Testing the Equivalence Principle in an Einstein Elevator: Detector Dynamics and Gravity Perturbations

We discuss specific, recent advances in the analysis of an experiment to test the Equivalence Principle (EP) in free fall. A differential accelerometer detector with two proof masses of different materials free falls inside an evacuated capsule previously released from a stratospheric balloon. The detector spins slowly about its horizontal axis during the fall. An EP violation signal (if present) will manifest itself at the rotational frequency of the detector. The detector operates in a quiet environment as it slowly moves with respect to the co-moving capsule. There are, however, gravitational and dynamical noise contributions that need to be evaluated in order to define key requirements for this experiment. Specifically, higher-order mass moments of the capsule contribute errors to the differential acceleration output with components at the spin frequency which need to be minimized. The dynamics of the free falling detector (in its present design) has been simulated in order to estimate the tolerable errors at release which, in turn, define the release mechanism requirements. Moreover, the study of the higher-order mass moments for a worst-case position of the detector package relative to the cryostat has led to the definition of requirements on the shape and size of the proof masses

OSIRIS – The scientific camera system onboard Rosetta

The Optical, Spectroscopic, and Infrared Remote Imaging System OSIRIS is the scientific camera system onboard the Rosetta spacecraft (Figure 1). The advanced high performance imaging system will be pivotal for the success of the Rosetta mission. OSIRIS will detect 67P/Churyumov-Gerasimenko from a distance of more than 106 km, characterise the comet shape and volume, its rotational state and find a suitable landing spot for Philae, the Rosetta lander. OSIRIS will observe the nucleus, its activity and surroundings down to a scale of ~2 cm px−1. The observations will begin well before the onset of cometary activity and will extend over months until the comet reaches perihelion. During the rendezvous episode of the Rosetta mission, OSIRIS will provide key information about the nature of cometary nuclei and reveal the physics of cometary activity that leads to the gas and dust coma. OSIRIS comprises a high resolution Narrow Angle Camera (NAC) unit and a Wide Angle Camera (WAC) unit accompanied by three electronics boxes. The NAC is designed to obtain high resolution images of the surface of comet 7P/Churyumov-Gerasimenko through 12 discrete filters over the wavelength range 250–1000 nm at an angular resolution of 18.6 μrad px−1. The WAC is optimised to provide images of the near-nucleus environment in 14 discrete filters at an angular resolution of 101 μrad px−1. The two units use identical shutter, filter wheel, front door, and detector systems. They are operated by a common Data Processing Unit. The OSIRIS instrument has a total mass of 35 kg and is provided by institutes from six European countrie

Apolipoprotein CIII polymorphism and triglyceride levels of a Japanese population living in Southern Brazil

Apolipoprotein CIII (apo-CIII) participates in the regulation of triglyceride-rich lipoprotein metabolism. Several polymorphic sites have been detected within and around the apo-CIII gene. Here, we examined the relationship between apo-CIII SstI polymorphism (CC, CG, GG genotypes) and plasma triglyceride (TG) levels in a group of 159 Japanese individuals living in Southern Brazil. The sample was divided into a group of Japanese descendants (N = 51) with high TG (HTG; >200 mg/dL) and a group of Japanese descendants (N = 108) with normal TG (NTG; <200 mg/dL). TG and total cholesterol levels were analyzed by an enzymatic method using the Labtest-Diagnostic kit and high- and low-density lipoproteins by a direct method using the Labtest-Diagnostic kit and DiaSys Diagnostic System International kit, respectively. A 428-bp sequence of apo-CIII gene was amplified using oligonucleotide primers 5' GGT GAC CGA TGG CTT CAG TTC CCT GA 3' and 5' CAG AAG GTG GAT AGA GCG CTG GCC T 3'. The PCR products were digested with a restriction endonuclease SstI. Rare G allele was highly prevalent in our study population (0.416) compared to Caucasians (0.00-0.11). G allele was almost two times more prevalent in the HTG group compared to the NTG group (P < 0.001). The genotype distribution was consistent with the Hardy-Weinberg equilibrium. There was a significant association between rare G allele and HTG in Japanese individuals living in Southern Brazil as indicated by one-way ANOVA, P < 0.05

An estimation method for the Shock Response Spectrum propagating into plates subjected to hypervelocity impact

The present work regards the prevision through Finite Element Analysis (FEA) codes of the Shock Response Spectrum (SRS) levels on thin plates subjected to Hypervelocity Impact (HVI). An experimental campaign has been performed to measure the accelerations caused by HVI and a method minimizing the number of simulations needed to predict the experimental curve has been sought. The method reconstructs an equivalent force impulse that is used as input for the model of the plate. The shape and amplitude are selected to numerically match the SRS curve obtained by experiments. The comparison between the experimental and the numerical SRS remains within an uncertainty band of \ub13 dB, thus sensibly smaller than the usual one for shock impacts (often \ub16 dB). Additionally, the equivalent force peak can be used as an input to evaluate acceleration in other points of the structure or to perform analyses using different models

Investigation of an anomalous failure of bearing on a fan within the columbus module of the ISS

A premature failure of an Inter module Return Fan Assembly (IRFA) within the Columbus module of the International Space Station (ISS) has been investigated to identify the root cause and the counteractions to be taken. The dismounted parts and the collected debris have been analysed using optical microscopy, Scanning Elecron Microscopy (SEM), Energy Dispersive spectroscopy (EDS) and dedicated dimensional measurements have been performed. The inspection indicated an anomalous wear of one only of the two support bearings and in particular a strong interaction between the cage and the lands of the outer ring with consequent friction and wear, while the other parts of both the bearings were in reasonable conditions. The analyses indicated a misalignment of one bearing this being the origin of the non-nominal load conditions that led to the premature wear of the bearing. The inspections conducted allowed the identification of the corrective actions to be implemented in order to minimize the likelihood of occurrence of the failure

Analisi dell\u2019accuratezza di un sistema di puntamento a 3 gdl per telecomunicazioni e sistemi di visione

Nel presente lavoro viene condotta un\u2019approfondita analisi dell\u2019incertezza di posizionamento angolare dell\u2019end-effector di un meccanismo in catena aperta, particolarmente adatto al puntamento di antenne di comunicazione per applicazioni spaziali o terrestri. Tale meccanismo presenta tre gradi di libert\ue0, ottenuti mediante tre giunti rotoidali aventi assi di rotazione inclinati. Allo scopo di evidenziare vantaggi e svantaggi, in termini di precisione di puntamento, \ue8 stata condotta un\u2019analisi dell\u2019incertezza mediante l\u2019utilizzo di tre differenti metodologie di rappresentazione e di propagazione dell\u2019incertezza stessa. In particolare, \ue8 stato seguito l\u2019approccio raccomandato nella Guide to the Expression of Uncertainty in Measurement, il metodo di simulazione di Monte Carlo, ed anche un innovativo approccio basato sulla Teoria dell\u2019Evidenza, che permette di trattare esplicitamente sia i contributi casuali sia i contributi sistematici all\u2019incertezza. L\u2019analisi condotta utilizza gli angoli di Eulero per la rappresentazione della posizione angolare dell\u2019end-effector, ed ha evidenziato che il meccanismo proposto, rispetto ad un gimbal tradizionale ad assi ortogonali, presenta un\u2019incertezza considerevolmente inferiore su due dei tre angoli di Eulero. Inoltre, il lavoro svolto ha permesso di confrontare differenti approcci di stima dell\u2019incertezza su un\u2019applicazione concreta, consentendo di evidenziare le caratteristiche peculiari del metodo molto innovativo mediante le variabili Random-Fuzzy