In vitro and in vivo evaluation of T and B lymphocyte functions in AKR mice.

To investigate whether AKR spontaneous leukaemogenesis is associated with a reduction in functional activity of T lymphocytes, the PHA response of AKR blood cells at different ages up to and including the preleukaemic period was studied. No significant differences were observed among young, adult and preleukaemic donors. In addition, the in vitro and in vivo AKR lymphocyte functions were compared with those of CBA lymphocytes by means of their response to stimulation with T and B lymphocyte selective mitogens (PHA, Con A and LSP respectively), and their response to immunization with thymus dependent (SRBC) or independent (LPS) antigens. We observed in vitro that while the B lymphocytes responded normally to mitogen, an intrinsic hyporeactivity to mitogens characterizes the T lymphocytes. Moreover, AKR mice exhibited a reduced in vivo response to both thymus dependent and independent antigens

Exomars entry and descent science

The entry, descent and landing of ExoMars offer a rare (once-per-mission) opportunity to perform in situ investigation of the martian environment over a wide altitude range. We present an initial assessment of the atmospheric science that can be performed using sensors of the Entry, Descent and Landing System (EDLS), over and above the expected engineering information. This is intended to help fulfill the concept of an Atmospheric Parameters Package (APP), as mentioned in the ExoMars draft Science Management Plan [ESA, 2005]. Mars' atmosphere is highly variable in time and space, due to phenomena including inertio-gravity waves, thermal tide effects, dust, solar wind conditions, and diurnal, seasonal and topographic effects. Atmospheric profile measurements, drawing on heritage from the Huygens Atmospheric Structure Instrument (HASI), which encountered Titan's atmosphere in 2005 [1], should allow us to address questions of the martian atmosphere's structure, dynamics and variability

Electro-thermal dynamic simulations and results of a deorbiting tethered system

Deorbiting techniques with small or better no propellant consumption are an important and critical field of space studies for the mitigation of orbital debris. Electrodynamic tethers (EDTs) are of particular interest because they make possible to deorbit space debris by exploiting the Lorentz force that is provided by the current flowing in the tether thanks to the interaction of the system with the Earth’s magnetosphere and the ionosphere. This paper focuses on the differences between two software packages built at the University of Padova (FLEX and FLEXSIM) and their results in simulating various deorbiting scenarios. Both FLEXSIM and FLEX simulate the electro-thermal behaviour and the dynamics of an EDT. However, while the first one has the simplifying assumption that the tether is always aligned with the local vertical, the second one considers also the overall system attitude with respect to the radial direction and the tether flexibility. The computational times of these S/W are very different and it is important to understand the scenarios that are more appropriate for their use. Results aim to show the impact of different solar activity (simulations are done at different epochs) and lengths of conductive and non conductive segments of tether, in the range of a few hundreds of meters, on the total re-entry time. As expected, deorbiting is faster for high solar activity and conductive tether length but the performance must be balanced against the dynamics stability. The issue of stability over the deorbiting time is evaluated numerically for specific cases by using FLEX

Deployment profile analysis for tethered deorbiting technologies

Over the past few decades, the man-made space debris has become an increasingly concerning problem for future space missions. Fortunately, some innovative "green" deorbiting technologies have been emerged. Among these strategies, electrodynamic tethers have demonstrated to be a promising option, thanks to their passive and fuel-free characteristics. By leveraging the Earth's ionosphere and the geomagnetic field, an electrodynamic tether generates a Lorentz drag force, that can significantly reduce the altitude of a satellite and ultimately cause it to re-enter the atmosphere. The goal of this research is to investigate a critical part of satellite tethered technology, namely the deployment phase. To accomplish this, we utilized a software tool developed by the University of Padova to simulate the dynamics of the deployment phase and optimize its trajectory, in order to meet the desired boundary conditions. This paper gives a description of the software and shows the results of a sensitivity analysis on the trajectory profile that examines the impact of variations in the release angle of the tether and the speed profile actuated by the motor that controls the deployment speed

ExoMars entry, descent and landing science

The entry, descent and landing of ExoMars offer a rare (once-per-mission) opportunity to perform in situ investigation of the martian environment over a wide altitude range. Entry, Descent and Landing System (EDLS) measurements can provide essential data for atmospheric scientific investigations. We intend to perform atmospheric science measurements by exploiting data from EDLS engineering sensors and exploiting their readings beyond the expected engineering information