Space Debris Mitigation in France,Germany, Italy and United Kingdom

The Space systems today provide growing benefits to enhance the quality of humankind. However, as a by-product, the orbiting objects inevitably leaves some debris which after 50 years of space activities represent a concern for all space agencies and manufacturers and operators. Since last year no international agreement was in place to mitigate the growing population of space debris objects. The successful result obtained at UN-COPUOS in 2007 and available in the OOSA web site, now gives to the public, a set of voluntary international guidelines that could, if adopted by each space fairing Country, help in maintaining the present space environment. More further steps are necessary in the future to define a legal and normative framework. The paper will present the seven established UN Space Debris guidelines as well as examples of the minimum steps to be carried out at national level to enable the UN-COPUOS to start the discussion of the legal aspect associated with the space debris issue.     

The gravitational lenses of alpha centauri a, b, c and of barnard''s star

The gravitational lenses of the three nearest stars, Alpha Centauri A, B and C (Proxima Centauri), are studied in this paper. For each star, the minimal focal distance is found, and turns out to equal 679.263, 563.485 and 112.138 AU, respectively, plus or minus the (large) uncertainties deriving from the uncertainties in the estimates of the star masses and radii. A comparison of these three minimal focal distances against the corresponding value for the Sun (550 AU, or, more correctly, 548.230 AU) is then made, but it is clearly pointed out that all these minimal focal distances are just the theoretical values given by Einstein's deflection formula for the corresponding “naked star”, i.e. the star as if it had no corona around! The study of the true focal distances that follow from taking the corona into account is much more difficult and uncertain, and has to be delayed to further research. For the naked stars, we study the deflection of radio waves for five different frequencies: the hydrogen line at 1.420 GHz, the water maser at 22 GHz, NASA's Interstellar Probe (ISP) telecommunication frequency at 32 GHz (K_a band), the Cosmic Microwave Background peak frequency at 160.378 GHz and finally the positronium frequency at 203.385 GHz. For each frequency the antenna patterns of the three naked stars gravitational lenses are given. Finally, all the above data are derived also for the fourth star in increasing distance from the Sun, Barnard's star.     

A ballistic-pendulum test stand to characterize small cold-gas thruster nozzles

This paper deals with the design, development and experimentation of a new test stand for the accurate and precise characterization of small cold-gas nozzles having thrust of the order of 0.1 N and specific impulse of the order of 10 s. As part of the presented research, a new cold-gas supersonic nozzle was designed and developed based on the quasi one-dimensional theory. The test stand is based on the ballistic-pendulum principle: in particular, it consists of a suspended gondola hosting the propulsion system and the sample nozzle. The propulsion system consists of an air tank, pressure regulator, solenoid valve, battery and digital timer to command the valve. The gondola is equipped with a fin, immersed in water, to provide torsional and lateral oscillation damping. A laser sensor measures the displacement of the gondola. The developed test stand was calibrated by using a mathematical model based on the inelastic collision theory. The obtained accuracy was of ～1%. Sample experimental results are reported regarding the comparison of the new supersonic nozzle with a commercially available subsonic nozzle. The obtained measurements of thrust, mass flow rate and specific impulse are precise to a level of ～3%. The broad goal of the presented research was to contribute to an upgraded design of a spacecraft simulator used for laboratory validation of guidance, navigation and control algorithms for autonomous docking manoeuvres.     

JIRAM, the image spectrometer in the near infrared on board the Juno mission to Jupiter

The Jovian InfraRed Auroral Mapper (JIRAM) has been accepted by NASA for inclusion in the New Frontiers mission "Juno," which will launch in August 2011. JIRAM will explore the dynamics and the chemistry of Jupiter's auroral regions by high-contrast imaging and spectroscopy. It will also analyze jovian hot spots to determine their vertical structure and infer possible mechanisms for their formation. JIRAM will sound the jovian meteorological layer to map moist convection and determine water abundance and other constituents at depths that correspond to several bars pressure. JIRAM is equipped with a single telescope that accommodates both an infrared camera and a spectrometer to facilitate a large observational flexibility in obtaining simultaneous images in the L and M bands with the spectral radiance over the central zone of the images. Moreover, JIRAM will be able to perform spectral imaging of the planet in the 2.0-5.0 microm interval of wavelengths with a spectral resolution better than 10 nm. Instrument design, modes, and observation strategy will be optimized for operations onboard a spinning satellite in polar orbit around Jupiter. The JIRAM heritage comes from Italian-made, visual-infrared imaging spectrometers dedicated to planetary exploration, such as VIMS-V on Cassini, VIRTIS on Rosetta and Venus Express, and VIR-MS on the Dawn mission.     

Going to Alpha Centauri B and setting up a Radio Bridge

How to exploit the Sun as a gravitational lens has been studied extensively during the last 20 years, especially by this author (Refs. 1, 2, 3, 4, 5, 6 and 7). In essence, a spacecraft dubbed FOCAL (an acronym for “Fast Outgoing Cyclopean Astronomical Lens”) should be launched in the direction of the sky opposite to the area of the sky we wish to see highly magnified both at radio and other frequencies. After FOCAL reached the minimal focal distance of 550 AU from the Sun, highly magnified radio images of celestial objects located on the opposite side of the Sun will automatically be produced. In this paper we apply the FOCAL mission concept to the goal of exploring the neighborhood of the Alpha Centauri B star, where the nearest exoplanet to the Solar system was recently discovered. We suggest that:     

SETI via Wormholes

The special theory of relativity rests on the assumption that in no case can the speed of light be exceeded. Rather surprisingly, however, recent advances in the general theory of relativity show that Faster-Than-Light (FTL) travel is allowed by Einstein’s gravitational theory. An explanation of this apparent contrast between special and general relativity lies in the fact that general relativity uses non-linear differential equations and non-Euclidean spacetime geometry that special relativity does not. Therefore, this larger mathematical armoury makes room for a whole new class of very subtle and unexpected relativistic phenomena to come to light. One of these is the Theory of Wormholes, more politely termed Tunnels into Space–Time. In 1988, Kip S. Thorne and Michael S. Morris published a path-breaking paper about Wormholes showing how spaceflight between two stars might be possible in a time of hours if a “tunnel” dug into space–time exists between them. However, they also showed that keeping the tunnel open for the spaceship to travel through would require a kind of matter, called “exotic” by them, that does not appear to exist in nature, because its tensional strength would have to exceed the energy density of its matter. This request is a severe constraint to the natural existence of Morris–Thorne Wormholes, or even to their artificial construction by an advanced civilization. In 1995, however, the present author sought to replace the exotic matter in a Morris–Thorne Wormhole by a very intense magnetic field. Such “Magnetic Wormholes” could indeed exist because very intense magnetic fields are already known to exist on the surface of neutron stars and pulsars. This paper discusses the consequences on SETI of the possible existence of Magnetic Wormholes. Phenomena of divergent gravitational lensing might possibly occur in the proximity of pulsars and neutron stars. These effects could help us detect signals from very far civilisations by virtue of ordinary SETI techniques already in use.     

The PRISMA payload optomechanical design, a high performance instrument for a new hyperspectral mission

PRISMA (PRecursore IperSpettrale della Missione Applicativa) hyperspectral instrument is an advanced hyperspectral sensor including a panchromatic camera at medium resolution. The instrument is the focus of the new Earth observation mission that a consortium of Italian companies has started developing under contract of Italian Space Agency. Key features of the instrument are the very high requirement for signal-to-noise and the high quality of data that have to be provided. To meet these demanding figures the optical system has been based on a high transmittance optical system, including a single mirror telescope and two prism spectrometers based on an innovative concept to minimize number of optical elements, while high performance detectors have been chosen for the photon detection. To provide the required data quality for the entire mission lifetime an accurate calibration unit (radiometric and spectral) will be included in the instrument optomechanical assembly. The thermo-mechanical design of the instrument is based on innovative concepts, considering that the use of prism spectrometers implies a tight control of temperature variations to guarantee the stability of all instrument features once in orbit. The presented paper describes the concepts and design principle of the optomechanical assembly of the instrument, at the present status of development.     

A different method to update monthly median hmF2 values

The height, h_mF2, and the electron density, N_mF2, of the F2 peak are key model parameters to characterize the actual state of the ionosphere. These parameters, or alternatively the propagation factor, M3000F2, and the critical frequency, f_oF2, of the F2 peak, which are related to h_mF2 and N_mF2, are used to anchor the electron density vertical profile computed with different models such as the International Reference Ionosphere ( Bilitza, 2002), as well as for radio propagation forecast purposes. Long time series of these parameters only exist in an inhomogeneous distribution of points over the surface of Earth, where dedicated instruments (typically ionosondes) have been working for many years. A commonly used procedure for representing median values of the aforementioned parameters all over the globe is the one recommended by the ITU-R ( ITU-R, 1997). This procedure, known as the Jones and Gallet mapping technique, was based on ionosondes measurements gathered from 1954 to 1958 by a global network of around 150 ionospheric stations (  and ). Even though several decades have passed since the development of that innovative work, only few efforts have been dedicated to establish a new mapping technique for computing h_mF2 and N_mF2 median values at global scale or to improve the old method using the increased observational database. Therefore, in this work three different procedures to describe the daily and global behavior of the height of the F2 peak are presented. All of them represent a different and simplified method to estimate h_mF2 and are based on different mathematical expressions. The advantages and disadvantages of these three techniques are analyzed, leading to the conclusion that the recommended procedure to represent h_mF2 is best characterized by a Spherical Harmonics expansion of degree and order equal to 15, since the differences between the h_mF2 values obtained with the Jones and Gallet technique and those obtained using the abovementioned procedure are of only 1%.     

JIRAM,the Jovian Infrared Auroral Mapper

JIRAM is an imager/spectrometer on board the Juno spacecraft bound for a polar orbit around Jupiter. JIRAM is composed of IR imager and spectrometer channels. Its scientific goals are to explore the Jovian aurorae and the planet’s atmospheric structure, dynamics and composition. This paper explains the characteristics and functionalities of the instrument and reports on the results of ground calibrations. It discusses the main subsystems to the extent needed to understand how the instrument is sequenced and used, the purpose of the calibrations necessary to determine instrument performance, the process for generating the commanding sequences, the main elements of the observational strategy, and the format of the scientific data that JIRAM will produce.