenna
A 700-mm boom to articulate the antenna.
Heat shield for the boom and thermal protection blankets of the APM.
A Hold-down and Release Mechanism
A single-axis Antenna Pointing Mechanism (APM) at the end of the boom.
Antenna Pointing Mechanism Electronics (APME) located inside the satellite.

The MGAMA has certain similarities with the assembly of the same name being developed at Sener for the BepiColombo Mission.

Low Gain Antennas (LGAs)

Two Low Gain Antennas (LGAs) with semi-omnidirectional coverage, the combination of which allows the satellite to establish a communications link with the Earth in emergences or loss of attitude.

Characteristics:
The high gain antenna operates on the X band with gains of more than 36.5 dBi in downlink and more than 35.0 dBi in uplink.
The antenna operates at a power of 48.45 dBm in the required setting at less than 0.28 AU (astronomical units). The temperatures it must withstand during the science phase are 585ºC in areas exposed to the sun, and it has a special coating developed specially to guarantee that it will operate even in such a harsh environment.
The unit operates on two axes at speeds of 0.5º/seconds with pointing stabilities compatible with the radio-frequency requirements.
The medium gain antenna also operates on the X band with a gain of 22.3 dBi in downlink and 20.5 dBi in uplink with a power of 48.48 dBm. The antenna also operates during the science phase at the minimum distance from the sun, withstanding temperatures of 550ºC.
The low gain antenna operates during the phase closest to Earth on the X band, transmitting the satellite’s telemetry data.

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SOLAR ORBITER. Instrument boom

Sener/InternationalPage 13

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Sener Space / Science & Earth observation / International

SOLAR ORBITER. Instrument boom

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Client: ADS UK / ESA

Country: International

The Solar Orbiter deployable boom function is to support and deploy four instruments which, due to their sensitivity to magnetic fields, need to be placed far from the electromagnetic disturbances generated by the satellite.

It consists of three rigid sections joined by two deployment mechanisms. Each section consists of titanium pieces affixed to CFRP pipes. During launch, the boom remains undeployed and secured to the satellite’s panels by means of a tripod and two hold-down mechanisms, while a third hold-down mechanism keeps the two deployable sections joined together. Once in orbit, deployment takes place in two sequences. Initially the two hold-down mechanisms are released and both sections are rotated 195° by the internal deployment mechanism until a stop point is reached, which defines the deployed position. The intermediate moving mechanism is then released and the external section rotates 180° with regard to the internal section by means of the external deployment mechanism, reaching the deployed position.

The deployment mechanisms consist of one hinge with spherical bearings and are clock spring-actuated. A viscous damper is included for smooth deployment. The mechanisms have a mechanical end-of-deployment stop point together with a hook-up system. They also include a potentiometer as a position sensor plus switches to monitor the final positions.

In order to adapt the subsystem to the thermal atmosphere, thermal control is included, which comprises both passive elements (thermal blankets and paint with suitable thermal-optical properties), and active elements (electric heaters and thermistors).

The subsystem includes the instrument cable bundles, the wiring required to transmit the signals from the position sensors and the thermistors, and the wiring to supply power to the electric heaters.

One important characteristic is the routing and fixing of the wiring along the pipes and around the deployment mechanisms.

Due to the strict magnetic cleanliness requirements, as far as possible, all the materials used are amagnetic (titanium, aluminium, CFRP, Vespel, beryllium copper, etc.), and in unavoidable cases of materials with a certain residual magnetism, exhaustive demagnetisation is performed.