August 22, 2016

Payload gondola

The main purpose of the PILOT scientific gondola is to carry and enable operation of the Pilot scientific Instrument. The primary components of the instrument are the photometer, including the cryostat and detectors, and the cold electronics used for signal conditioning.

The Pilot scientific gondola consists of the following subsystems:

The gondola

The structure that houses the payload is based on the generic Carmen gondola concept (gondola with pointing services), developed by CNES for scientific balloon flights with heavy payloads. This gondola allows the accurate pointing of the payload in both azimuth and elevation.

The Carmen gondola is equipped with a three-tonne pivot, which enables control over its orientation in azimuth. On the PILOT version of this gondola, the pointed payload can rotate around a horizontal axis (for elevation changes) inside the gondola walls. This pointed payload consists of the PILOT instrument and the stellar sensor ESTADIUS, which together weigh 528 kg. The photometer — the core of the instrument — weighs almost 500 kg.

The total mass of the gondola structure is 306 kg. All the equipment required for the flight is installed on the gondola, either on the instrument plate, or directly inside the wall cavities. The current mass of the complete PILOT scientific gondola (structure + payload) is 1058 kg.

The Pilot gondola is thermally protected by a cover. The gondola has four crash-pads underneath and six on the sides that protect the gondola and the payload from shocks that can occur during landing.


Pilot Gondola

PASTIS on-board and ground communication module

This subsystem has been developed and is operated under the responsibility of CNES. PASTIS is the module used to command and monitor the payload from the ground. The interface used for the Carmen payload is an Ethernet link and a first-order discrete system, which is used to re-initialize the C&C power distribution module.

Gondola command & control (CNES)

This subsystem has been developed and is operated under the responsibility of CNES. The on-board component is composed of a main module, the on-board computer, interconnected to a set of electronic and electromechanical equipment. It mainly performs the ESTADIUS attitude pointing as well as the power distribution for the C&C, ESTADIUS and the scientific payloads. It has a ground supervision used to command and observe the on-board component (gondola and payload). It communicates through an Ethernet link via the on board-ground available through the NOSYCA system. It uses a discrete order of the on-board PASTIS module to reset the power distribution module and switch back the whole command & control system in operational mode in case of damage. It also enables the monitoring of the thermal status of the equipment installed in the gondola by switching on and off the heaters or by changing the gondola's azimuth depending on the status and the sensitivity of each component on board. 

Pilot electronic module

This subsystem has been developed and is operated under the responsibility of CNES. The on-board component consists of a computer and the ground component consists of electrical ground support equipment (EGSE). Communication is made via the PASTIS ground and on-board modules.

ESTADIUS diurnal star tracker

The ESTADIUS star tracker (Estimateur STellaire d'Attitude DIUrne Stratosphérique) is part of the pointed payload and installed just above the Pilot instrument. It is co-aligned with the viewing direction of the instrument for light rays with submillimetre wavelengths. The ESTADIUS star tracker ensures that the viewing direction of the instrument is precisely known throughout the day as well as at night. The on-board component consists of a computer, a camera with a baffle, and an IMU90 optical fibre gyroscope. The baffle prevents stray light entering the camera. Communication between the ground and on-board segments of ESTADIUS is via NOSYCA and the PASTIS module. This subsystem has been developed and is operated under the responsibility of CNES.

Front side of the Estadius sensor