Martin E. Caldwell

The Geostationary Earth Radiation Budget Project

This paper reports on a new satellite sensor, the Geostationary Earth Radiation Budget (GERB) experiment. GERB is designed to make the first measurements of the Earths radiation budget from geostationary orbit. Measurements at high absolute accuracy of the reflected sunlight from the Earth, and the thermal radiation emitted by the Earth are made every 15 min, with a spatial resolution at the subsatellite point of 44.6 km (north–south) by 39.3 km (east–west). With knowledge of the incoming solar constant, this gives the primary forcing and response components of the top-of-atmosphere radiation. The first GERB instrument is an instrument of opportunity on Meteosat-8, a new spin-stabilized spacecraft platform also carrying the Spinning Enhanced Visible and Infrared (SEVIRI) sensor, which is currently positioned over the equator at 3.5°W. This overview of the project includes a description of the instrument design and its preflight and in-flight calibration. An evaluation of the instrument performance after ...

The LTP experiment on the LISA Pathfinder mission

We report on the development of the LISA Technology Package (LTP) experiment that will fly onboard the LISA Pathfinder mission of the European Space Agency in 2008. We first summarize the science rationale of the experiment aimed at showing the operational feasibility of the so-called transverse–traceless coordinate frame within the accuracy needed for LISA. We then show briefly the basic features of the instrument and we finally discuss its projected sensitivity and the extrapolation of its results to LISA.

The Visible and Infrared Survey Telescope for Astronomy (VISTA): Design, technical overview, and performance

The VISTA project was made possible by funding from the UK Joint Infrastructure Fund (JIF) and PPARC (later STFC).

Successful testing of the LISA Technology Package (LTP) interferometer engineering model

The LISA Technology Package (LTP), to be launched by ESA in 2008, is a technology demonstration mission in preparation for the LISA space-borne gravitational wave detector. A central part of the LTP is the optical metrology package (heterodyne interferometer with phasemeter) that measures the distance between two test masses with a noise level of 10 pm Hz−1/2 between 3 mHz and 30 mHz and also the test mass alignment with a noise level of <10 nrad Hz−1/2. An engineering model of the interferometer has been built and environmentally tested. Extensive functionality and performance tests were conducted. This paper reports on the successful test results.

The VISTA infrared camera

We describe the integration and test phase of the construction of the VISTA Infrared Camera, a 64 Megapixel, 1.65 degree field of view 0.9-2.4 micron camera which will soon be operating at the cassegrain focus of the 4m VISTA telescope. The camera incorporates sixteen IR detectors and six CCD detectors which are used to provide autoguiding and wavefront sensing information to the VISTA telescope control system.

Imaging FTS for Herschel SPIRE

The design of the Fourier Transform Spectrometer for the Herschel sub-millimetre Spectral and Photometric Imaging Receiver (SPIRE) is described. This is an innovative design for a sub-millimetre spectrometer as it uses intensity beam splitters in a Mach-Zehnder configuration rather than the traditional polarising beam splitters. The instrument is required to have a resolution of 0.04 cm-1; have a relatively large field of view (2.6 arcmin circular) and cover a large wavelength range - 200 to 670 microns. These performance requirements lay stringent requirements on all aspects of the design. The details of the optical; mechanical and electrical implementation of the instrument are discussed in the light of the science and engineering requirements and laboratory testing on development models of the mechanism and control system are reported.

FIRST-SPIRE spectrometer: a novel imaging FTS for the submillimeter

The SPIRE instrument for the FIRST mission will consist of a three band imaging submillimeter photometer and a two band imaging Fourier Transform Spectrometer (FTS) optimized for the 200 - 400 micrometers range, and with extended coverage out to 670 micrometers . The FTS will be used for follow-up spectroscopic studies of objects detected in photometric surveys by SPIRE and other facilities, and to perform medium resolving power (R approximately 500 at 250 micrometers ) imaging spectroscopy on galactic and nearby extra-galactic sources.

Project overview of OPTIMOS-EVE: the fibre-fed multi-object spectrograph for the E-ELT

OPTIMOS-EVE (OPTical Infrared Multi Object Spectrograph - Extreme Visual Explorer) is the fibre fed multi object spectrograph proposed for the European Extremely Large Telescope (E-ELT), planned to be operational in 2018 at Cerro Armazones (Chile). It is designed to provide a spectral resolution of 6000, 18000 or 30000, at wavelengths from 370 nm to 1.7 μm, combined with a high multiplex (>200) and a large spectral coverage. Additionally medium and large IFUs are available. The system consists of three main modules: a fibre positioning system, fibres and a spectrograph. The recently finished OPTIMOS-EVE Phase-A study, carried out within the framework of the ESO E-ELT instrumentation studies, has been performed by an international consortium consisting of institutes from France, Netherlands, United Kingdom and Italy. All three main science themes of the E-ELT are covered by this instrument: Planets and Stars; Stars and Galaxies; Galaxies and Cosmology. This paper gives an overview of the OPTIMOS-EVE project, describing the science cases, top level requirements, the overall technical concept and the project management approach. It includes a description of the consortium, highlights of the science drivers and resulting science requirements, an overview of the instrument design and telescope interfaces, the operational concept, expected performance, work breakdown and management structure for the construction of the instrument, cost and schedule.

The VISTA IR camera

The VISTA IR Camera has now completed its detailed design phase and is on schedule for delivery to ESO’s Cerro Paranal Observatory in 2006. The camera consists of 16 Raytheon VIRGO 2048x2048 HgCdTe arrays in a sparse focal plane sampling a 1.65 degree field of view. A 1.4m diameter filter wheel provides slots for 7 distinct science filters, each comprising 16 individual filter panes. The camera also provides autoguiding and curvature sensing information for the VISTA telescope, and relies on tight tolerancing to meet the demanding requirements of the f/1 telescope design. The VISTA IR camera is unusual in that it contains no cold pupil-stop, but rather relies on a series of nested cold baffles to constrain the light reaching the focal plane to the science beam. In this paper we present a complete overview of the status of the final IR Camera design, its interaction with the VISTA telescope, and a summary of the predicted performance of the system.

A Ground Calibration Facility for Herschel-SPIRE

We describe the requirements and the main design features of the ground test and calibration facility for the Herschel SPIRE instrument. SPIRE has a large cold focal plane unit (approx 700 x 400 x 400 mm) with several internal temperature stages, and is designed to operate in orbit viewing a low emissivity 80-K telescope. The calibration facility is designed to allow all aspects of instrument behaviour, performance, calibration, and optimisation of observing modes to be investigated under flight representative conditions. The facility includes the following features: - A large test cryostat replicating the in-orbit thermal environment - An external telescope simulator and sub-millimetre sources allowing the instrument to be fed with a beam that accurately simulates the beam from the Herschel telescope. - Internal cold black body for absolute radiometric and flat field calibration - Cold neutral density filters and an internal shutter for control of the photon background conditions - A far infrared laser used for spectral calibration of the SPIRE spectrometer channel and to present a source with well understood beam modes to the instrument. - An external FTS to characterise the spectral response of the instrument in both the camera and spectrometer channel The ground test facility will be used to evaluate the flight model before delivery and will also be used to house and carry out tests on the flight spare focal plane unit both before launch and during mission operations.