Depth dose distribution measurement on the Foton-M2 bio-satellite by TLD technique

In the framework of “Biology and Physics in Space” project of the European Space Agency (ESA), a returning satellite, Foton-M2, carried an open-to-space sample holder outside of the satellite body, called as BIOPAN-5, loaded with exo-biological experiments and dosemeters for RAdiation DOsimetry (RADO). One of the RADO experiments (Teflon – TLD) was dedicated to dose distribution measurements of the cosmic radiation by thermo-luminescent (TL) technique. It was found that the maximum surface absorbed dose rate, averaged over the first ∼8 mg/cm² thickness, was ∼2 Gy/d and showed a location dependence due the shading effect of the satellite construction elements. The dose rate decreased nearly by 3 orders of magnitude below 500 mg/cm².     

Hardware development and tests in the GIRL project

The German Infrared Laboratory GIRL is a liquid helium-cooled telescope with four focal plane instruments dedicated to astronomical and aeronomical observations.Hardware tests were performed with a thermal model of the cryostat and other components as active phase separator, optical switches, main mirror, baffle etc.In the test phase the thermal behavior of the system was checked out in a step by step procedure. The timeline of the individual experiments and of two representative orbits were simulated by electrical heaters. Temperatures and helium flow rates for the different operation modes were measured.An outlook shows that the project phase in 1982 is dedicated to further development and tests of hardware and complete definition and specification of all GIRL systems.     

Development overview of the revised NASA Ultra Long Duration Balloon

The desire for longer duration stratospheric flights at constant float altitudes for heavy payloads has been the focus of the development of the National Aeronautics and Space Administration’s (NASA) Ultra Long Duration Balloon (ULDB) effort. Recent efforts have focused on ground testing and analysis to understand the previously observed issue of balloon deployment. A revised approach to the pumpkin balloon design has been tested through ground testing of model balloons and through two test flights. The design approach does not require foreshortening, and will significantly reduce the balloon handling during manufacture reducing the chances of inducing damage to the envelope. Successful ground testing of model balloons lead to the fabrication and test flight of a ∼176,000 m³ (∼6.2 MCF – Million Cubic Foot) balloon. Pre-flight analytical predictions predicted that the proposed flight balloon design to be stable and should fully deploy. This paper provides an overview of this first test flight of the revised Ultra Long Duration Balloon design which was a short domestic test flight from Ft. Sumner, NM, USA. This balloon fully deployed, but developed a leak under pressurization. After an extensive investigation to the cause of the leak, a second test flight balloon was fabricated. This ∼176,000 m³ (∼6.2 MCF) balloon was flown from Kiruna, Sweden in June of 2006. Flight results for both test flights, including flight performance are presented.     

Validation of the in-flight calibration procedures for the MICROSCOPE space mission

The MICROSCOPE space mission aims to test the Equivalence Principle with an accuracy of 10^-15${10}^{-15}$. The drag-free micro-satellite will orbit around the Earth and embark a differential electrostatic accelerometer including two cylindrical test masses submitted to the same gravitational field and made of different materials. The experience consists in testing the equality of the electrostatic acceleration applied to the masses to maintain them relatively motionless. The accuracy of the measurements exploited for the test of the Equivalence Principle is limited by our a priori knowledge of several physical parameters of the instrument. These parameters are partially estimated on-ground, but with an insufficient accuracy, and an in-orbit calibration is therefore required to correct the measurements. The calibration procedures have been defined and their analytical performances have been evaluated. In addition, a simulator software including the dynamics model of the instrument, the satellite drag-free system and the perturbing environment has been developed to numerically validate the analytical results. After an overall presentation of the MICROSCOPE mission, this paper will describe the calibration procedures and focus on the simulator. Such an in-flight calibration is mandatory for similar space missions taking advantage of a drag-free system.     

Gravitational wave detection on the Moon and the moons of Mars

The Moon and the moons of Mars should be extremely quiet seismically and could therefore become sensitive gravitational wave detectors, if instrumented properly. Highly sensitive displacement sensors could be deployed on these planetary bodies to monitor the motion induced by gravitational waves. A superconducting displacement sensor with a 10-kg test mass cooled to 2 K will have an intrinsic instrument noise of 10⁻¹⁶ m Hz^−1/2. These sensors could be tuned to the lowest two quadrupole modes of the body or operated as a wideband detector below its fundamental mode. An interesting frequency range is 0.1–1 Hz, which will be missed by both the ground detectors on the Earth and LISA and would be the best window for searching for stochastic background gravitational waves. Phobos and Deimos have their lowest quadrupole modes at 0.2–0.3 Hz and could offer a sensitivity h_min ? 10⁻²² Hz^−1/2 within their resonance peaks, which is within two orders of magnitude from the goal of the Big Bang Observer (BBO). The lunar and Martian moon detectors would detect many interesting foreground sources in a new frequency window and could serve as a valuable precursor for BBO.     

First calibration measurements with the dust impact detector DIDSY-IPM

The IPM detector consists of two separate impact ionization detectors, one of them covered by a 2.5 μm thick plastic film and a piezoelectric sensor mounted to the back of the joint impact plate. First impact tests, with iron projectiles in the mass range 10^?15 to 10^?9 g and in the speed range 1 km/s to 70 km/s, were performed with the calibration (FS) and the flight (F) model of this detector. The charge yield at 69 km/s impact speed (flyby speed of GIOTTO) has been extrapolated from the data and amounts to 400 Coulombs per gram. This corresponds to a preliminary sensitivity threshold for the impact ionization detector of about 6×10^?17 g. The penetration limit introduced by the plastic film is about 10^?14 g for iron particles. Only the biggest particles used for the test produced signals at the piezoelectric sensor. If one assumes an energy dependence of the piozoelectric signal, a preliminary sensitivity threshold of about 10^?13 g at 69 km/s can be established.     

Full characterization of a compact 90Sr/90Y beta source for TID radiation testing

A new methodology for Total Ionizing Dose (TID) tests is proposed. It is based on the employment of an on-chip ⁹⁰Sr/⁹⁰Y beta source as alternative to standard methods such as ⁶⁰Co gamma rays and electrons from LINAC. The use of a compact beta source for TID tests has several advantages. In particular, the irradiation of devices with more than one radiation source results in a better representation of the complex space radiation environment composed of several types, energies and dose-rates. In addition, the use of an easy handling beta source allows the irradiation of electronic devices without any damage to other auxiliary circuit. In this work, ⁹⁰Sr/⁹⁰Y beta source dosimetry and related radiation field characteristics are discussed in depth.In order to validate the proposed source for TID tests, a rather complex device such as the “SPC56EL70L5” microcontroller from ST-Microelectronics was exposed to ⁹⁰Sr/⁹⁰Y beta rays. The results of this test were compared to that of a previous test of another sample from the same lot with a standard gamma ⁶⁰Co source. The electronic performances following the two irradiations have been found to be in excellent agreement, by demonstrating therefore the validity of the proposed beta source for TID tests.     

Simulation of ASTROD I test mass charging due to solar energetic particles and interplanetary electrons

As ASTROD I travels through space, its test mass will accrue charge due to exposure of the spacecraft to high-energy particles. This test mass charge will result in Coulomb forces between the test mass and the surrounding electrodes. In earlier work, we have used the GEANT 4 toolkit to simulate charging of the ASTROD test mass due to cosmic-ray protons of energies between 0.1 and 1000 GeV at solar maximum and at solar minimum. Here we use GEANT 4 to simulate the charging process due to solar energetic particle events and interplanetary electrons. We then estimate the test mass acceleration noise due to these fluxes. The predicted charging rates range from 2247 e⁺/s to 47,055 e⁺/s, at peak intensity, for the four largest SEP events in September and October 1989. Although the noise due to charging exceeds the ASTROD I budget for the two larger events, it can be suppressed through continuous discharging. The acceleration noise during the two small events is well below the design target. The charging rate of the ASTROD I test mass due to interplanetary electrons in this simulation is about −11% of the cosmic-ray protons at solar minimum, and over −37% at solar maximum. In addition to the Monte Carlo uncertainty, an error of ±30% in the net charging rates should be added to account for uncertainties in the spectra, physics models and geometry implementations.     

Developing strategies for automated remote plant production systems: Environmental control and monitoring of the Arthur Clarke Mars Greenhouse in the Canadian High Arctic

The Arthur Clarke Mars Greenhouse is a unique research facility dedicated to the study of greenhouse engineering and autonomous functionality under extreme operational conditions, in preparation for extraterrestrial biologically-based life support systems. The Arthur Clarke Mars Greenhouse is located at the Haughton Mars Project Research Station on Devon Island in the Canadian High Arctic. The greenhouse has been operational since 2002. Over recent years the greenhouse has served as a controlled environment facility for conducting scientific and operationally relevant plant growth investigations in an extreme environment. Since 2005 the greenhouse has seen the deployment of a refined nutrient control system, an improved imaging system capable of remote assessment of basic plant health parameters, more robust communication and power systems as well as the implementation of a distributed data acquisition system. Though several other Arctic greenhouses exist, the Arthur Clarke Mars Greenhouse is distinct in that the focus is on autonomous operation as opposed to strictly plant production. Remote control and autonomous operational experience has applications both terrestrially in production greenhouses and extraterrestrially where future long duration Moon/Mars missions will utilize biological life support systems to close the air, food and water loops. Minimizing crew time is an important goal for any space-based system. The experience gained through the remote operation of the Arthur Clarke Mars Greenhouse is providing the experience necessary to optimize future plant production systems and minimize crew time requirements. Internal greenhouse environmental data shows that the fall growth season (July–September) provides an average photosynthetic photon flux of 161.09 μmol m⁻² s⁻¹ (August) and 76.76 μmol m⁻² s⁻¹ (September) with approximately a 24 h photoperiod. The spring growth season provides an average of 327.51 μmol m⁻² s⁻¹ (May) and 339.32 μmol m⁻² s⁻¹ (June) demonstrating that even at high latitudes adequate light is available for crop growth during 4–5 months of the year. The Canadian Space Agency Development Greenhouse [now operational] serves as a test-bed for evaluating new systems prior to deployment in the Arthur Clarke Mars Greenhouse. This greenhouse is also used as a venue for public outreach relating to biological life support research and its corresponding terrestrial spin-offs.     

Impact of a novel hybrid accelerometer on satellite gravimetry performance

The state-of-the-art electrostatic accelerometers (EA) used for the retrieval of non-gravitational forces acting on a satellite constitute a core component of every dedicated gravity field mission. However, due to their difficult-to-control thermal drift in the low observation frequencies, they are also one of the most limiting factors of the achievable performance of gravity recovery. Recently, a hybrid accelerometer consisting of a regular EA and a novel cold atom interferometer (CAI) that features a time-invariant observation stability and constantly recalibrates the EA has been developed in order to remedy this major drawback. In this paper we aim to assess the value of the hybrid accelerometer for gravity field retrieval in the context of GRACE-type and Bender-type missions by means of numerical closed-loop simulations where possible noise specifications of the novel instrument are considered and different components of the Earth’s gravity field signal are added subsequently. It is shown that the quality of the gravity field solutions is mainly dependent on the CAI’s measurement accuracy. While a low CAI performance (10^?8 to 10^?9?m/s²/Hz^1/2) does not lead to any gains compared to a stand-alone EA, a sufficiently high one (10^?11?m/s²/Hz^1/2) may improve the retrieval performance by over one order of magnitude. We also show that improvements which are limited to low-frequency observations may even propagate into high spherical harmonic degrees. Further, the accelerometer performance seems to play a less prominent role if the overall observation geometry is improved as it is the case for a Bender-type mission. The impact of the accelerometer measurements diminishes further when temporal variations of the gravity field are introduced, pointing out the need for proper de-aliasing techniques. An additional study reveals that the hybrid accelerometer is – contrary to a stand-alone EA – widely unaffected by scale factor instabilities.     

Temporal and spatial variations observed in the ionospheric composition of Venus: Implications for empirical modelling

In situ measurements of the thermal ion composition of the ionosphere of Venus have been obtained for a period of two Venus years from the Bennett rf ion mass spectrometer on the Pioneer Venus Orbiter. Ion measurements within an altitude interval of 160 to 300 kilometers, corresponding to an overall latitude interval of about ?4° to 34°N, are assembled from the interval December 1978 to March 1980. This time interval corresponds to two revolutions of Venus about the Sun, designated as two “diurnal cycles”. The distributions of several ion species in this data base have been sorted to identify temporal and spatial variations, and to determine the feasibility of an analytical representation of the experimental results. The first results from the sorting of several prominent ions including O⁺, O₂⁺, and H⁺ and several minor ions including CO₂⁺, C⁺, and H₂⁺ reveal significant diurnal variations, with superimposed modulation associated with solar activity and solar wind variations. The diurnal variation consists of strong day to night contrast in the ion concentrations, with differences of one to two orders of magnitude, depending upon ion mass and altitude. The concentrations of O₂⁺, O⁺, CO₂⁺ and C⁺ peak throughout the dayside decreasing sharply at the terminators to nightside levels, lower by one to two orders of magnitude relative to the dayside. The diurnal variations of the light ions H⁺ and H₂⁺ peak during the night, exhibiting asymmetric nightside bulges favoring the pre-dawn sector, near 0400 solar hour angle. Superimposed upon the diurnal distributions are modulation signatures which correlate well with modulation in the F_10.7 index, indicating a strong influence of solar variability on the ion production and distribution. The influence of solar wind perturbations upon the ion distributions are also indicated, by a significant increase in the scatter of the observations with increasing altitude as higher altitudes, approaching 300 kilometers, are sampled. Together, these temporal and spatial variations make the task of modelling the ionosphere of Venus both very interesting and challenging.     

Design and Verification of the Feet Design used for the “Heat Flow Property Package Instrument” (HP3) on-board the Mars Mission InSight

The HP³ instrument measures the thermal flux through the Martian crust using a penetration probe. Launched on the InSight mission in 2018, HP³ was deployed for penetration activities in the beginning of 2019. During initial operation, the instrument is vulnerable to slip, due to a combination of low system mass (3.3 kg on Earth), shocks delivered by the penetration probe’s action, and the possibility of an inclined attitude on the surface. An uncontrolled position change of the instrument on the surface can reduce the scientific output and even lead to a loss of the experiment if the probe’s supporting structure moves laterally. Naturally, the design of the feet has major impact on the total amount of slippage. A new design for the feet with a high slippage resistance capability at a low level of complexity and mass was developed for this instrument’s supporting structure. The design provides sufficient slippage resistance while fulfilling the challenging set of requirements for a Mars surface mission. The design was verified by test campaigns which emulate launch environments and operational behavior on Mars. This paper gives a detailed overview of the HP³ instrument itself, the relevant requirements, the complex different test campaigns and the final flight design.     

Atomic oxygen concentrations in the lower auroral thermosphere

Atomic oxygen concentrations derived from the nightglow components of O₂(b¹Σ_g⁺ ? X³Σ_g^?) (0-0) Atmospheric Band emission profiles obtained during two rocket-borne photometer measurements of aurora are presented. The peak atomic oxygen concentrations of 2–3 × 10¹¹ cm^?3 are in better agreement with those of the MSIS-83 model than the CIRA 1972 mean reference atmosphere, although the shapes of the two derived profiles differ considerably from that of MSIS-83. The derived concentrations do not contradict the suggestion made by some investigators that the atomic oxygen concentrations in the auroral zone are depleted relative to their mid-latitude values.     

The infrared imaging channel of the IKS instrument for detection of Comet Halley nucleus

The imaging Channel of the IKS Instrument placed on board the Vega fly-by probes will perform measurements of the infrared emission of the central region of Comet Halley at distances in the 10⁴ ? 10⁵ km range. An encoding wheel analyses one spatial frequency of the infrared image during the whole fly-by. Inversion of this measurement will give low resolution brightness profiles of the nucleus and its immediate surroundings, in two wave-length bandpasses and in two directions of analysis.     

Antarctic meteor observations using the Davis MST and meteor radars

This paper presents the meteor observations obtained using two radars installed at Davis (68.6°S, 78.0°E), Antarctica. The Davis MST radar was installed primarily for observation of polar mesosphere summer echoes, with additional transmit and receive antennas installed to allow all-sky interferometric meteor radar observations. The Davis meteor radar performs dedicated all-sky interferometric meteor radar observations. The annual count rate variation for both radars peaks in mid-summer and minimizes in early Spring. The height distribution shows significant annual variation, with minimum (maximum) peak heights and maximum (minimum) height widths in early Spring (mid-summer). Although the meteor radar count rate and height distribution variations are consistent with a similar frequency meteor radar operating at Andenes (69.3°N), the peak heights show a much larger variation than at Andenes, while the count rate maximum-to-minimum ratios show a much smaller variation. Investigation of the effects of the temporal sampling parameters suggests that these differences are consistent with the different temporal sampling strategies used by the Davis and Andenes meteor radars. The new radiant mapping procedure of [Jones, J., Jones, W., Meteor radiant activity mapping using single-station radar observations, Mon. Not. R. Astron. Soc., 367(3), 1050–1056, doi: 10.1111/j.1365-2966.2006.10025.x, 2006] is investigated. The technique is used to detect the Southern delta-Aquarid meteor shower, and a previously unknown weak shower. Meteoroid speeds obtained using the Fresnel transform are presented. The diurnal, annual, and height variation of meteoroid speeds are presented, with the results found to be consistent with those obtained using specular meteor radars. Meteoroid speed estimates for echoes identified as Southern delta-Aquarid and Sextantid meteor candidates show good agreement with the theoretical pre-atmospheric speeds of these showers (41 km s⁻¹ and 32 km s⁻¹, respectively). The meteoroid speeds estimated for these showers show decreasing speed with decreasing height, consistent with the effects of meteoroid deceleration. Finally, we illustrate how the new radiant mapping and meteoroid speed techniques can be combined for unambiguous meteor shower detection, and use these techniques to detect a previously unknown weak shower.     

The VESTA project: Combined studies of Mars and small bodies of the solar system

A mission to Mars and small solar system bodies is presently studied as a possible collaboration between INTERCOSMOS, CNES, ESA and eventually other participants. The VESTA concept, based on the same strategy as the successful VEGA mission, is more ambitious, as two spacecrafts separate soon after launch: a soviet spacecraft, dedicated to the study of Mars, and a spacecraft dedicated to the study of small bodies, under the responsibility of CNES and ESA. This spacecraft would use Mars gravity assists to visit up to 4 small bodies in less than 5 years. The mission is duplicated, which means that up to 8 small bodies could be studied (e.g. 6 main belt asteroids, 1 apollo-amor asteroid and 1 short period comet). Low relative velocities (< 3.5 km/s) should allow to drop a penetrator on two large main belt asteroids, such as 4 Vesta and 1 Ceres (1994 launch).     

OPTIS – A Satellite test of Special and General Relativity

OPTIS has been proposed as a small satellite platform in a high elliptical orbit (apogee 40,000 km, perigee 10,000 km) and is designed for high precision tests of foundations of Special and General Relativity. The experimental set-up consists of two ultrastable Nd:YAG lasers, three crossed optical resonators (monolithic cavities), an ensemble of atomic clocks, an optical comb generator, laser tracking devices and a drag-free control system. OPTIS enables improved tests of (1) the isotropy and (2) constancy of the speed of light, (3) special relativistic time dilation, (4) the universality of the gravitational redshift by comparison of various clocks, can measure (5) the absolute value of the gravitational redshift, (6) the Lense–Thirring effect and (7) the perigee advance and (8) can make a test of a hypothetical Yukawa part in the gravitational potential. To avoid any influence from atmospheric drag, solar radiation, or Earth albedo, the satellite needs drag-free control to depress the residual acceleration down to 10⁻¹⁴ m/s² in the frequency range between 10⁻² and 10⁻³ Hz. Precise thermal control must be used to stabilize the cavity temperature to within one part in 10⁷ at time scales of 100 s and to one part in 10⁵ on the orbit time scale.     

Estimating canopy LAI and chlorophyll of tropical forest plantation (North India) using Sentinel-2 data

With the free and full access to images from Sentinel-2 satellite, the interest to use this data for quantitative retrieval of vegetation parameters is ever-increasing. LAI and chlorophyll are two key variables which are desired for studying productivity, nutrient and stress status of vegetation. Studies carried out on croplands using simulated Sentinel-2 MSI and parametric approach have identified vegetation indices (VIs) with high sensitivity to LAI and chlorophyll. To test how Sentinel-2 red-edge based VIs perform for retrieval of LAI and Chlorophyll of tropical mixed forest canopies, this study has been performed. The field measurements of LAI and chlorophyll content were recorded in a total of 28 ESUs (Elementary Sampling Units) in Bhakra range in the Tarai Central Forest Division, Uttarakhand (India). The in-situ measurements were statistically correlated with Sentinel-2VIs and strength of correlation was validated using Predicted Residual Error Sum of Squares (PRESS) statistic. Field LAI corrected for foliage clumpiness effect improved correlation of VIs with LAI. Among all VIs tested, Normalized Difference Index (NDI) offered highest positive correlation (R² = 0.79, p < 0.05) with LAI while Red-Edge Chlorophyll Index (RECI) (R² = 0.83, RMSE = 0.24 g/m², p < 0.05) and Simple Ratio (SR) 740/705 (R² = 0.79, RMSE = 0.27 g/m², p < 0.05) were the most closely related to chlorophyll content. VIs with red-edge and NIR combinations offered best results.     

General Relativity Accuracy Test (GReAT): New configuration for the differential accelerometer

We presents the results of an activity concerning the test of the Einstein Weak Equivalence Principle with an accuracy of about 5 × 10⁻¹⁵. The experiment will be performed in an “Einstein elevator” using a differential accelerometer with a final sensitivity of about 10⁻¹⁴ g_⊕/Hz^1/2. The differential accelerometer is spun about an horizontal axis at a frequency in the range 0.5–1 Hz in order to modulate, during the free fall, the signal from a possible violation of the Equivalence Principle. In the paper the perturbing effects with the same signature of the possible violation are analyzed and constrained. The experimental results obtained in the laboratory with a first prototype of the differential accelerometer are discussed, comparing this results with those obtained using a new prototype.     

Cosmic ray detection on the Foton-M2 satellite by a track etch detector stack

In the frame of the European Space Agency (ESA) project called “Biology and Physics in Space”, the returning satellite, Foton-M2, carried an open-to-space exposure platform outside of the satellite body, called as BIOPAN-5, loaded with exo-biological experiments and facilities for radiation dosimetry (RADO). One of the RADO experiments was dedicated to the detection of the primary galactic cosmic rays (GCR) and secondary neutrons by a track etch detector stack. The daily absorbed dose (D) and dose equivalent (H) were calculated from the experimental LET spectra (LET > 10 keV/μm). Under a shielding of ∼2.8 g/cm² the averaged H was found to be 658 ± 8 μSv/d, with a quality factor (Q) of 6.2 ± 1.2. The LET spectra showed a local peak at ∼105 keV/μm suggesting that the majority of tracks were created by trapped protons as it has been predicted by calculations. The low LET dose of the cosmic radiation was determined by 4 TLD stacks, and the total dose was found to be 795 ± 14 μSv/d.