In-orbit Performance Research Articles

In-orbit performance ofHerschel-HIFI

Aims. In this paper the calibration and in-orbit performance of the Heterodyne Instrument for the Far-Infrared (HIFI) is described. Methods. The calibration of HIFI is based on a combination of ground and in-flight tests. Dedicated ground tests to determine those instrument parameters that can only be measured accurately using controlled laboratory stimuli were carried out in the instrument level test (ILT) campaign. Special in-flight tests during the commissioning phase (CoP) and performance verification (PV) allowed the determination of the remaining instrument parameters. The various instrument observing modes, as specified in astronomical observation templates (AOTs), were validated in parallel during PV by observing selected celestial sources. Results. The initial calibration and in-orbit performance of HIFI has been established. A first estimate of the calibration budget is given. The overall in-flight instrument performance agrees with the original specification. Issues remain at only a few frequencies.

In-Orbit Performance of MAXI Gas Slit Camera (GSC) on ISS

Abstract We report on the in-orbit performance of the Gas Slit Camera (GSC) on the MAXI (Monitor of All-sky X-ray Image) mission carried on the International Space Station (ISS). Its commissioning operation, which started on 2009 August 8, confirmed the basic performances of the effective area in the energy band of 2–30 keV, the spatial resolution of the slit-and-slat collimator and detector with 1 $^\circ\!\!\!.$ 5 FWHM, the source visibility of 40–150 seconds for each scan cycle, and the sky coverage of 85% per 92-minute orbital period and 95% per day. The gas gains and read-out amplifier gains have been stable within 1%. The background rate is consistent with the past X-ray experiments operated at a similar low-earth orbit if its relation with the geomagnetic cutoff rigidity is extrapolated to high latitude. We also present the status of the in-orbit operation and a calibration of the effective area and the energy response matrix using Crab-nebula data.

A software simulator for the SPICA Safari instrument

A software simulator that has been developed for the Safari instrument proposed for the SPace Infrared telescope for Cosmology and Astrophysics (SPICA) mission is presented. The simulator can ingest a range of realistic input spectra and, following a thorough radiative transfer analysis, calculates the power reaching the detector as a function of the optical path difference within the interferometer. The simulator is modular in design so that it can be easily modified to ingest test data as they become available. The simulator will not only find use during the design phase of the Safari instrument, but also during ground performance verification campaigns of the flight model. Through validation of the simulator on ground test data, it will be possible to predict accurately the in-orbit performance of the Safari instrument.

In-Orbit Performance of the MAXI/SSC onboard the ISS

We report here the in-orbit performance of the CCD camera (MAXI/SSC) onboard the International Space Station (ISS). It was commissioned in 2009 August. This is the first all-sky survey mission employing X-ray CCDs. It consists of 32 CCDs, each of which is 1 inch square. It is a slit camera with a field of view of 1$^\circ\!\!\!.$5 $\times$ 90$^\circ$, and scans the sky as the rotation of the ISS. The CCD on the SSC is cooled down to the working temperature around $-$60$^\circ$C by the combination of a peltier cooler, a loop heat pipe and a radiator. The standard observation mode of the CCD is in a parallel sum mode (64-binning). The CCD functions properly, although it suffers an edge glow when the Sun is near the field of view (FOV), which reduces the observation efficiency of the SSC down to about 30%. The performance of the CCD is continuously monitored both by the Mn-K X-rays and by the Cu-K X-rays. There are many sources detected, not only point sources, but extended sources. Due to the lack of an effective observation time, we need more observation time to obtain an extended emission analysis extraction process.

TheHerschel-Heterodyne Instrument for the Far-Infrared (HIFI)

Aims. This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods. The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the 1410-1910 GHz range with hot electron bolometer (HEB) mixers. The local oscillator (LO) subsystem comprises a Ka-band synthesizer followed by 14 chains of frequency multipliers and 2 chains for each frequency band. A pair of auto-correlators and a pair of acousto-optical spectrometers process the two IF signals from the dual-polarization, single-pixel front-ends to provide instantaneous frequency coverage of 2 × 4 GHz, with a set of resolutions (125 kHz to 1 MHz) that are better than 0.1 km s-1. Results. After a successful qualification and a pre-launch TB/TV test program, the flight instrument is now in-orbit and completed successfully the commissioning and performance verification phase. The in-orbit performance of the receivers matches the pre-launch sensitivities. We also report on the in-orbit performance of the receivers and some first results of HIFI's operations.

The Photodetector Array Camera and Spectrometer (PACS) on the HerschelSpace Observatory

The Photodetector Array Camera and Spectrometer (PACS) is one of the three science instruments on ESA's far infrared and submillimetre observatory. It employs two Ge:Ga photoconductor arrays (stressed and unstressed) with 16x25 pixels, each, and two filled silicon bolometer arrays with 16x32 and 32x64 pixels, respectively, to perform integral-field spectroscopy and imaging photometry in the 60-210\mu\ m wavelength regime. In photometry mode, it simultaneously images two bands, 60-85\mu\ m or 85-125\mu\m and 125-210\mu\ m, over a field of view of ~1.75'x3.5', with close to Nyquist beam sampling in each band. In spectroscopy mode, it images a field of 47"x47", resolved into 5x5 pixels, with an instantaneous spectral coverage of ~1500km/s and a spectral resolution of ~175km/s. We summarise the design of the instrument, describe observing modes, calibration, and data analysis methods, and present our current assessment of the in-orbit performance of the instrument based on the Performance Verification tests. PACS is fully operational, and the achieved performance is close to or better than the pre-launch predictions.

Studying methane and other trace species in the Mars atmosphere using a SOIR instrument

Solar Occultation in the InfraRed (SOIR) is one of three spectrometers of the SPICAV/SOIR instrument suite ( Bertaux et al., 2007b) on board the Venus Express orbiter (VEX). VEX has been in orbit around Venus since April 2006 and to date SOIR has carried out over 674 measurements. Pre-launch and in-orbit performance analyses allow us to predict what SOIR would be capable of at Mars. SOIR spectra through the Martian atmosphere have been simulated with ASIMUT, a line-by-line (LBL) radiative transfer code also used for the retrieval of vertical profiles of atmospheric constituents of Venus ( Vandaele et al., 2008; Bertaux et al., 2007a). The code takes into account the temperature and pressure vertical profiles as well as those of the atmospheric species, but also the instrument function and the overlapping of the diffraction orders of the echelle grating. We will show these spectra and the detection limits of species that could be studied using a SOIR spectrometer making solar occultation or nadir measurements in Mars orbit.

Analysis and Control of Equivalent Physical Simulator for Nanosatellite Space Radiator

A realistic prediction of the in-orbit transient performance of a nanosatellite space radiator requires a ground-based equivalent space radiator with a small size, simple configuration, and fast response. For this purpose, we present in this paper the design concept, operating principle, and analysis algorithm of a novel equivalent physical simulator (EPS) consisting of a thermoelectric cooler (TEC), a plate-fin heat sink, and a forced cooling fan. The TEC-based EPS achieves the purpose of simulating the in-orbit transient heat radiation in earth's atmospheric environment by adapting two key parameters: the TEC cooling capacity and the thermal resistance of the heat sink cooling fan. This paper offers results of in-depth numerical parametric studies leading to an EPS design that enables robust simulations under both hot-case and cold-case operations. In addition, we present the design and evaluation of a fuzzy controller for the EPS as an attractive alternative to the traditional PID controller. The fuzzy control presented here will have other potential thermal control applications where TECs and forced cooling heat sinks are employed.

Calibration and in-orbit performance of the Argus 1000 spectrometer - the Canadian pollution monitor

Argus 1000 is a new generation miniature pollution-monitoring instrument to monitor greenhouse-gas emission from the space. Argus was launched on the CanX-2 micro-satellite April 28, 2008. Operating in the near infrared and in a nadir-viewing mode, Argus provides a capability for the monitoring of Earth-based sources and sinks of anthropogenic pollution. It has 136 near infrared channels in the spectral range of 0.9-1.7 µm with an instantaneous spatial resolution of 1.25 km. With a mass of just 228 g in flight-model configuration, the instrument is a demonstrator for a future micro-satellite network that can supply near-real time monitoring of pollution events in order to facilitate the detection of the sources causing climate change. In this Letter, we describe the instrument, the analysis concept behind Argus 1000 and its in-orbit performance. Recent spectral data taken over Ontario, Canada, are presented.

Long-Term Operation of the Energy Storage System for Lunar and Planetary Missions

The Japan Aerospace Exploration Agency (JAXA) has been developing lithium-ion secondary cells for aerospace applications. Lithium-ion secondary cells were first used for the interplanetary spacecraft, HAYABUSA. For the long-term operations on the moon and interplanetary orbit, in-orbit performance of the lithium-ion battery demonstrated by HAYABUSA has been precisely examined. Furthermore, the regenerative fuel cell system is also one of the most important candidates to the future lunar and planetary missions where the higher energy density is required.

Passive magnetic attitude stabilization of the UNISAT-4 microsatellite

UNISAT-4 is the fourth educational microsatellite, completely designed and built by students and professors of the research group GAUSS (Gruppo di Astrodinamica dell’Università degli Studi “la Sapienza”) at the Scuola di Ingegneria Aerospaziale of University of Rome “La Sapienza”. The spacecraft is stabilized using a passive magnetic attitude stabilization system, based on a permanent magnet and an energy dissipation system, which consists of magnetic hysteresis rods. The main features of passive magnetic stabilization are simplicity and reliability. However, sizing the system parameters, predicting the in-orbit performance and obtainable accuracy of passive magnetic stabilization systems is not trivial. The main problem in the system design is accurate modeling of the hysteresis rods magnetization and the evaluation of the rods magnetic parameters, such as apparent permeability, remanence and coercitive force, which are considerably affected by the rods’ manufacturing technological process. In this paper the design and ground test of the UNISAT-4 magnetic attitude stabilization system is described. A method to experimentally determine the hysteresis rod parameters is described and an accurate model of the satellite dynamics is obtained, based on the results of the measurements. One of the main design parameters is the number of hysteresis rods necessary to obtain satellite stabilization. Numerical simulations for two hysteresis rods per axis and eight hysteresis rods per axis are discussed, showing that the satellite stabilizes in about 14 days, with a residual oscillation amplitude of less than 10°, if eight rods are used.

Performance of the PAMELA Si-W imaging calorimeter in space

The Payload for Antimatter-Matter Exploration and Light Nuclei Astrophysics (PAMELA), primarily designed to directly measure antiparticles (antiprotons and positrons) in the cosmic radiation, was launched successfully on June 15th, 2006, and, since then, it is in continuous data taking. The calorimeter of the PAMELA apparatus has been designed to identify antiprotons from an electron background and positrons from a background of protons with high efficiency and rejection power. It is a sampling silicon-tungsten imaging calorimeter, which comprises 44 single-sided silicon sensor planes (380 μm thick) interleaved with 22 plates of tungsten absorber (0.74 X0 each). It is the first silicon-tungsten calorimeter to be launched in space. In this work we present the in-orbit performance of the calorimeter, including the measured identification capabilities. The calorimeter provides a proton rejection factor of ∼105 while keeping a high efficiency in selecting electrons and positrons, thus fulfilling the identification power needed to reach the primary scientific objectives of PAMELA. We show also that, after almost two years of operation in space, the calorimeter is still performing nominally.

Design and In-Orbit Performance of the Suzaku Wide-Band All-Sky Monitor

Abstract The Suzaku Wide-band All-sky Monitor (WAM) consists of thick BGO anti-coincidence shields of the Hard X-ray Detectors (HXD). It views about half of the sky and has a geometrical area of 800 cm$^2$ per sdide and an effective area of 400 cm$^2$, even at 1 MeV. Hence, the WAM can provide unique opportunities to detect high-energy emission from GRBs and solar flares in the sub-MeV to MeV range. The WAM has detected more than 400 GRBs and 100 solar flares since its launch. This paper describes the in-flight performance of the HXD/WAM during the initial two years of operations, including the in-flight energy response, spectral and timing capabilities, and in-orbit background.

AKARI—Infrared Satellite Mission—Present Status and Early Results

AKARI, formerly known as ASTRO-F, is a satellite mission dedicated to infrared astronomy for the first time in Japan. It has a 685-mm aperture telescope with two focal-plane instruments cooled by liquid helium (LHe) and mechanical coolers on board for observations in the 2–180 μm infrared spectral range. AKARI was launched on 2006 February 21 (UT) into a sun-synchronous polar orbit and started observations in May, 2006. It carried 179 liter LHe that lasted for 550 days and observations with LHe were carried out for more than 15 months. During the LHe holding period, AKARI made all-sky survey observations with six bands from 9 to 160 μm, which surpass the IRAS all-sky survey data in the sensitivity, spatial resolution, and spectral coverage. Together with the all-sky observation, AKARI also made pointing observations for about 10 min at a given position of the sky to execute deep imaging and spectroscopy from near- to far-infrared. Both focal-plane instruments work successfully on orbit and more than 90% of the sky was observed in the all-sky survey. After LHe exhaustion, near-infrared observations are planned to continue. This paper reports the in-orbit performance of AKARI and its early observational results so far obtained.

The PACS Instrument

The Photodetector Array Camera and Spectrometer on Herschel provides imaging line spectroscopy and imaging photometry in the 55–210 μm wavelength band. In photometry mode, two filled silicon bolometer arrays with 16×32 and 32×64 pixels, respectively, are used to simultaneously image two bands, 60–85 μm or 85–130 μm and 130–210 μm, over a field of view of ~1.75'×3.5', with Nyquist beam sampling in each band. In spectroscopy mode, two Ge:Ga photoconductor arrays (stressed and unstressed) with 16×25 pixels, each, are used to image a field of ~50''×50'', resolved into 5×5 pixels, with a spectral resolution of ~175 km s-1 and an instantaneous spectral coverage of ~1500 km s-1. In both modes the performance is expected to be not far from background-noise limited, with sensitivities (5σ in 1 h) of ~4 mJy or 3–20×10-18 W/m2, respectively. We summarise the design of the instrument and its subunits, describe the observing modes in combination with the telescope pointing modes, report results from instrument level performance tests of the Flight Model, and present our current prediction of the in-orbit performance of the instrument.

In-flight performances of the PAMELA satellite experiment

PAMELA is a satellite-borne experiment designed to study with great accuracy charged particles in the cosmic radiation with a particular focus on antiparticles. The experiment, housed on board the Russian Resurs-DK1 satellite, was launched on June 15, 2006 in a 350×600km orbit with an inclination of 70∘. The apparatus comprises a time-of-flight system, a silicon-microstrip magnetic spectrometer, a silicon–tungsten electromagnetic calorimeter, an anticoincidence system, a shower tail catcher scintillator and a neutron detector. The combination of these devices allows charged particle identification over a wide energy range. In this work, the detector design is reviewed and the in-orbit performances in the first months after the launch are presented.

Near-Infrared and Mid-Infrared Spectroscopy with the Infrared Camera (IRC) for AKARI

Abstract The Infrared Camera (IRC) is one of the two instruments on board the AKARI satellite, In addition to deep imaging from 1.8 to 26.5 $\mu$m for the pointed observation mode of the AKARI, it has a spectroscopic capability in its spectral range. By replacing the imaging filters by transmission-type dispersers on the filter wheels, it provides low-resolution ($\lambda$/$\delta \lambda \sim$ 20–120) spectroscopy with slits, or in a wide imaging field-of-view (approximately 10$\;\times\;$10). The IRC spectroscopic mode is unique for space infrared missions in that it has the capability to perform sensitive wide-field spectroscopic surveys in the near-and mid-infrared wavelength ranges. This paper describes the specifications of the IRC spectrograph and its in-orbit performance.

The X-Ray Observatory Suzaku

High-sensitivity wide-band X-ray spectroscopy is the key feature of the Suzaku X-ray observatory, launched on 2005 July 10. This paper summarizes the spacecraft, in-orbit performance, operations, and data processing that are related to observations. The scientific instruments, the high-throughput X-ray telescopes, X-ray CCD cameras, non-imaging hard X-ray detector are also described.

In-Orbit Performance of the Hard X-Ray Detector on Board Suzaku

Abstract The in-orbit performance and calibration of the Hard X-ray Detector (HXD) on board the X-ray astronomy satellite Suzaku are described. Its basic performances, including a wide energy bandpass of 10–600 keV, energy resolutions of $\sim 4 \,\mathrm{keV}$ (FWHM) at 40 keV and $\sim 11\%$ at 511 keV, and a high background rejection efficiency, have been confirmed by extensive in-orbit calibrations. The long-term gains of PIN-Si diodes have been stable within 1% for half a year, and those of scintillators have decreased by 5–20%. The residual non-X-ray background of the HXD is the lowest among past non-imaging hard X-ray instruments in energy ranges of 15–70 and 150–500 keV. We provide accurate calibrations of energy responses, angular responses, timing accuracy of the HXD, and relative normalizations to the X-ray CCD cameras using multiple observations of the Crab Nebula.

PAMELA – A payload for antimatter matter exploration and light-nuclei astrophysics

The PAMELA experiment is a satellite-borne apparatus designed to study charged particles in the cosmic radiation with a particular focus on antiparticles. PAMELA is mounted on the Resurs DK1 satellite that was launched from the Baikonur cosmodrome on June 15th 2006. The PAMELA apparatus comprises a time-of-flight system, a magnetic spectrometer, a silicon–tungsten electromagnetic calorimeter, an anticoincidence system, a shower tail catcher scintillator and a neutron detector. The combination of these devices allows antiparticles to be reliably identified from a large background of other charged particles. This paper reviews the design, space qualification and on-ground performance of PAMELA. The in-orbit performance will be discussed in future publications.