22 research outputs found
Heat treatment procedure of the Aluminium 6061-T651 for the Ariel Telescope mirrors
The Atmospheric Remote-Sensing Infrared Exoplanet Large Survey (Ariel) is the M4 mission adopted by ESA’s ”Cosmic Vision” program. Its launch is scheduled for 2029. The purpose of the mission is the study of exoplanetary atmospheres on a target of ∼ 1000 exoplanets. Ariel scientific payload consists of an off-axis, unobscured Cassegrain telescope. The light is directed towards a set of photometers and spectrometers with wavebands between 0.5 and 7.8 µm and operating at cryogenic temperatures. The Ariel Space Telescope consists of a primary parabolic mirror with an elliptical aperture of 1.1· 0.7 m, followed by a hyperbolic secondary, a parabolic collimating tertiary and a flat-folding mirror directing the output beam parallel to the optical bench; all in bare aluminium. The choice of bare aluminium for the realization of the mirrors is dictated by several factors: maximizing the heat exchange, reducing the costs of materials and technological advancement. To date, an aluminium mirror the size of Ariel’s primary has never been made. The greatest challenge is finding a heat treatment procedure that stabilizes the aluminium, particularly the Al6061T651 Laminated alloy. This paper describes the study and testing of the heat treatment procedure developed on aluminium samples of different sizes (from 50mm to 150mm diameter), on 0.7m diameter mirror, and discusses future steps
Rad-hard properties of the optical glass adopted for the PLATO space telescope refractive components
The detector control unit of the fine guidance sensor instrument on-board the ARIEL mission: design status
ARIEL is an ESA mission whose scientific goal is to investigate exoplanetary atmospheres. The payload is
composed by two instruments: AIRS (ARIEL IR Spectrometer) and FGS (Fine Guidance System).
The FGS detection chain is composed by two HgCdTe detectors and by the cold Front End Electronics
(SIDECAR), kept at cryogenic temperatures, interfacing with the F-DCU (FGS Detector Control Unit) boards
that we will describe thoroughly in this paper. The F-DCU are situated in the warm side of the payload in a
box called FCU (FGS Control Unit) and contribute to the FGS VIS/NIR imaging and NIR spectroscopy.
The F-DCU performs several tasks: drives the detectors, processes science data and housekeeping telemetries,
manages the commands exchange between the FGS/DPU (Data Processing Unit) and the SIDECARs and
provides high quality voltages to the detectors.
This paper reports the F-DCU status, describing its architecture, the operation and the activities, past and
future necessary for its development
Preliminary surface charging analysis of Ariel payload dielectrics in early transfer orbit and L2-relevant space environment
Ariel [1] is the M4 mission of the ESA’s Cosmic Vision Program 2015-2025, whose aim is to characterize by lowresolution transit spectroscopy the atmospheres of over one thousand warm and hot exoplanets orbiting nearby stars.
The operational orbit of the spacecraft is baselined as a large amplitude halo orbit around the Sun-Earth L2 Lagrangian
point, as it offers the possibility of long uninterrupted observations in a fairly stable radiative and thermo-mechanical
environment. A direct escape injection with a single passage through the Earth radiation belts and no eclipses is foreseen.
The space environment around Earth and L2 presents significant design challenges to all spacecraft, including the effects
of interactions with Sun radiation and charged particles owning to the surrounding plasma environment, potentially
leading to dielectrics charging and unwanted electrostatic discharge (ESD) phenomena endangering the Payload
operations and its data integrity.
Here, we present some preliminary simulations and analyses about the Ariel Payload dielectrics and semiconductors
charging along the transfer orbit from launch to L2 include
FEA testing the pre-flight Ariel primary mirror
Ariel (Atmospheric Remote-sensing Infrared Exoplanet Large-survey) is an ESA M class mission aimed at the study of exoplanets. The satellite will orbit in the lagrangian point L2 and will survey a sample of 1000 exoplanets simultaneously in visible and infrared wavelengths. The challenging scientific goal of Ariel implies unprecedented engineering efforts to satisfy the severe requirements coming from the science in terms of accuracy. The most important specification – an all-Aluminum telescope – requires very accurate design of the primary mirror (M1), a novel, off-set paraboloid honeycomb mirror with ribs, edge, and reflective surface. To validate such a mirror, some tests were carried out on a prototype – namely Pathfinder Telescope Mirror (PTM) – built specifically for this purpose. These tests, carried out at the Centre Spatial de Liège in Belgium – revealed an unexpected deformation of the reflecting surface exceeding a peek-to-valley of 1µm. Consequently, the test had to be re-run, to identify systematic errors and correct the setting for future tests on the final prototype M1. To avoid the very expensive procedure of developing a new prototype and testing it both at room and cryogenic temperatures, it was decided to carry out some numerical simulations. These analyses allowed first to recognize and understand the reasoning behind the faults occurred during the testing phase, and later to apply the obtained knowledge to a new M1 design to set a defined guideline for future testing campaigns
The CHEOPS mission
The CHaracterising ExOPlanet Satellite (CHEOPS) was selected in 2012, as the
first small mission in the ESA Science Programme and successfully launched in
December 2019. CHEOPS is a partnership between ESA and Switzerland with
important contributions by ten additional ESA Member States. CHEOPS is the
first mission dedicated to search for transits of exoplanets using ultrahigh
precision photometry on bright stars already known to host planets. As a
follow-up mission, CHEOPS is mainly dedicated to improving, whenever possible,
existing radii measurements or provide first accurate measurements for a subset
of those planets for which the mass has already been estimated from
ground-based spectroscopic surveys and to following phase curves. CHEOPS will
provide prime targets for future spectroscopic atmospheric characterisation.
Requirements on the photometric precision and stability have been derived for
stars with magnitudes ranging from 6 to 12 in the V band. In particular, CHEOPS
shall be able to detect Earth-size planets transiting G5 dwarf stars in the
magnitude range between 6 and 9 by achieving a photometric precision of 20 ppm
in 6 hours of integration. For K stars in the magnitude range between 9 and 12,
CHEOPS shall be able to detect transiting Neptune-size planets achieving a
photometric precision of 85 ppm in 3 hours of integration. This is achieved by
using a single, frame-transfer, back-illuminated CCD detector at the focal
plane assembly of a 33.5 cm diameter telescope. The 280 kg spacecraft has a
pointing accuracy of about 1 arcsec rms and orbits on a sun-synchronous
dusk-dawn orbit at 700 km altitude.
The nominal mission lifetime is 3.5 years. During this period, 20% of the
observing time is available to the community through a yearly call and a
discretionary time programme managed by ESA.Comment: Submitted to Experimental Astronom
Incoming inspection Report of the NI-DPU/DCU FM02
The purpose of this report is to provide the results of the incoming inspection performed on the DPU/DCU FM 02 delivered by OHB-I, after shipping to the LAM laboratory on 29 October 2019.
The inspection report contains the status of the unit after inspection and some pictures of the unpacking and the visual inspection
Incoming inspection Report of the NI-DPU/DCU PFM
The purpose of this report is to provide the results of the incoming inspection performed on the DPU/DCU PFM (FM01) delivered by OHB-I, after shipping to the LAM laboratory on 8 July 2019.
The inspection report contains the status of the unit after inspection and some pictures of the unpacking and the visual inspectio
Rosetta Lander: Philae on comet 67P/Churyumov-Gerasimenko
Rosetta is a Cornerstone Mission of the ESA Horizon 2000 programme. In August 2014 it reached comet 67P/ Churyumov-Gerasimenko after a 10 year cruise. Both its nucleus and coma have been studied with its orbiter payload of eleven PI instruments, allowing the selection of a landing site for Philae. The landing on the comet nucleus successfully took place on November 12th, 2014.
Philae touched the comet surface seven hours after ejection from the orbiter. After several bounces it came to rest and continued to send scientific data to Earth. All ten instruments of its payload have been operated at least once. Due to the fact that the Lander could not be anchored, the originally planned first scientific sequence had to be modified. Philae went into hibernation on
November 15th, after its batteries ran out of energy. Re-activation of the Lander was expected for May/June 2015, when CG would be closer to the sun and, indeed, radio contact with the Lander was re-established on June 13th and for (so far) seven more occasions.
Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta's Philae lander is provided by a consortium le al contributions from Hungary,UK, Finland, Ireland and Austri